Constructing composite active centers optimized with Cr-doped NiS/NiS2 heterostructure for efficiently catalyzing alkaline hydrogen evolution reaction

Transition metal sulfides, recognized for their platinum-like activity, were prominent in electrolytic water hydrogen production research. In this context, we reported a NiS/NiS2 heterostructure composite active center electrocatalyst optimized by Cr doping (Cr-NiS/NiS2@NF) based on the dual regulation of defect engineering and interface engineering. The electronic structure of Ni and S could be adjusted by Cr doping, and the creation of defects exposed more active sites. Meanwhile, the resulting NiS/NiS2 heterogeneous interface acted as a composite activity center, enhancing the alkaline HER process rate. The Cr-NiS/NiS2@NF achieved 100 mA cm−2 at an overpotential of 172.8 mV. Density functional theory analysis confirms the significant decrease in the water dissociation potential barrier, attributable to the electron redistribution caused by Cr doping. The optimized heterointerface functioned as a composite activity center. Here, the Cr-NiS component effectively facilitated water dissociation, while the NiS2 component primarily enhanced H2 generation and desorption. The introduction of Cr significantly improved the electronic coupling at the bi-phase interfaces, thereby accelerating the transport of hydrogen intermediates. This study revealed the modulation of electron distribution at the Cr-doped nickel sulfide heterointerface, offering deep atomic-scale insights. These findings provide novel perspectives for the field of hydrogen production via water electrolysis.