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@article{nokey,

title = {Cobalt-Based Catalyst Integration Into a Hierarchically Ordered Macro-Meso-microporous Carbon Cathode for High-performance Aqueous Zn-Sulfur Batteries},

author = {L Z Liu and M Z Hussain and D Lei and O Henrotte and E Cortes and A S Bandarenka and R A Fischer},

url = {\<Go to ISI\>://WOS:001554583800001},

doi = {10.1002/advs.202509945},

year  = {2025},

date = {2025-08-21},

journal = {Advanced Science},

abstract = {The pyrolytic synthesis of an ordered macro-meso-micro porous carbon cathode material (OM-PC) with integration of a Co3ZnC/Co catalyst is reported. It is derived from a Co-doped ZIF-8 framework via a templated in situ growth within the interstitial spaces of a preformed self-assembled polystyrene monolith, followed by the template removal. The hierarchical 3D architecture facilitates Zn2(+) diffusion and enhances reaction kinetics during charge-discharge processes. The integrated Co3ZnC/Co catalyst significantly improves the surface affinity of the porous carbon host for polysulfide trapping and accelerates polysulfide redox conversion, leading to enhanced sulfur utilization, mitigated shuttle effects, and longer cycling stability. The fabricated aqueous Zn-S battery with the sulfur-loaded cathode denoted as S@Co3ZnC/Co/OM-PC delivers a synergistic high discharge capacity of approximate to 1685 mA h g-1, which includes approximate to 115 mA h g-1 contributed from the I3 -/I- redox couple. The device shows low polarization and exhibits a minimal capacity decay of approximate to 0.027% per cycle over 400 cycles. It maintained a good rate performance of approximate to 1035 mA h g-1 at 3 A g-1, with long cycling stability. In-depth investigation reveals a multistep intermediate polysulfides conversion pathway in the aqueous electrolyte, which effectively avoids the sluggish solid-solid conversion.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A low-cost and high-energy aqueous potassium-ion battery},

author = {R L Streng and T Steeger and A Senyshyn and S Abel and P Schneider and C Benning and B M Naranjo and D Gryc and M Z Hussain and O Lieleg and M Elsner and A S Bandarenka and K Cicvari\'{c}},

url = {https://www.sciencedirect.com/science/article/pii/S2095495625001871},

doi = {https://doi.org/10.1016/j.jechem.2025.02.039},

issn = {2095-4956},

year  = {2025},

date = {2025-07-01},

journal = {Journal of Energy Chemistry},

volume = {106},

pages = {523-531},

abstract = {To address challenges related to the intermittency of renewable energy sources, aqueous potassium-ion batteries (AKIBs) are a promising and sustainable alternative to conventional systems for large-scale energy storage. To enable their practical application, maximizing energy density and longevity while minimizing production and material costs is a key goal. In this work, we propose an AKIB consisting only of abundant and cost-efficient materials, which delivers a high energy density of more than 70 Wh kg−1. We combine simple strategies to stabilize the Mn-rich Prussian blue analog cathode by Fe-doping, improving the crystallinity, and tuning the electrolyte composition without employing expensive water-in-salt electrolytes. Using a mixed 2.5 M Ca(NO3)2 + 1.5 M KNO3 electrolyte, we assemble a novel AKIB with a Fe-doped manganese hexacyanoferrate cathode and an organic poly(naphthalene-4-formyl-ethylenediamine) anode. Besides a high energy density, the full cell delivers a specific capacity of approximately 60 mA h g−1, a power density of 5000 W kg−1, and 80% capacity retention after 600 cycles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Role of Manganese Oxide Nanosheets in Pyrolyzed Carbonaceous Supports for Water Oxidation},

author = {A Wark and T O Schmidt and R W Haid and R M Kluge and S Suzuki and Z Siroma and E Sk\'{u}lason and A S Bandarenka and J Maruyama},

url = {\<Go to ISI\>://WOS:001516876000001},

doi = {10.1021/acs.chemmater.5c00212},

issn = {0897-4756},

year  = {2025},

date = {2025-06-23},

journal = {Chemistry of Materials},

abstract = {The oxygen-evolving complex in photosystem II, a manganese-oxide-based cluster, is nature's solution for water oxidation, while most efficient artificial catalysts consist of costly noble-metal-based oxides. However, tackling the upcoming challenges of the climate crisis requires sustainable electrocatalysts based on affordable and efficient materials. Herein, we extensively probe carbonized iron phthalocyanine without and with deposited manganese-oxide nanosheets as model electrocatalysts mimicking the biological solution. We employed electrochemical and spectroscopic techniques, noise electrochemical scanning tunneling microscopy, and density functional theory calculations to understand their water-splitting performance holistically. Both compound materials show remarkable electrocatalytic activity, outperforming previously investigated systems based on earth-abundant elements. The origin of this enhanced performance is assigned to the metal centers and the edges at the substrate-nanosheet interface, providing the design guidelines to optimize further sustainable and affordable electrocatalysts for water oxidation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Sustainable High-Performance Aqueous Batteries Enabled by Optimizing Electrolyte Composition},

author = {R L Streng and S Reiser and A Senyshyn and S Wager and J Sterzinger and P Schneider and D Gryc and M Z Hussain and A S Bandarenka},

url = {https://doi.org/10.1002/advs.202417587},

doi = {https://doi.org/10.1002/advs.202417587},

issn = {2198-3844},

year  = {2025},

date = {2025-05-05},

journal = {Advanced Science},

volume = {n/a},

number = {n/a},

pages = {2417587},

abstract = {Lithium-free aqueous batteries (LFABs) offer a sustainable alternative to lithium-ion batteries for large-scale energy storage, addressing issues like material scarcity and flammability. However, their economic viability is limited by low energy density and cycle life due to the narrow electrochemical stability window of water and active material dissolution. High-concentration water-in-salt electrolytes typically used to tackle these issues are expensive and potentially hazardous. This work presents a novel, cost-efficient electrolyte design using safe salts at lower concentrations. The influence of different cation species on the copper hexacyanoferrate cathode and polyimide anode is systematically explored, optimizing the electrolyte for improved cell voltage and cycling stability. The resulting battery, with a 1.8 mol kg?1 MgCl2 + 1.8 mol kg?1 KCl aqueous electrolyte, achieves a competitive energy density of 48 Wh kg?? and 95% efficiency. It also shows 70% capacity retention even at extremely high (dis-)charge rates of 50 C and a maximum specific power of over 10000 W kg??, indicating its strong potential for supercapacitor applications. Utilizing exclusively inexpensive and safe salts, this work significantly advances the practical application of low-cost LFABs for large-scale energy storage.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Controlling the Morphology and Electrochemical Properties of Electrodeposited Nickel Hexacyanoferrate},

author = {T Steeger and R L Streng and A Senyshyn and V Dyadkin and X Lamprecht and R List and A S Bandarenka},

url = {https://doi.org/10.1002/celc.202500073},

doi = {https://doi.org/10.1002/celc.202500073},

issn = {2196-0216},

year  = {2025},

date = {2025-04-14},

journal = {ChemElectroChem},

volume = {n/a},

number = {n/a},

pages = {2500073},

abstract = {In recent years, Prussian blue analogs (PBAs) have gained significant attention due to their broad applicability. The synthesis routines of this material class have been shown to allow for great tunability by varying the corresponding parameters. The control of crystal phase, defect, and water content, as well as electrochemical properties, have been studied extensively for the state-of-the-art coprecipitation method. In turn, electrochemical deposition, which is particularly suited for thin-film production, remains mainly underexplored. This study investigates the effects of synthesis temperature, scan rate, precursor concentration, and supporting electrolyte pH on nickel hexacyanoferrate (NiHCF) films electrodeposited onto a high surface area carbon-based substrate via cyclic voltammetry. Electrochemical analysis and morphological characterization reveal that higher deposition temperatures increase cation-specific capacity, influence NiHCF coverage, and promote larger, more crystalline structures. Scan rate, precursor concentration, and pH variations further demonstrate the correlation between deposition parameters, crystallite size, and NiHCF structure. These findings highlight the tunability of electrodeposited PBAs for tailored electrochemical performance and morphology.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Influence of the Electrolyte pH on the Double Layer Capacitance of Polycrystalline Pt and Au Electrodes in Acidic Solutions},

author = {K-T Song and P M Schneider and I Grabovac and B Garlyyev and S A Watzele and A S Bandarenka},

url = {https://doi.org/10.1002/celc.202400587},

doi = {https://doi.org/10.1002/celc.202400587},

issn = {2196-0216},

year  = {2025},

date = {2025-02-16},

journal = {ChemElectroChem},

volume = {12},

number = {4},

pages = {e202400587},

abstract = {Abstract A deeper understanding of electrified solid/liquid interfaces of polycrystalline materials is crucial for optimizing energy conversion and storage devices, such as fuel cells, electrolyzers, and supercapacitors. After more than a century of research, the double-layer capacitance (CDL) has proven to be one of the few relatively easily experimentally accessible quantitative measures for characterizing such interfaces. However, despite their great importance, systematic CDL measurements are still not frequently associated with other interfacial properties. This work investigates the effect of the electrolyte pH on the CDL for polycrystalline platinum (Pt(pc)) and gold (Au(pc)) electrodes using cyclic voltammetry and impedance spectroscopy in acidic solutions with a pH ranging from 0 to 2 without adding any supporting electrolyte. Interestingly, under these conditions, the CDL for the Pt(pc) electrode increases with increasing electrolyte pH, while the CDL for the Au(pc) electrode shows the opposite trend. The increasing trend for Pt(pc) cannot be quantitatively described by the classical Stern model due to the stronger adsorption phenomenon on Pt surfaces. Moreover, positive linear trends with pH were found for the potentials of minimum CDL values and the potentials of maximum entropy for both electrodes, which closely correlate with reaction activities. However, the transition potentials of the constant phase element exponent (an element commonly used to approximate the behavior of the double layer in experiments) are only observed for the Pt electrode due to the phase transitions within the hydrogen adsorption/desorption and double-layer regions. These findings pose an important step toward revealing the interplay between essential interfacial parameters, which is crucial for a complete understanding of the electrical double layer.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Scanning impedance microscopy under oxygen reduction reaction conditions. Proof of the concept},

author = {C Schott and L Hofbauer and E Gubanova and P Schneider and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S0013468624017699},

doi = {https://doi.org/10.1016/j.electacta.2024.145533},

issn = {0013-4686},

year  = {2025},

date = {2025-02-10},

journal = {Electrochimica Acta},

volume = {513},

pages = {145533},

abstract = {In this study, we demonstrate that localized electrochemical impedance spectroscopy (LEIS) can successfully probe the solid-liquid interface of a model gold surface in low-concentrated aqueous electrolytes. The approach utilizes scanning electrochemical microscopy (SECM) under potential control of the sample, marking a notable improvement over previous SECM-based LEIS studies, which were conducted under open circuit potential conditions. The accuracy of the results was validated by comparing the interfacial parameters, such as the double-layer capacitance minimum and the potential of zero charge, with the results obtained from conventional global measurements. Additionally, local kinetic parameters for the oxygen reduction reaction (ORR) were examined via LEIS by fitting the acquired impedance spectra to a simplified, physical equivalent circuit model. Gold was chosen as a model surface for the ORR with its well-defined ORR potential region due to the absence of hydrogen adsorption and overlapping OH⁻ adsorption. The local kinetic parameter determined from the LEIS experiments corresponds to the apparent rate coefficient (kapp) of the ORR, reflecting the average kapp of individual active sites within the probed area. The dependence of kapp on the ORR overpotential aligns well with the kinetics of the 2-electron reduction of O2 taking place at the gold sample. This proof-of-concept study demonstrates that SECM-based LEIS serves as a powerful tool for the advanced characterization of complex electrochemical interfaces for future experiments, especially those with heterogeneities or different structures/materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {All-solid-state Li-ion batteries with commercially available electrolytes: A feasibility review},

author = {R G\"{o}tz and R Streng and J Sterzinger and T Steeger and M M Kaye and M Vitort and A S Bandarenka},

url = {https://doi.org/10.1002/inf2.12627},

doi = {https://doi.org/10.1002/inf2.12627},

year  = {2024},

date = {2024-12-01},

journal = {InfoMat},

volume = {6},

number = {12},

pages = {e12627},

abstract = {Abstract The all-solid-state battery (ASSB) concept promises increases in energy density and safety; consequently recent research has focused on optimizing each component of an ideal fully solid battery. However, by doing so, one can also lose oversight of how significantly the individual components impact key parameters. Although this review presents a variety of materials, the included studies limit electrolyte-separator choices to those that are either fully commercial or whose ingredients are readily available; their thicknesses are predefined by the manufacturer or the studies in which they are included. However, we nevertheless discuss both electrode materials. Apart from typical materials, the list of anode materials includes energy-dense candidates, such as lithium metal, or anode-free approaches that are already used in Li-ion batteries. The cathode composition of an ASSB contains a fraction of the solid electrolyte, in addition to the active material and binders/plasticizers, to improve ionic conductivity. Apart from the general screening of reported composites, promising composite cathodes together with constant-thickness separators and metallic lithium anodes are the basis for studying theoretically achievable gravimetric energy densities. The results suggest that procurable oxide electrolytes in the forms of thick pellets (\>300??m) are unable to surpass the performance of already commercially available Li-ion batteries. All-solid-state cells are already capable of exceeding the performance of current batteries with energy densities of 250?Wh?kg?1 by pairing composite cathodes with high mass loadings and using separators that are less than 150??m thick, with even thinner electrolytes (20??m) delivering more than 350?Wh?kg?1.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ion-Transport Kinetics and Interface Stability Augmentation of Zinc Anodes Based on Fluorinated Covalent Organic Framework Thin Films},

author = {D Lei and W Shang and L Cheng and Poonam and W Kaiser and P Banerjee and S Tu and O Henrotte and J Zhang and A Gagliardi and J Jinschek and E Cort\'{e}s and P M\"{u}ller-Buschbaum and A S Bandarenka and M Z Hussain and R A Fischer},

url = {https://doi.org/10.1002/aenm.202403030},

doi = {https://doi.org/10.1002/aenm.202403030},

issn = {1614-6832},

year  = {2024},

date = {2024-12-01},

journal = {Advanced Energy Materials},

volume = {14},

number = {46},

pages = {2403030},

abstract = {Abstract Zinc (Zn) emerges as an ideal anode for aqueous-based energy storage devices because of its safety, non-toxicity, and cost-effectiveness. However, the reversibility of zinc anodes is constrained by unchecked dendrite proliferation and parasitic side reactions. To minimize these adverse effects, a highly oriented, crystalline 2D porous fluorinated covalent organic framework (denoted as TpBD-2F) thin film is in situ synthesized on the Zn anode as a protective layer. The zincophilic and hydrophobic TpBD-2F provides numerous 1D fluorinated nanochannels, which facilitate the hopping/transfer of Zn2+ and repel H2O infiltration, thus regulating Zn2+ flux and inhibiting interfacial corrosion. The resulting TpBD-2F protective film enabled stable plating/stripping in symmetric cells for over 1200 h at 2 mA cm?2. Furthermore, assembled full cells (Zn-ion capacitors) deliver an ultra-long cycling life of over 100 000 cycles at a current density of 5 A g?1, outperforming nearly all reported porous crystalline materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {How to Assess and Predict Electrical Double Layer Properties. Implications for Electrocatalysis},

author = {C M Schott and P M Schneider and K-T Song and H Yu and R G\"{o}tz and F Haimerl and E Gubanova and J Zhou and T O Schmidt and Q Zhang and V Alexandrov and A S Bandarenka},

