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

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A unique bifunctional oxide electrocatalyst capable of catalyzing both half-reactions of water splitting, namely, oxygen-evolution reaction (OER) and hydrogen-evolution reaction (HER), with the added capability of catalyzing HER in both acidic and basic media, a rare property in water-splitting catalysts, is reported. In addition to the bifunctional electrocatalytic properties, CaSrFeMnO 6−δ shows OER activity, which is even superior to the reported activities of precious-metal electrocatalysts, IrO 2 and RuO 2 . The correlation of electrocatalysis with the charge-transport properties in the series Ca 2 FeMnO 6−δ, CaSrFeMnO 6−δ, and Sr 2 FeMnO 6−δ is demonstrated. Given the dependence of charge transport on structure and defects, this work unravels the interesting correlations between the triangle of structure, charge transport, and electrocatalytic activity for water splitting.