Vacancy and Dopant Co‐Constructed Active Microregion in Ru–MoO 3− x /Mo 2 AlB 2 for Enhanced Acidic Hydrogen Evolution

Abstract Accurate identification of catalytic active regions is crucial for the rational design and construction of hydrogen evolution catalysts as well as the targeted regulation of their catalytic performance. Herein, the low crystalline‐crystalline hybrid MoO 3− x /Mo 2 AlB 2 with unsaturated coordination and rich defects is taken as the precursor. Through the Joule heating reaction, the Ru‐doped MoO 3− x /Mo 2 AlB 2 catalyst is successfully constructed. Building on the traditional view that individual atoms or vacancies act as active sites, this article innovatively proposes the theory that vacancies and doped atoms synergistically construct active microregions, and multiple electron‐rich O atoms within the active microregions jointly serve as hydrogen evolution active sites. Based on X‐ray absorption fine structure analysis and first‐principles calculations, there is a strong electron transfer among Ru atoms, Mo atoms, and O atoms, leading to extensive O atoms with optimized electronic structure in the active microregions. These O atoms exhibit an H * adsorption free energy close to zero, thereby enhancing the catalytic activity for hydrogen evolution. This work provides a brand‐new strategy for the design and preparation of electrocatalytic materials and the systematic regulation of the local electronic structure of catalysts.