Elektrochemische Eigenschaften epitaktischer Metalloxidkatalysatoren

• Antragsteller: Professor Dr. Olaf Magnussen
• Fachliche Zuordnung: Physikalische Chemie von Festkörpern und Oberflächen, Materialcharakterisierung ; Experimentelle Physik der kondensierten Materie
• Förderung: Förderung von 2015 bis 2020
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 284207613

• Erstellungsjahr: 2020

Zusammenfassung der Projektergebnisse

In this project, we performed studies aiming at a better microscopic understanding of iron-group oxide electrocatalysts for oxygen evolution, focusing on Co and Fe oxides. We developed experimental approaches for the preparation of model oxide catalysts with well-defined surface structure, specifically Co3O4(111), CoOOH(001), Fe3O4(111) and (FexCo1-x)3O4(111) thin film electrodes and Fe3O4(100) single crystals. As new experimental tools, new instrumentation and methods for in situ and operando studies were developed that enabled obtaining structural data under conditions resembling those in technological processes. In combination with in situ X-ray absorbtion spectroscopy, microscopic methods and electrochemical measurements, these revealed complex potentialdependent structural changes of the model oxide catalysts that were affected by pH as well as sample history and morphology. In particularly, our studies revealed the formation of ultrathin skin layers with altered structure and higher oxidation state, which seem to play a significant role in the electrocatalytic reactivity of these materials. In summary, these studies provided significant advances towards an improved fundamental understanding of these electrode materials, both from a methodolocical point of view and in terms of the obtained microscopic insights.

Projektbezogene Publikationen (Auswahl)

• Transmission surface diffraction for in operando studies of heterogeneous interfaces, J. Phys. Chem. Lett., 8, 1067-1071 (2017)
  F. Reikowski, T. Wiegmann, J. Stettner, J. Drnec, V. Honkimäki, F. Maroun, P. Allongue, O.M. Magnussen
  
• Potential dependence of the structure and magnetism of electrodeposited Pd/Co/Au(111) layers, J. Electroanal. Chem., 819, 322-330 (2018)
  F. Maroun, F. Reikowski, T. Wiegmann, N. Di, J. Stettner, O.M. Magnussen, P. Allongue, J.
  
• Operando Surface X-ray Diffraction Studies of Structurally-defined Co3O4 and CoOOH Thin Films during Oxygen Evolution, ACS Catalysis, 9, 3811-3821 (2019)
  F. Reikowski, F. Maroun, I. Pacheco, T. Wiegmann, P. Allongue, J. Stettner, O.M. Magnussen
  
• Electrochemical stability of the reconstructed Fe3O4(001) surface, Angew. Chem. Int. Ed. (2020)
  D. Grumelli, T. Wiegmann, S. Barja, F. Reikowski, F. Maroun, P. Allongue, J. Balajka, G.S. Parkinson, U. Diebold, K. Kern, O.M. Magnussen
  
• In situ transmission X-ray micro-diffraction from thin metal films electrodeposited in microfluidic channels, J. Electrochem. Soc., 167, 112505 1-8 (2020)
  T. Wiegmann, J. Drnec, F. Reikowski, J. Stettner, F. Maroun, O. M. Magnussen