url = {https://doi.org/10.1021/acs.chemrev.3c00806},

doi = {10.1021/acs.chemrev.3c00806},

issn = {0009-2665},

year  = {2024},

date = {2024-11-27},

journal = {Chemical Reviews},

volume = {124},

number = {22},

pages = {12391-12462},

abstract = {The electrical double layer (EDL) plays a central role in electrochemical energy systems, impacting charge transfer mechanisms and reaction rates. The fundamental importance of the EDL in interfacial electrochemistry has motivated researchers to develop theoretical and experimental approaches to assess EDL properties. In this contribution, we review recent progress in evaluating EDL characteristics such as the double-layer capacitance, highlighting some discrepancies between theory and experiment and discussing strategies for their reconciliation. We further discuss the merits and challenges of various experimental techniques and theoretical approaches having important implications for aqueous electrocatalysis. A strong emphasis is placed on the substantial impact of the electrode composition and structure and the electrolyte chemistry on the double-layer properties. In addition, we review the effects of temperature and pressure and compare solid\textendashliquid interfaces to solid\textendashsolid interfaces.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Characterization of the Lithium/Solid Electrolyte Interface in the Presence of Nanometer-thin TiOx Layers for All-Solid-State Batteries},

author = {R G\"{o}tz and E Pugacheva and Z Ahaliabadeh and P S Llanos and T Kallio and A S Bandarenka},

url = {https://doi.org/10.1002/cssc.202401026},

doi = {https://doi.org/10.1002/cssc.202401026},

issn = {1864-5631},

year  = {2024},

date = {2024-11-25},

journal = {ChemSusChem},

volume = {17},

number = {22},

pages = {e202401026},

abstract = {Abstract It is still unclear which role space charge layers (SCLs) play within an all-solid-state battery during operation with high current densities, as well as to which extent they form. Herein, we use a solid electrolyte with a known SCL formation and investigate it in a symmetric cell under non-blocking conditions with Li metal electrodes. Since the used LICGC? electrolyte is known for its instability against lithium, it is protected from rapid degradation by nanometer-thin layers of TiOx deployed by atomic layer deposition. Close attention is given to the interfacial properties, as now additional Li+ can traverse through the interface depending on the applied bias potential. The interlayer?s impedance response shows efficient lithium-ion conduction for low bias potentials and a diffusion-limiting effect towards high positive and negative potentials. SCLs grow up to a thickness of 5.1??m. Additionally, estimating the apparent rate constant of the charge transfer across the interface indicates that the potentials where kinetics are hindered coincide with the widest SCLs. In conclusion, the investigation under higher steady-state currents was only possible because of the improved stability due to the interlayer. No chemo-physical failure could be observed after 800+ hours of cycling. However, an ex-situ SEM study shows a new phase at the interface, which grows into the electrolyte.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Tuning the Reconstruction of Metal\textendashOrganic Frameworks during the Oxygen Evolution Reaction},

author = {X Ma and L Schr\"{o}ck and G Gao and Q Ai and M Zarrabeitia and C Liang and M Z Hussain and R Khare and K-T Song and D J Zheng and M Koch and I E L Stephens and S Hou and Y Shao-Horn and J Warnan and A S Bandarenka and R A Fischer},

url = {https://doi.org/10.1021/acscatal.4c03618},

doi = {10.1021/acscatal.4c03618},

year  = {2024},

date = {2024-11-01},

journal = {ACS Catalysis},

volume = {14},

number = {21},

pages = {15916-15926},

abstract = {Recently, there has been growing interest in the conversion of metal\textendashorganic frameworks (MOFs) into metal-hydroxide catalysts for alkaline oxygen evolution reactions (OERs). While studies have shown that the initial OER performance of MOF-derived intermediates surpasses that of traditional metal-hydroxide catalysts, ongoing debates persist regarding these catalysts' durability and electrochemical stability. Moreover, the inevitable reorganization (aging) of MOF-derived catalysts from disordered to ordered phases, particularly those primarily composed of nickel oxyhydroxides, remains a topic of discussion. To address these issues, we propose a straightforward approach to mitigating MOF reconstruction and modulating aging in harsh alkaline environments by introducing additional organic carboxylate linkers into electrolytes. Specifically, we focus on two examples: Ni-BPDC-MOFs and NiFe-BPDC-MOFs, of formula [M2(OH)2BPDC] (M: Ni and Fe; BPDC = 4,4′-biphenyldicarboxylate). Experimental results indicate that alkaline electrolytes containing additional BPDC linkers exhibit enhanced OER activity and a prolonged electrochemical lifespan. Complemented by in situ Raman spectroscopy, our findings suggest that manipulating the coordination equilibrium of the organic linker involved in Ni-MOF formation (linker assembly) and reconstruction (linker leaching) leads to the formation of more disordered nickel oxyhydroxide phases as the active catalyst material, which shows enhanced OER performance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Combined Impedance and Electron Paramagnetic Resonance Spectroscopy for Investigating the Dynamics of Li/Solid Li-ion Conductor Interfaces},

author = {R G\"{o}tz and M Wagner and K-T Song and L Katzenmeier and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/batt.202400570},

doi = {https://doi.org/10.1002/batt.202400570},

year  = {2024},

date = {2024-10-29},

journal = {Batteries \& Supercaps},

volume = {n/a},

number = {n/a},

pages = {e202400570},

abstract = {Abstract Electrochemical impedance spectroscopy (EIS) is a widely used tool for the electrochemical characterization of all-solid-state batteries (ASSBs) with Li-metal anodes. However, an unambiguous interpretation of the observed impedance response often requires additional independent information on the actual interfacial phenomena obtained. The measurement methodology presented in this study allows to conduct electron paramagnetic resonance (EPR) spectroscopy and EIS concurrently. Therefore, the informative power of EIS experiments can be significantly improved via monitoring of structural changes of paramagnetic lithium at the electrochemical interface. As the solid-electrolyte-lithium interface is a critical part of all-solid-state batteries, this study employs a model oxide solid electrolyte in contact with lithium metal. During the polarization of the cell with thin evaporated lithium electrodes, the ratio between positive and negative peaks (a/b) of the EPR signal momentarily rises, which indicates an accumulation of lithium on one side of the electrolyte. The peak ratio a/b then drops abruptly, accompanied by current irregularities. Both are indicative of a diminishing contact area, and as a result, finer lithium morphologies form. Shortly after that, a contact loss is observed. The change of the EPR signal shape before cell breakdown can hence be associated with the worsening Li-electrolyte contact, providing a tool for physical in-situ cell diagnostics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Fast and Highly Stable Aqueous Calcium-Ion Battery for Sustainable Energy Storage},

author = {R L Streng and S Reiser and S Wager and N Pommer and A S Bandarenka},

url = {https://doi.org/10.1002/cssc.202401469},

doi = {https://doi.org/10.1002/cssc.202401469},

issn = {1864-5631},

year  = {2024},

date = {2024-10-23},

journal = {ChemSusChem},

volume = {n/a},

number = {n/a},

pages = {e202401469},

abstract = {Abstract Aqueous alkali-ion batteries are gaining traction as a low-cost, sustainable alternative to conventional organic lithium-ion batteries. However, the rapid degradation of commonly used electrode materials, such as Prussian Blue Analogs and carbonyl-based organic compounds, continues to challenge the economic viability of these devices. While stability issues can be addressed by employing highly concentrated water-in-salt electrolytes, this approach often requires expensive and, in many cases, fluorinated salts. Here, we show that replacing monovalent K+ ions with divalent Ca2+ ions in the electrolyte significantly enhances the stability of both a copper hexacyanoferrate cathode and a polyimide anode. These findings have direct implications for developing an optimized aqueous Ca-ion battery that demonstrates exceptional fast-charging capabilities and ultra-long cycle life and points toward applying Ca-based batteries for large-scale energy storage.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Impedance Spectroscopy of Lithium Intercalation into Cathode Materials in Coin Cells},

author = {G Yesilbas and D Grieve and D Rettmann and K G\"{u}lderen and A S Bandarenka and J Yun},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202400390},

doi = {https://doi.org/10.1002/celc.202400390},

issn = {2196-0216},

year  = {2024},

date = {2024-09-06},

journal = {ChemElectroChem},

volume = {11},

number = {19},

pages = {e202400390},

abstract = {Abstract Understanding the internal reactions in Li-ion batteries is crucial to analyze them more accurately and improve their efficiency since they are involved in almost every aspect of everyday life. Electrochemical impedance spectroscopy is a valuable research technique to investigate such batteries, as it reveals sensitive properties and essential information about cell reaction mechanisms and kinetics. Physical understanding of the electrochemical process and system of a battery can be analyzed using equivalent electric circuits (EECs) with rational selection of electric circuit elements and their combination. However, impedance analysis of a battery is often conducted using oversimplified EEC models in practice due to the complexity and difficulty of the physics and mathematics of the modeling. This study proposes and verifies an EEC model that represents a three-stage mechanism for intercalation-type materials. For the systematic model study and verifications, we investigated cathode half cells using four different layered structured cathode materials, namely, LiCoO2, LiNi1/3Mn1/3Co1/3O2, LiNi0.9Mn0.05Co0.05O2, and Ni0.815Co0.15Al0.035O2. Parametric analysis of the impedance fittings for the four different cathode materials showed similar behavior depending on the states of charge. We also provided the complete set of parameters of the four systems: charge transfer resistance, double-layer capacitance, and solid-electrolyte interphase (SEI) resistance and capacitance. Lastly, we explain how different electrochemical processes, such as intercalation and alloying, can be analyzed and modeled in EEC models.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Factors Shaping the Morphology in Sol-Gel Derived Mesoporous Zinc Titanate Films: Unveiling the Role of Precursor Competition and Concentration},

author = {Y Li and N Li and C Harder and S Yin and Y Bulut and A Vagias and P M Schneider and W Chen and S V Roth and A S Bandarenka and P M\"{u}ller-Buschbaum},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/admi.202400215},

doi = {https://doi.org/10.1002/admi.202400215},

issn = {2196-7350},

year  = {2024},

date = {2024-09-04},

journal = {Advanced Materials Interfaces},

volume = {11},

number = {34},

pages = {2400215},

abstract = {Abstract Zinc titanate films with mesoporous structures have widespread applications ranging from sensors to supercapacitors and bio-devices owing to their photoelectric properties and specific surface area. The present work investigates the morphology of mesoporous zinc titanate films obtained by calcination of hybrid thin films containing polymer templates and precursor mixtures of zinc acetate dihydrate (ZAD) and titanium isopropoxide (TTIP). ZnO and TiO2 films are fabricated for reference. The influences of hydrochloric acid contents (HCl), the ratios of ZAD and TTIP, and the solution concentrations on the film morphologies are studied. The amphiphilic diblock copolymer, polystyrene-block-polyethylene oxide (PS-b-PEO), plays the role of a structure directing template, as it self-assembles into micelles in a solvent-acid mixture of N, N-dimethylformamide (DMF) and HCl. Thin films are prepared with spin-coating and subsequent calcination. Adjusting the ratio of TTIP and ZAD leads to the structure evolution from order to disorder in a film. It depends on the hydrolysis and condensation processes of the precursors, providing different time-to-growth processes to control the film morphologies. An increase in solution concentration enhances the surface coverage. As probed with grazing-incidence small-angle X-ray scattering, the inner structures are larger than the surface structures seen in scanning electron microscopy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Impact of Organic Anions on Metal Hydroxide Oxygen Evolution Catalysts},

author = {S Hou and L Xu and S Mukherjee and J Zhou and K-T Song and Z Zhou and S Zhang and X Ma and J Warnan and A S Bandarenka and R A Fischer},

url = {https://doi.org/10.1021/acscatal.4c01907},

doi = {10.1021/acscatal.4c01907},

year  = {2024},

date = {2024-08-16},

journal = {ACS Catalysis},

volume = {14},

number = {16},

pages = {12074-12081},

abstract = {Structural metamorphosis of metal\textendashorganic frameworks (MOFs) eliciting highly active metal-hydroxide catalysts has come to the fore lately, with much promise. However, the role of organic ligands leaching into electrolytes during alkaline hydrolysis remains unclear. Here, we elucidate the influence of organic carboxylate anions on a family of Ni or NiFe-based hydroxide type catalysts during the oxygen evolution reaction. After excluding interfering variables, i.e., electrolyte purity, Ohmic loss, and electrolyte pH, the experimental results indicate that adding organic anions to the electrolyte profoundly impacts the redox potential of the Ni species versus with only a negligible effect on the oxygen evolution activities. In-depth studies demonstrate plausible reasons behind those observations and allude to far-reaching implications in controlling electrocatalysis in MOFs, mainly where compositional modularity entails fine-tuning organic anions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {The Electrocatalytic Activity of Au Electrodes Changes Significantly in Various Na+/K+ Supporting Electrolyte Mixtures},

author = {T K Sarpey and A V Himmelreich and K-T Song and E L Gubanova and A S Bandarenka},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smsc.202400042},

doi = {https://doi.org/10.1002/smsc.202400042},

year  = {2024},

date = {2024-04-13},

journal = {Small Science},

volume = {4},

number = {7},

pages = {2400042},

abstract = {The potential of maximum entropy (PME) is an indicator of extreme disorder at the electrode/electrolyte interface and can predict changes in catalytic activity within electrolytes of varying compositions. The laser-induced current transient technique is employed to evaluate the PME for Au polycrystalline (Aupc) electrodes immersed in Ar-saturated cation electrolyte mixtures containing potassium and sodium ions at pH = 8. Five cation ratios (0.5 M K2SO4:0.5 M Na2SO4 = 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0) are explored, considering earlier studies that unveil cation-dependent shifts at near-neutral pH. Moreover, for all electrolyte compositions, electrochemical impedance spectroscopy is utilized to determine the double-layer capacitance (CDL), the minimum of which should be close to the potential of zero charge (PZC). By correlating cation molar ratios with the PMEs and PZCs, the impact on the model oxygen reduction reaction (ORR) activity, assessed via the rotating disk electrode method, is analyzed. The results demonstrate a linear relationship between electrolyte cation mixtures and PME, while ORR activity exhibits an exponential trend. This observation validates the PME\textendashactivity link hypothesis, underscoring electrolyte components’ pivotal role in tailoring interfacial properties for electrocatalytic systems. These findings introduce a new degree of freedom for designing optimal electrocatalytic systems by adjusting various electrolyte components.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Influence of Alkali Metal Cations on the Oxygen Reduction Activity of Pt5Y and Pt5Gd Alloys},

author = {K-T Song and A Zagalskaya and C M Schott and P M Schneider and B Garlyyev and V Alexandrov and A S Bandarenka},

url = {https://doi.org/10.1021/acs.jpcc.4c00531},

doi = {10.1021/acs.jpcc.4c00531},

issn = {1932-7447},

year  = {2024},

date = {2024-03-18},

urldate = {2024-03-18},

journal = {The Journal of Physical Chemistry C},

volume = {128},

number = {12},

pages = {4969-4977},

abstract = {Electrolyte species can significantly influence the electrocatalytic performance. In this work, we investigate the impact of alkali metal cations on the oxygen reduction reaction (ORR) on active Pt5Gd and Pt5Y polycrystalline electrodes. Due to the strain effects, Pt alloys exhibit a higher kinetic current density of ORR than pure Pt electrodes in acidic media. In alkaline solutions, the kinetic current density of ORR for Pt alloys decreases linearly with the decreasing hydration energy in the order of Li+ \> Na+ \> K+ \> Rb+ \> Cs+, whereas Pt shows the opposite trend. To gain further insights into these experimental results, we conduct complementary density functional theory calculations considering the effects of both electrode surface strain and electrolyte chemistry. The computational results reveal that the different trends in the ORR activity in alkaline media can be explained by the change in the adsorption energy of reaction intermediates with applied surface strain in the presence of alkali metal cations. Our findings provide important insights into the effects of the electrolyte and the strain conditions on the electrocatalytic performance and thus offer valuable guidelines for optimizing Pt-based electrocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Engineering ORR Electrocatalysts from Co8Pt4 Carbonyl Clusters via ZIF-8 Templating},

