Publications

@article{,

title = {Revealing Nanoscale Chemical Heterogeneities in Polycrystalline Mo-BiVO(4)Thin Films},

author = {J Eichhorn and S E Reyes-Lillo and S Roychoudhury and S Sallis and J Weis and D M Larson and J K Cooper and I D Sharp and D Prendergast and F M Toma},

url = {\<Go to ISI\>://WOS:000555446200001},

doi = {10.1002/smll.202001600},

issn = {1613-6810},

year  = {2020},

date = {2020-08-01},

urldate = {2020-08-01},

journal = {Small},

volume = {16},

pages = {2001600},

abstract = {The activity of polycrystalline thin film photoelectrodes is impacted by local variations of the material properties due to the exposure of different crystal facets and the presence of grain/domain boundaries. Here a multi-modal approach is applied to correlate nanoscale heterogeneities in chemical composition and electronic structure with nanoscale morphology in polycrystalline Mo-BiVO4. By using scanning transmission X-ray microscopy, the characteristic structure of polycrystalline film is used to disentangle the different X-ray absorption spectra corresponding to grain centers and grain boundaries. Comparing both spectra reveals phase segregation of V(2)O(5)at grain boundaries of Mo-BiVO(4)thin films, which is further supported by X-ray photoelectron spectroscopy and many-body density functional theory calculations. Theoretical calculations also enable to predict the X-ray absorption spectral fingerprint of polarons in Mo-BiVO4. After photo-electrochemical operation, the degraded Mo-BiVO(4)films show similar grain center and grain boundary spectra indicating V(2)O(5)dissolution in the course of the reaction. Overall, these findings provide valuable insights into the degradation mechanism and the impact of material heterogeneities on the material performance and stability of polycrystalline photoelectrodes.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Key Factor Study for Amphiphilic Block Copolymer-Templated Mesoporous SnO(2)Thin Film Synthesis: Influence of Solvent and Catalyst},

author = {S S Yin and T Tian and K S Wienhold and C L Weindl and R J Guo and M Schwartzkopf and S V Roth and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000550676200001},

doi = {10.1002/admi.202001002},

issn = {2196-7350},

year  = {2020},

date = {2020-07-21},

journal = {Advanced Materials Interfaces},

abstract = {As a crucial material in the field of energy storage, SnO(2)thin films are widely applied in daily life and have been in the focus of scientific research. Compared to the planar counterpart, mesoporous SnO(2)thin films with high specific surface area possess more attractive physical and chemical properties. In the present work, a novel amphiphilic block copolymer-assisted sol-gel chemistry is utilized for the synthesis of porous tin oxide (SnO2). Two key factors for the sol-gel stock solution preparation, the solvent category and the catalyst content, are systematically varied to tune the thin film morphologies. A calcination process is performed to remove the polymer template at 500 degrees C in ambient conditions. The surface morphology and the buried inner structure are probed with scanning electron microscope and grazing-incidence small-angle X-ray scattering. Crystallinity is characterized by X-ray diffraction. The multi-dimensional characterization results suggest that cassiterite SnO(2)with spherical, cylindrical, and vesicular pore structures are obtained. The variation of the film morphology is governed by the preferential affinity of the utilized solvent mixture and the hydrogen bond interaction between the employed cycloether and H2O molecules in the solution.},

keywords = {Foundry Inorganic, Solid-Liquid},

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 = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Important components for accurate hyperfine coupling constants: electron correlation, dynamic contributions, and solvation effects},

author = {S Vogler and J C B Dietschreit and L D M Peters and C Ochsenfeld},

url = {\<Go to ISI\>://WOS:000543577500001},

doi = {10.1080/00268976.2020.1772515},

issn = {0026-8976},

year  = {2020},

date = {2020-06-03},

journal = {Molecular Physics},

abstract = {The calculation of hyperfine coupling constants is a challenging task in balancing accuracy and computational effort. While previous work has shown the importance of electron correlation and molecular dynamic contributions, we present a systematic study simultaneously analyzing the influence of both effects on hyperfine coupling constants. To this end, we thoroughly study two organic radicals, namely the dimethylamino radical and ethanal radical cation, proving the need to account for conformational flexibility as well as the large influence of electron correlation. Based on these results, we analyse the effect of electron correlation and dynamic simulations on a set of 12 organic radicals, illustrating that both effects are vital for an accuratein silicodescription on the same scale. Furthermore, we study the influence of solvation using the efficient nuclei-selected algorithm to obtain hyperfine coupling constants with electron correlation for large systems, indicating the necessity to include explicit solvent molecules. Finally, we introduce a composite approach to incorporate all contributions for hyperfine coupling of radicals in solution at comparatively low computational cost. This is successfully tested on the hydroxylated TEMPO radical in aqueous solution, where we are able to compute aN-HFCC of 44.4 MHz compared to the experimentally measured 47.6 MHz. [GRAPHICS] .},

keywords = {Solid-Liquid},

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 = {Foundry Inorganic, Solid-Liquid},

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 = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Enhancing Hydrogen Evolution Activity of Au(111) in Alkaline Media through Molecular Engineering of a 2D Polymer},

author = {P Alexa and J M Lombardi and P Abufager and H F Busnengo and D Grumelli and V S Vyas and F Haase and B V Lotsch and R Gutzler and K Kern},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201915855},

doi = {10.1002/anie.201915855},

issn = {1433-7851},

year  = {2020},

date = {2020-05-05},

journal = {Angewandte Chemie International Edition},

volume = {n/a},

number = {n/a},

abstract = {Abstract The electrochemical splitting of water holds promise for the storage of energy produced intermittently by renewable energy sources. The evolution of hydrogen currently relies on the use of platinum as a catalyst\textemdashwhich is scarce and expensive\textemdashand ongoing research is focused towards finding cheaper alternatives. In this context, 2D polymers grown as single layers on surfaces have emerged as porous materials with tunable chemical and electronic structures that can be used for improving the catalytic activity of metal surfaces. Here, we use designed organic molecules to fabricate covalent 2D architectures by an Ullmann-type coupling reaction on Au(111). The polymer-patterned gold electrode exhibits a hydrogen evolution reaction activity up to three times higher than that of bare gold. Through rational design of the polymer on the molecular level we engineered hydrogen evolution activity by an approach that can be easily extended to other electrocatalytic reactions.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Lateral silicon oxide/gold interfaces enhance the rate of electrochemical hydrogen evolution reaction in alkaline media},

