Self-Supported Ternary Ni–S–Se Nanorod Arrays as Highly Active Electrocatalyst for Hydrogen Generation in Both Acidic and Basic Media: Experimental Investigation and DFT Calculation

In this study, a novel three-dimensional self-supported ternary NiS–Ni₉S₈–NiSe nanorod (NR) array cathode has been successfully in situ constructed by a two-step hydrothermal route. When applied to hydrogen evolution, the synthesized NiS–Ni₉S₈–NiSe-NR electrode demonstrates optimized electrocatalytic activity and long-term durability, only requiring overpotentials as low as 120 and 112 mV to drive 10 mA cm^–2 for hydrogen evolution reaction in 0.5 M H₂SO₄ and 1.0 M KOH, respectively. Density functional theory calculation reveals that after Se doping Se 3d orbitals are bonded to Ni 3d orbitals and S p orbitals near Fermi level, attesting a significant electron transfer between nickel and selenium atoms. The success of enhancing the electrocatalytic performance via introducing the Se dopant holds great promise for the potential optimization of other transition-metal compounds in highly efficient electrochemical water splitting for large-scale hydrogen production