Investigation of FeCo-based core-shell particles annealing using HERFD-XANES

Water electrolysis is a promising and environmentally friendly means for renewable energy storage. However, the difficulties met to replace Ir anodes by more abundant transition metal oxides (TMO) is hindering its development on a large scale. Despite numerous publications devoted to the investigation of TMOs for the oxygen evolution reaction (OER), which occurs at the anode and largely dominates the energy losses, the nature of the active sites is not fully understood yet, hindering the development of materials for water electrolysis. TMOs with spinel structure constitute a promising class of materials due to a relatively low synthesis temperature, and to their composition-dependent and widely tunable properties. In this project we study core-shell Fe3O4@CoFe2O4 nanoparticles (NPs) annealed under an oxidative atmosphere to advance the understanding of the oxidation states of the NPs under these conditions and compare it to the oxidation under a potential performed previously.