author = {T L Maier and M Golibrzuch and S Mendisch and W Schindler and M Becherer and K Krischer},

url = {\<Go to ISI\>://WOS:000529243500002},

doi = {10.1063/5.0003295},

issn = {0021-9606},

year  = {2020},

date = {2020-04-21},

journal = {Journal of Chemical Physics},

volume = {152},

number = {15},

abstract = {The production of solar hydrogen with a silicon based water splitting device is a promising future technology, and silicon-based metal-insulator-semiconductor (MIS) electrodes have been proposed as suitable architectures for efficient photocathodes based on the electronic properties of the MIS structures and the catalytic properties of the metals. In this paper, we demonstrate that the interfaces between the metal and oxide of laterally patterned MIS electrodes may strongly enhance the catalytic activity of the electrode compared to bulk metal surfaces. The employed electrodes consist of well-defined, large-area arrays of gold structures of various mesoscopic sizes embedded in a silicon oxide support on silicon. We demonstrate that the activity of these electrodes for hydrogen evolution reaction (HER) increases with an increase in gold/silicon oxide boundary length in both acidic and alkaline media, although the enhancement of the HER rate in alkaline electrolytes is considerably larger than in acidic electrolytes. Electrodes with the largest interfacial length of gold/silicon oxide exhibited a 10-times larger HER rate in alkaline electrolytes than those with the smallest interfacial length. The data suggest that at the metal/silicon oxide boundaries, alkaline HER is enhanced through a bifunctional mechanism, which we tentatively relate to the laterally structured electrode geometry and to positive charges present in silicon oxide: Both properties change locally the interfacial electric field at the gold/silicon oxide boundary, which, in turn, facilitates a faster transport of hydroxide ions away from the electrode/electrolyte interface in alkaline solution. This mechanism boosts the alkaline HER activity of p-type silicon based photoelectrodes close to their HER activity in acidic electrolytes.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Control of Band Gap and Band Edge Positions in Gallium-Zinc Oxynitride Grown by Molecular Beam Epitaxy},

author = {M Kraut and E Sirotti and F Pantle and C M Jiang and G Grotzner and M Koch and L I Wagner and I D Sharp and M Stutzmann},

url = {\<Go to ISI\>://WOS:000526331500009},

doi = {10.1021/acs.jpcc.0c00254},

issn = {1932-7447},

year  = {2020},

date = {2020-04-09},

journal = {Journal of Physical Chemistry C},

volume = {124},

number = {14},

pages = {7668-7676},

abstract = {Gallium-zinc oxynitride (GZNO) is a promising material system for solar-driven overall water splitting, as it exhibits a tunable band gap in the visible range, beneficial positions of valence and conduction band edges, and promising long-term stability. Fabrication of GZNO is traditionally accomplished via a solid state reaction pathway. This limits the growth of thin films or large single crystals and the precise control of the composition, which complicates investigations about fundamental properties of the material, including, for example, the influence of the single constituent ratios on the band gap. In this work, we present the growth of GZNO thin films on sapphire by plasma-assisted molecular beam epitaxy (MBE). The thin films exhibit a crystallite size of up to 50 nm and a wurtzite crystal structure with distinct short-range disorder. Variations of Ga/Zn and N/O flux ratios are found to influence the optical absorption edge of the alloy without major impact on the Urbach energy. Controlled change of the composition of the alloy reveals that the band gap reduction is caused by both an increased valence band energy, which is correlated with the N content, and a decrease of the conduction band energy which is induced by increasing Zn content. Based on these findings, GZNO thin films with band gaps of down to 2.0 eV were fabricated and their photoelectrical properties assessed. Using MBE, we overcome compositional restrictions typically associated with stoichiometric GaN:ZnO solid solutions and provide unprecedented access to new compounds within this materials class. In doing so, we elucidate the specific role of individual elements on band edge energetics and demonstrate new routes to band gap engineering for future photocatalytic and photoelectrochemical applications.},

keywords = {Foundry Inorganic, Solid-Liquid},

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 = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Magnetic pulses enable multidimensional optical spectroscopy of dark states},

author = {S Oviedo-Casado and F \v{S}anda and J Hauer and J Prior},

url = {https://doi.org/10.1063/1.5139409},

doi = {10.1063/1.5139409},

issn = {0021-9606},

year  = {2020},

date = {2020-02-28},

journal = {The Journal of Chemical Physics},

volume = {152},

number = {8},

pages = {084201},

keywords = {Solid-Liquid},

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 = {Solid-Liquid},

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 = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Interplay of exciton annihilation and transport in fifth order electronic spectroscopy},

author = {C Heshmatpour and J Hauer and F Sanda},

url = {\<Go to ISI\>://WOS:000490758300009},

doi = {10.1016/j.chemphys.2019.110433},

issn = {0301-0104},

year  = {2020},

date = {2020-01-01},

journal = {Chemical Physics},

volume = {528},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Manipulation and statistical analysis of the fluid flow of polymer semiconductor solutions during meniscus-guided coating},

author = {L Shaw and Y Diao and G C Martin-Noble and H Yan and P Hayoz and R T Weitz and D Kaelblein and M F Toney and Z Bao},

url = {https://www.cambridge.org/core/article/manipulation-and-statistical-analysis-of-the-fluid-flow-of-polymer-semiconductor-solutions-during-meniscusguided-coating/B89C6C7985E43178910D8DAA53FF77C3},

