Advances in Oxygen Vacancy-Driven Hydrogen Production via Water Electrolysis

Oxygen vacancy (O_v), as a central strategy in defect engineering, plays a pivotal regulatory role in hydrogen production via water electrolysis. This review systematically addresses the scientific understanding of O_v in the hydrogen evolution reaction (HER). First, the relationship between the spatial distribution of O_v and the intrinsic mechanisms that enhance catalytic activity is summarized, along with the hydrogen production pathways on O_v-containing catalysts. Second, the principles of O_v construction strategies and their impacts on structural stability, defect density, and overall catalytic performance are comprehensively examined. Third, a series of complementary characterization techniques for O_v are elaborated, which lays a solid experimental foundation for verifying the existence of O_v, quantifying its concentration, and establishing structure-activity relationships. Fourth, the superior performance of O_v-modified catalysts in HER has been analyzed. The catalytic effects produced by different mechanisms were quantitatively described through measurable indicators. This review establishes connections among O_v characteristics, preparation strategies, characterization techniques, reaction pathways, and HER catalytic performance, thereby enhancing the potential for applying O_v strategies in the efficient, large-scale hydrogen production.