author = {P M Schneider and K L Kollmannsberger and C Cesari and R Khare and M Boniface and B Rold\'{a}n Cuenya and T Lunkenbein and M Elsner and S Zacchini and A S Bandarenka and J Warnan and R A Fischer},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202300476},

doi = {https://doi.org/10.1002/celc.202300476},

issn = {2196-0216},

year  = {2024},

date = {2024-02-07},

journal = {ChemElectroChem},

volume = {11},

number = {5},

pages = {e202300476},

abstract = {Abstract To reduce the costs of proton exchange membrane fuel cells, the amount of Pt necessary to drive efficient oxygen reduction reaction (ORR) should be minimized. Particle nanostructuring, (nano-)alloying, and metal-doping can yield higher activities per Pt mass through tailoring catalysts owning a high number of active sites and precise electronic properties. In this work, the atom-precise [NBnMe3]2[Co8Pt4C2(CO)24] (Co8Pt4) cluster is encapsulated and activated in a zeolitic imidazolate framework (ZIF)-8, which unlocks the access to defined, bare Pt−Co nanoclusters, Co8±xPt4±yNC@ZIF-8, for the fabrication of highly active ORR catalysts. Upon controlled C-interfacing and ZIF-8-digestion, Co-doped Pt NPs (Pt27Co1) with a homogenous and narrow size distribution of (1.1±0.4) nm are produced on Vulcan® carbon. Restructuring of the Pt27Co1/C catalyst throughout the ORR measurement was monitored via high-angle annular dark field-scanning transmission electron microscopy and X-ray photoelectron spectroscopy. The measured ORR mass activity of (0.42±0.07) A mgPt−1 and the specific activity of (0.67±0.06) mA cmECSA−2 compare favourably with the catalyst obtained by direct C-interfacing the pristine Co8Pt4 cluster and with state-of-the-art Pt/C reference catalysts. Our results demonstrate the potential of ZIF-8-mediated Pt−Co NP synthesis toward devising ORR catalysts with high Pt-mass activity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Impact of Pt(hkl) Electrode Surface Structure on the Electrical Double Layer Capacitance},

author = {S Xue and P Chaudhary and M R Nouri and E Gubanova and B Garlyyev and V Alexandrov and A S Bandarenka},

url = {https://doi.org/10.1021/jacs.3c11403},

doi = {10.1021/jacs.3c11403},

issn = {0002-7863},

year  = {2024},

date = {2024-02-05},

urldate = {2024-02-05},

journal = {Journal of the American Chemical Society},

volume = {146},

number = {6},

pages = {3883-3889},

abstract = {The classical theory of the electrical double layer (EDL) does not consider the effects of the electrode surface structure on the EDL properties. Moreover, the best agreement between the traditional EDL theory and experiments has been achieved so far only for a very limited number of ideal systems, such as liquid metal mercury electrodes, for which it is challenging to operate with specific surface structures. In the case of solid electrodes, the predictive power of classical theory is often not acceptable for electrochemical energy applications, e.g., in supercapacitors, due to the effects of surface structure, electrode composition, and complex electrolyte contributions. In this work, we combine ab initio molecular dynamics (AIMD) simulations and electrochemical experiments to elucidate the relationship between the structure of Pt(hkl) surfaces and the double-layer capacitance as a key property of the EDL. Flat, stepped, and kinked Pt single crystal facets in contact with acidic HClO4 media are selected as our model systems. We demonstrate that introducing specific defects, such as steps, can substantially reduce the EDL capacitances close to the potential of zero charge (PZC). Our AIMD simulations reveal that different Pt facets are characterized by different net orientations of the water dipole moment at the interface. That allows us to rationalize the experimentally measured (inverse) volcano-shaped capacitance as a function of the surface step density.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Impedance Response Analysis of Anion Exchange Membrane Electrolyzers for Determination of the Electrochemically Active Catalyst Surface Area},

author = {S A Watzele and R M Kluge and A Maljusch and P Borowski and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/cmtd.202300035},

doi = {https://doi.org/10.1002/cmtd.202300035},

issn = {2628-9725},

year  = {2024},

date = {2024-01-12},

journal = {Chemistry\textendashMethods},

volume = {4},

number = {3},

pages = {e202300035},

abstract = {Abstract Polymer membrane electrolyzers benefit from high-pressure operation conditions and low gas cross-over and can either conduct protons (H+) or hydroxide ions (OH−). Both types of electrolyzers have a similar design, but differ in power density and the choice of catalysts. Despite the significant endeavor of their optimization, to date, there is no well-established impedance model for detailed analysis for either type of these devices. This complicates the in-situ characterization of electrolyzers, hindering the investigation of degradation mechanisms and electrocatalytic processes as a function of applied current density or time. Nevertheless, a detailed understanding of such individual processes and distinguishing the performance-limiting factors are the keystones for sophisticated device optimization. In this work, an impedance model based on electrode processes has been developed for an anion exchange membrane electrolyzer utilizing iridium oxide anode and platinum cathode electrocatalysts. This model allows to deconvolute the measured impedances into constituents related to the individual electrode processes and to estimate actual physico-chemical quantities such as the reaction kinetic parameters and double-layer capacitances. We discuss the meaning of the fitting parameters and show that this model enables, for the first time, the estimation of the electrochemically active surface area of the anode electrocatalysts under reaction conditions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Top-down Surfactant-Free Synthesis of Supported Palladium-Nanostructured Catalysts},

author = {C M Schott and P M Schneider and K Sadraoui and K-T Song and B Garlyyev and S A Watzele and J Michali\v{c}ka and J M Macak and A Viola and F Maillard and A Senyshyn and J A Fischer and A S Bandarenka and E L Gubanova},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smsc.202300241},

doi = {https://doi.org/10.1002/smsc.202300241},

issn = {2688-4046},

year  = {2024},

date = {2024-01-11},

journal = {Small Science},

volume = {4},

number = {3},

pages = {2300241},

abstract = {Nanostructured palladium (Pd) is a universal catalyst that is widely used in applications ranging from catalytic converters of combustion engine cars to hydrogenation catalysts in industrial processes. Standard protocols for synthesizing such nanoparticles (NPs) typically use bottom-up approaches. They utilize special and often expensive physical techniques or wet-chemical methods requiring organic surfactants. These surfactants should often be removed before catalytic applications. In this article, the synthesis of Pd NPs immobilized on carbon support by electrochemical erosion without using any surfactants or toxic materials is reported. The Pd NPs synthesis essentially relies on a Pd bulk pretreatment, which causes material embrittlement and allows the erosion process to evolve more efficiently, producing homogeneously distributed NPs on the support. Moreover, the synthesized catalyst is tested for hydrogen evolution reaction. The activity evaluations identify optimal synthesis parameters related to the erosion procedure. The electrocatalytic properties of the Pd NPs produced with sizes down to 6.4 ± 2.9 nm are compared with a commercially available Pd/C catalyst. The synthesized catalyst outperforms the commercial catalyst within all properties, like specific surface area, geometric activity, mass activity, specific activity, and durability.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Investigation of active electrocatalytic centers under reaction conditions using operando microscopies},

author = {H Yu and C Schott and T Schmidt and P M Schneider and K-T Song and Q Zhang and A Capogrosso and L Deville and E Gubanova and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S2451910323001795},

doi = {https://doi.org/10.1016/j.coelec.2023.101386},

issn = {2451-9103},

year  = {2023},

date = {2023-12-01},

journal = {Current Opinion in Electrochemistry},

volume = {42},

pages = {101386},

abstract = {Electrocatalysis is crucial for transitioning from a fossil fuel-based to a renewable energy society. In situ identification of electrocatalytic active centers is required to realize this vision, enabling observing the catalytic behavior comprehensively and continuously in real-time under relevant reaction conditions and providing insight into reaction steps. Operando methodology incorporates in situ analysis and simultaneous measurements of catalytic performance. In this manuscript, we analyze the recent progress in the observation of active sites in a wide range of electrocatalysts and various electrocatalytic reactions by employing operando microscopies, including liquid cell transmission electron microscopy (LCTEM), electrochemical scanning tunneling microscopy (EC-STM), scanning electrochemical microscopy (SECM) and scanning electrochemical cell microscopy (SECCM). We showcase their capability to correlate the electrocatalytic activity with catalyst topological and structural properties.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Electrochemical impedance spectroscopy of PEM fuel cells at low hydrogen partial pressures: efficient cell tests for mass production},

author = {F Haimerl and S Kumar and M Heere and A S Bandarenka},

url = {http://dx.doi.org/10.1039/D3IM00075C},

doi = {10.1039/D3IM00075C},

issn = {2755-2608},

year  = {2023},

date = {2023-10-24},

journal = {Industrial Chemistry \& Materials},

abstract = {Quality testing costs hinder the large-scale production of PEM fuel cell systems due to long testing times and high safety measures for hydrogen. While eliminating both issues, electrochemical impedance spectroscopy at low hydrogen concentrations can provide valuable insights into fuel cell processes. However, the influence of high anode stream dilutions on PEM fuel cell performance is not yet completely understood. This study presents a new equivalent circuit model to analyze impedance spectra at low hydrogen partial pressures. The proposed model accurately describes the impedance response and explains the performance decrease at low hydrogen concentrations. First, the reduced availability of hydrogen at the anode leads to rising reaction losses from the hydrogen side. Further, the resulting losses lead to potential changes also influencing the cathode processes. The findings indicate that impedance spectroscopy at low hydrogen partial pressure might provide a reliable fuel cell quality control tool, simplifying production processes, reducing costs, and mitigating risks in fuel cell production. Keywords: PEM fuel cells; Electrochemical impedance spectroscopy; EIS; Large scale PEMFC production; Anodes; Cathodes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Physical Impedance Model of Lithium Intercalation into Graphite Electrodes for a Coin-Cell Assembly},

author = {G Yesilbas and C-Y Chou and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202300270},

doi = {https://doi.org/10.1002/celc.202300270},

issn = {2196-0216},

year  = {2023},

date = {2023-10-04},

journal = {ChemElectroChem},

volume = {10},

number = {21},

pages = {e202300270},

abstract = {Abstract Graphite electrodes are widely used in commercial metal-ion batteries as anodes. Electrochemical impedance spectroscopy serves as one of the primary non-destructive techniques to obtain key information about various batteries during their operation. However, interpretation of the impedance response of graphite electrodes in contact with common organic electrolytes can be complicated. It is especially challenging, particularly when utilizing the 2-electrode configuration that is common in battery research. In this work, we elaborate on a physical impedance model capable of accurately describing the impedance spectra of a graphite|electrolyte|metallic Li system in a coin-cell assembly during two initial charge/discharge cycles. We analyze the dependencies of the model parameters for graphite and metallic lithium as a function of the state of charge to verify the model. Additionally, we suggest that the double layer capacitance values obtained during specific intercalation stages could help to determine if the area-normalized values align with the expected range. The data and the procedure necessary for calibration are provided.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Understanding the Electrolyte Chemistry Induced Enhanced Stability of Si Anodes in Li-Ion Batteries based on Physico-Chemical Changes, Impedance, and Stress Evolution during SEI Formation},

author = {R Tripathi and G Yesilbas and X Lamprecht and P Gandharapu and A S Bandarenka and R O Dusane and A Mukhopadhyay},

url = {https://dx.doi.org/10.1149/1945-7111/acfb3f},

doi = {10.1149/1945-7111/acfb3f},

issn = {1945-7111 0013-4651},

year  = {2023},

date = {2023-10-04},

journal = {Journal of The Electrochemical Society},

volume = {170},

number = {9},

pages = {090544},

abstract = {The volume expansion/contraction of Si-based anodes during electrochemical lithiation/delithiation cycles causes a loss in mechanical integrity and accrued instability of the solid electrolyte interphase (SEI) layer, culminating into capacity fade. Electrolyte additives like fluoroethylene carbonate (FEC) improve SEI stability, but the associated causes still under debate. This work reveals some of the roles of FEC via post-mortem observations/analyses, operando stress measurements and a comprehensive study of the impedance associated with the formation/evolution of SEI during lithiation/delithiation. Usage of 10 vol.% FEC as electrolyte additive leads to significant improvements in cyclic stability, Coulombic efficiency and facilitates smoother/compact/crack-free surface/SEI, in contrast to the cracked/pitted/uneven surface upon non-usage of FEC. Operando stress measurements during SEI formation reveal compressive stress development, followed by loss in mechanical integrity, upon non-usage of electrolyte additive, in contrast to insignificant stress development associated with SEI formation upon usage of FEC. The EIS model proposed here facilitates good fit with the impedance data at all states-of-charges, with the SEI resistance and capacitance exhibiting expected variations with cycling and the SEI resistance progressively decreasing with cycle number in the presence of FEC. By contrast, in the absence of FEC, severe fluctuations observed with the SEI resistance and capacitance indicate instability.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Elucidating the Active Sites and Synergies in Water Splitting on Manganese Oxide Nanosheets on Graphite Support},

author = {T O Schmidt and A Wark and R W Haid and R M Kluge and S Suzuki and K Kamiya and A S Bandarenka and J Maruyama and E Sk\'{u}lason},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202302039},

doi = {https://doi.org/10.1002/aenm.202302039},

issn = {1614-6832},

year  = {2023},

date = {2023-10-02},

journal = {Advanced Energy Materials},

volume = {13},

number = {43},

pages = {2302039},

abstract = {Abstract Photosystem II is nature's solution for driving the oxygen evolution reaction to oxidize water. A manganese-oxide cluster is this protein's active center for water splitting, while the most efficient man-made catalysts are costly noble metal-based oxides. Facing the climate change, research on affordable and abundant electrocatalysts is crucial. To mimic the biological solution, manganese oxide nanosheets are synthesized and deposited on highly-oriented pyrolytic graphite. This electrocatalyst is then examined with spectroscopic and electrochemical measurements, electrochemical noise scanning tunneling microscopy, and density functional theory calculations. The detailed investigation assigns the origin of its enhanced water-splitting performance to detected activity at the nanosheet edges which the proposed mechanism explains further. Therefore, the results provide a blueprint for how to design efficient electrocatalysts for water oxidation with abundant materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Electrochemical Scanning Tunneling Microscopy as a Tool for the Detection of Active Electrocatalytic Sites},

author = {T O Schmidt and R W Haid and E L Gubanova and R M Kluge and A S Bandarenka},

url = {https://doi.org/10.1007/s11244-023-01807-6},

doi = {10.1007/s11244-023-01807-6},

issn = {1572-9028},

year  = {2023},

date = {2023-09-01},

journal = {Topics in Catalysis},

volume = {66},

number = {15},

pages = {1270-1279},

abstract = {To advance meaningful guidelines in the design of electrocatalytically active catalysts, a knowledge of the nature of active sites is the starting point. However, multiple factors such as material composition, site coordination, electrolyte effects, the support material, surface strain, and others influence catalytic behavior. Therefore, the identification of active sites can be complex. A substantial contributor can be in-situ experiments, which are able to identify active centers in a specific system while the reaction takes place. An example of such a technique is electrochemical scanning tunneling microscopy (EC-STM), which relates locally confined noise features to local electrocatalytic activity. In this work, we spotlight recent achievements of this technique with respect to palladium (Pd) surfaces for the hydrogen reduction reaction, where strain due to hydride formation comes into play in addition to surface coordination. Secondly, we demonstrate the high resolution of the technique on graphite-based surfaces. Here, edge sites are particularly active. Thus, with the EC-STM technique, we take strain effects (like on Pd) or effects of coordination (like on carbon) into account. Therefore, we can determine active sites with great accuracy under reaction conditions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Mass transport and charge transfer through an electrified interface between metallic lithium and solid-state electrolytes},

author = {L Katzenmeier and M G\"{o}\sswein and L Carstensen and J Sterzinger and M Ederer and P M\"{u}ller-Buschbaum and A Gagliardi and A S Bandarenka},