doi = {10.1557/mrs.2020.306},

issn = {0883-7694},

year  = {2020},

date = {2020-01-01},

journal = {MRS Bulletin},

pages = {1-14},

abstract = {Recent work in structure\textendashprocessing relationships of polymer semiconductors have demonstrated the versatility and control of thin-film microstructure offered by meniscus-guided coating (MGC) techniques. Here, we analyze the qualitative and quantitative aspects of solution shearing, a model MGC method, using coating blades augmented with arrays of pillars. The pillars induce local regions of high strain rates\textemdashboth shear and extensional\textemdashnot otherwise possible with unmodified blades, and we use fluid mechanical simulations to model and study a variety of pillar spacings and densities. We then perform a statistical analysis of 130 simulation variables to find correlations with three dependent variables of interest: thin-film degree of crystallinity and transistor field-effect mobilities for charge-transport parallel (μpara) and perpendicular (μperp) to the coating direction. Our study suggests that simple fluid mechanical models can reproduce substantive correlations between the induced fluid flow and important performance metrics, providing a methodology for optimizing blade design.},

keywords = {Foundry Organic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Rational strain engineering in delafossite oxides for highly efficient hydrogen evolution catalysis in acidic media},

author = {F Podjaski and D Weber and S Zhang and L Diehl and R Eger and V Duppel and E Alarc\'{o}n-Llad\'{o} and G Richter and F Haase and A Fontcuberta I Morral and C Scheu and B V Lotsch},

url = {https://doi.org/10.1038/s41929-019-0400-x},

doi = {10.1038/s41929-019-0400-x},

issn = {2520-1158},

year  = {2020},

date = {2020-01-01},

journal = {Nature Catalysis},

volume = {3},

number = {1},

pages = {55-63},

abstract = {The rational design of hydrogen evolution reaction electrocatalysts that can compete with platinum is an outstanding challenge in the process of designing viable power-to-gas technologies. Here, we introduce delafossites as a family of hydrogen evolution reaction electrocatalysts in acidic media. We show that, in PdCoO2, the inherently strained Pd metal sublattice acts as a pseudomorphic template for the growth of a tensile-strained Pd-rich capping layer under reductive conditions. The surface modification ranges up to 400 nm and continuously improves the electrocatalytic activity by simultaneously increasing the exchange current density and by reducing the Tafel slope down to 38 mV dec−1, leading to overpotentials η10 \< 15 mV. The improved activity is attributed to the operando stabilization of a β-PdHx phase with enhanced surface catalytic properties with respect to pure or nanostructured palladium. These findings illustrate how operando-induced electrodissolution can be used as a top-down design concept through the strain-stabilized formation of catalytically active phases.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Rational strain engineering in delafossite oxides for highly efficient hydrogen evolution catalysis in acidic media},

author = {F Podjaski and D Weber and S Zhang and L Diehl and R Eger and V Duppel and Alarcon E Llado and G Richter and F Haase and A Fontcuberta I Morral and C Scheu and B V Lotsch},

doi = {10.1038/s41929-019-0400-x},

year  = {2019},

date = {2019-12-01},

journal = {Nature Catalysis},

volume = {3},

pages = {1-9},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nonadiabatic Molecular Dynamics on Graphics Processing Units: Performance and Application to Rotary Molecular Motors},

author = {L D M Peters and J Kussmann and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jctc.9b00859},

doi = {10.1021/acs.jctc.9b00859},

issn = {1549-9618},

year  = {2019},

date = {2019-11-25},

journal = {Journal of Chemical Theory and Computation},

volume = {15},

number = {12},

pages = {6647-6659},

abstract = {Nonadiabatic molecular dynamics (NAMD) simulations of molecular systems require the efficient evaluation of excited-state properties, such as energies, gradients, and nonadiabatic coupling vectors. Here, we investigate the use of graphics processing units (GPUs) in addition to central processing units (CPUs) to efficiently calculate these properties at the time-dependent density functional theory (TDDFT) level of theory. Our implementation in the FermiONs++ program package uses the J-engine and a preselective screening procedure for the calculation of Coulomb and exchange kernels, respectively. We observe good speed-ups for small and large molecular systems (comparable to those observed in ground-state calculations) and reduced (down to sublinear) scaling behavior with respect to the system size (depending on the spatial locality of the investigated excitation). As a first illustrative application, we present efficient NAMD simulations of a series of newly designed light-driven rotary molecular motors and compare their S1 lifetimes. Although all four rotors show different S1 excitation energies, their ability to rotate upon excitation is conserved, making the series an interesting starting point for rotary molecular motors with tunable excitation energies.},

keywords = {Foundry Organic, Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Towards a transferable design of solid-state embedding models on the example of a rutile TiO2 (110) surface},

author = {M Kick and H Oberhofer},

url = {\<Go to ISI\>://WOS:000497760200011},

doi = {10.1063/1.5125204},

issn = {0021-9606},

year  = {2019},

date = {2019-11-14},

journal = {Journal of Chemical Physics},

volume = {151},

number = {18},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Electrochemically Tunable Proton-Coupled Electron Transfer in Pd-Catalyzed Benzaldehyde Hydrogenation},

author = {K Koh and U Sanyal and M S Lee and G H Cheng and M Song and V A Glezakou and Y Liu and D S Li and R Rousseau and O Y Gutierrez and A Karkamkar and M Derewinski and J A Lercher},

url = {\<Go to ISI\>://WOS:000502162100001},

doi = {10.1002/anie.201912241},

issn = {1433-7851},

year  = {2019},

date = {2019-10-21},

journal = {Angewandte Chemie-International Edition},

volume = {59},

number = {4},

pages = {1501-1505},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In Situ Monitoring Mesoscopic Deformation of Nanostructured Porous Titania Films Caused by Water Ingression},

author = {L Song and M Rawolle and N Hohn and J S Gutmann and H Frielinghaus and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsami.9b10750},

