Lattice Strain with Stabilized Oxygen Vacancies Boosts Ceria for Robust Alkaline Hydrogen Evolution Outperforming...

Earth-abundant metal oxides are usually considered as stable but catalytically inert toward hydrogen evolution reaction (HER) due to their unfavorable hydrogen intermediate adsorption performance. Herein, a heavy rare earth (Y) and transition metal (Co) dual-doping induced lattice strain and oxygen vacancy stabilization strategy is proposed to boost CeO₂ toward robust alkaline HER. The induced lattice compression and increased oxygen vacancy (O_v) concentration in CeO₂ synergistically improve the water dissociation on O_v sites and sequential hydrogen adsorption at activated O_v-neighboring sites, leading to significantly enhanced HER kinetics. Meanwhile, Y doping offers stabilization effect on O_v by its stronger Y─O bonding over Ce─O, which endows the catalyst with excellent stability. The Y,Co-CeO₂ electrocatalyst exhibits an ultra-low HER overpotential (27 mV at 10 mA cm^-2) and Tafel slope (48 mV dec^-1), outperforming the benchmark Pt electrocatalyst. Moreover, the anion exchange membrane water electrolyzer incorporated with Y,Co-CeO₂ achieves excellent stability of 500 h under 600 mA cm^-2. This synergistic lattice strain and oxygen vacancy stabilization strategy sheds new light on the rational development of efficient and stable oxide-based HER electrocatalysts.