Electronic structure regulation of an ultra-thin MOF-derived NiSe2/NiS2@NC heterojunction for promoting the hydrogen evolution reaction

Abstract

Transition metal selenides (TMSes) are considered promising electrocatalysts for the hydrogen evolution reaction (HER) due to their narrow bandgap, unique morphology and low cost. Herein, using a metal–organic framework (MOF) as a precursor, a NiSe₂/NiS₂@NC electrocatalyst with abundant heterogeneous interfaces was designed and synthesized through a simultaneous selenization/sulfurization process. The heterojunction could provide more catalytic sites, accelerate the transfer of ions/gas, and optimize the electronic structure of the interface, and then exhibit overpotentials of 188 mV and 211 mV at 10 mA cm⁻² in acidic and alkaline media. The density functional theory (DFT) calculation results showed that the heterogeneous interface can optimize the electronic structure. Meanwhile, the Gibbs free-energy for H* adsorption was reduced to −0.35 eV, which means that the interface can effectively accelerate the HER kinetics. This work provides a strategy for constructing heterojunction electrocatalysts and understanding the role of electronic structure in the HER.