doi = {10.1021/acsami.9b10750},

issn = {1944-8244},

year  = {2019},

date = {2019-09-04},

journal = {ACS Applied Materials \& Interfaces},

volume = {11},

number = {35},

pages = {32552-32558},

abstract = {Nanostructured porous titania films are used in many energy-related applications. In this work, the temporal evolution of the mesoscopic deformation of mesoporous titania films synthesized via block copolymer-assisted sol\textendashgel chemistry is investigated with in situ grazing incidence small-angle neutron scattering (GISANS) during exposure to D2O vapor. Two types of mesoporous titania films are compared, which have a different degree of structural stability, depending on the applied annealing temperature (400 °C vs 600 °C) in a nitrogen atmosphere. Water ingression causes a gradual structure deformation in terms of decreasing center-to-center distances and broadening of the size distribution of the titania nanostructures. Based on the evolution of the mesopore size obtained from in situ GISANS measurements, the results show that structures synthesized at lower temperature undergo a stronger deformation because of the lower elastic modulus originating from larger pores, despite having a higher degree of order.},

keywords = {Foundry Inorganic, Solid-Liquid},

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 = {Solid-Liquid},

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 = {Solid-Liquid},

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 = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Coupled Dynamics of Anode and Cathode in Proton-Exchange Membrane Fuel Cells},

author = {J A Nogueira and K Krischer and H Varela},

url = {\<Go to ISI\>://WOS:000478934200001},

doi = {10.1002/cphc.201900531},

issn = {1439-4235},

year  = {2019},

date = {2019-07-19},

journal = {Chemphyschem},

volume = {20},

number = {22},

pages = {3081-3088},

keywords = {Solid-Liquid},

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 = {Solid-Liquid},

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 = {Solid-Liquid},

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 = {Foundry Organic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Ruthenium Oxide Nanosheets for Enhanced Oxygen Evolution Catalysis in Acidic Medium},

author = {S Laha and Y Lee and F Podjaski and D Weber and V Duppel and L M Schoop and F Pielnhofer and C Scheurer and K Muller and U Starke and K Reuter and B V Lotsch},

url = {\<Go to ISI\>://WOS:000465464500007},

doi = {10.1002/aenm.201803795},

issn = {1614-6832},

year  = {2019},

date = {2019-02-21},

journal = {Advanced Energy Materials},

volume = {9},

number = {15},

keywords = {Solid-Liquid},

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 = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Carbonaceous Oxygen Evolution Reaction Catalysts: From Defect and Doping-Induced Activity over Hybrid Compounds to Ordered Framework Structures},

author = {F Zoller and S H\"{a}ringer and D B\"{o}hm and J Luxa and Z Sofer and D Fattakhova-Rohlfing},

doi = {10.1002/smll.202007484},

issn = {1613-6810},

journal = {Small},

pages = {e2007484},

abstract = {Oxygen evolution reaction (OER) is expected to be of great importance for the future energy conversion and storage in form of hydrogen by water electrolysis. Besides the traditional noble-metal or transition metal oxide-based catalysts, carbonaceous electrocatalysts are of great interest due to their huge structural and compositional variety and unrestricted abundance. This review provides a summary of recent advances in the field of carbon-based OER catalysts ranging from "pure" or unintentionally doped carbon allotropes over heteroatom-doped carbonaceous materials and carbon/transition metal compounds to metal oxide composites where the role of carbon is mainly assigned to be a conductive support. Furthermore, the review discusses the recent developments in the field of ordered carbon framework structures (metal organic framework and covalent organic framework structures) that potentially allow a rational design of heteroatom-doped 3D porous structures with defined composition and spatial arrangement of doping atoms to deepen the understanding on the OER mechanism on carbonaceous structures in the future. Besides introducing the structural and compositional origin of electrochemical activity, the review discusses the mechanism of the catalytic activity of carbonaceous materials, their stability under OER conditions, and potential synergistic effects in combination with metal (or metal oxide) co-catalysts.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Optoelectronic perovskite film characterization via machine vision},

author = {M Harth and L Vesce and I Kouroudis and M Stefanelli and A Di Carlo and A Gagliardi},

url = {https://www.sciencedirect.com/science/article/pii/S0038092X23004656},

doi = {https://doi.org/10.1016/j.solener.2023.111840},

issn = {0038-092X},

journal = {Solar Energy},

volume = {262},

pages = {111840},

abstract = {We present our research for fast and reliable extraction of bandgap and absorption quality values for triple-cation perovskite thin films from sample scans. Our approach leverages machine learning methods, namely convolutional neural networks, to perform regression tasks aimed at predicting the properties of interest. To this end, thin film samples were synthesized via blade-coating and their photoluminescence and ultraviolet\textendashvisible spectra collected, along with the film thickness. We propose a method of computing a dimensionless figure of merit we called the Area Under Absorption Coefficient (AUAC), its purpose being to qualitatively evaluate the absorption quality of perovskite films for use in photovoltaic modules. This work demonstrates the usability of simple imaging techniques to analyze experimental samples while requiring only a feasibly acquirable initial amount of data. Our reported method can help speed up time consuming material optimizations by reducing lab time spent on recurrent characterization, nicely synergizes with high throughput production lines and could be adapted for quick extraction of other optoelectrical quantities.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Utilizing Data-Driven Optimization to Automate the Parametrization of Kinetic Monte Carlo Models},

