Facile Engineering of CoS@NiS Heterostructures for Efficient Oxygen Evolution Reaction.

Hydrogen production by the electrolysis of water has become an important way to prepare green hydrogen because of its simple process and high product purity. However, the oxygen evolution reaction (OER) in the electrolysis process has a high overpotential, which leads to the increase of energy consumption. Developing efficient, stable and low-cost electrolytic water catalyst is the core challenge to reduce the reaction energy barrier and improve the energy conversion efficiency. CoS@NiS-80% nanosheets with rich heterogeneous interfaces were successfully synthesized by hydrothermal reaction and sulfuration. Heterogeneous interface not only promotes the effective charge transfer between different materials and reduces the charge transfer resistance but also accelerates the four-electron transfer process through the synergistic effect of nickel and cobalt atoms. Under alkaline conditions, the overpotential of CoS@NiS-80% nanosheets was only 280 mV at a current density of 10 mA cm, with a Tafel slope of 100.87 mV dec. Furthermore, it could work continuously for 100 h, exhibiting its outstanding stability. This work provides a novel approach for improving the OER performance of transition metal sulfide-based electrocatalysts through heterogeneous interface engineering.