Prof. Dr. Thomas Lunkenbein
Academic Research Focus
- Local structure analysis
- Complementary techniques
- Operando electron microscopy
- Method development
- Correlative microscopy
- Complementary techniques
- Operando electron microscopy
- Method development
- Correlative microscopy
Fields of Application
Publications
16.
K Dembélé, J H Wang, M Boniface, J Folke, L S Diaz, F Girgsdies, A Hammud, D Kordus, G Koch, Z Gheisari, R Blume, W L Y Jiang, A Knop-Gericke, R Eckert, S Reitmeier, A Reitzmann, R Schlögl, B R Cuenya, J Timoshenko, H Ruland, T Lunkenbein
The Haber Bosch Catalyst from Solid state Chemistry to Mesotechnology Journal Article
In: Advanced Energy Materials, 2025, ISSN: 1614-6832.
@article{nokey,
title = {The Haber Bosch Catalyst from Solid state Chemistry to Mesotechnology},
author = {K Demb\'{e}l\'{e} and J H Wang and M Boniface and J Folke and L S Diaz and F Girgsdies and A Hammud and D Kordus and G Koch and Z Gheisari and R Blume and W L Y Jiang and A Knop-Gericke and R Eckert and S Reitmeier and A Reitzmann and R Schl\"{o}gl and B R Cuenya and J Timoshenko and H Ruland and T Lunkenbein},
url = {\<Go to ISI\>://WOS:001510987900001},
doi = {10.1002/aenm.202500159},
issn = {1614-6832},
year = {2025},
date = {2025-06-19},
journal = {Advanced Energy Materials},
abstract = {Ammonia is industrially synthesized over multi-promoted Fe-based catalysts for more than a century. Although ammonia synthesis reflects a prototypical catalytic reaction, rational catalyst design is still impossible as the full structural complexity of this catalyst system often referred to as ammonia iron and its structural entanglement is barely understood. Here, the mesoscopic structure of a technical, multi-promoted ammonia synthesis catalyst is uncovered using a scale-bridging electron microscopy approach complemented by X-ray diffraction and spectroscopy to explore the structural integrity of ammonia iron. Amorphous contributions and structures of the melilite type and tricalcium aluminate as additional phases are identified. Furthermore, the understanding of the ammonia iron family by unveiling the role of the platelet-Fe perimeter, framework Fe, thin film Fe, and refractory Fe is extended. Their interconnectedness is highlighted, suggesting that each component has to be present to fulfill a specific task. The study demonstrates that catalysis science can only proceed if it openly explores the full complexity of catalytic systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ammonia is industrially synthesized over multi-promoted Fe-based catalysts for more than a century. Although ammonia synthesis reflects a prototypical catalytic reaction, rational catalyst design is still impossible as the full structural complexity of this catalyst system often referred to as ammonia iron and its structural entanglement is barely understood. Here, the mesoscopic structure of a technical, multi-promoted ammonia synthesis catalyst is uncovered using a scale-bridging electron microscopy approach complemented by X-ray diffraction and spectroscopy to explore the structural integrity of ammonia iron. Amorphous contributions and structures of the melilite type and tricalcium aluminate as additional phases are identified. Furthermore, the understanding of the ammonia iron family by unveiling the role of the platelet-Fe perimeter, framework Fe, thin film Fe, and refractory Fe is extended. Their interconnectedness is highlighted, suggesting that each component has to be present to fulfill a specific task. The study demonstrates that catalysis science can only proceed if it openly explores the full complexity of catalytic systems.
15.
H Türk, X Q Tran, P König, A Hammud, V Vibhu, F-P Schmidt, D Berger, S Selve, V Roddatis, D Abou-Ras, F Girgsdies, Y-T Chan, T Götsch, H Ali, I C Vinke, L G J De Haart, M Lehmann, A Knop-Gericke, K Reuter, R-A Eichel, C Scheurer, T Lunkenbein
Boon and Bane of Local Solid State Chemistry on the Performance of LSM-Based Solid Oxide Electrolysis Cells Journal Article
In: Advanced Energy Materials, vol. n/a, no. n/a, pp. 2405599, 2024, ISSN: 1614-6832.
@article{nokey,
title = {Boon and Bane of Local Solid State Chemistry on the Performance of LSM-Based Solid Oxide Electrolysis Cells},
author = {H T\"{u}rk and X Q Tran and P K\"{o}nig and A Hammud and V Vibhu and F-P Schmidt and D Berger and S Selve and V Roddatis and D Abou-Ras and F Girgsdies and Y-T Chan and T G\"{o}tsch and H Ali and I C Vinke and L G J De Haart and M Lehmann and A Knop-Gericke and K Reuter and R-A Eichel and C Scheurer and T Lunkenbein},
url = {https://doi.org/10.1002/aenm.202405599},
doi = {https://doi.org/10.1002/aenm.202405599},
issn = {1614-6832},
year = {2024},
date = {2024-12-31},
urldate = {2024-12-31},
journal = {Advanced Energy Materials},
volume = {n/a},
number = {n/a},
pages = {2405599},
abstract = {Abstract High-temperature solid oxide cells are highly efficient energy converters. However, their lifetime is limited by rapid deactivation. Little is known about the local, atomic scale transformation that drive this degradation. Here, reaction-induced changes are unraveled at the atomic scale of a solid oxide electrolysis cell (SOEC) operated for 550 h by combining high-resolution scanning transmission electron microscopy with first-principles and force-field-based atomistic simulations. We focus on the structural evolution of lanthanum strontium manganite (LSM)/yttria-stabilized zirconia (YSZ) regions and the corresponding solid?solid interface. It is found that the strong inter-diffusion of cations leads to the additional formation and growth of a multitude of localized structures such as a solid solution of La/Mn, nano-domains of secondary structures or antisite defects in the YSZ, as well as a mixed ion and electron conduction region in the LSM and complexion. These local structures can be likewise beneficial or detrimental to the performance, by either increasing the catalytically active area or by limiting the supply of reactants. The work provides unprecedented atomistic insights into the influence of local solid-state chemistry on the functioning of SOECs and deepens the understanding of the degradation mechanism in SOECs, paving the way towards nanoscopic rational interface design for more efficient and durable cells.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract High-temperature solid oxide cells are highly efficient energy converters. However, their lifetime is limited by rapid deactivation. Little is known about the local, atomic scale transformation that drive this degradation. Here, reaction-induced changes are unraveled at the atomic scale of a solid oxide electrolysis cell (SOEC) operated for 550 h by combining high-resolution scanning transmission electron microscopy with first-principles and force-field-based atomistic simulations. We focus on the structural evolution of lanthanum strontium manganite (LSM)/yttria-stabilized zirconia (YSZ) regions and the corresponding solid?solid interface. It is found that the strong inter-diffusion of cations leads to the additional formation and growth of a multitude of localized structures such as a solid solution of La/Mn, nano-domains of secondary structures or antisite defects in the YSZ, as well as a mixed ion and electron conduction region in the LSM and complexion. These local structures can be likewise beneficial or detrimental to the performance, by either increasing the catalytically active area or by limiting the supply of reactants. The work provides unprecedented atomistic insights into the influence of local solid-state chemistry on the functioning of SOECs and deepens the understanding of the degradation mechanism in SOECs, paving the way towards nanoscopic rational interface design for more efficient and durable cells.
