Correlated Atomic Vacancy Pairs Enable Electronic and Geometric Cooperation in Electrocatalysis

Atomic single vacancies (SVs) are powerful catalytic motifs for tailoring local coordination and electronic structures, yet isolated SVs often lack the spatial and functional complexity required for cooperative multisubstrate transformations. Here, we introduce correlated atomic vacancy pairs (CAVPs) as a distinct catalytic architecture that enables simultaneous electronic and geometric cooperation between adjacent, electronically asymmetric anionic SVs. Leveraging the intrinsic in-plane structural anisotropy of 1T″-phase ReSe₂, we identify multiple nonequivalent anionic Se vacancies with markedly different formation energies and electron-donating characteristics. Guided by theoretical insights, we develop a stepwise vacancy-engineering strategy to construct well-defined CAVPs composed of a weak anionic vacancy (SV₁) and a strong anionic vacancy (SV₂) in atomically thin ReSe₂. These CAVPs exhibit exceptional performance for the electroreduction of nitrobenzene, delivering a turnover frequency of 0.32 s^-1 and >99% selectivity at -0.1 V versus RHE, substantially outperforming SV analogues and state-of-the-art catalysts. Density functional theory calculations reveal that SV₁ preferentially stabilizes water-derived intermediates, while SV₂ selectively activates nitrobenzene; their optimized spatial arrangement in CAVPs enables cooperative interactions between the two reactants, lowers hydrogenation energy barriers, suppresses intermediate accumulation, and steers the reaction pathway toward selective arylamine formation. This work establishes CAVPs as a powerful catalytic motif for cooperative multireactant activation and selective multistep transformations, opening new avenues for vacancy-based catalyst design.