Quasi-layer Co2P-polarized Cu3P nanocomposites with enhanced intrinsic interfacial charge transfer for efficient overall water splitting

Abstract

The search for efficient, stable and low-cost electrocatalysts for water splitting is a big challenge faced by energy conversion systems. In this work, Cu₃P–Co₂P nanocomposites with numerous interfaces are employed as catalysts for water splitting in alkaline solution. The quasi-layer structure of Co₂P and the polarized plane of Cu₃P endow the nanocomposites with large surface areas and active sites, which substantially favors the intrinsic charge transfer and boosts the catalytic activity. In addition, Cu₃P reduces the lattice mismatch between Co₂P and nickel foam and then enhances the catalytic stability. For the optimized Cu₃P·0.75Co₂P catalyst, a low overpotential of 124.6 mV@−20 mA cm⁻² is required with a Tafel slope of 65 mV dec⁻¹ for the hydrogen evolution reaction (HER) and an overpotential of 334 mV (at 20 mA cm⁻²) is required for the oxygen evolution reaction (OER). The potential for the overall-water-splitting@10 mA cm⁻² is about 1.55 V with the optimized Cu₃P·0.75Co₂P catalysts. Theoretical and experimental results both reveal the significance of coupling of Cu₃P in the two processes of water-splitting for the Cu₃P–Co₂P nanocomposite catalyst.