Construction of CoS2/NiS@NCNTs heterojunction for enhanced oxygen evolution reaction

Transition metal sulfides (TMSs) are highly promising electrocatalysts for the oxygen evolution reaction (OER), but insufficient stability limits their application. To this end, we prepared cobalt-based nitrogen-doped carbon nanotube-supported binary sulfide heterojunction catalysts (CoS 2 /NiS@Co@NCNTs) via a two-step high-temperature pyrolysis-sulfurization method. The energy-band structure of CoS 2 matches that of NiS, a feature that enables the formation of a high-quality interface, this accelerates electron transfer and charge redistribution, and enhances reaction kinetics. In contrast, the cobalt-based NCNTs enhance electrical conductivity and improve the reaction stability of CoS 2 and NiS. As expected, the CoS 2 /NiS@Co@NCNTs had high OER catalytic activity with an overpotential of 256 mV at a current density of 10 mA cm −2 , which was superior to that of commercial RuO 2 (η 10  = 293 mV). In addition, the prepared catalysts showed good stability and no significant degradation after 50 h of i-t test at a current density of 10 mA cm −2 . This study provides a new strategy for achieving efficient OER in overall water splitting.