14.
L J Falling, W Jang, S Laha, T Götsch, M W Terban, S Bette, R Mom, J-J Velasco-Vélez, F Girgsdies, D Teschner, A Tarasov, C-H Chuang, T Lunkenbein, A Knop-Gericke, D Weber, R Dinnebier, B V Lotsch, R Schlögl, T E Jones
Atomic Insights into the Competitive Edge of Nanosheets Splitting Water Journal Article
In: Journal of the American Chemical Society, vol. 146, no. 40, pp. 27886-27902, 2024, ISSN: 0002-7863.
@article{nokey,
title = {Atomic Insights into the Competitive Edge of Nanosheets Splitting Water},
author = {L J Falling and W Jang and S Laha and T G\"{o}tsch and M W Terban and S Bette and R Mom and J-J Velasco-V\'{e}lez and F Girgsdies and D Teschner and A Tarasov and C-H Chuang and T Lunkenbein and A Knop-Gericke and D Weber and R Dinnebier and B V Lotsch and R Schl\"{o}gl and T E Jones},
url = {https://doi.org/10.1021/jacs.4c10312},
doi = {10.1021/jacs.4c10312},
issn = {0002-7863},
year = {2024},
date = {2024-10-09},
journal = {Journal of the American Chemical Society},
volume = {146},
number = {40},
pages = {27886-27902},
abstract = {The oxygen evolution reaction (OER) provides the protons for many electrocatalytic power-to-X processes, such as the production of green hydrogen from water or methanol from CO2. Iridium oxohydroxides (IOHs) are outstanding catalysts for this reaction because they strike a unique balance between activity and stability in acidic electrolytes. Within IOHs, this balance varies with the atomic structure. While amorphous IOHs perform best, they are least stable. The opposite is true for their crystalline counterparts. These rules-of-thumb are used to reduce the loading of scarce IOH catalysts and retain the performance. However, it is not fully understood how activity and stability are related at the atomic level, hampering rational design. Herein, we provide simple design rules (Figure 12) derived from the literature and various IOHs within this study. We chose crystalline IrOOH nanosheets as our lead material because they provide excellent catalyst utilization and a predictable structure. We found that IrOOH signals the chemical stability of crystalline IOHs while surpassing the activity of amorphous IOHs. Their dense bonding network of pyramidal trivalent oxygens (μ3Δ-O) provides structural integrity, while allowing reversible reduction to an electronically gapped state that diminishes the destructive effect of reductive potentials. The reactivity originates from coordinative unsaturated edge sites with radical character, i.e., μ1-O oxyls. By comparing to other IOHs and literature, we generalized our findings and synthesized a set of simple rules that allow prediction of stability and reactivity of IOHs from atomistic models. We hope that these rules will inspire atomic design strategies for future OER catalysts.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oxygen evolution reaction (OER) provides the protons for many electrocatalytic power-to-X processes, such as the production of green hydrogen from water or methanol from CO2. Iridium oxohydroxides (IOHs) are outstanding catalysts for this reaction because they strike a unique balance between activity and stability in acidic electrolytes. Within IOHs, this balance varies with the atomic structure. While amorphous IOHs perform best, they are least stable. The opposite is true for their crystalline counterparts. These rules-of-thumb are used to reduce the loading of scarce IOH catalysts and retain the performance. However, it is not fully understood how activity and stability are related at the atomic level, hampering rational design. Herein, we provide simple design rules (Figure 12) derived from the literature and various IOHs within this study. We chose crystalline IrOOH nanosheets as our lead material because they provide excellent catalyst utilization and a predictable structure. We found that IrOOH signals the chemical stability of crystalline IOHs while surpassing the activity of amorphous IOHs. Their dense bonding network of pyramidal trivalent oxygens (μ3Δ-O) provides structural integrity, while allowing reversible reduction to an electronically gapped state that diminishes the destructive effect of reductive potentials. The reactivity originates from coordinative unsaturated edge sites with radical character, i.e., μ1-O oxyls. By comparing to other IOHs and literature, we generalized our findings and synthesized a set of simple rules that allow prediction of stability and reactivity of IOHs from atomistic models. We hope that these rules will inspire atomic design strategies for future OER catalysts.
13.
L Masliuk, K Nam, M W Terban, Y Lee, P Kube, D Delgado, F Girgsdies, K Reuter, R Schlögl, A Trunschke, C Scheurer, M Zobel, T Lunkenbein
Linking Bulk and Surface Structures in Complex Mixed Oxides Journal Article
In: ACS Catalysis, vol. 14, no. 11, pp. 9018-9033, 2024.
