Enhanced Antibacterial Activity of Sodium Titanate/Graphene Quantum Dot Self-Supporting Membranes via Synergistic Photocatalysis and Physical Cutting

Graphene quantum dots (GQDs) show significant promise as antibacterial agents, but their application is hindered by several limitations, including potential cytotoxicity at high concentrations, as well as concerns regarding aggregation and reusability. In this study, sodium titanate (NTO) ultralong nanotubes were utilized as both a photocatalyst and support for GQDs. The NTO/GQDs heterojunction was formed by embedding GQDs nanoplates onto the walls of NTO nanotubes. This integration significantly improved the visible light absorption and enhanced the separation and transfer of electron-hole pairs, leading to an efficient photocatalytic antibacterial process. The NTO/GQD-8 self-supporting membrane composed of these ultralong nanotubes demonstrated outstanding antibacterial efficiency (99.99%) against <i>E. coli</i> and exhibited remarkable cycling stability. Radical scavenging experiments revealed that ∙OH and e^- were the primary reactive species driving the photocatalytic antibacterial process. Notably, NTO and NTO/GQDs-8 exhibited distinct antibacterial outcomes. After photocatalytic treatment with NTO/GQDs-8, <i>E. coli</i> cells were completely fragmented, with no intact cell structures remaining due to the synergy effect of GQDs' physical cutting during photocatalytic treatment.