author = {I Kouroudis and M G\"{o}\sswein and A Gagliardi},

url = {https://doi.org/10.1021/acs.jpca.3c02482},

doi = {10.1021/acs.jpca.3c02482},

issn = {1089-5639},

journal = {The Journal of Physical Chemistry A},

volume = {127},

number = {28},

pages = {5967-5978},

abstract = {Kinetic Monte Carlo (kMC) simulations are a popular tool to investigate the dynamic behavior of stochastic systems. However, one major limitation is their relatively high computational costs. In the last three decades, significant effort has been put into developing methodologies to make kMC more efficient, resulting in an enhanced runtime efficiency. Nevertheless, kMC models remain computationally expensive. This is in particular an issue in complex systems with several unknown input parameters where often most of the simulation time is required for finding a suitable parametrization. A potential route for automating the parametrization of kinetic Monte Carlo models arises from coupling kMC with a data-driven approach. In this work, we equip kinetic Monte Carlo simulations with a feedback loop consisting of Gaussian Processes (GPs) and Bayesian optimization (BO) to enable a systematic and data-efficient input parametrization. We utilize the results from fast-converging kMC simulations to construct a database for training a cheap-to-evaluate surrogate model based on Gaussian processes. Combining the surrogate model with a system-specific acquisition function enables us to apply Bayesian optimization for the guided prediction of suitable input parameters. Thus, the amount of trial simulation runs can be considerably reduced facilitating an efficient utilization of arbitrary kMC models. We showcase the effectiveness of our methodology for a physical process of growing industrial relevance: the space-charge layer formation in solid-state electrolytes as it occurs in all-solid-state batteries. Our data-driven approach requires only 1\textendash2 iterations to reconstruct the input parameters from different baseline simulations within the training data set. Moreover, we show that the methodology is even capable of accurately extrapolating into regions outside the training data set which are computationally expensive for direct kMC simulation. Concluding, we demonstrate the high accuracy of the underlying surrogate model via a full parameter space investigation eventually making the original kMC simulation obsolete.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Engineering Defects and Interfaces of Atomic Layer-Deposited TiOx-Protective Coatings for Efficient III\textendashV Semiconductor Photocathodes},

author = {O Bienek and B Fuchs and M Kuhl and T Rieth and J K\"{u}hne and L I Wagner and L M Todenhagen and L Wolz and A Henning and I D Sharp},

url = {https://doi.org/10.1021/acsphotonics.3c00818},

doi = {10.1021/acsphotonics.3c00818},

journal = {ACS Photonics},

volume = {10},

number = {11},

pages = {3985-3997},

abstract = {III\textendashV compound semiconductors offer optoelectronic properties that are well suited for the conversion of solar energy to chemical fuels. While such materials suffer from poor stability under photoelectrochemical (PEC) conditions, atomic layer deposition (ALD) of titanium oxide (TiOx) has emerged as a powerful approach for creating corrosion protection layers, thereby enabling efficient and robust interfaces. However, the role of defects within TiOx layers and at the semiconductor/TiOx interface on the PEC performance remains poorly understood and controlled. Here, we use p-type InP as a model III\textendashV semiconductor to investigate the impact of defects in ALD TiOx on junction formation, interfacial charge transport, and photocarrier recombination, which underpin characteristics of PEC devices. We show that defect concentrations in TiOx can be tuned over a broad range, resulting in significant modulation of the optical constants, electrical conductivity, and interface chemistry. While plasma-enhanced ALD yields films with low midgap-state concentrations, it introduces series resistance losses due to oxidation of the substrate. In contrast, thermal ALD suppresses interface oxidation but leads to electronically active defect states within the band gap of TiOx. By controlling these defect states, the nature of junction formation can be tuned, and high photovoltage photocathodes can be achieved. In particular, ALD TiOx layers possessing high carrier concentrations form buried InP/TiOx pn heterojunctions, whereas less defective layers preserve semiconductor/electrolyte junction energetics to achieve large photovoltages and applied bias photon-to-current efficiencies. These results highlight the power of ALD for engineering photoelectrode interfaces and provide a new route for tailoring the junction formation between buried and PEC junctions.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Annealing-Free Ohmic Contacts to n-Type GaN via Hydrogen Plasma-Assisted Atomic Layer Deposition of Sub-Nanometer AlOx},

author = {M Christis and A Henning and J D Bartl and A Zeidler and B Rieger and M Stutzmann and I D Sharp},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/admi.202300758},

doi = {https://doi.org/10.1002/admi.202300758},

issn = {2196-7350},

journal = {Advanced Materials Interfaces},

volume = {n/a},

number = {n/a},

pages = {2300758},

abstract = {Abstract A plasma-assisted atomic layer deposition (PE-ALD) process is reported for creating ohmic contacts to n-type GaN that combines native oxide reduction, near-surface doping, and encapsulation of GaN in a single processing step, thereby eliminating the need for both wet chemical etching of the native oxide before metallization and thermal annealing after contact formation. Repeated ALD cycling of trimethyl aluminum (TMA) and high-intensity hydrogen (H2) plasma results in the deposition of a sub-nanometer-thin (≈8 r{A}) AlOx layer via the partial transformation of the GaN surface oxide into AlOx. Hydrogen plasma-induced nitrogen vacancies in the near-surface region of GaN serve as shallow donors, promoting efficient out-of-plane electrical transport. Subsequent metallization with a Ti/Al/Ti/Au stack results in low contact resistance, ohmic behavior, and smooth morphology without requiring annealing. This electrical contracting approach thus meets the thermal budget requirements for Si-based complementary metal\textendashoxide\textendashsemiconductor structures and can facilitate the design and fabrication of advanced GaN-on-Si heterodevices.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Multi-band metasurface-driven surface-enhanced infrared absorption spectroscopy for improved characterization of in-situ electrochemical reactions},