@article{nokey,
title = {Linking Bulk and Surface Structures in Complex Mixed Oxides},
author = {L Masliuk and K Nam and M W Terban and Y Lee and P Kube and D Delgado and F Girgsdies and K Reuter and R Schl\"{o}gl and A Trunschke and C Scheurer and M Zobel and T Lunkenbein},
url = {https://doi.org/10.1021/acscatal.3c05230},
doi = {10.1021/acscatal.3c05230},
year = {2024},
date = {2024-06-07},
journal = {ACS Catalysis},
volume = {14},
number = {11},
pages = {9018-9033},
abstract = {The interface between a solid catalyst and the reacting medium plays a crucial role in the function of the material in catalysis. In the present work, we show that the surface termination of isostructural molybdenum\textendashvanadium oxides is strongly linked to the real structure of the bulk. This conclusion is based on comparing (scanning) transmission electron microscopy images with pair distribution function (PDF) data obtained for (Mo,V)Ox and (Mo,V,Te,Nb)Ox. Distance-dependent analyses of the PDF results demonstrate that (Mo,V,Te,Nb)Ox exhibits stronger deviations from the averaged orthorhombic crystal structure than (Mo,V)Ox in the short and intermediate regimes. These deviations are explained by higher structural diversity, which is facilitated by the increased chemical complexity of the quinary oxide and in particular by the presence of Nb. This structural diversity is seemingly important to form intrinsic bulk-like surface terminations that are highly selective in alkane oxidation. More rigid (Mo,V)Ox is characterized by defective surfaces that are more active but less selective for the same reactions. In line with machine learning interatomic potential (MLIP) calculations, we highlight that the surface termination of (Mo,V,Te,Nb)Ox is characterized by a reconfiguration of the pentagonal building blocks, causing a preferential exposure of Nb sites. The presented results foster hypotheses that chemical complexity is superior for the performance of multifunctional catalysts. The underlying principle is not the presence of multiple chemically different surface centers but instead the ability of structural diversity to optimally align and distribute the elements at the surface and, thus, to shape the structural environment around the active sites. This study experimentally evidences the origin of the structure-directing impact of the real structure of the bulk on functional interfaces and encourages the development of efficient surface engineering strategies toward improved high-performance selective oxidation catalysts.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interface between a solid catalyst and the reacting medium plays a crucial role in the function of the material in catalysis. In the present work, we show that the surface termination of isostructural molybdenum–vanadium oxides is strongly linked to the real structure of the bulk. This conclusion is based on comparing (scanning) transmission electron microscopy images with pair distribution function (PDF) data obtained for (Mo,V)Ox and (Mo,V,Te,Nb)Ox. Distance-dependent analyses of the PDF results demonstrate that (Mo,V,Te,Nb)Ox exhibits stronger deviations from the averaged orthorhombic crystal structure than (Mo,V)Ox in the short and intermediate regimes. These deviations are explained by higher structural diversity, which is facilitated by the increased chemical complexity of the quinary oxide and in particular by the presence of Nb. This structural diversity is seemingly important to form intrinsic bulk-like surface terminations that are highly selective in alkane oxidation. More rigid (Mo,V)Ox is characterized by defective surfaces that are more active but less selective for the same reactions. In line with machine learning interatomic potential (MLIP) calculations, we highlight that the surface termination of (Mo,V,Te,Nb)Ox is characterized by a reconfiguration of the pentagonal building blocks, causing a preferential exposure of Nb sites. The presented results foster hypotheses that chemical complexity is superior for the performance of multifunctional catalysts. The underlying principle is not the presence of multiple chemically different surface centers but instead the ability of structural diversity to optimally align and distribute the elements at the surface and, thus, to shape the structural environment around the active sites. This study experimentally evidences the origin of the structure-directing impact of the real structure of the bulk on functional interfaces and encourages the development of efficient surface engineering strategies toward improved high-performance selective oxidation catalysts.
12.
P M Schneider, K L Kollmannsberger, C Cesari, R Khare, M Boniface, B Roldán Cuenya, T Lunkenbein, M Elsner, S Zacchini, A S Bandarenka, J Warnan, R A Fischer
Engineering ORR Electrocatalysts from Co8Pt4 Carbonyl Clusters via ZIF-8 Templating Journal Article
In: ChemElectroChem, vol. 11, no. 5, pp. e202300476, 2024, ISSN: 2196-0216.
@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}
}
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.
11.
L Sandoval-Diaz, D Cruz, M Vuijk, G Ducci, M Hävecker, W Jiang, M Plodinec, A Hammud, D Ivanov, T Götsch, K Reuter, R Schlögl, C Scheurer, A Knop-Gericke, T Lunkenbein
Metastable nickel–oxygen species modulate rate oscillations during dry reforming of methane Journal Article
In: Nature Catalysis, vol. 7, no. 2, pp. 161-171, 2024, ISSN: 2520-1158.
@article{nokey,
title = {Metastable nickel\textendashoxygen species modulate rate oscillations during dry reforming of methane},
author = {L Sandoval-Diaz and D Cruz and M Vuijk and G Ducci and M H\"{a}vecker and W Jiang and M Plodinec and A Hammud and D Ivanov and T G\"{o}tsch and K Reuter and R Schl\"{o}gl and C Scheurer and A Knop-Gericke and T Lunkenbein},
url = {https://doi.org/10.1038/s41929-023-01090-4},
doi = {10.1038/s41929-023-01090-4},
issn = {2520-1158},
year = {2024},
date = {2024-02-01},
journal = {Nature Catalysis},
volume = {7},
number = {2},
pages = {161-171},
abstract = {When a heterogeneous catalyst is active, it forms metastable structures that constantly transform into each other. These structures contribute differently to the catalytic function. Here we show the role of different metastable oxygen species on a Ni catalyst during dry reforming of methane by combining environmental scanning electron microscopy, near ambient pressure X-ray photoelectron spectroscopy, on-line product detection and computer vision. We highlight the critical role of dissociative CO2 adsorption in regulating the oxygen content of the catalyst and in CH4 activation. We also discover rate oscillations during dry reforming of methane resulting from the sequential transformation of metastable oxygen species that exhibit different catalytic properties: atomic surface oxygen, subsurface oxygen and bulk NiOx. The imaging approach allowed the localization of fluctuating surface regions that correlated directly with catalytic activity. The study highlights the importance of metastability and operando analytics in catalysis science and provides impetus towards the design of catalytic systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
When a heterogeneous catalyst is active, it forms metastable structures that constantly transform into each other. These structures contribute differently to the catalytic function. Here we show the role of different metastable oxygen species on a Ni catalyst during dry reforming of methane by combining environmental scanning electron microscopy, near ambient pressure X-ray photoelectron spectroscopy, on-line product detection and computer vision. We highlight the critical role of dissociative CO2 adsorption in regulating the oxygen content of the catalyst and in CH4 activation. We also discover rate oscillations during dry reforming of methane resulting from the sequential transformation of metastable oxygen species that exhibit different catalytic properties: atomic surface oxygen, subsurface oxygen and bulk NiOx. The imaging approach allowed the localization of fluctuating surface regions that correlated directly with catalytic activity. The study highlights the importance of metastability and operando analytics in catalysis science and provides impetus towards the design of catalytic systems.
