Amorphous/Crystalline ZrO₂ with Oxygen Vacancies Anchored Nano‐Ru Enhance Reverse Hydrogen Spillover in Alkaline Hydrogen Evolution

Abstract Hydrogen spillover‐based binary (HSBB) system has attracted significant attention in alkaline hydrogen evolution reaction (HER). Accelerating hydrogen spillover in the HSBB system is crucial for the HER activity. Herein, a highly efficient HSBB system is developed by anchoring nano‐Ru on oxygen vacancy (Vo) rich amorphous/crystal ZrO₂. Theoretical and experimental results reveal that the water molecules dissociate on the Vo of ZrO₂ into protons, which then couple with electrons to form H^*, and the produced H^* are spilled over to the nano‐Ru to evolve H₂. The amorphous regions enhance the adsorption and desorption rates of hydrogen while exposing a greater number of active sites; meanwhile, the Vo significantly reduce the work function of ZrO₂, facilitates electron transfer from ZrO₂ to Ru, and thereby accelerates hydrogen spillover. As a result, the Ru/ac‐ZrO₂ delivers a low overpotential of 14 mV at 10 mA cm⁻² and a high mass activity of 46.47 A mg_metal⁻² at 300 mV for alkaline HER, bypass those of commercial Pt/C (19 mV and 0.09 A mg_metal⁻², respectively).