Boosting Superoxide Radical Selectivity in Photocatalytic O2 Activation via Metal–Oxygen Vacancy Synergy Tuning Local Polarized Electronic Configurations

Selective photocatalytic generation of superoxide radicals (·O2-) via single-electron reduction of molecular oxygen remains challenging due to the critical trade-off between O2 activation and product desorption. In this work, the density functional theory calculations were employed to investigate the regulation of electronic configuration of OV sites over TiO2 and 6 types of single-atom metal-doped catalysts and their influence on the generation of ·O2-. The results demonstrate that the introduction of metal dopants significantly reduce the formation energy of OV, facilitating surface oxygen vacancies stabilization. Crucially, the synergistic effects between dopants and OV induce a localized polarized electronic configuration, featuring electron-rich oxygen vacancies sites adjacent to electron-deficient Ti sites. This unique configuration modulates interfacial electron transfer, creating a balanced thermodynamic environment for O2 adsorption and ·O2- desorption. The doped catalysts are categorized into an active group with spontaneous activation and desorption and an inactive group with endothermic activation. Notably, within the active group, Cu/TiO2-OV and Ni/TiO2-OV dopants thermodynamically favor ·O2- desorption over protonation, whereas Co dopants favor further protonation toward OOH. Cu/TiO2-OV exhibits the optimal activation energy and superior carrier mobility, thereby promoting selective photocatalytic ·O2- generation. This work reveals the intrinsic link between the electronic structure of OV and O2 activation, providing theoretical insights for rational design of photocatalysts with enhanced selective ·O2- generation capabilities for environmental applications.