url = {https://doi.org/10.1038/s42004-023-00923-4},

doi = {10.1038/s42004-023-00923-4},

issn = {2399-3669},

year  = {2023},

date = {2023-06-15},

journal = {Communications Chemistry},

volume = {6},

number = {1},

pages = {124},

abstract = {All-solid-state Li-ion batteries are one of the most promising energy storage devices for future automotive applications as high energy density metallic Li anodes can be safely used. However, introducing solid-state electrolytes needs a better understanding of the forming electrified electrode/electrolyte interface to facilitate the charge and mass transport through it and design ever-high-performance batteries. This study investigates the interface between metallic lithium and solid-state electrolytes. Using spectroscopic ellipsometry, we detected the formation of the space charge depletion layers even in the presence of metallic Li. That is counterintuitive and has been a subject of intense debate in recent years. Using impedance measurements, we obtain key parameters characterizing these layers and, with the help of kinetic Monte Carlo simulations, construct a comprehensive model of the systems to gain insights into the mass transport and the underlying mechanisms of charge accumulation, which is crucial for developing high-performance solid-state batteries.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Structure\textendashActivity Relationships in Ni- Carboxylate-Type Metal\textendashOrganic Frameworks’ Metamorphosis for the Oxygen Evolution Reaction},

author = {X Ma and D J Zheng and S Hou and S Mukherjee and R Khare and G Gao and Q Ai and B Garlyyev and W Li and M Koch and J Mink and Y Shao-Horn and J Warnan and A S Bandarenka and R A Fischer},

url = {https://doi.org/10.1021/acscatal.3c00625},

doi = {10.1021/acscatal.3c00625},

year  = {2023},

date = {2023-05-22},

journal = {ACS Catalysis},

volume = {13},

number = {11},

pages = {7587-7596},

abstract = {Metal\textendashorganic frameworks (MOFs) have been reported to catalyze the oxygen evolution reaction (OER). Despite the established links between the pristine MOFs and their derived metal hydroxide electrocatalysts, several limitations still preclude understanding of the critical factors determining the OER performance. Of prime importance appears the choice of MOF and how its compositions relate to the catalyst stability and in turn to the reconstruction or metamorphosis mechanisms into the active species under OER conditions. An isoreticular series of Ni-carboxylate-type MOFs [Ni2(OH)2L] was chosen to elucidate the effects of the carboxylate linker length expansion and modulation of the linker\textendashlinker π\textendashπ interactions (L = 1,4-benzodicarboxylate, 2,6-napthalenedicarboxylate, biphenyl-4,4′-dicarboxylate, and p-terphenyl-4,4″-dicarboxylate). Degradation and reconstruction of MOFs were systematically investigated. The linker controls the transformation of Ni-MOF into distinct nickel hydroxide phases, and the conversion from α-Ni(OH)2 to β-Ni(OH)2, thus correlating the Ni-MOF composition with the OER activity of the Ni-MOF-derived metastable nickel hydroxide phase mixture.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Fast-Charging Capability of Thin-Film Prussian Blue Analogue Electrodes for Aqueous Sodium-Ion Batteries},

author = {X Lamprecht and P Zellner and G Yesilbas and L Hromadko and P Moser and P Marzak and S Hou and R Haid and F Steinberger and T Steeger and J M Macak and A S Bandarenka},

url = {https://doi.org/10.1021/acsami.3c02633},

doi = {10.1021/acsami.3c02633},

issn = {1944-8244},

year  = {2023},

date = {2023-05-05},

journal = {ACS Applied Materials \& Interfaces},

volume = {15},

number = {19},

pages = {23951-23962},

abstract = {Prussian blue analogues are considered as promising candidates for aqueous sodium-ion batteries providing a decently high energy density for stationary energy storage. However, suppose the operation of such materials under high-power conditions could be facilitated. In that case, their application might involve fast-response power grid stabilization and enable short-distance urban mobility due to fast re-charging. In this work, sodium nickel hexacyanoferrate thin-film electrodes are synthesized via a facile electrochemical deposition approach to form a model system for a robust investigation. Their fast-charging capability is systematically elaborated with regard to the electroactive material thickness in comparison to a ″traditional″ composite-type electrode. It is found that quasi-equilibrium kinetics allow extremely fast (dis)charging within a few seconds for sub-micron film thicknesses. Specifically, for a thickness below ≈ 500 nm, 90% of the capacity can be retained at a rate of 60C (1 min for full (dis)charge). A transition toward mass transport control is observed when further increasing the rate, with thicker films being dominated by this mode earlier than thinner films. This can be entirely attributed to the limiting effects of solid-state diffusion of Na+ within the electrode material. By presenting a PBA model cell yielding 25 Wh kg\textendash1 at up to 10 kW kg\textendash1, this work highlights a possible pathway toward the guided design of hybrid battery\textendashsupercapacitor systems. Furthermore, open challenges associated with thin-film electrodes are discussed, such as the role of parasitic side reactions, as well as increasing the mass loading.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Electron Tunneling at Electrocatalytic Interfaces},

author = {M R Nouri and R M Kluge and R W Haid and J Fortmann and A Ludwig and A S Bandarenka and V Alexandrov},

url = {https://doi.org/10.1021/acs.jpcc.3c00207},

doi = {10.1021/acs.jpcc.3c00207},

issn = {1932-7447},

year  = {2023},

date = {2023-03-27},

journal = {The Journal of Physical Chemistry C},

volume = {127},

number = {13},

pages = {6321-6327},

abstract = {It was recently proposed that tunneling current fluctuations in electrochemical scanning tunneling microscopy (EC-STM) can be used to map the electrocatalytic activity of surfaces with high spatial resolution. However, the relation between the increased noise in the electron tunneling signal and the local reactivity for such complex electrode/electrolyte interfaces is only explained qualitatively or hypothetically. Herein, we employ electron transport calculations to examine tunneling at Pt surfaces under the conditions of the oxygen reduction reaction as a case study. By computing current\textendashvoltage characteristics, we reveal that the tunneling barrier strongly depends on the chemical identity of the adsorbed reaction intermediate as well as on the orientation of the average dipole moment of water species mediating electron tunneling. Our theoretical results combined with EC-STM measurements suggest that detecting reaction intermediates at electrified interfaces in operando conditions is possible based on tunneling noise amplitudes. This study also aims to stimulate further explorations of tunneling-based electron-proton transfers to enable quantum electrocatalysis beyond conventional approaches.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Mechanisms of Degradation of Na2Ni[Fe(CN)6] Functional Electrodes in Aqueous Media: A Combined Theoretical and Experimental Study},

author = {X Lamprecht and I Evazzade and I Ungerer and L Hromadko and J M Macak and A S Bandarenka and V Alexandrov},

url = {https://doi.org/10.1021/acs.jpcc.2c08222},

doi = {10.1021/acs.jpcc.2c08222},

issn = {1932-7447},

year  = {2023},

date = {2023-01-30},

journal = {The Journal of Physical Chemistry C},

volume = {127},

number = {5},

pages = {2204-2214},

abstract = {Prussian blue analogues (PBAs) are versatile functional materials with numerous applications ranging from electrocatalysis and batteries to sensors and electrochromic devices. Their electrochemical performance involving long-term cycling stability strongly depends on the electrolyte composition. In this work, we use density functional theory calculations and experiments to elucidate the mechanisms of degradation of model Na2Ni[Fe(CN)6] functional electrodes in aqueous electrolytes. Next to the solution pH and cation concentration, we identify anion adsorption as a major driving force for electrode dissolution. Notably, the nature of adsorbed anions can control the mass and charge transfer mechanisms during metal cation intercalation as well as the electrode degradation rate. We find that weakly adsorbing anions, such as NO3\textendash, impede the degradation, while strongly adsorbing anions, such as SO42\textendash, accelerate it. The results of this study provide practical guidelines for electrolyte optimization and can likely be extrapolated to the whole family of PBAs operating in aqueous media.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Combining impedance and hydrodynamic methods in electrocatalysis. Characterization of Pt(pc), Pt5Gd, and nanostructured Pd for the hydrogen evolution reaction},

author = {K-T Song and C M Schott and P M Schneider and S A Watzele and R M Kluge and E L Gubanova and A S Bandarenka},

url = {http://iopscience.iop.org/article/10.1088/2515-7655/acabe5},

issn = {2515-7655},

year  = {2022},

date = {2022-12-15},

journal = {Journal of Physics: Energy},

abstract = {Electrochemical hydrodynamic techniques typically involve electrodes that move relative to the solution. Historically, approaches involving rotating disc electrode (RDE) configurations have become very popular, as one can easily control the electroactive species' mass transport in those cases. The combination of cyclic voltammetry and RDE is nowadays one of the standard characterization protocols in electrocatalysis. On the other hand, impedance spectroscopy is one of the most informative electrochemistry techniques, enabling the acquisition of information on the processes taking place simultaneously at the electrode/electrolyte interface. In this work, we investigated the hydrogen evolution reaction (HER) catalyzed by polycrystalline Pt (Pt(pc)) and Pt5Gd disc electrodes and characterized them using RDE and EIS techniques simultaneously. Pt5Gd shows higher HER activities than Pt in acidic and alkaline media due to strain and ligand effects. The mechanistic study of the reaction showed that the rotation rates in acidic media have no effect on the contribution of the Volmer-Heyrovsky and Volmer-Tafel pathways. However, the Volmer-Heyrovsky pathway dominates at lower rotation rates in alkaline media. Besides, the HER in acidic solutions depends more strongly on mass diffusion than in alkaline media. In addition to simple and clearly defined systems, the combined method of both techniques is applicable for systems with greater complexity, such as Pd/C nanostructured catalysts. Applying the above-presented approach, we found that the Volmer-Tafel pathway is the dominating mechanism of the HER for this catalytic system.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Alkali metal cations change the hydrogen evolution reaction mechanisms at Pt electrodes in alkaline media},

author = {Y Taji and A Zagalskaya and I Evazzade and S Watzele and K-T Song and S Xue and C Schott and B Garlyyev and V Alexandrov and E Gubanova and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S2589965122000514},

doi = {https://doi.org/10.1016/j.nanoms.2022.09.003},

issn = {2589-9651},

year  = {2022},

date = {2022-10-29},

journal = {Nano Materials Science},

abstract = {The effects of seemingly inert alkali metal (AM) cations on the electrocatalytic activity of electrode materials towards reactions essential for energy provision have become the emphasis of substantial research efforts in recent years. The hydrogen and oxygen evolution reactions during alkaline water electrolysis and the oxygen electro-reduction taking place in fuel cells are of particular importance. There is no universal theory explaining all the details of the AM cation effect in electrocatalysis. For example, it remains unclear how “spectator” AM-cations can change the kinetics of electrocatalytic reactions often more significantly than the modifications of the electrode structure and composition. This situation originates partly from a lack of systematic experimental and theoretical studies of this phenomenon. The present work exploits impedance spectroscopy to investigate the influence of the AM cations on the mechanism of the hydrogen evolution reaction at Pt microelectrodes. The activity follows the trend: Li+≥Na+\>K+\>Cs+, where the highest activity corresponds to 0.1 ​M LiOH electrolytes at low overpotentials. We demonstrate that the nature of the AM cations also changes the relative contribution of the Volmer\textendashHeyrovsky and Volmer\textendashTafel mechanisms to the overall reaction, with the former being more important for LiOH electrolytes. Our density functional theory-based thermodynamics and molecular dynamics calculations support these findings.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A trade-off between ligand and strain effects optimizes the oxygen reduction activity of Pt alloys},

author = {R M Kluge and R W Haid and A Riss and Y Bao and K Seufert and T O Schmidt and S A Watzele and J V Barth and F Allegretti and W Auw\"{a}rter and F Calle-Vallejo and A S Bandarenka},

url = {http://dx.doi.org/10.1039/D2EE01850K},

doi = {10.1039/D2EE01850K},

issn = {1754-5692},

year  = {2022},

date = {2022-10-20},

journal = {Energy \& Environmental Science},

volume = {15},

number = {12},

pages = {5181-5191},

abstract = {To optimize the performance of catalytic materials, it is paramount to elucidate the dependence of the chemical reactivity on the atomic arrangement of the catalyst surface. Therefore, identifying the nature of the active sites that provide optimal binding of reaction intermediates is the first step toward a rational catalyst design. In this work, we focus on the oxygen reduction reaction (ORR), an essential constituent of several energy provision and storage devices. Among the state-of-the-art ORR catalysts are platinum (Pt) and its alloys. The latter benefit from the so-called ligand and strain effects, which influence the electronic properties of the surface. Here, we “visualize” the active sites on Pt3Ni(111) in an acidic medium with a lateral resolution in the nanometre regime via an in situ technique based on electrochemical scanning tunnelling microscopy. In contrast to pure Pt, where the active sites are located at concave sites close to steps, Pt3Ni(111) terraces contain the most active centres, while steps show activity to a comparable or lesser extent. We confirm the experimental findings by a model based on alloy- and strain-sensitive generalized coordination numbers. With this model, we are also able to assess both the composition and the geometric configuration of optimal catalytic active sites on various Pt alloy catalysts. In general, the interplay of ligand effects and lattice compression resulting from the alloying of Pt with 3d transition metals (Ti, Co, Ni, Cu) gradually increases the generalized coordination number of surface Pt atoms, thereby making (111) terraces highly active. This combination of theoretical and experimental tools provides clear strategies to design more efficient Pt alloy electrocatalysts for oxygen reduction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Improvement of the thermoelectric properties of PEDOT:PSS films via DMSO addition and DMSO/salt post-treatment resolved from a fundamental view},

author = {S Tu and T Tian and A Lena Oechsle and S Yin and X Jiang and W Cao and N Li and M A Scheel and L K Reb and S Hou and A S Bandarenka and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://www.sciencedirect.com/science/article/pii/S1385894721038742},

doi = {https://doi.org/10.1016/j.cej.2021.132295},

issn = {1385-8947},

year  = {2022},

date = {2022-09-06},

urldate = {2022-09-06},

journal = {Chemical Engineering Journal},

volume = {429},

pages = {132295},

abstract = {The combination of dimethyl sulfoxide (DMSO)-solvent doping and physical\textendashchemical DMSO/salt de-doping in a sequence has been used to improve the thermoelectric (TE) properties of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) films. A high power factor of ca.105.2 µW m−1 K−2 has been achieved for the PEDOT:PSS film after post-treatment with 10 % sodium sulfite (Na2SO3) in the DMSO/salt mixture (v/v), outperforming sodium bicarbonate (NaHCO3). The initial DMSO-doping treatment induces a distinct phase separation by facilitating the aggregation of the PEDOT molecules. At the same time, the subsequent DMSO/salt de-doping post-treatment strengthens the selective removal of the surplus non-conductive PSS chains. Substantial alterations in the oxidation level, chain conformations, PEDOT crystallites and their preferential orientation are observed upon treatment on the molecular level. At the mesoscale level, the purification and densification of PEDOT-rich domains enable the realization of inter-grain coupling by the formation of the electronically well-percolated network. Thereby, both electrical conductivity and Seebeck coefficient are optimized.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Structure-Dependent Electrical Double-Layer Capacitances of the Basal Plane Pd(hkl) Electrodes in HClO4},

author = {E Gubanova and T O Schmidt and S Watzele and V Alexandrov and A S Bandarenka},

url = {https://doi.org/10.1021/acs.jpcc.2c03117},

doi = {10.1021/acs.jpcc.2c03117},

issn = {1932-7447},

year  = {2022},

date = {2022-07-05},

journal = {The Journal of Physical Chemistry C},

volume = {126},

number = {27},

pages = {11414-11420},

abstract = {Electrical double-layer capacitance (CDL) measurements are among the key experiments in physical electrochemistry aimed to understand the properties of electrified solid/liquid interfaces. CDL serves as a critical parameter for developing physical models of electrochemical interfaces. Palladium (Pd) electrodes are among the most widely used functional materials in many applications, including (electro)catalysis. In this work, we report on double-layer capacitances of the basal plane Pd(111), Pd(100), and Pd(110) electrodes in aqueous HClO4 electrolytes measured using electrochemical impedance spectroscopy. Importantly, we find that the CDL values estimated at the minima of the capacitance vs electrode potential curves can be correlated with the density-functional-theory (DFT)-calculated adsorption energies for water molecules and the coordination of electrode surface atoms. Our results thus suggest that it might be possible to find simple descriptors of the electrical double layer (EDL) analogous to those used for functional electrode materials. Taken together, such descriptors could be employed for efficient high-throughput screening of various electrode/electrolyte interfaces, such as in supercapacitor and electrocatalytic systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Modeling of Space-Charge Layers in Solid-State Electrolytes: A Kinetic Monte Carlo Approach and Its Validation},

