Asymmetric Zn─N3O1 Single-Atom Sites Promote Hydroxyl Radical Generation for Natural-Light-Driven Inactivation of Drug-Resistant Bacteria.

Waterborne drug-resistant bacteria pose a serious global health threat, underscoring the urgent need for highly efficient disinfection strategies. The photocatalytic generation of hydroxyl radicals (•OH) represents a green and powerful route for bacterial inactivation, yet its efficiency is often limited by the sluggish kinetics of the stepwise single-electron oxygen reduction pathway. Herein, we report an atomic-level design strategy by anchoring asymmetric Zn─N3O1 sites onto ultrathin graphitic carbon nitride nanosheets (Zn1/OCN) to accelerate •OH production. The introduced Zn─N3O1 sites create localized intermediate states that enable rapid trapping of photogenerated electrons at Zn single-atom sites and prolong their lifetime, thereby driving a stepwise single-electron oxygen reduction reaction (ORR) for efficient •OH generation. Simultaneously, adjacent C═O moieties act as hole-trapping centers to drive water oxidation reaction (WOR), establishing a local reservoir of H2O2 and protons that couples with the ORR process, thus forming a cooperative redox pathway for enhanced •OH production. Additionally, these asymmetric sites effectively lower the formation energies of *OOH and *OH intermediates, thereby accelerating both ORR and WOR processes and facilitating •OH generation. Consequently, Zn1/OCN achieves outstanding bactericidal performance, inactivating 99.9% of drug-resistant bacteria, within 30 min under natural light, markedly outperforming representative photocatalytic antibacterial materials reported to date.