Co–Fe Bimetal Phosphate Composite Loaded on Reduced Graphene Oxide for Oxygen Evolution

Development of high-performance nonprecious metal-based catalysts for oxygen evolution reaction (OER) is crucial to improve the efficiency of water electrolysis and photoelectrochemical water splitting for harvesting and storage of solar energy. Herein, Co–Fe phosphates and their composites with reduced graphene oxide (rGO) were prepared by a simple hydrothermal method, which then acted as oxygen evolution reaction catalysts. In 1.0 M KOH aqueous solution, the as-obtained optimal composite, Co–Fe phosphate/rGO, can catalyze oxygen evolution reaction with a very sharp onset potential and a small over-potential of 338[Formula: see text]mV to achieve a current density of 10[Formula: see text]mA[Formula: see text]cm[Formula: see text]. It was found that in these Co–Fe phosphates, the optimal Co:Fe ratio is 0.75:0.25. The excellent electrocatalytic performance of the Co–Fe phosphate/rGO composite would benefit from the synergistic effects between Fe and Co species, as well as rGO substrate providing conductive channels. The formed Co–Fe phosphate/rGO electrocatalysts can be the promising replacement of precious metal-based catalysts for more practical and cost-efficient water splitting.