Electrocatalytic Activity of Tetravalent Fe–Co Mixed Oxide for Oxygen and Hydrogen Evolution Reactions

Electrochemical water splitting is a useful way for sustainable hydrogen production, whereas sluggish kinetics of oxygen/hydrogen evolution reactions (OER/HER) limits the efficiency; thus, active electrocatalysts to reduce overpotentials are desired. Mixing of multiple transition-metal elements is a promising way to enhance electrochemical catalysis. In the present study, we investigated the OER and HER catalytic activities of tetravalent Fe–Co mixed perovskite oxide CaFe0.5Co0.5O3. CaFe0.5Co0.5O3 demonstrated a higher OER activity than those of the parent compounds CaFeO3 and CaCoO3. In contrast, the HER activity of CaFe0.5Co0.5O3 was not significantly enhanced. These observations suggest that the mixing of Fe4+ and Co4+ ions is an efficient way to activate OER.