Ultrathin, Porous CoPS Nanosheets: GO Self-Sacrificing Template Synthesis as Bifunctional Catalysts for Overall Water Splitting

The exploitation of low-cost, porous, and ultrathin 2D electrocatalysts in the bifunctional electrocatalysis reaction and overall water splitting is a meaningful route to renewable energy technologies. Herein, as efficient bifunctional electrocatalysts toward the water-splitting process, the desirable cobalt phosphosulfide (CoPS) nanosheets stem from Co2+ cross-linking to form strong coordination bonds with negatively charged oxygen-containing functional groups on a graphene oxide (GO) sacrificial template via electrostatic interactions. The prepared CoPS catalyst exhibits a distinguished electrochemical performance with a low overpotential (η) of hydrogen evolution reaction (∼52 mV) and oxygen evolution reaction (∼280.7 mV) at 10 mA cm–2 and better durability and higher turnover frequencies under alkaline environments. When it was used as the cathode and anode in alkaline media, the CoPS required only 1.62 V to achieve a current density of 10 mA cm–2, outperforming most of the low-cost bifunctional electrocatalysts reported to date. The bond energy of the P═S bond not only effectively adsorb protons but also suitably weakens the adsorption on the Co–Co bridge site, thereby improving the multifunctional electrocatalysis for water splitting. The excellent performance of porous and ultrathin CoPS nanosheets is conducive to the complete exposure of active sites and facile ion transport kinetics, and they serve as a promising non-precious-metal-based electrocatalysts for the water-splitting reaction.