author = {M Duportal and L M Berger and S A Maier and A Tittl and K Krischer},

url = {https://arxiv.org/abs/2307.10951},

doi = {https://doi.org/10.48550/arXiv.2307.10951},

journal = {arXiv preprint arXiv:2307.10951},

abstract = {Surface-enhanced spectroscopy techniques are the method-of-choice to characterize adsorbed intermediates occurring during electrochemical reactions, which are crucial in realizing a green sustainable future. Characterizing species with low coverages or short lifetimes have so far been limited by low signal enhancement. Recently, metasurface-driven surface-enhanced infrared absorption spectroscopy (SEIRAS) has been pioneered as a promising narrowband technology to study single vibrational modes of electrochemical interfaces during CO oxidation. However, many reactions involve several species or configurations of adsorption that need to be monitored simultaneously requiring reproducible and broadband sensing platforms to provide a clear understanding of the underlying electrochemical processes. Here, we experimentally realize multi-band metasurface-driven SEIRAS for the in-situ study of electrochemical CO2 reduction on a Pt surface. We develop an easily reproducible and spectrally-tunable platinum nano-slot metasurface. Two CO adsorption configurations at 2030 cm-1 and 1840 cm-1 are locally enhanced as a proof of concept that can be extended to more vibrational bands. Our platform provides a 41-fold enhancement in the detection of characteristic absorption signals compared to conventional broadband electrochemically roughened platinum films. A straightforward methodology is outlined starting by baselining our system in CO saturated environment and clearly detecting both configurations of adsorption, in particular the hitherto hardly detectable CO bridge configuration. Then, thanks to the signal enhancement provided by our platform, we find that the CO bridge configuration on platinum does not play a significant role during CO2 reduction in an alkaline environment. We anticipate that our technology will guide researchers in developing similar sensing platforms.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Toward a Comprehensive Understanding of Photocatalysis: What Systematic Studies and Alcohol Surface Chemistry on TiO2(110) Have to Offer for Future Developments},

author = {M Eder and M Tschurl and U Heiz},

url = {https://doi.org/10.1021/acs.jpclett.3c00504},

doi = {10.1021/acs.jpclett.3c00504},

journal = {The Journal of Physical Chemistry Letters},

volume = {14},

number = {26},

pages = {6193-6201},

abstract = {Heterogeneous photocatalytic systems are usually described based on electrochemistry, which the vast majority of interpretations and strategies for optimizing photocatalysts rely on. Charge carrier dynamics are usually in the spotlight, whereas the surface chemistry of the photocatalyst is neglected. This is unjustified, because studies on alcohol photoreforming on metal-decorated rutile single crystals revealed that the electrochemical reaction model is not generally applicable. Hence, many photocatalytic reactions may proceed in a different manner and the thermal chemistry needs to be accounted for. The new mechanism is particularly relevant for reactions in gaseous environments in the absence of solvated ionic species. Here, we compare both mechanisms and highlight their differences and consequences for photocatalysis. Based on alcohol photochemistry, we demonstrate the importance of thermal reactions in photocatalytic mechanisms and the relevance of systematic studies in different environments for a holistic understanding of photocatalysis.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Characterization of Different Au/Electrolyte Interfaces via In Situ Differential Cyclic Plasmo-Voltammetry},

author = {M J Feil and T L Maier and M Golibrzuch and A C Sterr and M Becherer and K Krischer},

url = {https://doi.org/10.1021/acs.jpcc.3c04727},

doi = {10.1021/acs.jpcc.3c04727},

issn = {1932-7447},

journal = {The Journal of Physical Chemistry C},

volume = {127},

number = {40},

pages = {20137-20145},

abstract = {In this article, we describe an improved method that uses in situ plasmonic spectroscopy to reliably track changes of the metal\textendashelectrolyte interface over a large potential window. Utilizing the specific sensitivity of the plasmonic resonance toward changes in the interfacial properties of nanoparticles (NPs), processes such as double-layer charging, surface oxidation/reduction, adsorption and desorption of anions, as well as metal under- and overpotential deposition are resolved. The main contributions to this signal are changes in the charge of the NPs and chemical interface damping due to the adsorbed species. We employ highly homogeneous macroscopic Au nanoarrays with controlled interfaces produced by lift-off nanoimprint lithography (LO-NIL) as the working electrodes for multiparticle differential cyclic plasmo-voltammetry (dCPV). First, plasmonic signals are recorded and compared to known electrochemical processes before the plasmonic signals are used to gain insights beyond those achievable by electrochemical means. These include observation of forced HSO4\textendash and H2PO4\textendash desorption by the onset of the Au oxidation and resolution of the different steps of the monolayer buildup during Cu underpotential deposition on Au.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {The Role of Electrolytes in the Relaxation of Near-Surface Spin Defects in Diamond},

author = {F A Freire-Moschovitis and R Rizzato and A Pershin and M R Schepp and R D Allert and L M Todenhagen and M S Brandt and A Gali and D B Bucher},

url = {https://doi.org/10.1021/acsnano.3c01298},

doi = {10.1021/acsnano.3c01298},

issn = {1936-0851},

journal = {ACS Nano},

volume = {17},

number = {11},

pages = {10474-10485},

abstract = {Quantum sensing with spin defects in diamond, such as the nitrogen vacancy (NV) center, enables the detection of various chemical species on the nanoscale. Molecules or ions with unpaired electronic spins are typically probed by their influence on the NV center’s spin relaxation. Whereas it is well-known that paramagnetic ions reduce the NV center’s relaxation time (T1), here we report on the opposite effect for diamagnetic ions. We demonstrate that millimolar concentrations of aqueous diamagnetic electrolyte solutions increase the T1 time of near-surface NV center ensembles compared to pure water. To elucidate the underlying mechanism of this surprising effect, single and double quantum NV experiments are performed, which indicate a reduction of magnetic and electric noise in the presence of diamagnetic electrolytes. In combination with ab initio simulations, we propose that a change in the interfacial band bending due to the formation of an electric double layer leads to a stabilization of fluctuating charges at the interface of an oxidized diamond. This work not only helps to understand noise sources in quantum systems but could also broaden the application space of quantum sensors toward electrolyte sensing in cell biology, neuroscience, and electrochemistry.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

