Two-dimensional bimetallic phosphide ultrathin nanosheets as non-noble electrocatalysts for a highly efficient oxygen evolution reaction

Abstract

Highly efficient non-noble metal oxygen evolution reaction (OER) catalysts are urgently needed for the practical application of electrochemical energy technology. Herein, we report two-dimensional (2D) bimetallic phosphide (Co_1−xFe_xP) ultrathin nanosheets as new OER catalysts. The two-dimensional (2D) morphology of the nanosheets and the synergistic effect between different transition-metal elements made contributions to the OER catalysis. By optimizing the doping ratio of the Fe atoms, the Co_0.8Fe_0.2P nanosheets showed the best OER performance with a small overpotential of 270 mV versus a rotating hydrogen electrode at a current density of 10 mA cm⁻² and low Tafel slope of 50 mV dec⁻¹ in an alkaline electrolyte. Moderate iron doping improved the degree of oxidation at the surface of CoP nanosheets and preserved the conductive and chemically stabilizing host, thereby enhancing the OER activity. Our findings could aid the rational design of novel non-layered 2D nanomaterial OER catalysts.