Cr‐Doped Ni ₃ S ₂ Nanosheet Arrays as Efficient and Stable Electrocatalysts for Alkaline Hydrogen Evolution Reaction

ABSTRACT Developing efficient and stable non‐precious metal electrocatalysts for hydrogen evolution reaction (HER) is of great significance for advancing water electrolysis hydrogen production technology. This paper presents a Cr‐doped Ni 3 S 2 nanosheet array catalyst prepared on nickel foam via a one‐step hydrothermal method. Experimental results show that the introduction of Cr effectively improves conductivity and accelerates interfacial electron transfer, resulting in the catalyst exhibiting excellent hydrogen evolution performance in a 1.0 M KOH electrolyte, achieving a current density of 10 mA cm −2 with only a 122 mV overpotential, and maintaining long‐term operational stability for over 20 h. Furthermore, XPS and Raman results show that Cr doping not only optimizes the electronic structure of Ni 3 S 2 but also induces the formation of a surface oxygen sulfide layer thereby promoting the dissociation of water. This study provides a new approach for designing superior hydrogen evolution catalysts by synergistically controlling electronic structure and surface reconstruction through doping engineering.