10.
R Glatthaar, F-P Schmidt, A Hammud, T Lunkenbein, T Okker, F Huster, S Seren, B Cela Greven, G Hahn, B Terheiden
Silver Metallization with Controlled Etch Stop Using SiO Layers in Passivating Contacts for Improved Silicon Solar Cell Performance Journal Article
In: Solar RRL, vol. 7, no. 21, pp. 2300491, 2023, ISSN: 2367-198X.
@article{nokey,
title = {Silver Metallization with Controlled Etch Stop Using SiO Layers in Passivating Contacts for Improved Silicon Solar Cell Performance},
author = {R Glatthaar and F-P Schmidt and A Hammud and T Lunkenbein and T Okker and F Huster and S Seren and B Cela Greven and G Hahn and B Terheiden},
url = {https://doi.org/10.1002/solr.202300491},
doi = {https://doi.org/10.1002/solr.202300491},
issn = {2367-198X},
year = {2023},
date = {2023-11-01},
journal = {Solar RRL},
volume = {7},
number = {21},
pages = {2300491},
abstract = {Metallization of polycrystalline-silicon/silicon oxide (poly-Si/SiOx) passivating contacts with fire-through silver paste is a crucial process for implementation of passivating contacts in industrial manufacturing of solar cells. For a microscopic understanding of the metallization process, the contact forming interface between the Ag crystallites and the poly-Si layer is investigated with high-resolution transmission electron microscopy. For this purpose, multilayer atmospheric pressure chemical vapor deposition poly-Si samples with a SiOx layer between the individual poly-Si layers are fabricated, screen printed with a lead-free Ag paste, and contact fired. Electron micrographs show that in this process the etching of the paste and the subsequent Ag crystallite formation is stopped by this interface with the SiOx layer. Additionally, energy-dispersive X-Ray mapping reveals the presence of an oxide layer around the Ag crystallites. This finding differs significantly from well-investigated classical cell concepts with contact formation on diffused crystalline silicon. Moreover, an analysis of the Ag crystallite orientation in correlation to the neighboring Si crystallite orientation indicates no direct relationship. Finally, it is shown that the use of this multilayer approach is favorable for integration into a solar cell concept leading to a higher passivation quality at the metallized area and lower contact resistivity.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Metallization of polycrystalline-silicon/silicon oxide (poly-Si/SiOx) passivating contacts with fire-through silver paste is a crucial process for implementation of passivating contacts in industrial manufacturing of solar cells. For a microscopic understanding of the metallization process, the contact forming interface between the Ag crystallites and the poly-Si layer is investigated with high-resolution transmission electron microscopy. For this purpose, multilayer atmospheric pressure chemical vapor deposition poly-Si samples with a SiOx layer between the individual poly-Si layers are fabricated, screen printed with a lead-free Ag paste, and contact fired. Electron micrographs show that in this process the etching of the paste and the subsequent Ag crystallite formation is stopped by this interface with the SiOx layer. Additionally, energy-dispersive X-Ray mapping reveals the presence of an oxide layer around the Ag crystallites. This finding differs significantly from well-investigated classical cell concepts with contact formation on diffused crystalline silicon. Moreover, an analysis of the Ag crystallite orientation in correlation to the neighboring Si crystallite orientation indicates no direct relationship. Finally, it is shown that the use of this multilayer approach is favorable for integration into a solar cell concept leading to a higher passivation quality at the metallized area and lower contact resistivity.
9.
S Müllner, T Held, T Tichter, P Rank, D Leykam, W Jiang, T Lunkenbein, T Gerdes, C Roth
Impact of Functional Groups in Reduced Graphene Oxide Matrices for High Energy Anodes in Lithium-Ion Batteries Journal Article
In: Journal of The Electrochemical Society, vol. 170, no. 7, pp. 070523, 2023, ISSN: 1945-7111 0013-4651.
@article{nokey,
title = {Impact of Functional Groups in Reduced Graphene Oxide Matrices for High Energy Anodes in Lithium-Ion Batteries},
author = {S M\"{u}llner and T Held and T Tichter and P Rank and D Leykam and W Jiang and T Lunkenbein and T Gerdes and C Roth},
url = {https://dx.doi.org/10.1149/1945-7111/ace70a},
doi = {10.1149/1945-7111/ace70a},
issn = {1945-7111
0013-4651},
year = {2023},
date = {2023-07-25},
journal = {Journal of The Electrochemical Society},
volume = {170},
number = {7},
pages = {070523},
abstract = {Most high capacity anode materials for lithium-ion batteries (LiB) require a carbonaceous matrix. In this context one promising material is reduced graphene oxide (rGO). Herein, we present the influence of different reduction degrees of rGO on its physico-chemical properties, such as crystallinity, specific surface area, electrical conductivity and electrochemical lithiation/delithiation behavior. It is found that a heat treatment under inert and reducing atmospheres increases the long-range order of rGO up to a temperature of 700 °C. At temperatures around 1000 °C, the crystallinity decreases. With decreasing oxygen content, a linear decrease in irreversible capacity during cycle 1 can be observed, along with a significant increase in electrical conductivity. This decrease in irreversible capacity can be observed despite an increase in specific surface area indicating the more significant influence of the oxygen content on the capacity loss. Consequently, the reversible capacity increases continuously up to a carbon content of 84.4 at% due to the thermal reduction. Contrary to expectations, the capacity decreases with further reduction. This can be explained by the loss of functional groups that will be lithiated reversibly, and a simultaneous reduction of long-range order, as concluded from dq/dU analysis in combination with XRD analysis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Most high capacity anode materials for lithium-ion batteries (LiB) require a carbonaceous matrix. In this context one promising material is reduced graphene oxide (rGO). Herein, we present the influence of different reduction degrees of rGO on its physico-chemical properties, such as crystallinity, specific surface area, electrical conductivity and electrochemical lithiation/delithiation behavior. It is found that a heat treatment under inert and reducing atmospheres increases the long-range order of rGO up to a temperature of 700 °C. At temperatures around 1000 °C, the crystallinity decreases. With decreasing oxygen content, a linear decrease in irreversible capacity during cycle 1 can be observed, along with a significant increase in electrical conductivity. This decrease in irreversible capacity can be observed despite an increase in specific surface area indicating the more significant influence of the oxygen content on the capacity loss. Consequently, the reversible capacity increases continuously up to a carbon content of 84.4 at% due to the thermal reduction. Contrary to expectations, the capacity decreases with further reduction. This can be explained by the loss of functional groups that will be lithiated reversibly, and a simultaneous reduction of long-range order, as concluded from dq/dU analysis in combination with XRD analysis.
