Engineered gradient oxygen vacancies by ambient ball-milling boost ampere-level water electrolysis stability

Balancing the activity and stability of catalysts has become one of the key approaches to breakthrough the bottleneck of ampere-level water electrolysis. Oxygen vacancy is one of the most important active structures in catalysts. The complex structure of oxygen vacancy, such as the spatial distribution, profoundly affects the catalytic activity and mechanism. Here, we present a mechanochemical method that utilizes controlled environment pressure to create oxygen vacancies and modulate its spatial distribution in Pr0.5Ba0.5CoO3 by regulating the surface desorption and lattice diffusion process of lattice oxygen. Combining computational and experimental results, we proposed a detailed synthesis mechanism that outlines the formation and diffusion behavior of vacancies at the atomic scales. Further electrochemical studies developed two OER descriptors, surface and bulk oxygen vacancy concentrations, suitable for different catalytic mechanisms. Also, the above research further proposed an oxygen vacancy distribution control strategy, which can significantly improve the stability of the catalyst at ampere-level current density and under practical working conditions while maintaining their high intrinsic activity through the switching of catalytic mechanisms. This work offers a mechanochemical method for synthesizing oxygen vacancies and paves the new way for the development of ampere-level industrial electrolytic water catalysts.