Interfacial engineering of CoSe@Co9S8 heterojunctions for efficient overall water splitting

Exploration of sustainable, highly efficient, and low-budget non-precious transition metal-based catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is exceedingly challenging and warranted. In this paper, a series of CoSe@Co9S8 nanocomposites are rationally contrived and synthesized through a simple interfacial engineering strategy. The as-prepared CoSe@Co9S8 exhibits the most outstanding activities for both HER and OER, providing low overpotentials of 210 and 278 mV at 100 mA cm-2 , respectively, along with low Tafel slope and remarkable long-term durability. When the CoSe@Co9S8 is used in a self-made dual-electrode system, it requires 1.50 V cell voltage to drive 10 mA center dot cm-2, demonstrating that CoSe@Co9S8 is a superior bifunctional electrocatalyst for overall water splitting. The innovative exploration of this study may carve a new approach for the reasonable construction of multiphase heterojunctions with non-precious transition metal-based electrocatalysts for efficient and stable total water splitting.