8.
K L Kollmannsberger, Poonam, C Cesari, R Khare, T Kratky, M Boniface, O Tomanec, J Michalička, E Mosconi, A Gagliardi, S Günther, W Kaiser, T Lunkenbein, S Zacchini, J Warnan, R A Fischer
Mechanistic Insights into ZIF-8 Encapsulation of Atom-Precise Pt(M) Carbonyl Clusters Journal Article
In: Chemistry of Materials, vol. 35, no. 14, pp. 5475-5486, 2023, ISSN: 0897-4756.
@article{nokey,
title = {Mechanistic Insights into ZIF-8 Encapsulation of Atom-Precise Pt(M) Carbonyl Clusters},
author = {K L Kollmannsberger and Poonam and C Cesari and R Khare and T Kratky and M Boniface and O Tomanec and J Michali\v{c}ka and E Mosconi and A Gagliardi and S G\"{u}nther and W Kaiser and T Lunkenbein and S Zacchini and J Warnan and R A Fischer},
url = {https://doi.org/10.1021/acs.chemmater.3c00807},
doi = {10.1021/acs.chemmater.3c00807},
issn = {0897-4756},
year = {2023},
date = {2023-07-12},
journal = {Chemistry of Materials},
volume = {35},
number = {14},
pages = {5475-5486},
abstract = {Precisely designing metal nanoparticles (NPs) is the cornerstone for maximizing their efficiency in applications like catalysis or sensor technology. Metal\textendashorganic frameworks (MOFs) with their defined and tunable pore systems provide a confined space to host and stabilize small metal NPs. In this work, the MOF encapsulation of various atom-precise clusters following the bottle-around-ship approach is investigated, providing general insights into the scaffolding mechanism. Eleven carbonyl-stabilized Pt(M) (M = Co, Ni, Fe, and Sn) clusters are employed for the encapsulation in the zeolitic imidazolate framework (ZIF)-8. Infrared and UV/Vis spectroscopy, density functional theory, and ab initio molecular dynamics revealed structure\textendashencapsulation relationship guidelines. Thereby, cluster polarization, size, and composition were found to condition the scaffolding behavior. Encaging of [NBnMe3]2[Co8Pt4C2(CO)24] (Co8Pt4) is thus achieved as the first MOF-encapsulated bimetallic carbonyl cluster, Co8Pt4@ZIF-8, and is fully characterized including X-ray absorption near edge and extended X-ray absorption spectroscopy. ZIF-8 confinement not only promotes property changes, like the T-dependent magnetism, but it also further allows heat-induced ligand-stripping without altering the cluster size, enabling the synthesis of naked, heterometallic, close to atom-precise clusters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Precisely designing metal nanoparticles (NPs) is the cornerstone for maximizing their efficiency in applications like catalysis or sensor technology. Metal–organic frameworks (MOFs) with their defined and tunable pore systems provide a confined space to host and stabilize small metal NPs. In this work, the MOF encapsulation of various atom-precise clusters following the bottle-around-ship approach is investigated, providing general insights into the scaffolding mechanism. Eleven carbonyl-stabilized Pt(M) (M = Co, Ni, Fe, and Sn) clusters are employed for the encapsulation in the zeolitic imidazolate framework (ZIF)-8. Infrared and UV/Vis spectroscopy, density functional theory, and ab initio molecular dynamics revealed structure–encapsulation relationship guidelines. Thereby, cluster polarization, size, and composition were found to condition the scaffolding behavior. Encaging of [NBnMe3]2[Co8Pt4C2(CO)24] (Co8Pt4) is thus achieved as the first MOF-encapsulated bimetallic carbonyl cluster, Co8Pt4@ZIF-8, and is fully characterized including X-ray absorption near edge and extended X-ray absorption spectroscopy. ZIF-8 confinement not only promotes property changes, like the T-dependent magnetism, but it also further allows heat-induced ligand-stripping without altering the cluster size, enabling the synthesis of naked, heterometallic, close to atom-precise clusters.
7.
R V Mom, L-E Sandoval-Diaz, D Gao, C-H Chuang, E A Carbonio, T E Jones, R Arrigo, D Ivanov, M Hävecker, B Roldan Cuenya, R Schlögl, T Lunkenbein, A Knop-Gericke, J-J Velasco-Vélez
Assessment of the Degradation Mechanisms of Cu Electrodes during the CO2 Reduction Reaction Journal Article
In: ACS Applied Materials & Interfaces, vol. 15, no. 25, pp. 30052-30059, 2023, ISSN: 1944-8244.