author = {L Katzenmeier and M G\"{o}\sswein and A Gagliardi and A S Bandarenka},

url = {https://doi.org/10.1021/acs.jpcc.2c02481},

doi = {10.1021/acs.jpcc.2c02481},

issn = {1932-7447},

year  = {2022},

date = {2022-06-23},

journal = {The Journal of Physical Chemistry C},

volume = {126},

number = {26},

pages = {10900-10909},

abstract = {The space-charge layer (SCL) phenomenon in Li+-ion-conducting solid-state electrolytes (SSEs) is gaining much interest in different fields of solid-state ionics. Not only do SCLs influence charge-transfer resistance in all-solid-state batteries but also are analogous to their electronic counterpart in semiconductors; they could be used for Li+-ionic devices. However, the rather “elusive” nature of these layers, which occur on the nanometer scale and with only small changes in concentrations, makes them hard to fully characterize experimentally. Theoretical considerations based on either electrochemical or thermodynamic models are limited due to missing physical, chemical, and electrochemical parameters. In this work, we use kinetic Monte Carlo (kMC) simulations with a small set of input parameters to model the spatial extent of the SCLs. The predictive power of the kMC model is demonstrated by finding a critical range for each parameter in which the space-charge layer growth is significant and must be considered in electrochemical and ionic devices. The time evolution of the charge redistribution is investigated, showing that the SCLs form within 500 ms after applying a bias potential.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Elucidation of Structure\textendashActivity Relations in Proton Electroreduction at Pd Surfaces: Theoretical and Experimental Study},

author = {T O Schmidt and A Ngoipala and R L Arevalo and S A Watzele and R Lipin and R M Kluge and S Hou and R W Haid and A Senyshyn and E L Gubanova and A S Bandarenka and M Vandichel},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202202410},

doi = {https://doi.org/10.1002/smll.202202410},

issn = {1613-6810},

year  = {2022},

date = {2022-06-20},

journal = {Small},

volume = {18},

number = {30},

pages = {2202410},

abstract = {Abstract The structure\textendashactivity relationship is a cornerstone topic in catalysis, which lays the foundation for the design and functionalization of catalytic materials. Of particular interest is the catalysis of the hydrogen evolution reaction (HER) by palladium (Pd), which is envisioned to play a major role in realizing a hydrogen-based economy. Interestingly, experimentalists observed excess heat generation in such systems, which became known as the debated “cold fusion” phenomenon. Despite the considerable attention on this report, more fundamental knowledge, such as the impact of the formation of bulk Pd hydrides on the nature of active sites and the HER activity, remains largely unexplored. In this work, classical electrochemical experiments performed on model Pd(hkl) surfaces, “noise” electrochemical scanning tunneling microscopy (n-EC-STM), and density functional theory are combined to elucidate the nature of active sites for the HER. Results reveal an activity trend following Pd(111) \> Pd(110) \> Pd(100) and that the formation of subsurface hydride layers causes morphological changes and strain, which affect the HER activity and the nature of active sites. These findings provide significant insights into the role of subsurface hydride formation on the structure\textendashactivity relations toward the design of efficient Pd-based nanocatalysts for the HER.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Revealing the Nature of Active Sites on Pt\textendashGd and Pt\textendashPr Alloys during the Oxygen Reduction Reaction},

author = {R M Kluge and E Psaltis and R W Haid and S Hou and T O Schmidt and O Schneider and B Garlyyev and F Calle-Vallejo and A S Bandarenka},

url = {https://doi.org/10.1021/acsami.2c03604},

doi = {10.1021/acsami.2c03604},

issn = {1944-8244},

year  = {2022},

date = {2022-04-20},

journal = {ACS Applied Materials \& Interfaces},

volume = {14},

number = {17},

pages = {19604-19613},

abstract = {For large-scale applications of hydrogen fuel cells, the sluggish kinetics of the oxygen reduction reaction (ORR) have to be overcome. So far, only platinum (Pt)-group catalysts have shown adequate performance and stability. A well-known approach to increase the efficiency and decrease the Pt loading is to alloy Pt with other metals. Still, for catalyst optimization, the nature of the active sites is crucial. In this work, electrochemical scanning tunneling microscopy (EC-STM) is used to probe the ORR active areas on Pt5Gd and Pt5Pr in acidic media under reaction conditions. The technique detects localized fluctuations in the EC-STM signal, which indicates differences in the local activity. The in situ experiments, supported by coordination\textendashactivity plots based on density functional theory calculations, show that the compressed Pt\textendashlanthanide (111) terraces contribute the most to the overall activity. Sites with higher coordination, as found at the bottom of step edges or concavities, remain relatively inactive. Sites of lower coordination, as found near the top of step edges, show higher activity, presumably due to an interplay of strain and steric hindrance effects. These findings should be vital in designing nanostructured Pt\textendashlanthanide electrocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Spatially Resolved Electrochemical Impedance Spectroscopy of Automotive PEM Fuel Cells},

author = {A S Bandarenka and F Haimerl and J P Sabawa and T A Dao},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202200069},

doi = {https://doi.org/10.1002/celc.202200069},

issn = {2196-0216},

year  = {2022},

date = {2022-04-13},

urldate = {2022-04-13},

journal = {ChemElectroChem},

volume = {n/a},

number = {n/a},

abstract = {Fuel cell electric vehicles (FCEVs), which use polymer electrolyte membrane fuel cells (PEMFCs), provide a prospect to add to a future mobility. However, an in-depth understanding of degradation mechanisms and contributions to performance losses is needed to commercialize FCEVs further. Previous PEMFC degradation research has focused on global indicators of the cell condition. Failure occurs typically due to inhomogeneities in operation, leading to localized regions of high degradation rates. Here, we present the results of a comprehensive study of spatial distributions of essential PEMFC parameters using electrochemical impedance spectroscopy across the cell surface of automotive-size fuel cells with an active area of 285cm2. In particular, the results reveal increasing mass transport problems with increasing distance from the air inlet and a tendency of lower proton resistances in the center of the cell. One hundred twenty realistic freeze-start cycles degenerated the cell performance drastically. The outer cell regions, subject to the lowest temperatures, showed the most substantial degradation rates, partly compensated by central cell regions with slightly higher temperatures. These findings bridge the gap between simulation and experiment and provide valuable insights for future fuel cell design and operating strategies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Li+ Conductivity of Space Charge Layers Formed at Electrified Interfaces Between a Model Solid-State Electrolyte and Blocking Au-Electrodes},

author = {L Katzenmeier and L Carstensen and A S Bandarenka},

url = {https://doi.org/10.1021/acsami.2c00650},

doi = {10.1021/acsami.2c00650},

issn = {1944-8244},

year  = {2022},

date = {2022-04-06},

journal = {ACS Applied Materials \& Interfaces},

volume = {14},

number = {13},

pages = {15811-15817},

abstract = {The formation of space charge layers in solid-state ion conductors has been investigated as early as the 1980s. With the advent of all-solid-state batteries as an alternative to traditional Li-ion batteries, possibly improving performance and safety, the phenomenon of space charge formation caught the attention of researchers as a possible origin for the observed high interfacial resistance. Following classical space charge theory, such high resistances result from the formation of the depletion layers. These layers of up to hundreds of nanometers in thickness are almost free of mobile cations. With the prediction of a Debye-like screening effect, the thickness of the depletion layer is expected to scale with the square root of the absolute temperature. In this work, we studied the temperature dependence of the depletion layer properties in model solid Ohara LICGC Li+ conducting electrolytes using electrochemical impedance spectroscopy. We show that the activation energy inside the depletion layer increases to ca 0.42 eV compared to ca 0.39 eV in the bulk electrolyte. Moreover, the proportionality between temperature and depletion layer thickness, correlating to the Debye length, is tested and validated.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Finding efficient catalyst designs: A high-precision method to reveal active sites},

author = {R W Haid and R M Kluge and T O Schmidt and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S2667109322001695},

doi = {https://doi.org/10.1016/j.checat.2022.03.024},

issn = {2667-1093},

year  = {2022},

date = {2022-03-16},

journal = {Chem Catalysis},

volume = {2},

number = {4},

pages = {657-659},

abstract = {Designing efficient electrocatalytic structures requires reliable guidelines. For this purpose, experimental approaches for the characterization of model electrodes in operando conditions are valuable. Reporting in Joule, Agnoli et al. showcase the determination of site-specific reaction onset potentials and Tafel slopes by using electrochemical scanning tunneling microscopy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Dual In-situ Laser Techniques Underpin the Role of Cations in Impacting Electrocatalysts},

author = {S Hou and L Xu and X Ding and R M Kluge and T K Sarpey and R W Haid and B Garlyyev and S Mukherjee and J Warnan and M Koch and S Zhang and W Li and A S Bandarenka and R A Fischer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202201610},

doi = {https://doi.org/10.1002/anie.202201610},

issn = {1433-7851},

year  = {2022},

date = {2022-03-10},

journal = {Angewandte Chemie International Edition},

volume = {n/a},

number = {n/a},

abstract = {Understanding the electrode/electrolyte interface is crucial for optimizing electrocatalytic performances. Here, we demonstrate that the nature of alkali metal cations can profoundly impact the oxygen evolution activity of surface-mounted metal-organic framework (SURMOF) derived electrocatalysts, which are based on NiFe(OOH). In-situ Raman spectroscopy results show that Raman shifts of the Ni-O bending vibration are inversely proportional to the mass activities from Cs+ to Li+. Particularly, a laser-induced current transient technique was introduced to study the cation-dependent electric double layer properties and their effects on the activity. The catalytic trend appeared to be closely related to the potential of maximum entropy of the system, suggesting a strong cation impact on the interfacial water layer structure. Our results highlight how the electrolyte composition can be used to maximize the performance of SURMOF derivatives toward electrochemical water splitting.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Electrolyte Effects on the Stabilization of Prussian Blue Analogue Electrodes in Aqueous Sodium-Ion Batteries},

author = {X Lamprecht and F Speck and P Marzak and S Cherevko and A S Bandarenka},

url = {https://doi.org/10.1021/acsami.1c21219},

doi = {10.1021/acsami.1c21219},

issn = {1944-8244},

year  = {2022},

date = {2022-01-06},

urldate = {2022-01-06},

journal = {ACS Applied Materials \& Interfaces},

volume = {14},

pages = {3515-3525},

abstract = {Aqueous sodium-ion batteries based on Prussian Blue Analogues (PBA) are considered as promising and scalable candidates for stationary energy storage systems, where longevity and cycling stability are assigned utmost importance to maintain economic viability. Although degradation due to active material dissolution is a common issue of battery electrodes, it is hardly observable directly due to a lack of in operando techniques, making it challenging to optimize the performance of electrodes. By operating Na2Ni[Fe(CN)6] and Na2Co[Fe(CN)6] model electrodes in a flow-cell setup connected to an inductively coupled plasma mass spectrometer, in this work, the dynamics of constituent transition-metal dissolution during the charge\textendashdischarge cycles was monitored in real time. At neutral pHs, the extraction of nickel and cobalt was found to drive the degradation process during charge\textendashdischarge cycles. It was also found that the nature of anions present in the electrolytes has a significant impact on the degradation rate, determining the order ClO4\textendash \> NO3\textendash \> Cl\textendash \> SO42\textendash with decreasing stability from the perchlorate to sulfate electrolytes. It is proposed that the dissolution process is initiated by detrimental specific adsorption of anions during the electrode oxidation, therefore scaling with their respective chemisorption affinity. This study involves an entire comparison of the effectiveness of common stabilization strategies for PBAs under very fast (dis)charging conditions at 300C, emphasizing the superiority of highly concentrated NaClO4 with almost no capacity loss after 10 000 cycles for Na2Ni[Fe(CN)6].},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Systematic Study of the Influence of Electrolyte Ions on the Electrode Activity},

author = {X Ding and D Scieszka and S Watzele and S Xue and B Garlyyev and R W Haid and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202101088},

doi = {https://doi.org/10.1002/celc.202101088},

issn = {2196-0216},

year  = {2022},

date = {2022-01-01},

urldate = {2021-11-22},

journal = {ChemElectroChem},

volume = {9},

number = {1},

pages = {e202101088},

abstract = {Abstract Efficient electrocatalysis is most likely an answer to recent energy related challenges. Countless studies have been trying to find the links between the electrode/electrolyte interface structure, its composition, and the resulting activity in order to improve the performance of numerous devices, such as electrolyzers, fuel cells, and certain types of batteries. However, this scientific field currently meets serious complications associated with the prediction and explanation of an unexpected influence of seemingly inert electrolyte components on the observed activity. Herein, we investigate various electrocatalytic systems using a unique laser-induced current transient technique to answer a long-lasting fundamental question: How can “inert” electrolytes change the activity so drastically? Different metal electrodes in contact with various aqueous solutions and two energy important reactions were used as model systems. We experimentally determine the potential of maximum entropy of the electrodes and find the connections between its position and the electrocatalytic performance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Exploration of the Electrical Double Layer Structure: Influence of Electrolyte Components on the Double Layer Capacitance and Potential of Maximum Entropy},

author = {R W Haid and X Ding and T K Sarpey and A S Bandarenka and B Garlyyev},

url = {https://www.sciencedirect.com/science/article/pii/S2451910321001964},

doi = {https://doi.org/10.1016/j.coelec.2021.100882},

issn = {2451-9103},

year  = {2022},

date = {2022-01-01},

urldate = {2021-11-17},

journal = {Current Opinion in Electrochemistry},

volume = {32},

pages = {100882},

abstract = {Understanding the electrical double layer structure is of paramount importance for designing efficient electrochemical energy conversion systems. Under this aspect, this short review explores the influence of the electrolyte on parameters such as the double layer capacitance and the potential of maximum entropy. Investigation of those parameters offers a deeper understanding on how the interfacial structure changes near reaction conditions. As a consequence, one can tune the catalyst activity by creating a more favorable environment in the electrolyte. The aim of this short review is to provide the reader with recent studies examining the electrode/electrolyte interface from experimental and theoretical standpoints.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Avoiding Pyrolysis and Calcination: Advances in the Benign Routes Leading to MOF-Derived Electrocatalysts},

author = {S Mukherjee and S Hou and S A Watzele and B Garlyyev and W Li and A S Bandarenka and R A Fischer},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202101476},

doi = {https://doi.org/10.1002/celc.202101476},

issn = {2196-0216},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {ChemElectroChem},

volume = {9},

number = {9},

pages = {e202101476},

abstract = {Abstract Taking cognizance of the United Nations Sustainable Development Goal 7 “affordable and clean energy”, metal\textendashorganic frameworks (MOFs) and derived materials have spurred research interest in electrocatalysis. New findings have made headway in water splitting (oxygen evolution reaction and hydrogen evolution reaction) and other electrocatalysis, including the oxygen reduction reaction and electrochemical CO2 reduction. Thanks to their structural versatility and compositional modularity, MOFs offer bespoke design paradigms for electrocatalyst development. Albeit most advances in this area are predicated upon direct carbonization (pyrolysis) of MOFs/MOF composites, eschewing these energy-intensive and high-cost methods, this review summarizes all recent advances in MOF-based electrocatalysts exclusively prepared through indirect post-treatments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Prospects of Using the Laser-Induced Temperature Jump Techniques for Characterisation of Electrochemical Systems},

