Tungsten–Nickel Alloy Boosts Alkaline Hydrogen Evolution Reaction

The alkaline electrocatalytic hydrogen evolution can produce clean and high-purity hydrogen gas that meets sustainable demands. Metal oxides supported transition metal alloys (e.g., WNi4@WOx, MoNi4@MoOx) can work in synergy to alter the sluggish kinetics of alkaline HER electrocatalysis. However, to date the formation mechanism of the metal alloys extracted from nickel tungstate/molybdate precursors is unclear. Moreover, the synergistic effects of W/Mo and Ni atoms were solely based on the density functional theory calculations, and no sufficient practical evidence can support the results of the simulations. Here, we demonstrate the formation mechanism of WNi4@W–WO2 using in situ variable temperature near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) measurements. The as-obtained WNi4@W–WO2 heterostructures exhibited markedly high alkaline HER performance with a low overpotential (83 mV) at 10 mA/cm2 and a small Tafel slope (83 mV/dec). The quasi in situ alkaline HER electrocatalysis determined that the enhanced mechanism of alkaline HER activity can be attributed to the synergistic effects of the neighboring W and Ni atoms. This work paves a feasible route for designing desired transition metal alloy catalysts toward highly efficient alkaline HER electrocatalysis and the elucidation of the catalytic mechanism.