@article{nokey,
title = {Assessment of the Degradation Mechanisms of Cu Electrodes during the CO2 Reduction Reaction},
author = {R V Mom and L-E Sandoval-Diaz and D Gao and C-H Chuang and E A Carbonio and T E Jones and R Arrigo and D Ivanov and M H\"{a}vecker and B Roldan Cuenya and R Schl\"{o}gl and T Lunkenbein and A Knop-Gericke and J-J Velasco-V\'{e}lez},
url = {https://doi.org/10.1021/acsami.2c23007},
doi = {10.1021/acsami.2c23007},
issn = {1944-8244},
year = {2023},
date = {2023-06-15},
journal = {ACS Applied Materials \& Interfaces},
volume = {15},
number = {25},
pages = {30052-30059},
abstract = {Catalyst degradation and product selectivity changes are two of the key challenges in the electrochemical reduction of CO2 on copper electrodes. Yet, these aspects are often overlooked. Here, we combine in situ X-ray spectroscopy, in situ electron microscopy, and ex situ characterization techniques to follow the long-term evolution of the catalyst morphology, electronic structure, surface composition, activity, and product selectivity of Cu nanosized crystals during the CO2 reduction reaction. We found no changes in the electronic structure of the electrode under cathodic potentiostatic control over time, nor was there any build-up of contaminants. In contrast, the electrode morphology is modified by prolonged CO2 electroreduction, which transforms the initially faceted Cu particles into a rough/rounded structure. In conjunction with these morphological changes, the current increases and the selectivity changes from value-added hydrocarbons to less valuable side reaction products, i.e., hydrogen and CO. Hence, our results suggest that the stabilization of a faceted Cu morphology is pivotal for ensuring optimal long-term performance in the selective reduction of CO2 into hydrocarbons and oxygenated products.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Catalyst degradation and product selectivity changes are two of the key challenges in the electrochemical reduction of CO2 on copper electrodes. Yet, these aspects are often overlooked. Here, we combine in situ X-ray spectroscopy, in situ electron microscopy, and ex situ characterization techniques to follow the long-term evolution of the catalyst morphology, electronic structure, surface composition, activity, and product selectivity of Cu nanosized crystals during the CO2 reduction reaction. We found no changes in the electronic structure of the electrode under cathodic potentiostatic control over time, nor was there any build-up of contaminants. In contrast, the electrode morphology is modified by prolonged CO2 electroreduction, which transforms the initially faceted Cu particles into a rough/rounded structure. In conjunction with these morphological changes, the current increases and the selectivity changes from value-added hydrocarbons to less valuable side reaction products, i.e., hydrogen and CO. Hence, our results suggest that the stabilization of a faceted Cu morphology is pivotal for ensuring optimal long-term performance in the selective reduction of CO2 into hydrocarbons and oxygenated products.
6.
N Deka, T E Jones, L J Falling, L-E Sandoval-Diaz, T Lunkenbein, J-J Velasco-Velez, T-S Chan, C-H Chuang, A Knop-Gericke, R V Mom
On the Operando Structure of Ruthenium Oxides during the Oxygen Evolution Reaction in Acidic Media Journal Article
In: ACS Catalysis, vol. 13, no. 11, pp. 7488-7498, 2023.
@article{nokey,
title = {On the Operando Structure of Ruthenium Oxides during the Oxygen Evolution Reaction in Acidic Media},
author = {N Deka and T E Jones and L J Falling and L-E Sandoval-Diaz and T Lunkenbein and J-J Velasco-Velez and T-S Chan and C-H Chuang and A Knop-Gericke and R V Mom},
url = {https://doi.org/10.1021/acscatal.3c01607},
doi = {10.1021/acscatal.3c01607},
year = {2023},
date = {2023-05-19},
urldate = {2023-05-19},
journal = {ACS Catalysis},
volume = {13},
number = {11},
pages = {7488-7498},
abstract = {In the search for rational design strategies for oxygen evolution reaction (OER) catalysts, linking the catalyst structure to activity and stability is key. However, highly active catalysts such as IrOx and RuOx undergo structural changes under OER conditions, and hence, structure\textendashactivity\textendashstability relationships need to take into account the operando structure of the catalyst. Under the highly anodic conditions of the oxygen evolution reaction (OER), electrocatalysts are often converted into an active form. Here, we studied this activation for amorphous and crystalline ruthenium oxide using X-ray absorption spectroscopy (XAS) and electrochemical scanning electron microscopy (EC-SEM). We tracked the evolution of surface oxygen species in ruthenium oxides while in parallel mapping the oxidation state of the Ru atoms to draw a complete picture of the oxidation events that lead to the OER active structure. Our data show that a large fraction of the OH groups in the oxide are deprotonated under OER conditions, leading to a highly oxidized active material. The oxidation is centered not only on the Ru atoms but also on the oxygen lattice. This oxygen lattice activation is particularly strong for amorphous RuOx. We propose that this property is key for the high activity and low stability observed for amorphous ruthenium oxide.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the search for rational design strategies for oxygen evolution reaction (OER) catalysts, linking the catalyst structure to activity and stability is key. However, highly active catalysts such as IrOx and RuOx undergo structural changes under OER conditions, and hence, structure–activity–stability relationships need to take into account the operando structure of the catalyst. Under the highly anodic conditions of the oxygen evolution reaction (OER), electrocatalysts are often converted into an active form. Here, we studied this activation for amorphous and crystalline ruthenium oxide using X-ray absorption spectroscopy (XAS) and electrochemical scanning electron microscopy (EC-SEM). We tracked the evolution of surface oxygen species in ruthenium oxides while in parallel mapping the oxidation state of the Ru atoms to draw a complete picture of the oxidation events that lead to the OER active structure. Our data show that a large fraction of the OH groups in the oxide are deprotonated under OER conditions, leading to a highly oxidized active material. The oxidation is centered not only on the Ru atoms but also on the oxygen lattice. This oxygen lattice activation is particularly strong for amorphous RuOx. We propose that this property is key for the high activity and low stability observed for amorphous ruthenium oxide.
5.
M Plodinec, H C Nerl, T Lunkenbein, R Schlögl
Deactivation Mechanism of Ni Nanoparticles in Dry Reforming of Methane Revealed by Operando TEM Journal Article
In: Microscopy and Microanalysis, vol. 28, no. S1, pp. 146-148, 2022, ISSN: 1431-9276.
