Plasmon-boosted S-scheme g-C3N4-Co3O4-Ag 2D nanostructure for highly efficient visible-light antibacterial photocatalysis.

The rapid emergence of multidrug-resistant bacteria has created an urgent need for safe and efficient antimicrobial strategies. Here, we present a rationally engineered 2D plasmonic photocatalyst based on g-C3N4 nanosheets coupled with Co3O4 and Ag nanoparticles to construct an S-scheme heterojunction. The ternary g-C3N4-Co3O4-Ag (GCA) nanocomposite was successfully fabricated, as confirmed by XRD, TEM, and SEM analyses, while UV-Vis DRS revealed the strong surface plasmon resonance (SPR) effect of Ag. The charge-transfer pathway was validated by XPS, ESR, and radical-trapping experiments, demonstrating the efficiency of the S-scheme mechanism in promoting charge separation and reactive oxygen species (ROS) generation. Under visible LED irradiation, the GCA nanocomposite exhibited outstanding antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), non-typhoidal Salmonella enteritidis (NTS), and enteroaggregative Escherichia coli (EAEC), with MIC and MBC values of 140 and 280 µg mL-1, respectively. The photocatalytic disinfection efficiency significantly surpassed that of pristine g-C3N4 and binary g-C3N4-Co3O4 composites. Importantly, negligible antibacterial effects were observed under dark conditions, underscoring the material's safety and selectivity. This study highlights the synergistic contribution of plasmonic Ag and S-scheme heterojunction engineering in enhancing visible-light-driven antibacterial performance. The findings provide a promising pathway for the development of advanced photocatalytic nanomaterials aimed at controlling healthcare-associated infections and addressing the global challenge of antibiotic resistance.