Fabrication of P25/Ag₃PO₄/graphene oxide heterostructures for enhanced solar photocatalytic degradation of organic pollutants and bacteria

Herein we demonstrate a facile and general process for fabricating P25/silver orthophosphate/graphene oxide (P25/Ag₃PO₄/GO) ternary composite materials using electrostatically-driven assembly and ion-exchange method. The composite materials reveal a well-defined heterostructure where few-layer GO sheets are decorated with microsized Ag₃PO₄ particles and TiO₂ nanoparticles. The photodegradation of dye molecule and inactivation of bacteria can be tuned by varying the added amount of GO and the molar ratio of Ag₃PO₄/P25. The photocatalytic activity for degrading organic dye molecule and bactericidal performance could be improved by synergistic effects derived from the P25/Ag₃PO₄/GO heterostructure. A detailed analysis of the reactions mechanism by radical-capture agents suggests photo-induced active holes and reactive oxygen species (ROS) are responsible for the enhanced photocatalytic degradation activity owing to effective visible light harvesting, improved separation efficiency and fast interfacial charge transfer. Intrinsic antibacterial activity of dissolved Ag⁺ ions is also considered to play an important role in determining the excellent bactericidal performance of the P25/Ag₃PO₄/GO ternary composite. We believe that this work provides new insights into the low-cost, large-scale production of multifunctional composite materials for the applications in solar photocatalytic degradation of harmful volatile organic compounds (VOCs) and common pathogenic bacteria in wastewater.