Oxide Electrocatalysts Based on Earth-Abundant Metals\nfor Both Hydrogen- and Oxygen-Evolution Reactions

Abstract

A unique bifunctional\noxide electrocatalyst capable of catalyzing\nboth half-reactions of water splitting, namely, oxygen-evolution reaction\n(OER) and hydrogen-evolution reaction (HER), with the added capability\nof catalyzing HER in both acidic and basic media, a rare property\nin water-splitting catalysts, is reported. In addition to the bifunctional\nelectrocatalytic properties, CaSrFeMnO_6−δ shows\nOER activity, which is even superior to the reported activities of\nprecious-metal electrocatalysts, IrO₂ and RuO₂. The correlation of electrocatalysis with the charge-transport properties\nin the series Ca₂FeMnO_6−δ, CaSrFeMnO_6−δ, and Sr₂FeMnO_6−δ is demonstrated. Given the dependence of charge transport on structure\nand defects, this work unravels the interesting correlations between\nthe triangle of structure, charge transport, and electrocatalytic\nactivity for water splitting.