MXene-Mediated Internal Electric Field in WO3/AgBr Nanocomposites Enhances Visible-Light-Driven Peroxymonosulfate-Activation and Dual-Mode Antibacterial Performance.

Designing heterojunctions that enable efficient charge separation without compromising redox potential is key to advancing visible-light-active photocatalysts for water treatment via advanced oxidation processes (AOPs). In this study, a rationally engineered WO₃/AgBr/Ti₃C₂T_x MXene ternary composite is synthesized and comprehensively evaluated for photocatalytic and antibacterial efficacy. Electron paramagnetic resonance and radical scavenging analyses confirmed the light-induced generation of reactive oxygen species (ROS) such as ^•OH and O₂ ^•-. Supported by X-ray photoelectron spectroscopy and density functional theory, an "indirect S-scheme" charge transfer mechanism is proposed, where MXene facilitates selective recombination of low-energy carriers while conserving high-energy electrons and holes for efficient ROS production. The optimized composite exhibited a six-fold improvement in photocatalytic activity over pristine WO₃, which further doubled with peroxymonosulfate (PMS), achieving a twelve-fold enhancement overall. Antibacterial studies under dark and light conditions reveal potent dual-mode disinfection, with effective inactivation of Escherichia coli and Staphylococcus aureus. Agarose gel electrophoresis confirmed substantial DNA degradation in PMS-assisted conditions, minimizing the risk of bacterial resuscitation. This multifunctional material, combining efficient charge dynamics, visible-light responsiveness, and strong biocidal action, holds significant promise for integrated pollutant degradation and microbial disinfection in next-generation AOP frameworks.