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.