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

Abstract

In this work, bifunctional TiO₂/Ag₃PO₄/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/Ag₃PO₄/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 Ag₃PO₄ and the deposition of Degussa P25 on the GO surface. Consequently, the hydrothermal treatment leads to the generation of TiO₂/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 Ag₃PO₄/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/Ag₃PO₄/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 Ag₃PO₄-based function materials for practical applications.