Controllable synthesis of MoO linkage enhanced CoP ultrathin nanosheet arrays for efficient overall water splitting

Developing cost-effective and high-performance bifunctional catalysts for overall water splitting is of enormous importance for the realization of sustainable clean-energy technologies. Herein, the unique MoO linkage enhanced CoP nanosheets supported on Ni foam (NF) and the systematical investigation of their performance for overall water splitting as a function of the composition are reported. The fine-tuning of Co/Mo ratios in the CoMo precursors realized by controlling the dosages of capping agent (urea), which enables CoO to grow along its (111) crystalline orientation and retard the incorporation of MoO. As a result, the optimized CoP/MOL/NF-10 exhibits the best hydrogen evolution reaction (HER) activity with low overpotentials (η) of 87 mV at 10 mA cm⁻². DFT calculation confirmed the O-site on surface is more advantageous to the adsorption of H, when CoP with proper mounts of MoO linkages and giving rise to a decent ΔG_H value. When the CoP/MOL/NF-10 employed as anode for OER, the current density of 20 mA cm⁻² is achieved at a low overpotential of 270 mV. In the end, a symmetric electrolyzer built by CoP/MOL/NF-10 deliveries a current density of 10 mA cm⁻² at a cell voltage of 1.52 V with excellent stability.