author = {X Ding and T K Sarpey and S Hou and B Garlyyev and W Li and R A Fischer and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202101175},

doi = {https://doi.org/10.1002/celc.202101175},

issn = {2196-0216},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {ChemElectroChem},

volume = {9},

number = {4},

pages = {e20210117},

abstract = {Abstract Understanding the processes, phenomena, and mechanisms occurring at the electrode/electrolyte interface is a prerequisite and significant for optimizing electrochemical systems. To this end, the advent of sub-microsecond laser pulses has paved the way and eased the investigations of the electrochemical interface (e. g., electric double layer), which hitherto is difficult. The laser-induced current transient (LICT) and laser-induced potential transient (LIPT) techniques have proven to be valuable and unique tools for measuring key parameters of the electrified interface, such as the potential of maximum entropy (PME) and the potential of zero charge (PZC). Herein, we present a summary of studies performed in recent years using laser-induced temperature jump techniques. The relation between the PME/PZC and the electrocatalytic properties of various electrochemical interfaces are particularly highlighted. Special attention is given to its applications in investigating different systems and analyzing the influence of the electrolyte components, electrode composition and structure on the PME/PZC and various electrochemical processes. Moreover, possible applications of the LICT/LIPT techniques to investigate the interfacial properties of a myriad of materials, including surface-mounted metal-organic frameworks and metal oxides, are elaborated.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nanosized and metastable molybdenum oxides as negative electrode materials for durable high-energy aqueous Li-ion batteries},

author = {J Yun and R Sagehashi and Y Sato and T Masuda and S Hoshino and H B Rajendra and K Okuno and A Hosoe and A S Bandarenka and N Yabuuchi},

url = {https://www.pnas.org/doi/abs/10.1073/pnas.2024969118},

doi = {doi:10.1073/pnas.2024969118},

year  = {2021},

date = {2021-11-23},

urldate = {2021-11-23},

journal = {Proceedings of the National Academy of Sciences},

volume = {118},

number = {48},

pages = {e2024969118},

abstract = {The development of inherently safe energy devices is a key challenge, and aqueous Li-ion batteries draw large attention for this purpose. Due to the narrow electrochemical stable potential window of aqueous electrolytes, the energy density and the selection of negative electrode materials are significantly limited. For achieving durable and high-energy aqueous Li-ion batteries, the development of negative electrode materials exhibiting a large capacity and low potential without triggering decomposition of water is crucial. Herein, a type of a negative electrode material (i.e., LixNb2/7Mo3/7O2) is proposed for high-energy aqueous Li-ion batteries. LixNb2/7Mo3/7O2 delivers a large capacity of ∼170 mA ⋅ h ⋅ g−1 with a low operating potential range of 1.9 to 2.8 versus Li/Li+ in 21 m lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) aqueous electrolyte. A full cell consisting of Li1.05Mn1.95O4/Li9/7Nb2/7Mo3/7O2 presents high energy density of 107 W ⋅ h ⋅ kg−1 as the maximum value in 21 m LiTFSA aqueous electrolyte, and 73% in capacity retention is achieved after 2,000 cycles. Furthermore, hard X-ray photoelectron spectroscopy study reveals that a protective surface layer is formed at the surface of the negative electrode, by which the high-energy and durable aqueous batteries are realized with LixNb2/7Mo3/7O2. This work combines a high capacity with a safe negative electrode material through delivering the Mo-based oxide with unique nanosized and metastable characters.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Metamorphosis of Heterostructured Surface-Mounted Metal\textendashOrganic Frameworks Yielding Record Oxygen Evolution Mass Activities},

author = {S Hou and W Li and S Watzele and R M Kluge and S Xue and S Yin and X Jiang and M D\"{o}blinger and A Welle and B Garlyyev and M Koch and P M\"{u}ller-Buschbaum and C W\"{o}ll and A S Bandarenka and R A Fischer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202103218},

doi = {https://doi.org/10.1002/adma.202103218},

issn = {0935-9648},

year  = {2021},

date = {2021-08-01},

urldate = {2021-08-01},

journal = {Advanced Materials},

volume = {33},

pages = {2103218},

abstract = {Abstract Materials derived from surface-mounted metal\textendashorganic frameworks (SURMOFs) are promising electrocatalysts for the oxygen evolution reaction (OER). A series of mixed-metal, heterostructured SURMOFs is fabricated by the facile layer-by-layer deposition method. The obtained materials reveal record-high electrocatalyst mass activities of ≈2.90 kA g−1 at an overpotential of 300 mV in 0.1 m KOH, superior to the benchmarking precious and nonprecious metal electrocatalysts. This property is assigned to the particular in situ self-reconstruction and self-activation of the SURMOFs during the immersion and the electrochemical treatment in alkaline aqueous electrolytes, which allows for the generation of NiFe (oxy)hydroxide electrocatalyst materials of specific morphology and microstructure.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Temperature dependences of the double layer capacitance of some solid/liquid and solid/solid electrified interfaces. An experimental study},

author = {S A Watzele and L Katzenmeier and J P Sabawa and B Garlyyev and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S0013468621012597},

doi = {https://doi.org/10.1016/j.electacta.2021.138969},

issn = {0013-4686},

year  = {2021},

date = {2021-07-30},

journal = {Electrochimica Acta},

volume = {391},

pages = {138969},

abstract = {This study investigates the influence of the temperature on the electrical double layer capacitance (CDL) of various materials, which are essential for fuel cells and solid-state Li-ion batteries. Electrochemical impedance spectroscopy is utilized to measure the CDL of polycrystalline Pt/aqueous electrolytes interfaces, cathode catalyst layers of polymer electrolyte membrane fuel cells (PEMFC), and Au or Li electrodes in contact with a solid-state electrolyte (SSE), a prime example for solid-state ionics. Our results show that within the investigated temperature ranges, the CDL decreases with an increase in the temperature for Pt electrodes in an aqueous acidic electrolyte. However, for SSE and PEMFC cathode catalyst layers, the CDL increases with temperature. The CDL behavior with the temperature of herein presented systems is important for understanding and modeling of the interface processes for renewable energy conversion systems such as fuel cells, water electrolyzers, and batteries.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Review on Experimental Identification of Active Sites in Model Bifunctional Electrocatalytic Systems for Oxygen Reduction and Evolution Reactions},

author = {S Hou and R M Kluge and R W Haid and E L Gubanova and S A Watzele and A S Bandarenka and B Garlyyev},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202100584},

doi = {https://doi.org/10.1002/celc.202100584},

issn = {2196-0216},

year  = {2021},

date = {2021-07-08},

urldate = {2021-07-08},

journal = {ChemElectroChem},

volume = {8},

number = {18},

pages = {3433-3456},

abstract = {Abstract Efficient electrocatalysis of the oxygen reduction (ORR) and evolution (OER) reactions is essential in numerous renewable energy conversion systems, such as fuel cells, metal-air batteries, and water electrolyzers. Design and optimization of electrocatalytic materials for such systems primarily rely on understanding the nature of active centers on the catalyst surface. This review focuses on several important aspects of the experimental identification of active sites on various model bifunctional ORR/OER electrocatalytic surfaces. Applications of the state-of-the-art experimental techniques are analyzed. In addition, approaches to investigate and understand the influence of some supporting electrolyte components on the ORR and OER activities are discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Solid-State Electrolytes: Characterization and Quantification of Depletion and Accumulation Layers in Solid-State Li+-Conducting Electrolytes Using In Situ Spectroscopic Ellipsometry (Adv. Mater. 24/2021)},

author = {L Katzenmeier and L Carstensen and S J Schaper and P M\"{u}ller-Buschbaum and A S Bandarenka},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202170190},

doi = {https://doi.org/10.1002/adma.202170190},

issn = {0935-9648},

year  = {2021},

date = {2021-06-18},

urldate = {2021-06-18},

journal = {Advanced Materials},

volume = {33},

number = {24},

pages = {2100585},

abstract = {Layers depleted of Li-ions in solid-state electrolytes have a substantial impact on the performance of all-solid-state batteries. In article number 2100585, Aliaksandr S. Bandarenka and co-workers develop a practical strategy to measure the thickness of such space charge layers and the corresponding concentration of Li-ions by applying spectroscopic ellipsometry to emerging battery materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Enhancing the Hydrogen Evolution Reaction Activity of Platinum Electrodes in Alkaline Media Using Nickel-Iron Clusters},

author = {S Xue and R W Haid and R M Kluge and X Ding and B Garlyyev and J Fichtner and S Watzele and S J Hou and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000529657400001},

doi = {10.1002/anie.202000383},

issn = {1433-7851},

year  = {2021},

date = {2021-06-18},

urldate = {2020-06-26},

journal = {Angewandte Chemie-International Edition},

volume = {59},

number = {27},

pages = {10934-10938},

abstract = {Herein, we demonstrate an easy way to improve the hydrogen evolution reaction (HER) activity of Pt electrodes in alkaline media by introducing Ni-Fe clusters. As a result, the overpotential needed to achieve a current density of 10 mA cm(-2) in H-2-saturated 0.1 m KOH is reduced for the model single-crystal electrodes down to about 70 mV. To our knowledge, these modified electrodes outperform any other reported electrocatalysts tested under similar conditions. Moreover, the influence of 1) Ni to Fe ratio, 2) cluster coverage, and 3) the nature of the alkali-metal cations present in the electrolyte on the HER activity has been investigated. The observed catalytic performance likely originates from both the improved water dissociation at the Ni-Fe clusters and the subsequent optimal hydrogen adsorption and recombination at Pt atoms present at the Ni-Fe/Pt boundary.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Spotlight on the Effect of Electrolyte Composition on the Potential of Maximum Entropy: Supporting Electrolytes Are Not Always Inert},

author = {X Ding and B Garlyyev and S A Watzele and T Kobina Sarpey and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202101537},

doi = {https://doi.org/10.1002/chem.202101537},

issn = {0947-6539},

year  = {2021},

date = {2021-05-29},

urldate = {2021-05-29},

journal = {Chemistry \textendash A European Journal},

volume = {27},

number = {39},

pages = {10016-10020},

abstract = {Abstract The influence of electrolyte pH, the presence of alkali metal cations (Na+, K+), and the presence of O2 on the interfacial water structure of polycrystalline gold electrodes has been experimentally studied in detail. The potential of maximum entropy (PME) was determined by the laser-induced current transient (LICT) technique. Our results demonstrate that increasing the electrolyte pH and introducing O2 shift the PME to more positive potentials. Interestingly, the PME exhibits a higher sensitivity to the pH change in the presence of K+ than Na+. Altering the pH of the K2SO4 solution from 4 to 6 can cause a drastic shift in the PME. These findings reveal that, for example, K2SO4 and Na2SO4 cannot be considered as equal supporting electrolytes: it is not a viable assumption. This can likely be extrapolated to other common “inert” supporting electrolytes. Beyond this, knowledge about the near-ideal electrolyte composition can be used to optimize electrochemical devices such as electrolyzers, fuel cells, batteries, and supercapacitors.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Fast and accurate determination of the electroactive surface area of MnOx},

author = {M H Aufa and S A Watzele and S Hou and R W Haid and R M Kluge and A S Bandarenka and B Garlyyev},

url = {https://www.sciencedirect.com/science/article/pii/S0013468621009828},

doi = {https://doi.org/10.1016/j.electacta.2021.138692},

issn = {0013-4686},

year  = {2021},

date = {2021-05-27},

journal = {Electrochimica Acta},

volume = {389},

pages = {138692},

abstract = {Manganese oxide (MnOx)-based materials are widely utilized in the field of electrocatalysis as bifunctional electrocatalysts for the oxygen reduction and evolution reactions. However, for an accurate assessment of their performance, the determination of their electrochemical active surface area (ECSA) is of paramount importance. So far, there is no fast and reproducible methodology. This article presents an easily applicable and affordable technique to determine the ECSA of MnOx accurately. The presented methodology makes use of the specific adsorption capacitance of reaction intermediates close to the onset potential of the oxygen evolution reaction. The electrochemical impedance spectroscopy is utilized to measure the specific adsorption capacitances at different potentials. Using MnOx thin-film electrodes, we determine the specific adsorption capacitances and present calibration values, which can be used for an accurate determination of the ECSA of different, for instance, nanostructured materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Characterization and Quantification of Depletion and Accumulation Layers in Solid-State Li+-Conducting Electrolytes Using In Situ Spectroscopic Ellipsometry},

author = {L Katzenmeier and L Carstensen and S J Schaper and P M\"{u}ller-Buschbaum and A S Bandarenka},

url = {http://europepmc.org/abstract/MED/33955614 

https://doi.org/10.1002/adma.202100585},

doi = {10.1002/adma.202100585},

issn = {0935-9648},

year  = {2021},

date = {2021-05-06},

journal = {Advanced Materials},

pages = {e2100585},

abstract = {The future of mobility depends on the development of next-generation battery technologies, such as all-solid-state batteries. As the ionic conductivity of solid Li^{+} -conductors can, in some cases, approach that of liquid electrolytes, a significant remaining barrier faced by solid-state electrolytes (SSEs) is the interface formed at the anode and cathode materials, with chemical instability and physical resistances arising. The physical properties of space charge layers (SCLs), a widely discussed phenomenon in SSEs, are still unclear. In this work, spectroscopic ellipsometry is used to characterize the accumulation and depletion layers. An optical model is developed to quantify their thicknesses and corresponding concentration changes. It is shown that the Li^{+} -depleted layer (≈190 nm at 1 V) is thinner than the accumulation layer (≈320 nm at 1 V) in a glassy lithium-ion-conducting glass ceramic electrolyte (a trademark of Ohara Corporation). The in situ approach combining electrochemistry and optics resolves the ambiguities around SCL formation. It opens up a wide field of optical measurements on SSEs, allowing various experimental studies in the future.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Review on physical impedance models in modern battery research},

author = {R R Gaddam and L Katzenmeier and X Lamprecht and A S Bandarenka},

url = {http://dx.doi.org/10.1039/D1CP00673H},

doi = {10.1039/D1CP00673H},

issn = {1463-9076},

year  = {2021},

date = {2021-05-04},

journal = {Physical Chemistry Chemical Physics},

volume = {23},

number = {23},

pages = {12926-12944},

abstract = {Electrochemical impedance spectroscopy (EIS) is a versatile tool to understand complex processes in batteries. This technique can investigate the effects of battery components like the electrode and electrolyte, electrochemical reactions, interfaces, and interphases forming in the electrochemical systems. The interpretation of the EIS data is typically made using models expressed in terms of the so-called electrical equivalent circuits (EECs) to fit the impedance spectra. Therefore, the EECs must unambiguously represent the electrochemistry of the system. EEC models with a physical significance are more relevant than the empirical ones with their inherent imperfect description of the ongoing processes. This review aims to present the readers with the importance of physical EEC modeling within the context of battery research. A general introduction to EIS and EEC models along with a brief description of the mathematical formalism is provided, followed by showcasing the importance of physical EEC models for EIS on selected examples from the research on traditional, aqueous, and newer all-solid-state battery systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {In-situ Detection of Active Sites for Carbon-Based Bifunctional Oxygen Reduction and Evolution Catalysis},

author = {R W Haid and R M Kluge and T O Schmidt and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S0013468621005752},

