Engineering Ternary Pyrite‐Type CoPS Nanosheets with an Ultrathin Porous Structure for Efficient Electrocatalytic Water Splitting

Abstract

AbstractFor electrochemical water splitting, the development of low‐cost, efficient, and robust electrocatalysts for both the oxygen evolution reaction and hydrogen evolution reaction remains challenging. Herein, we report stoichiometric ternary‐phase CoPS with a two‐dimensional ultrathin porous nanosheet structure as an efficient bifunctional electrocatalyst for overall water splitting. Owing to the stable stoichiometric ternary phase, abundant octahedral Co3+ is observed in CoPS, serving as active sites to boost electrocatalytic activities. With the introduction of the ultrathin porous nanosheet structure, more active sites are exposed to enhance the electrochemical performance. Therefore, the samples display remarkable oxygen evolution activity with a low overpotential of 316 mV at 10 mA cm−2 and a small Tafel slope of 50.2 mV dec−1. Combined with their highly efficient hydrogen evolution activity, CoPS ultrathin porous nanosheets are demonstrated to have extraordinary activities for overall water splitting, with a cell voltage of 1.57 V to reach 10 mA cm−2 current density. This work not only provides a bifunctional catalyst with outstanding performance, but also offers a facile route for improving electrocatalytic activity by synergistic morphology design and electronic modulation.