Electron-transfer enhanced sponge-like CrP-Re2P as a robust bifunctional electrocatalyst for high-current overall water splitting and Zn–H2O cell

Developing dual functions, high-performance and stable catalysts for simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at high-current density is highly desirable but still remaining as a challenge. Herein, a porous sponge-like structure of CrP-Re2P composite was successfully constructed on nickel foam (NF) via a facile hydrothermal, drop casting, and subsequent phosphating treatment. Remarkably, the CrP-Re2P/NF exhibits extraordinary performance with an ultralow overpotential of 148 mV at a current density of 100 mA cm−2 for HER and 255 mV at 20 mA cm−2 for OER in 1.0 M KOH, respectively. In addition, the bifunctional catalyst also manifests high-efficiency overall water splitting performance that drives a two-electrode system with 500/1000 mA cm−2 at a voltage as low as 1.89/2.02 V in 30% KOH. Moreover, the overall water-splitting device can achieve superior durability for 100 h at a current density of 100 mA cm−2 without obvious degradation. More significantly, the CrP-Re2P/NF is used as the cathode of alkaline Zn-H2O cell with a power density of 8.8 mW cm−2 and robust stability for 180 h, indicating that the catalyst has an encouraging industrial perspective. The excellent electrocatalytic performance of CrP-Re2P/NF is mainly attributed to the porous structure exposing more active sites, high conductivity resulted better charge transfer, as well as the strong synergy between CrP and Re2P species to regulate the binding energy with reactant intermediates. The strategy provides a novel and feasible approach for the development of highly efficient and stable bifunctional catalysts for overall water splitting and Zn–H2O cell.