Dual Active Site Engineering of Nickel Selenides by a Substrate Effect for Alkaline Hydrogen Evolution.

Developing efficient catalysts for alkaline hydrogen evolution reaction (HER) requires rapid water/hydrogen adsorption/dissociation kinetics. However, challenges remain in reducing energy barriers by simultaneously activating the anionic and cationic sites in a single compound. In this article, a heterogeneous substrate (NiS₂-NiS) regulatory strategy is developed to construct dual active sites in NiSe₂ toward the HER. The obtained NiSe₂/NiS₂-NiS electrode delivers excellent catalytic performance, achieving an overpotential of 46 mV at the current density of 10 mA cm^-2 under alkaline conditions. Density functional theory calculations demonstrate that the NiS₂-NiS heterogeneous substrate induces charge distribution and activates Ni 3d electrons. Combined with in situ Raman spectroscopy analysis, the Ni and Se atoms, as the dual active site for the HER, possess the minimum water adsorption-dissociation energy barrier and the optimal hydrogen adsorption Gibbs free energy, respectively. This finding provides novel insights into the dual active site engineering for highly efficient catalysts based on the substrate effect.