doi = {https://doi.org/10.1016/j.electacta.2021.138285},

issn = {0013-4686},

year  = {2021},

date = {2021-04-02},

urldate = {2021-04-02},

journal = {Electrochimica Acta},

volume = {382},

pages = {138285},

abstract = {Due to their availability and electrochemical versatility, carbon-based electrodes are becoming an increasingly popular option as electrocatalysts for fuel cells and metal-air batteries. Additionally, they show great potential as bifunctional catalysts for the oxygen reduction and evolution reaction (ORR/OER) in an alkaline medium. However, to compete with state-of-the-art catalysts, the nature of the active sites and the surface stability under reaction conditions need to be understood in depth. Here, we present a principle study on highly oriented pyrolytic graphite (HOPG), evaluating the surface behavior under both ORR and OER conditions in 0.1 M KOH. We use noise analysis in electrochemical scanning tunneling microscopy (n-EC-STM) to monitor and compare ORR and OER active sites with resolution down to the nanoscale. Furthermore, surface degradation can be evaluated during the operation. We find that close to the respective reaction onset, step sites and defects are active for both ORR and OER. Terraces sites are largely inactive and only become involved in the OER at higher potentials. This could imply corrosion of the carbon. However, since the observed surface structures remain unaltered before and after applying the OER in our experiments, we find no clear evidence of surface destruction. These fundamental insights could inspire further research concerning the active sites and stability of carbon-based catalysts as well as carbon support structures, to discover ways to tune the surface activity and stability to the dedicated purpose.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Assessment of active areas for the oxygen evolution reaction on an amorphous iridium oxide surface},

author = {R M Kluge and R W Haid and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S0021951721000531},

doi = {https://doi.org/10.1016/j.jcat.2021.02.007},

issn = {0021-9517},

year  = {2021},

date = {2021-04-01},

urldate = {2021-04-01},

journal = {Journal of Catalysis},

volume = {396},

pages = {14-22},

abstract = {Electrocatalytic “green” production of hydrogen from water for sustainable energy provision schemes is currently inefficient due to the sluggish kinetics of the oxygen evolution reaction (OER) at the anodes of the electrolysers. In the case of acidic polymer electrolyte membrane electrolysers, iridium (Ir) oxide catalysts pose a promising compromise between good OER activity and stability. However, the structure\textendashactivity relations for these materials remain largely unknown because the surface of a “real” oxide catalyst under reaction conditions becomes amorphous. In order to contribute to the understanding of these systems, we use electrochemical scanning tunnelling microscopy under reaction conditions (‘noise’ or n-EC-STM). With this technique, active areas can be detected by an increased noise level of the STM signal compared to inactive sites. The n-EC-STM measurements are applied to an amorphous iridium oxide surface, which is formed during electrochemical cycling of Ir(111). By doing so, we can monitor OER activity in-situ while simultaneously assessing the surface morphology. In order to elucidate the active areas, step and terrace sites were quantitatively compared to each other. The measurements reveal that terraces, step sites and concavities lead to a similar noise level increase in the STM signal. We, thus, conclude that the OER on the amorphous extended iridium oxide surface shows little structure-sensitivity. Subsequently, we suggest that in contrast to, e.g., metallic Pt for the oxygen electro-reduction, the shape of amorphous IrOx nanoparticles in an acidic medium should not significantly influence the OER turnover frequency.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Monitoring the active sites for the hydrogen evolution reaction at model carbon surfaces},

author = {R Kluge and R W Haid and I Stephens and F Calle-Vallejo and A S Bandarenka},

url = {http://dx.doi.org/10.1039/D1CP00434D},

doi = {10.1039/D1CP00434D},

issn = {1463-9076},

year  = {2021},

date = {2021-03-25},

urldate = {2021-03-25},

journal = {Physical Chemistry Chemical Physics},

volume = {23},

pages = {10051-10058},

abstract = {Carbon is ubiquitous as an electrode material in electrochemical energy conversion devices. If used as support material, the evolution of H2 is undesired on carbon. However, recently carbon-based materials are of high interest as economic and eco-conscious alternative to noble metal catalysts. The targeted design of improved carbon electrode materials requires atomic scale insight into the structure of the sites that catalyse H2 evolution. This work demonstrates that electrochemical scanning tunnelling microscopy under reaction conditions (n-EC-STM) can monitor active sites of highly oriented pyrolytic graphite for the hydrogen evolution reaction. With down to atomic resolution, the most active sites in acidic medium are pinpointed near edge sites and defects, whereas the basal planes remain inactive. Density functional theory calculations support these findings and reveal that only specific defects on graphite are active. Motivated by these results, the extensive usage of n-EC-STM on doped carbon-based materials is encouraged to locate their active sites and guide the synthesis of enhanced electrocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Investigation of degradation mechanisms in PEM fuel cells caused by low-temperature cycles},

author = {J P Sabawa and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S0360319921005917},

doi = {https://doi.org/10.1016/j.ijhydene.2021.02.088},

issn = {0360-3199},

year  = {2021},

date = {2021-03-05},

urldate = {2021-03-05},

journal = {International Journal of Hydrogen Energy},

volume = {46},

pages = {15951-15964},

abstract = {Environmental influences, especially temperatures below the freezing point, can affect the performance and long-term stability of PEMFCs. Within the scope of this research, a completely new test procedure was developed to characterize PEMFC single cells with respect to their long-term stability at temperature cycles between 80 °C and −10 °C. Using this procedure, the behavior of PEMFC single cells (active surface area of 43.6 cm2) with different cathode-ionomer-to-carbon (I/C) weight ratios (0.5/1.0/1.5) was evaluated. The generated in-situ measurement data clearly demonstrate that the performance of each PEMFC single cell changes individually as a function of the cathode I/C-ratio during the 120 stress cycles. While the MEA with an I/C ratio of 0.5 showed a power loss of ~1.49%, the MEAs with an I/C ratio of 1.0 and 1.5 showed a power loss of about ~7.75% and ~24.7%, respectively. The subsequent post-mortem ex-situ analyses clearly showed how the test procedure and the different I/C-ratios affected the changes in the catalyst layers (CL). The destructive mechanisms responsible for the changes can be divided into two categories: One part was driven by rapid enthalpy change leading to mechanical failure, and the other part, which led to the reduction of cathode CL thickness, was driven by rapid potential changes and potential shifts (overpotentials). This reduction in cathode CL thickness ultimately leads to an accumulation and excessive load of ionomer in the direction of GDL, resulting in a reduction in pore size, a shift in the core reaction area, and high O2 transport resistance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The Potential of Zero Charge and the Electrochemical Interface Structure of Cu(111) in Alkaline Solutions},

author = {A Auer and X Ding and A S Bandarenka and J Kunze-Liebh\"{a}user},

url = {https://doi.org/10.1021/acs.jpcc.0c09289},

doi = {10.1021/acs.jpcc.0c09289},

issn = {1932-7447},

year  = {2021},

date = {2021-03-01},

urldate = {2021-03-01},

journal = {The Journal of Physical Chemistry C},

volume = {125},

pages = {5020-5028},

abstract = {Copper (Cu) is a unique electrocatalyst, which is able to efficiently oxidize CO at very low overpotentials and reduce CO2 to valuable fuels with reasonable Faradaic efficiencies. Yet, knowledge of its electrochemical properties at the solid/liquid interface is still scarce. Here, we present the first two-stranded correlation of the potential of zero free charge (pzfc) of Cu(111) in alkaline electrolyte at different pH values through application of nanosecond laser pulses and the corresponding interfacial structure changes by in situ electrochemical scanning tunneling microscopy imaging. The pzfc of Cu(111) at pH 13 is identified at −0.73 VSHE in the apparent double layer region, prior to the onset of hydroxide adsorption. It shifts by (88 ± 4) mV to more positive potentials per decreasing pH unit. At the pzfc, Cu(111) shows structural dynamics at both pH 13 and pH 11, which can be understood as the onset of surface restructuring. At higher potentials, full reconstruction and electric field dependent OH adsorption occurs, which causes a remarkable decrease in the atomic density of the first Cu layer. The expansion of the Cu\textendashCu distance to 0.3 nm generates a hexagonal Moir\'{e} pattern, on which the adsorbed OH forms a commensurate (1 × 2) adlayer structure with a steady state coverage of 0.5 monolayers at pH 13. Our experimental findings shed light on the true charge distribution and its interrelation with the atomic structure of the electrochemical interface of Cu.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Properties of the Space Charge Layers Formed in Li-Ion Conducting Glass Ceramics},

author = {L Katzenmeier and S Helmer and S Braxmeier and E Knobbe and A S Bandarenka},

url = {https://doi.org/10.1021/acsami.0c21304},

doi = {10.1021/acsami.0c21304},

issn = {1944-8244},

year  = {2021},

date = {2021-02-03},

journal = {ACS Applied Materials \& Interfaces},

volume = {13},

number = {4},

pages = {5853-5860},

abstract = {For years, the space charge layer formation in Li-conducting solid electrolytes and its relevance to so-called all solid-state batteries have been controversially discussed from experimental and theoretical perspectives. In this work, we observe the phenomenon of space charge layer formation using impedance spectroscopy at different electrode polarizations. We analyze the properties of these space charge layers using a physical equivalent circuit describing the response of the solid electrolytes and solid/solid electrified interfaces under blocking conditions. The elements corresponding to the interfacial layers are identified and analyzed with different electrode metals and applied biases. The effective thickness of the space charge layer was calculated to be ∼60 nm at a bias potential of 1 V. In addition, it was possible to estimate the relative permittivity of the electrolytes, specific resistance of the space charge layer, and the effective thickness of the electric double layer (∼0.7 nm).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Electrochemical top-down synthesis of C-supported Pt nano-particles with controllable shape and size: Mechanistic insights and application},

author = {B Garlyyev and S Watzele and J Fichtner and J Michali\v{c}ka and A Sch\"{o}kel and A Senyshyn and A Perego and D Pan and H A El-Sayed and J M Macak and P Atanassov and I V Zenyuk and A S Bandarenka},

url = {https://doi.org/10.1007/s12274-020-3281-z},

doi = {10.1007/s12274-020-3281-z},

issn = {1998-0000},

year  = {2020},

date = {2020-12-29},

journal = {Nano Research},

volume = {14},

number = {8},

pages = {2762-2769},

abstract = {In this work, we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes (in the range from ~ 2 to ~ 10 nm). Carbon supported nanoparticles with narrow size distributions have been synthesized by applying an alternating voltage to macroscopic bulk platinum structures, such as disks or wires. Without using any surfactants, the size and shape of the particles can be changed by adjusting simple parameters such as the applied potential, frequency and electrolyte composition. For instance, application of a sinusoidal AC voltage with lower frequencies results in cubic nanoparticles; whereas higher frequencies lead to predominantly spherical nanoparticles. On the other hand, the amplitude of the sinusoidal signal was found to affect the particle size; the lower the amplitude of the applied AC signal, the smaller the resulting particle size. Pt/C catalysts prepared by this approach showed 0.76 A/mg mass activity towards the oxygen reduction reaction which is ~ 2 times higher than the state-of-the-art commercial Pt/C catalyst (0.42 A/mg) from Tanaka. In addition to this, we discussed the mechanistic insights about the nanoparticle formation pathways.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In Situ Quantification of the Local Electrocatalytic Activity via Electrochemical Scanning Tunneling Microscopy},

author = {R W Haid and R M Kluge and Y Liang and A S Bandarenka},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smtd.202000710},

doi = {https://doi.org/10.1002/smtd.202000710},

issn = {2366-9608},

year  = {2020},

date = {2020-09-29},

journal = {Small Methods},

volume = {5},

number = {2},

pages = {2000710},

abstract = {Abstract Identification of catalytically active sites at solid/liquid interfaces under reaction conditions is an essential task to improve the catalyst design for sustainable energy devices. Electrochemical scanning tunneling microscopy (EC-STM) combines the control of the surface reactions with imaging on a nanoscale. When performing EC-STM under reaction conditions, the recorded analytical signal shows higher fluctuations (noise) at active sites compared to non-active sites (noise-EC-STM or n-EC-STM). In the past, this approach has been proven as a valid tool to identify the location of active sites. In this work, the authors show that this method can be extended to obtain quantitative information of the local activity. For the platinum(111) surface under oxygen reduction reaction conditions, a linear relationship between the STM noise level and a measure of reactivity, the turn-over frequency is found. Since it is known that the most active sites for this system are located at concave sites, the method has been applied to quantify the activity at steps. The obtained activity enhancement factors appeared to be in good agreement with the literature. Thus, n-EC-STM is a powerful method not only to in situ identify the location of active sites but also to determine and compare local reactivity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Real-Time Impedance Analysis for the On-Road Monitoring of Automotive Fuel Cells},

author = {T Lochner and M Perchthaler and J T Binder and J P Sabawa and T A Dao and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202000510},

doi = {https://doi.org/10.1002/celc.202000510},

issn = {2196-0216},

year  = {2020},

date = {2020-06-09},

journal = {ChemElectroChem},

volume = {7},

number = {13},

pages = {2784-2791},

abstract = {Abstract The on-road monitoring of polymer electrolyte membrane fuel cells (PEMFCs) in automotive systems optimizes their efficiency and fuel consumption in addition to increasing their lifetime. In this work, electrochemical impedance spectroscopy (EIS) measurements and special EIS data analysis algorithms were used to quickly identify fuel cell operational modes and failures during cell operation. The approach developed enables the measurement and analysis time of only a few seconds and allows the accurate extraction of information about the membrane and charge transfer resistance. The data analysis procedures show similar accuracy to that of the complex non-linear least square fitting algorithms. As a result, typical operational failures like air and hydrogen starvation were able to be easily distinguished, and different operational states (membrane humidification, air stoichiometry) of the PEMFCs could be identified.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Temperature Effects in Polymer Electrolyte Membrane Fuel Cells},

author = {T Lochner and R M Kluge and J Fichtner and H A El-Sayed and B Garlyyev and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000546625300001},

doi = {10.1002/celc.202000588},

issn = {2196-0216},

year  = {2020},

date = {2020-06-05},

journal = {Chemelectrochem},

abstract = {The behavior of proton exchange membrane fuel cells (PEMFCs) strongly depends on the operational temperatures. In mobile applications, for instance in fuel cell electric vehicles, PEMFC stacks are often subjected to temperatures as low as -20 degrees C, especially during cold start periods, and to temperatures up to 120 degrees C during regular operation. Therefore, it is important to understand the impact of temperature on the performance and degradation of hydrogen fuel cells to ensure a stable system operation. To get a comprehensive understanding of the temperature effects in PEMFCs, this manuscript addresses and summarizesin- situandex- situinvestigations of fuel cells operated at different temperatures. Initially, different measurement techniques for thermal monitoring are presented. Afterwards, the temperature effects related to the degradation and performance of main membrane electrode assembly components, namely gas diffusion layers, proton exchange membranes and catalyst layers, are analyzed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Prospects of Value-Added Chemicals and Hydrogen via Electrolysis},

author = {B Garlyyev and S Xue and J Fichtner and A S Bandarenka and C Andronescu},

url = {\<Go to ISI\>://WOS:000520259100001},

doi = {10.1002/cssc.202000339},

issn = {1864-5631},

year  = {2020},

date = {2020-05-22},

journal = {Chemsuschem},

volume = {13},

number = {10},

pages = {2513-2521},

abstract = {Cost is a major drawback that limits the industrial-scale hydrogen production through water electrolysis. The overall cost of this technology can be decreased by coupling the electrosynthesis of value-added chemicals at the anode side with electrolytic hydrogen generation at the cathode. This Minireview provides a directory of anodic oxidation reactions that can be combined with cathodic hydrogen generation. The important parameters for selecting the anodic reactions, such as choice of catalyst material and its selectivity towards specific products are elaborated in detail. Furthermore, various novel electrolysis cell architectures for effortless separation of value-added products from hydrogen gas are described.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {How the Nature of the Alkali Metal Cations Influences the Double-Layer Capacitance of Cu, Au, and Pt Single-Crystal Electrodes},

author = {S Xue and B Garlyyev and A Auer and J Kunze-Liebhauser and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000541745800029},

