Bifunctional TiO₂/Ag₃PO₄/graphene composites with superior visible light photocatalytic performance and synergistic inactivation of bacteria

In this work, bifunctional TiO₂/Ag₃PO ₄/graphene (GR) composites have been prepared via the combination of ion-exchange method and hydrothermal approach, and the fabrication of "pizza-like" three-phase TiO₂/Ag₃PO ₄/GR composites has been achieved through the electrostatic-driven assembly of positively-charged Ag⁺ on negatively-charged graphene oxide (GO) sheets, followed by the nucleation & controlled growth of Ag ₃PO₄ and the deposition of Degussa P25 on the GO surface. Consequently, the hydrothermal treatment leads to the generation of TiO ₂/Ag₃PO₄/GR composites with well-defined structures. The as-prepared composites exhibited highly efficient visible light photocatalytic activity toward organic dye molecule degradation and showed excellent bactericidal performance. This is the first report on the production of bifunctional three-phase metal oxide-Ag₃PO₄-GR composite materials with improved photocatalytic and antibacterial properties. The improved photocatalytic activity is attributed to the effective separation of photoexcited electron-hole pairs and fast charge transfer between components in the composite, while its excellent bactericidal performance is believed to come from intrinsic bacterial inactivation of Ag₃PO₄ and photo-induced antibacterial activity of active oxygen-containing radicals generated in the irradiated system. The proper molar ratio of Ag ₃PO₄/TiO₂ and the added amount of GO in the precursor have been considered to play crucial roles in the formation of bifunctional composites with promising properties. The TiO₂/Ag ₃PO₄/GR composite significantly decreases the percentage of expensive Ag-containing material while it reveals better photocatalytic and antibacterial performance than Ag₃PO₄, providing new insights into the low-cost, large-scale production of Ag₃PO ₄-based function materials for practical applications.