Efficient modulation of NiS2 catalyst via the Cu doping strategy to improve hydrogen evolution reactions in alkaline media

Among efficient electrocatalysts used for hydrogen evolution reaction (HER) from electrocatalytic water splitting, the nickel-based sulfides exhibit promising applications via effective heteroatom doping strategy. Herein, we deeply investigate the fundamental mechanism of the Cu doping towards the HER performance improvement of NiS₂ catalyst. Firstly, based on the density functional theory calculations, the Cu doping can efficiently modulate the electronic structure of NiS₂, thereby optimizing the adsorption free energies of hydrogen and H₂O, and enhancing the kinetics of H₂O dissociation. Secondly, we prepare the Cu-doped NiS₂ nanosheet arrays on carbon fiber paper (Cu–NiS₂/CFP), exhibiting superior alkaline HER performances compared with NiS₂ nanosheet arrays on CFP (NiS₂/CFP). Specifically, Cu–NiS₂/CFP shows a low HER overpotential of 75 mV at the cathodic current density of 10 mA/cm² in 1 M KOH. Both aspects of theory calculations and experiments together certify the Cu doping can efficiently modulate NiS₂ catalyst to improve alkaline HER performances.