@article{nokey,
title = {Deactivation Mechanism of Ni Nanoparticles in Dry Reforming of Methane Revealed by Operando TEM},
author = {M Plodinec and H C Nerl and T Lunkenbein and R Schl\"{o}gl},
url = {https://doi.org/10.1017/S1431927622001489},
doi = {10.1017/s1431927622001489},
issn = {1431-9276},
year = {2022},
date = {2022-08-01},
journal = {Microscopy and Microanalysis},
volume = {28},
number = {S1},
pages = {146-148},
abstract = {Many studies have shown that catalysts are metastable and dynamic systems, where the nature of the active state depends on the applied chemical potential, associated “chemical dynamics” and the formation of transient active sites. Therefore, active surfaces could be unstable at non-active conditions, leading to misinterpretation of inactive structures as active states in ex situ studies. Recent progress in the development of in situ and operando techniques allows access to live information at high temporal and spatial resolution for the first time. Operando transmission electron microscopy (TEM) allows to directly probe the active-state/-sites of catalysts under relevant reaction conditions and at high resolution. The structure-function relationship remains unsolved in many catalytic reactions, including in the important industrial reaction - dry reforming of methane (DRM). This lack of fundamental understanding of DRM is hindering the choice and design of efficient catalyst material since an empirical approach to discovering new catalysts still prevails. Using operando TEM techniques presents a unique opportunity to gain fundamental insights into the DRM reaction to reveal what constitutes the active structure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Many studies have shown that catalysts are metastable and dynamic systems, where the nature of the active state depends on the applied chemical potential, associated “chemical dynamics” and the formation of transient active sites. Therefore, active surfaces could be unstable at non-active conditions, leading to misinterpretation of inactive structures as active states in ex situ studies. Recent progress in the development of in situ and operando techniques allows access to live information at high temporal and spatial resolution for the first time. Operando transmission electron microscopy (TEM) allows to directly probe the active-state/-sites of catalysts under relevant reaction conditions and at high resolution. The structure-function relationship remains unsolved in many catalytic reactions, including in the important industrial reaction - dry reforming of methane (DRM). This lack of fundamental understanding of DRM is hindering the choice and design of efficient catalyst material since an empirical approach to discovering new catalysts still prevails. Using operando TEM techniques presents a unique opportunity to gain fundamental insights into the DRM reaction to reveal what constitutes the active structure.
4.
H Türk, T Götsch, F-P Schmidt, A Hammud, D Ivanov, L G J De Haart, I Vinke, R-A Eichel, R Schlögl, K Reuter, A Knop-Gericke, T Lunkenbein, C Scheurer
Sr Surface Enrichment in Solid Oxide Cells - Approaching the Limits of EDX Analysis by Multivariate Statistical Analysis and Simulations Journal Article
In: ChemCatChem, vol. n/a, no. n/a, 2022, ISSN: 1867-3880.
@article{nokey,
title = {Sr Surface Enrichment in Solid Oxide Cells - Approaching the Limits of EDX Analysis by Multivariate Statistical Analysis and Simulations},
author = {H T\"{u}rk and T G\"{o}tsch and F-P Schmidt and A Hammud and D Ivanov and L G J De Haart and I Vinke and R-A Eichel and R Schl\"{o}gl and K Reuter and A Knop-Gericke and T Lunkenbein and C Scheurer},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/cctc.202200300},
doi = {https://doi.org/10.1002/cctc.202200300},
issn = {1867-3880},
year = {2022},
date = {2022-07-08},
journal = {ChemCatChem},
volume = {n/a},
number = {n/a},
abstract = {In solid oxide cells, Sr segregation has been correlated with degradation. Yet, the atomistic mechanism remains unknown. Here we begin to localize the origin of Sr surface nucleation by combining force field based simulations, energy dispersive X-ray spectroscopy (EDX) and multi-variate statistical analysis. We find increased ion mobility in the complexion between yttria-stabilized zirconia and strontium-doped lanthanum manganite. Furthermore, we developed a robust and automated routine to detect localized nucleation seeds of Sr at the complexion/vacuum interface. This hints at a mechanism originating at the complexion and requires in-depths studies at the atomistic level, where the developed routine can be beneficial for analysing large hyperspectral EDX datasets.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In solid oxide cells, Sr segregation has been correlated with degradation. Yet, the atomistic mechanism remains unknown. Here we begin to localize the origin of Sr surface nucleation by combining force field based simulations, energy dispersive X-ray spectroscopy (EDX) and multi-variate statistical analysis. We find increased ion mobility in the complexion between yttria-stabilized zirconia and strontium-doped lanthanum manganite. Furthermore, we developed a robust and automated routine to detect localized nucleation seeds of Sr at the complexion/vacuum interface. This hints at a mechanism originating at the complexion and requires in-depths studies at the atomistic level, where the developed routine can be beneficial for analysing large hyperspectral EDX datasets.
3.
F Reiter, M Pielmeier, A Vogel, C Jandl, M Plodinec, C Rohner, T Lunkenbein, K Nisi, A W Holleitner, T Nilges
SnBrP-A SnIP-type representative in the Sn−Br−P system Journal Article
In: Zeitschrift für anorganische und allgemeine Chemie, vol. n/a, no. n/a, pp. e202100347, 2022, ISSN: 0044-2313.
@article{nokey,
title = {SnBrP-A SnIP-type representative in the Sn−Br−P system},
author = {F Reiter and M Pielmeier and A Vogel and C Jandl and M Plodinec and C Rohner and T Lunkenbein and K Nisi and A W Holleitner and T Nilges},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/zaac.202100347},
doi = {https://doi.org/10.1002/zaac.202100347},
issn = {0044-2313},
year = {2022},
date = {2022-01-07},
urldate = {2022-01-07},
journal = {Zeitschrift f\"{u}r anorganische und allgemeine Chemie},
volume = {n/a},
number = {n/a},
pages = {e202100347},
abstract = {Abstract One-dimensional semiconductors are interesting materials due to their unique structural features and anisotropy, which grant them intriguing optical, dielectric and mechanical properties. In this work, we report on SnBrP, a lighter homologue of the first inorganic double helix compound SnIP. This class of compounds is characterized by intriguing mechanical and electronic properties, featuring a high flexibility without modulation of physical properties. Semiconducting SnBrP can be synthesized from red phosphorus, tin and tin(II)bromide at elevated temperatures and crystallizes as red-orange, cleavable needles. Raman measurements pointed towards a double helical building unit in SnBrP, showing similarities to the SnIP structure. After taking PL measurements, HR-TEM, and quantum chemical calculations into account, we were able to propose a sense full structure model for SnBrP.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract One-dimensional semiconductors are interesting materials due to their unique structural features and anisotropy, which grant them intriguing optical, dielectric and mechanical properties. In this work, we report on SnBrP, a lighter homologue of the first inorganic double helix compound SnIP. This class of compounds is characterized by intriguing mechanical and electronic properties, featuring a high flexibility without modulation of physical properties. Semiconducting SnBrP can be synthesized from red phosphorus, tin and tin(II)bromide at elevated temperatures and crystallizes as red-orange, cleavable needles. Raman measurements pointed towards a double helical building unit in SnBrP, showing similarities to the SnIP structure. After taking PL measurements, HR-TEM, and quantum chemical calculations into account, we were able to propose a sense full structure model for SnBrP.
