Fabrication of a three-dimensional visible-light-driven Ag–AgBr/TiO2/graphene aerogel composite for enhanced photocatalytic destruction of organic dyes and bacteria

Abstract

A novel three-dimensional (3D) porous Ag–AgBr/TiO₂/graphene aerogel (Ag–AgBr/TiO₂/GA) photocatalyst has been fabricated successfully through a facile hydrothermal and freeze-drying treatment. The obtained Ag–AgBr/TiO₂/GA is beneficial to carrier migration, mass transport and re-utilization in wastewater treatment in virtue of its 3D macroscopically porous structure with high conductivity. Additionally, the in situ grown TiO₂ nanocrystals and the well-dispersed AgBr nanoparticles in the GA support act as efficient heterojunctions, which significantly promote light absorption and charge separation efficiency. In view of the structural and functional advantages, the as-prepared Ag–AgBr/TiO₂/GA exhibited excellent photocatalytic activity for methyl orange (MO), approximately 94.57% within 30 min under visible light irradiation, which was about 12.36 and 4.09 times higher than those of TiO₂ and TiO₂/GA under the identical conditions. Moreover, Ag–AgBr/TiO₂/GA possessed superior long-term stability/reusability and its removal efficiency could be 94.06% even after eight degradation processes. Meanwhile, Ag–AgBr/TiO₂/GA showed remarkable sterilization of E. coli (approximately 7 log inactivation) and S. aureus (approximately 3.8 log inactivation) under 42 min visible light irradiation, and the excellent disinfection effect on E. coli has remained after three applications.