doi = {10.1021/acs.jpcc.0c01715},

issn = {1932-7447},

year  = {2020},

date = {2020-05-09},

journal = {Journal of Physical Chemistry C},

volume = {124},

number = {23},

pages = {12442-12447},

abstract = {In this work, we have investigated the influence of alkali metal cations on the electrical double-layer (EDL) properties for various metal electrodes. Using electrochemical impedance spectroscopy, we demonstrate that those cations significantly affect the EDL capacitance in the case of single-crystalline Cu(111), Cu(100), Au(111), Pt(111), stepped Pt(775), and kinked Pt(12 10 5) electrodes in 0.05 M MeClO4 (Me+ = Li+, Na+, K+, Rb+, and Cs+) electrolytes. For all the electrodes, the capacitance always linearly increases with decreasing hydration energy of Me+ in the following order: Li+ \< Na+ \< K+ \< Rb+ \< Cs+. Moreover, we estimate the effective concentrations of the alkali metal cations near the electrode surfaces by correlating the capacitances with the relative permittivity. For all the electrodes, the concentrations near the electrode surface were calculated to be similar to 60 to 80 times higher than in the bulk solutions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Tailoring the Oxygen Reduction Activity of Pt Nanoparticles through Surface Defects: A Simple Top-Down Approach},

author = {J Fichtner and S Watzele and B Garlyyev and R M Kluge and F Haimerl and H A El-Sayed and W J Li and F M Maillard and L Dubau and R Chattot and J Michalicka and J M Macak and W Wang and D Wang and T Gigl and C Hugenschmidt and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000518876300024},

doi = {10.1021/acscatal.9b04974},

issn = {2155-5435},

year  = {2020},

date = {2020-03-06},

urldate = {2020-03-06},

journal = {Acs Catalysis},

volume = {10},

number = {5},

pages = {3131-3142},

abstract = {Results from Pt model catalyst surfaces have demonstrated that surface defects, in particular surface concavities, can improve the oxygen reduction reaction (ORR) kinetics. It is, however, a challenging task to synthesize nanostructured catalysts with such defective surfaces. Hence, we present a one-step and upscalable top-down approach to produce a Pt/C catalyst (with similar to 3 nm Pt nanoparticle diameter). Using high-resolution transmission electron microscopy and tomography, electrochemical techniques, high-energy X-ray measurements, and positron annihilation spectroscopy, we provide evidence of a high density of surface defects (including surface concavities). The ORR activity of the developed catalyst exceeds that of a commercial Pt/C catalyst, at least 2.7 times in terms of specific activity (similar to 1.62 mA/cm(Pt)(2), at 0.9 V vs the reversible hydrogen electrode) and at least 1.7 times in terms of mass activity (similar to 712 mA/mg(Pt)), which can be correlated to the enhanced amount of surface defects. In addition, the technique used here reduces the complexity of the synthesis (and therefore production costs) in comparison to state of the art bottom-up techniques.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Oxygen Reduction Activities of Strained Platinum Core\textendashShell Electrocatalysts Predicted by Machine Learning},

author = {M R\"{u}ck and B Garlyyev and F Mayr and A S Bandarenka and A Gagliardi},

url = {https://doi.org/10.1021/acs.jpclett.0c00214},

doi = {10.1021/acs.jpclett.0c00214},

year  = {2020},

date = {2020-02-14},

urldate = {2020-02-14},

journal = {The Journal of Physical Chemistry Letters},

volume = {11},

pages = {1773-1780},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Advanced Bifunctional Oxygen Reduction and Evolution Electrocatalyst Derived from Surface-Mounted Metal-Organic Frameworks},

author = {W J Li and S Xue and S Watzele and S J Hou and J Fichtner and A L Semrau and L J Zhou and A Welle and A S Bandarenka and R A Fischer},

url = {\<Go to ISI\>://WOS:000509752400001},

doi = {10.1002/anie.201916507},

issn = {1433-7851},

year  = {2020},

date = {2020-01-08},

journal = {Angewandte Chemie-International Edition},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Determination of Electroactive Surface Area of Ni-, Co-, Fe-, and Ir-Based Oxide Electrocatalysts},

author = {S Watzele and P Hauenstein and Y C Liang and S Xue and J Fichtner and B Garlyyev and D Scieszka and F Claude and F Maillard and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000489204000043},

doi = {10.1021/acscatal.9b02006},

issn = {2155-5435},

year  = {2019},

date = {2019-08-30},

journal = {Acs Catalysis},

volume = {9},

number = {10},

pages = {9222-9230},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Recent Approaches to Design Electrocatalysts Based on Metal\textendashOrganic Frameworks and Their Derivatives},

author = {J Liu and S Hou and W Li and A S Bandarenka and R A Fischer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/asia.201900748},

doi = {https://doi.org/10.1002/asia.201900748},

issn = {1861-4728},

year  = {2019},

date = {2019-08-20},

journal = {Chemistry \textendash An Asian Journal},

volume = {14},

number = {20},

pages = {3474-3501},

abstract = {Abstract Rational design and synthesis of efficient electrocatalysts are important constituents in addressing the currently growing provision issues. Typical reactions, which are important to catalyze in this respect, include CO2 reduction, the hydrogen and oxygen evolution reactions as well as the oxygen reduction reaction. The most efficient catalysts known up-to-date for these processes usually contain expensive and scarce elements, substantially impeding implementation of such electrocatalysts at a larger scale. Metal-organic frameworks (MOFs) and their derivatives containing affordable components and building blocks, as an emerging class of porous functional materials, have been recently attracting a great attention thanks to their tunable structure and composition together with high surface area, just to name a few. Up to now, several MOFs and MOF-derivatives have been reported as electrode materials for the energy-related electrocatalytic application. In this review article, we summarize and analyze current approaches to design such materials. The design strategies to improve the Faradaic efficiency and selectivity of these catalysts are discussed. Last but not least, we discuss some novel strategies to enhance the conductivity, chemical stability and efficiency of MOF-derived electrocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {A Cell for Controllable Formation and In Operando Electrochemical Characterization of Intercalation Materials for Aqueous Metal-Ion Batteries},

author = {P Marzak and P Moser and S Schreier and D Scieszka and J Yun and O Schneider and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000481312300001},

doi = {10.1002/smtd.201900445},

issn = {2366-9608},

year  = {2019},

date = {2019-08-16},

urldate = {2019-08-16},

journal = {Small Methods},

volume = {3},

pages = {1900445},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Revealing the nature of active sites in electrocatalysis},

author = {B Garlyyev and J Fichtner and O Pique and O Schneider and A S Bandarenka and F Calle-Vallejo},

url = {\<Go to ISI\>://WOS:000486045200001},

doi = {10.1039/c9sc02654a},

issn = {2041-6520},

year  = {2019},

date = {2019-07-23},

journal = {Chemical Science},

volume = {10},

number = {35},

pages = {8060-8075},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {In-situ visualization of hydrogen evolution sites on helium ion treated molybdenum dichalcogenides under reaction conditions},

author = {E Mitterreiter and Y Liang and M Golibrzuch and D Mclaughlin and C Csoklich and J D Bartl and A W Holleitner and U Wurstbauer and A S Bandarenka},

url = {https://doi.org/10.1038/s41699-019-0107-5},

doi = {10.1038/s41699-019-0107-5},

issn = {2397-7132},

year  = {2019},

date = {2019-07-15},

journal = {npj 2D Materials and Applications},

volume = {3},

number = {1},

pages = {25},

abstract = {Nanostructured 2D transition metal dichalcogenides play an increasingly important role in heterogeneous catalysis. These materials are abundant (co-)catalysts with tunable properties to catalyze a number of key reactions related to energy provision, for instance the hydrogen evolution reaction (HER). It is vital to understand which surface sites are active in order to maximize their number and to improve the overall (photo-)catalytic behavior of those materials. Here, we visualize these active sites under HER conditions at the surface of molybdenum dichalcogenides (MoX2, X = Se, S) with lateral resolution on the nanometer scale by means of electrochemical scanning tunneling microscopy. The edges of single MoX2 flakes show high catalytic activity, whereas their terraces are inactive. We demonstrate how the inert basal planes of these materials can be activated towards the HER with the help of a focused beam of a He-ion microscope. Our findings demonstrate that the He-ion induced defects contribute at lower overpotentials to the HER, while the activity of the edges exceeds the activity of the basal defects for sufficiently high overpotentials. Given the lithographic resolution of the helium ion microscope, our results show the possibility to generate active sites in transition metal dichalcogenides with a spatial resolution below a few nanometers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Degradation mechanisms in polymer electrolyte membrane fuel cells caused by freeze-cycles: Investigation using electrochemical impedance spectroscopy},

author = {J P Sabawa and A S Bandarenka},

url = {http://www.sciencedirect.com/science/article/pii/S0013468619307881},

doi = {https://doi.org/10.1016/j.electacta.2019.04.102},

issn = {0013-4686},

year  = {2019},

date = {2019-07-10},

journal = {Electrochimica Acta},

volume = {311},

pages = {21-29},

abstract = {The performance of the polymer electrolyte membrane (PEM) fuel cells is sensitive to the exposure of these devices to subzero temperatures. In general, it is important to precondition the fuel cells prior to the shut-down preventing degradation after the start-up. Standard tests with conventional climatic chambers are nowadays costly and very time consuming. In this work, we introduce a method, which uses a simplified process with a PEM single-cell. The new design uses a Peltier-Element-Tempered (PET) single-cell with an active area size of 43.56 cm2. Now it is possible to achieve efficient and temperature controlled cold starts without a climate chamber or chiller plant. With the PET-controlled single cell, it was possible to do a series of complex accelerated freeze stress tests within the shortest time. To classify the performance change, polarization curves, cyclic voltammetry with the CV-CO-stripping method and Electrochemical Impedance Spectroscopy (EIS) at different current densities were performed. The measured impedance spectra were analyzed with a physical impedance model consisting of only 6 equivalent circuit elements. The charge-transfer resistance and the parameters of the Warburg diffusion element clearly reveal irreversible changes of the cathode during repeated freeze-cycles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Optimizing the Size of Platinum Nanoparticles for Enhanced Mass Activity in the Electrochemical Oxygen Reduction Reaction},

author = {B Garlyyev and K Kratzl and M R\"{u}ck and J Michali\v{c}ka and J Fichtner and J M Macak and T Kratky and S G\"{u}nther and M Cokoja and A S Bandarenka and A Gagliardi and R A Fischer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201904492},

doi = {10.1002/anie.201904492},

issn = {1433-7851},

year  = {2019},

date = {2019-05-03},

journal = {Angewandte Chemie International Edition},

volume = {58},

number = {28},

pages = {9596-9600},

abstract = {Abstract High oxygen reduction (ORR) activity has been for many years considered as the key to many energy applications. Herein, by combining theory and experiment we prepare Pt nanoparticles with optimal size for the efficient ORR in proton-exchange-membrane fuel cells. Optimal nanoparticle sizes are predicted near 1, 2, and 3 nm by computational screening. To corroborate our computational results, we have addressed the challenge of approximately 1 nm sized Pt nanoparticle synthesis with a metal\textendashorganic framework (MOF) template approach. The electrocatalyst was characterized by HR-TEM, XPS, and its ORR activity was measured using a rotating disk electrode setup. The observed mass activities (0.87±0.14 A mgPt−1) are close to the computational prediction (0.99 A mgPt−1). We report the highest to date mass activity among pure Pt catalysts for the ORR within similar size range. The specific and mass activities are twice as high as the Tanaka commercial Pt/C catalysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Unprecedented High Oxygen Evolution Activity of Electrocatalysts Derived from Surface-Mounted Metal\textendashOrganic Frameworks},

author = {W Li and S Watzele and H A El-Sayed and Y Liang and G Kieslich and A S Bandarenka and K Rodewald and B Rieger and R A Fischer},

url = {https://doi.org/10.1021/jacs.9b00549},

doi = {10.1021/jacs.9b00549},

issn = {0002-7863},

year  = {2019},

date = {2019-03-19},

journal = {Journal of the American Chemical Society},

volume = {141},

number = {14},

pages = {5926-5933},

abstract = {The oxygen evolution reaction (OER) is a key process for renewable energy storage. However, developing non-noble metal OER electrocatalysts with high activity, long durability and scalability remains a major challenge. Herein, high OER activity and stability in alkaline solution were discovered for mixed nickel/cobalt hydroxide electrocatalysts, which were derived in one-step procedure from oriented surface-mounted metal\textendashorganic framework (SURMOF) thin films that had been directly grown layer-by-layer on macro- and microelectrode substrates. The obtained mass activity of ∼2.5 mA·μg\textendash1 at the defined overpotential of 300 mV is 1 order of magnitude higher than that of the benchmarked IrO2 electrocatalyst and at least 3.5 times higher than the mass activity of any state-of-the-art NiFe-, FeCoW-, or NiCo-based electrocatalysts reported in the literature. The excellent morphology of the SURMOF-derived ultrathin electrocatalyst coating led to a high exposure of the most active Ni- and Co-based sites.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Top-Down Synthesis of Nanostructured Platinum\textendashLanthanide Alloy Oxygen Reduction Reaction Catalysts: PtxPr/C as an Example},

author = {J Fichtner and B Garlyyev and S Watzele and H A El-Sayed and J N Schw\"{a}mmlein and W-J Li and F M Maillard and L Dubau and J Michali\v{c}ka and J M Macak and A W Holleitner and A S Bandarenka},

url = {https://doi.org/10.1021/acsami.8b20174},

doi = {10.1021/acsami.8b20174},

issn = {1944-8244},

year  = {2019},

date = {2019-02-06},

journal = {ACS Applied Materials \& Interfaces},

volume = {11},

number = {5},

pages = {5129-5135},

abstract = {The oxygen reduction reaction (ORR) is of great interest for future sustainable energy conversion and storage, especially concerning fuel cell applications. The preparation of active, affordable, and scalable electrocatalysts and their application in fuel cell engines of hydrogen cars is a prominent step toward the reduction of air pollution, especially in urban areas. Alloying nanostructured Pt with lanthanides is a promising approach to enhance its catalytic ORR activity, whereby the development of a simple synthetic route turned out to be a nontrivial endeavor. Herein, for the first time, we present a successful single-step, scalable top-down synthetic route for Pt\textendashlanthanide alloy nanoparticles, as witnessed by the example of Pr-alloyed Pt nanoparticles. The catalyst was characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and photoelectron spectroscopy, and its electrocatalytic oxygen reduction activity was investigated using a rotating disk electrode technique. PtxPr/C showed ∼3.5 times higher [1.96 mA/cm2Pt, 0.9 V vs reversible hydrogen electrode (RHE)] specific activity and ∼1.7 times higher (0.7 A/mgPt, 0.9 V vs RHE) mass activity compared to commercial Pt/C catalysts. On the basis of previous findings and characterization of the PtxPr/C catalyst, the activity improvement over commercial Pt/C originates from a lattice strain introduced by the alloying process.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Oxygen Reduction Reaction: Rapid Prediction of Mass Activity of Nanostructured Platinum Electrocatalysts},

author = {M R\"{u}ck and A S Bandarenka and F Calle-Vallejo and A Gagliardi},

url = {https://doi.org/10.1021/acs.jpclett.8b01864},

doi = {10.1021/acs.jpclett.8b01864},

year  = {2018},

date = {2018-07-20},

urldate = {2018-07-20},

journal = {The Journal of Physical Chemistry Letters},

volume = {9},

number = {15},

pages = {4463-4468},

abstract = {Tailored Pt nanoparticle catalysts are promising candidates to accelerate the oxygen reduction reaction (ORR) in fuel cells. However, the search for active nanoparticle catalysts is hindered by the laborious effort of experimental synthesis and measurements. On the other hand, density functional theory-based approaches are still time-consuming and often not efficient. In this study, we introduce a computational model which enables rapid catalytic activity calculation of unstrained pure Pt nanoparticle electrocatalysts. Regarding particle size effects on Pt nanoparticles, experimental catalytic mass activities from previous studies are accurately reproduced by our computational model. Moreover, beyond available experiments, our computational model identifies potential enhancement in mass activity up to 190% over the experimentally detected maximum. Importantly, the rapid activity calculation enabled by our computational model may pave the way for extensive nanoparticle screening to expedite the search for improved electrocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}