Bridging oxygen adsorption and activation by Ag single-atom/cluster hybrid for efficient photocatalytic sterilization.

Oxygen adsorption and activation are pivotal steps that drive the reactive oxygen species (ROS) cascade and fundamentally govern the efficacy of photocatalytic antibacterial processes. However, reconciling the distinct electronic requirements for O2 capture and subsequent activation at a unified catalytic site remains a significant challenge. Herein, we report a hybrid-state catalyst (AgACs+1/CNs), fabricated by anchoring silver single atoms (Ag1) onto carbon nitride and subsequently converting part of the Ag1 into atomically precise silver clusters (AgACs). In this architecture, the coordinatively unsaturated edge Ag atoms of AgACs serve as oxygen adsorption sites. Simultaneously, neighboring Ag1 sites act as electron donors, which is proposed to elevate the Fermi level of AgACs above the lowest unoccupied molecular orbital (LUMO) of O2. This elevated Fermi level promotes oxygen activation by enabling spontaneous electron injection from AgACs into O2, elongating the OO bond, and thereby facilitating the formation of superoxide radicals (•O2-). As a result, AgACs+1/CNs demonstrate exceptional bactericidal activity under visible light irradiation at a low concentration of 2 μg/mL, achieving over 99.9% inactivation of both E. coli and S. aureus within 1.5 h. This work presents a design paradigm for hybrid single-atom/cluster catalysts, which provides an integrated strategy to synergistically enhance adsorption and activation at unified active sites.