Oxygen vacancy-induced efficient hydrogen spillover in Ni₁₇W₃/WO_3−x/MoO_3−x for a superior pH-universal hydrogen evolution reaction

Searching for a stable and efficient electrocatalyst for the hydrogen evolution reaction is still challenging, especially under a wider pH operation condition. In this study, a multicomponent Ni₁₇W₃/MoO_3−x/WO_3−x catalyst was designed and synthesized, in which the unique hierarchical structure of entangled nanorods confined in a polyhedral framework ensures the maximum utilization of active sites. Significantly, electrochemical performance can be regulated by adjusting the oxygen vacancy concentration of the metal support. Combined with various characterization techniques, we discovered that abundant oxygen vacancies in the MoO_3−x/WO_3−x support not only significantly enhanced the hydrogen insertion/extraction kinetics in the metal oxide but also increased the hydration capacity, resulting in an efficient hydrogen adsorption/transfer/desorption kinetics on the Ni₁₇W₃/MoO_3−x/WO_3−x surface and interface. As a result, the fabricated electrocatalyst exhibits an ultralow overpotential of 16, 42, and 14 mV at 10 mA cm⁻² in alkaline, neutral, and acid electrolytes, respectively. Our work proves the important role of metal oxide supports in the hydrogen spillover process.