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},

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 = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Cu/Ag\textendashSb\textendashI Rudorffite Thin Films for Photovoltaic Applications},

author = {R Hooijer and A Weis and W Kaiser and A Biewald and P D\"{o}rflinger and C Maheu and O Arsatiants and D Helminger and V Dyakonov and A Hartschuh and E Mosconi and F De Angelis and T Bein},

url = {https://doi.org/10.1021/acs.chemmater.3c01837},

doi = {10.1021/acs.chemmater.3c01837},

issn = {0897-4756},

journal = {Chemistry of Materials},

volume = {35},

number = {23},

pages = {9988-10000},

abstract = {In the search for lead-free perovskites, silver pnictohalides recently gained attention as novel perovskite-inspired materials for photovoltaics due to their high stability, low toxicity, and promising early efficiencies, especially for indoor applications. Recent research on such “rudorffites” mainly addresses silver bismuth iodides (Ag\textendashBi\textendashI), while their antimony analogues are hardly investigated due to intrinsic challenges in the synthesis of Sb-based thin films. Here, we establish a synthetic route to prepare Ag\textendashSb\textendashI thin films by employing thiourea as a Lewis-base additive. Thin film morphologies were further optimized by alloying them with Cu, resulting in solar cells with an improved power conversion efficiency of 0.7% by reducing undesired side phases. Density functional theory calculations and optical characterization methods support the incorporation of Cu into a Cu1\textendashxAgxSbI4 phase, keeping the overall stoichiometry and band gap virtually unchanged upon alloying. Our results further reveal the detrimental role of Ag point defects representing trap states in the band gap, being responsible for low open-circuit voltages and subgap absorption and emission features. Moreover, additional minor amounts of Bi are shown to boost the efficiency and stabilize the performance over a wider compositional range. Despite the remaining challenges regarding device performance, we demonstrate a strong increase in external quantum efficiency when reducing the light intensity, highlighting the potential of Ag\textendashSb\textendashI rudorffites for indoor photovoltaics.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Converging Divergent Paths: Constant Charge vs. Constant Potential Energetics in Computational Electrochemistry},

author = {N G H\"{o}rmann and S D Beinlich and K Reuter},

url = {https://arxiv.org/abs/2312.00911},

doi = {https://doi.org/10.48550/arXiv.2312.00911},

journal = {arXiv preprint arXiv:2312.00911},

abstract = {Using the example of a proton adsorption process, we analyze and compare two prominent modelling approaches in computational electrochemistry at metallic electrodes - electronically canonical, constant-charge and electronically grand-canonical, constant-potential calculations. We first confirm that both methodologies yield consistent results for the differential free energy change in the infinite cell size limit. This validation emphasizes that, fundamentally, both methods are equally valid and precise. In practice, the grand-canonical, constant-potential approach shows superior interpretability and size convergence as it aligns closer to experimental ensembles and exhibits smaller finite-size effects. On the other hand, constant-charge calculations exhibit greater resilience against discrepancies, such as deviations in interfacial capacitance and absolute potential alignment, as their results inherently only depend on the surface charge, and not on the modelled charge vs. potential relation. The present analysis thus offers valuable insights and guidance for selecting the most appropriate ensemble when addressing diverse electrochemical challenges.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Study on the properties of wafer-scale grown MoS2 deposited via thermally induced chemical vapor deposition with Mo(CO)6 and H2S precursors},

author = {A Klumpp and R Hooijer and N Kr\"{u}ger and J Boudaden and F Wolf and M D\"{o}blinger and T Bein},

url = {https://dx.doi.org/10.1088/2053-1591/acf7ae},

doi = {10.1088/2053-1591/acf7ae},

issn = {2053-1591},

journal = {Materials Research Express},

volume = {10},

number = {9},

pages = {095903},

abstract = {To realize profitable applications with 2D-materials the transition from research scale to microelectronic fabrication methods is needed. This means the use of equipment for larger substrates and assessment of the process flows. In this study we demonstrate an effective way to assess MoS2 as semiconducting material, deposited with the lower priced precursors Mo(CO)6 and H2S on 200 mm silicon wafers. We could show how the evolution of layer quality develops depending on temperature and interface pretreatment. It is not possible to achieve mono-layers of 0.6 nm with high quality due to seeding kinetics and mechanism. In contrast, layers with thicknesses above 3 nm have suitable electrical and optical qualities to proceed with the design of active devices on 200 mm wafers.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {On-Surface Carbon Nitride Growth from Polymerization of 2,5,8-Triazido-s-heptazine},

author = {M Krinninger and N Bock and S Kaiser and J Reich and T Bruhm and F Haag and F Allegretti and U Heiz and K K\"{o}hler and B J Lechner and F Esch},

url = {https://doi.org/10.1021/acs.chemmater.3c01030},

doi = {10.1021/acs.chemmater.3c01030},

issn = {0897-4756},

journal = {Chemistry of Materials},

volume = {35},

number = {17},

pages = {6762-6770},

abstract = {Carbon nitrides have recently come into focus for photo- and thermal catalysis, both as support materials for metal nanoparticles as well as photocatalysts themselves. While many approaches for the synthesis of three-dimensional carbon nitride materials are available, only top-down approaches by exfoliation of powders lead to thin-film flakes of this inherently two-dimensional material. Here, we describe an in situ on-surface synthesis of monolayer 2D carbon nitride films as a first step toward precise combination with other 2D materials. Starting with a single monomer precursor, we show that 2,5,8-triazido-s-heptazine can be evaporated intact, deposited on a single crystalline Au(111) or graphite support, and activated via azide decomposition and subsequent coupling to form a covalent polyheptazine network. We demonstrate that the activation can occur in three pathways, via electrons (X-ray illumination), via photons (UV illumination), and thermally. Our work paves the way to coat materials with extended carbon nitride networks that are, as we show, stable under ambient conditions.},

keywords = {Solid-Liquid},

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},

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 = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Negative Nonlinear CD\textendashee Dependence in Polycrystalline BINOL Thin Films},

author = {K Liang and F Ristow and K Li and J Pittrich and N Fehn and L D\"{o}rringer and U Heiz and R Kienberger and G Pescitelli and H Iglev and A Kartouzian},

