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

Abstract

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 CaFe_0.5Co_0.5O₃. CaFe_0.5Co_0.5O₃ demonstrated a higher OER activity than those of the parent compounds CaFeO₃ and CaCoO₃. In contrast, the HER activity of CaFe_0.5Co_0.5O₃ was not significantly enhanced. These observations suggest that the mixing of Fe⁴⁺ and Co⁴⁺ ions is an efficient way to activate OER.