Fe-doped Co₃O₄(111) spinel oxide epitaxial thin films for OER

ABTRACT

The use of well-defined epitaxial oxide thin films allows to establish precise structure-property relationships and to better understand the mechanisms of electrocatalytic reactions. In the context of water splitting, we studied OER on epitaxial Fe-doped Co₃O₄(111) spinel oxide thin films on Au(111) prepared by electrodeposition. The presentation will focus on their operando characterizations under OER conditions, using in combination surface X-ray diffraction (SXRD) and X-ray absorption spectroscopy (XAS). It will be shown that a surface restructuring occurs in the pre-OER regime (a highly defective skin layer develops), whose average thickness depends on the film morphology and on its composition, i.e., the Fe content. Simultaneously, there is an increase in the average oxidation state of cobalt whose magnitude is correlated with . The role of the skin layer and the beneficial effect of Fe doping on the OER activity will be discussed.

PAST AND CURRRENT RESEARCH TOPICS

My past research interests encompassed a variety of fields catalysis, magnetism, chemical andbio‐sensing. My approach has always been establishing relationships between the structure atthe atomic level and properties (e.g. OER activity, magnetism). For these reasons, I privilegedstudies of well‐defined model systems prepared by electrodeposition on single crystalelectrodes. I also used relevant characterization methods such as scanning probe microscopy,x‐ray diffraction, x‐ray absorption, magnetic characterizations and IR spectroscopy all employedin situ or operando to investigate the sample “at work” whenever this is possible. Most of thesetechniques, in particular STM were using home built instruments.Since 2023, my research is conducted in collaborations with colleagues from various countries.