Facile Synthesis of Vanadium-Doped Ni₃S₂ Nanowire Arrays as Active Electrocatalyst for Hydrogen Evolution Reaction

Ni₃S₂ nanowire arrays doped with vanadium(V) are directly grown on nickel foam by a facile one-step hydrothermal method. It is found that the doping can promote the formation of Ni₃S₂ nanowires at a low temperature. The doped nanowires show excellent electrocatalytic performance toward hydrogen evolution reaction (HER), and outperform pure Ni₃S₂ and other Ni₃S₂-based compounds. The stability test shows that the performance of V-doped Ni₃S₂ nanowires is improved and stabilized after thousands of linear sweep voltammetry test. The onset potential of V-doped Ni₃S₂ nanowire can be as low as 39 mV, which is comparable to platinum. The nanowire has an overpotential of 68 mV at 10 mA cm^-2, a relatively low Tafel slope of 112 mV dec^-1, good stability and high Faradaic efficiency. First-principles calculations show that the V-doping in Ni₃S₂ extremely enhances the free carrier density near the Fermi level, resulting in much improved catalytic activities. We expect that the doping can be an effective way to enhance the catalytic performance of metal disulfides in hydrogen evolution reaction and V-doped Ni₃S₂ nanowire is one of the most promising electrocatalysts for hydrogen production.