Engineering Co-ion vacancy in dynamically reconstructed Co-based catalysts for practical anion-exchange membrane electrolysis

Precisely engineering metal-ion vacancy in dynamically reconstructed electrocatalysts provides an attractive symmetry-breaking tool to develop robust electrocatalysts under operation conditions. Herein, we demonstrate a convenient Sr-ion-mediated reconstruction strategy to fabricate Co-vacancy-enriched Sr-CoOOH nanosheets under oxygen evolution reaction conditions with balanced activation and refilling of lattice oxygen for practical anion-exchange membrane water electrolysis. The Sr-ion substitution in pre-catalysts can weaken bond strength for facilitated Co-ion vacancies formation in reconstructed oxyhydroxides. These Co-ion vacancies not only strengthen Co-O covalency for lattice oxygen activation, but also improve hydroxyl affinity for lattice oxygen refilling. The corresponding water electrolyzer exhibits a cutting-edge current of 3.3 A cm^-² at 2.0 V with a lowered energy consumption of 43.5 kWh kg^-1_H2, and negligible degradation of 0.10 mV h^-1 for 1000 h. This work paves an enlightening guideline to finely engineer metal-ion vacancy in dynamically reconstructed electrocatalysts, demonstrating the feasibility to develop targeted catalysts under practical conditions.