| Autor: |
Haase FT; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Rabe A; Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 7 Universitätsstr., Essen 45141, Germany.; Inorganic Chemistry, Christian Albrechts University, 2 Max-Eyth-Straße, Kiel 24118, Germany., Schmidt FP; Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany.; Max Planck Institute for Chemical Energy Conversion, 34-36 Stiftstrasse, Mülheim an der Ruhr 45470, Germany., Herzog A; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Jeon HS; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Frandsen W; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Narangoda PV; Max Planck Institute for Chemical Energy Conversion, 34-36 Stiftstrasse, Mülheim an der Ruhr 45470, Germany., Spanos I; Max Planck Institute for Chemical Energy Conversion, 34-36 Stiftstrasse, Mülheim an der Ruhr 45470, Germany., Friedel Ortega K; Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 7 Universitätsstr., Essen 45141, Germany., Timoshenko J; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Lunkenbein T; Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Behrens M; Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 7 Universitätsstr., Essen 45141, Germany.; Inorganic Chemistry, Christian Albrechts University, 2 Max-Eyth-Straße, Kiel 24118, Germany., Bergmann A; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany., Schlögl R; Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany.; Max Planck Institute for Chemical Energy Conversion, 34-36 Stiftstrasse, Mülheim an der Ruhr 45470, Germany., Roldan Cuenya B; Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 4-6 Faradayweg, Berlin 14195, Germany. |
| Abstrakt: |
Spinel-type catalysts are promising anode materials for the alkaline oxygen evolution reaction (OER), exhibiting low overpotentials and providing long-term stability. In this study, we compared two structurally equal Co 2 FeO 4 spinels with nominally identical stoichiometry and substantially different OER activities. In particular, one of the samples, characterized by a metastable precatalyst state, was found to quickly achieve its steady-state optimum operation, while the other, which was initially closer to the ideal crystallographic spinel structure, never reached such a state and required 168 mV higher potential to achieve 1 mA/cm 2 . In addition, the enhanced OER activity was accompanied by a larger resistance to corrosion. More specifically, using various ex situ , quasi in situ , and operando methods, we could identify a correlation between the catalytic activity and compositional inhomogeneities resulting in an X-ray amorphous Co 2+ -rich minority phase linking the crystalline spinel domains in the as-prepared state. Operando X-ray absorption spectroscopy revealed that these Co 2+ -rich domains transform during OER to structurally different Co 3+ -rich domains. These domains appear to be crucial for enhancing OER kinetics while exhibiting distinctly different redox properties. Our work emphasizes the necessity of the operando methodology to gain fundamental insight into the activity-determining properties of OER catalysts and presents a promising catalyst concept in which a stable, crystalline structure hosts the disordered and active catalyst phase. |