url = {https://doi.org/10.1021/jacs.3c12253},

doi = {10.1021/jacs.3c12253},

issn = {0002-7863},

journal = {Journal of the American Chemical Society},

abstract = {Generally, the relationship between the observed circular dichroism and the enantiomeric excess in chiral systems (CD\textendashee dependence) is linear. While positive nonlinear behavior has often been reported in the past, examples of negative nonlinear (NN) behavior in CD\textendashee dependence are rare and not well understood. Here, we present a strong NN CD\textendashee dependence within polycrystalline thin films of BINOL by using second-harmonic-generation circular dichroism (SHG-CD) and commercial CD spectroscopy studies. Theoretical calculations, microscopy, and FTIR studies are employed to further clarify the underlying cause of this observation. This behavior is attributed to the changing supramolecular chirality of the system. Systems exhibiting NN CD\textendashee dependence hold promise for highly accurate enantiomeric excess characterization, which is essential for the refinement of enantio-separating and -purifying processes in pharmaceuticals, asymmetric catalysis, and chiral sensing. Our findings suggest that a whole class of single-species systems, i.e., racemate crystals, might possess NN CD\textendashee dependence and thus provide us a vast playground to better understand and exploit this phenomenon.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ionic Liquid-Induced Inversion of the Humidity-Dependent Conductivity of Thin PEDOT:PSS Films},

author = {A L Oechsle and T Sch\"{o}ner and L Deville and T Xiao and T Tian and A Vagias and S Bernstorff and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsami.3c08208},

doi = {10.1021/acsami.3c08208},

issn = {1944-8244},

journal = {ACS Applied Materials \& Interfaces},

volume = {15},

number = {40},

pages = {47682-47691},

abstract = {The humidity influence on the electronic and ionic resistance properties of thin post-treated poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films is investigated. In particular, the resistance of these PEDOT:PSS films post-treated with three different concentrations (0, 0.05, and 0.35 M) of ethyl-3-methylimidazolium dicyanamide (EMIM DCA) is measured while being exposed to a defined humidity protocol. A resistance increase upon elevated humidity is observed for the 0 M reference sample, while the EMIM DCA post-treated samples demonstrate a reverse behavior. Simultaneously performed in situ grazing-incidence small-angle X-ray scattering (GISAXS) measurements evidence changes in the film morphology upon varying the humidity, namely, an increase in the PEDOT domain distances. This leads to a detriment in the interdomain hole transport, which causes a rise in the resistance, as observed for the 0 M reference sample. Finally, electrochemical impedance spectroscopy (EIS) measurements at different humidities reveal additional contributions of ionic charge carriers in the EMIM DCA post-treated PEDOT:PSS films. Therefrom, a model is proposed, which describes the hole and cation transport in different post-treated PEDOT:PSS films dependent on the ambient humidity.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Alloying Effects on Charge-Carrier Transport in Silver\textendashBismuth Double Perovskites},

author = {M Righetto and S Caicedo-D\'{a}vila and M T Sirtl and V J Y Lim and J B Patel and D A Egger and T Bein and L M Herz},

url = {https://doi.org/10.1021/acs.jpclett.3c02750},

doi = {10.1021/acs.jpclett.3c02750},

journal = {The Journal of Physical Chemistry Letters},

volume = {14},

number = {46},

pages = {10340-10347},

abstract = {Alloying is widely adopted for tuning the properties of emergent semiconductors for optoelectronic and photovoltaic applications. So far, alloying strategies have primarily focused on engineering bandgaps rather than optimizing charge-carrier transport. Here, we demonstrate that alloying may severely limit charge-carrier transport in the presence of localized charge carriers (e.g., small polarons). By combining reflection\textendashtransmission and optical pump\textendashterahertz probe spectroscopy with first-principles calculations, we investigate the interplay between alloying and charge-carrier localization in Cs2AgSbxBi1\textendashxBr6 double perovskite thin films. We show that the charge-carrier transport regime strongly determines the impact of alloying on the transport properties. While initially delocalized charge carriers probe electronic bands formed upon alloying, subsequently self-localized charge carriers probe the energetic landscape more locally, thus turning an alloy’s low-energy sites (e.g., Sb sites) into traps, which dramatically deteriorates transport properties. These findings highlight the inherent limitations of alloying strategies and provide design tools for newly emerging and highly efficient semiconductors.},

keywords = {Foundry Organic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Extending the coherence of spin defects in hBN enables advanced qubit control and quantum sensing},

author = {R Rizzato and M Schalk and S Mohr and J C Hermann and J P Leibold and F Bruckmaier and G Salvitti and C Qian and P Ji and G V Astakhov and U Kentsch and M Helm and A V Stier and J J Finley and D B Bucher},

url = {https://doi.org/10.1038/s41467-023-40473-w},

doi = {10.1038/s41467-023-40473-w},

issn = {2041-1723},

journal = {Nature Communications},

volume = {14},

number = {1},

pages = {5089},

abstract = {Negatively-charged boron vacancy centers ($$V_B^-$$) in hexagonal Boron Nitride (hBN) are attracting increasing interest since they represent optically-addressable qubits in a van der Waals material. In particular, these spin defects have shown promise as sensors for temperature, pressure, and static magnetic fields. However, their short spin coherence time limits their scope for quantum technology. Here, we apply dynamical decoupling techniques to suppress magnetic noise and extend the spin coherence time by two orders of magnitude, approaching the fundamental T1 relaxation limit. Based on this improvement, we demonstrate advanced spin control and a set of quantum sensing protocols to detect radiofrequency signals with sub-Hz resolution. The corresponding sensitivity is benchmarked against that of state-of-the-art NV-diamond quantum sensors. This work lays the foundation for nanoscale sensing using spin defects in an exfoliable material and opens a promising path to quantum sensors and quantum networks integrated into ultra-thin structures.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

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},

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 = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}