2.
H Türk, F-P Schmidt, T Götsch, F Girgsdies, A Hammud, D Ivanov, I C Vinke, L G J De Haart, R-A Eichel, K Reuter, R Schlögl, A Knop-Gericke, C Scheurer, T Lunkenbein
Complexions at the Electrolyte/Electrode Interface in Solid Oxide Cells Journal Article
In: Advanced Materials Interfaces, vol. 8, no. 18, pp. 2100967, 2021, ISSN: 2196-7350.
@article{nokey,
title = {Complexions at the Electrolyte/Electrode Interface in Solid Oxide Cells},
author = {H T\"{u}rk and F-P Schmidt and T G\"{o}tsch and F Girgsdies and A Hammud and D Ivanov and I C Vinke and L G J De Haart and R-A Eichel and K Reuter and R Schl\"{o}gl and A Knop-Gericke and C Scheurer and T Lunkenbein},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/admi.202100967},
doi = {https://doi.org/10.1002/admi.202100967},
issn = {2196-7350},
year = {2021},
date = {2021-08-21},
journal = {Advanced Materials Interfaces},
volume = {8},
number = {18},
pages = {2100967},
abstract = {Abstract Rapid deactivation presently limits a wide spread use of high-temperature solid oxide cells (SOCs) as otherwise highly efficient chemical energy converters. With deactivation triggered by the ongoing conversion reactions, an atomic-scale understanding of the active triple-phase boundary between electrolyte, electrode, and gas phase is essential to increase cell performance. Here, a multi-method approach is used comprising transmission electron microscopy and first-principles calculations and molecular simulations to untangle the atomic arrangement of the prototypical SOC interface between a lanthanum strontium manganite (LSM) anode and a yttria-stabilized zirconia (YSZ) electrolyte in the as-prepared state after sintering. An interlayer of self-limited width with partial amorphization and strong compositional gradient is identified, thus exhibiting the characteristics of a complexion that is stabilized by the confinement between two bulk phases. This offers a new perspective to understand the function of SOCs at the atomic scale. Moreover, it opens up a hitherto unrealized design space to tune the conversion efficiency.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Rapid deactivation presently limits a wide spread use of high-temperature solid oxide cells (SOCs) as otherwise highly efficient chemical energy converters. With deactivation triggered by the ongoing conversion reactions, an atomic-scale understanding of the active triple-phase boundary between electrolyte, electrode, and gas phase is essential to increase cell performance. Here, a multi-method approach is used comprising transmission electron microscopy and first-principles calculations and molecular simulations to untangle the atomic arrangement of the prototypical SOC interface between a lanthanum strontium manganite (LSM) anode and a yttria-stabilized zirconia (YSZ) electrolyte in the as-prepared state after sintering. An interlayer of self-limited width with partial amorphization and strong compositional gradient is identified, thus exhibiting the characteristics of a complexion that is stabilized by the confinement between two bulk phases. This offers a new perspective to understand the function of SOCs at the atomic scale. Moreover, it opens up a hitherto unrealized design space to tune the conversion efficiency.
1.
M Boniface, M Plodinec, R Schlögl, T Lunkenbein
Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope? Journal Article
In: Topics in Catalysis, vol. 63, no. 15, pp. 1623-1643, 2020, ISSN: 1572-9028.
@article{nokey,
title = {Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?},
author = {M Boniface and M Plodinec and R Schl\"{o}gl and T Lunkenbein},
url = {https://doi.org/10.1007/s11244-020-01398-6},
doi = {10.1007/s11244-020-01398-6},
issn = {1572-9028},
year = {2020},
date = {2020-11-01},
journal = {Topics in Catalysis},
volume = {63},
number = {15},
pages = {1623-1643},
abstract = {During the last decade, modern micro-electro-mechanical systems (MEMS) technology has been used to create cells that can act as catalytic nanoreactors and fit into the sample holders of transmission electron microscopes. These nanoreactors can maintain atmospheric or higher pressures inside the cells as they seal gases or liquids from the vacuum of the TEM column and can reach temperatures exceeding 1000 °C. This has led to a paradigm shift in electron microscopy, which facilitates the local characterization of structural and morphological changes of solid catalysts under working conditions. In this review, we outline the development of state-of-the-art nanoreactor setups that are commercially available and are currently applied to study catalytic reactions in situ or operando in gaseous or liquid environments. We also discuss challenges that are associated with the use of environmental cells. In catalysis studies, one of the major challenge is the interpretation of the results while considering the discrepancies in kinetics between MEMS based gas cells and fixed bed reactors, the interactions of the electron beam with the sample, as well as support effects. Finally, we critically analyze the general role of MEMS based nanoreactors in electron microscopy and catalysis communities and present possible future directions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
During the last decade, modern micro-electro-mechanical systems (MEMS) technology has been used to create cells that can act as catalytic nanoreactors and fit into the sample holders of transmission electron microscopes. These nanoreactors can maintain atmospheric or higher pressures inside the cells as they seal gases or liquids from the vacuum of the TEM column and can reach temperatures exceeding 1000 °C. This has led to a paradigm shift in electron microscopy, which facilitates the local characterization of structural and morphological changes of solid catalysts under working conditions. In this review, we outline the development of state-of-the-art nanoreactor setups that are commercially available and are currently applied to study catalytic reactions in situ or operando in gaseous or liquid environments. We also discuss challenges that are associated with the use of environmental cells. In catalysis studies, one of the major challenge is the interpretation of the results while considering the discrepancies in kinetics between MEMS based gas cells and fixed bed reactors, the interactions of the electron beam with the sample, as well as support effects. Finally, we critically analyze the general role of MEMS based nanoreactors in electron microscopy and catalysis communities and present possible future directions.