An improved plasmonic Au–Ag/TiO2/rGO photocatalyst through entire visible range absorption, charge separation and high adsorption ability

Abstract

Small size AuAg colloidal nanoparticles (AuAg NPs) are prepared through the mild decomposition of the organometallic precursor [Au₂Ag₂(C₆F₅)₄(OEt₂)₂]_n in THF, using polyvinylpyrrolidone (PVP) as the stabilizing polymer. These nanoparticles are directly deposited on the surface of TiO₂ NPs through impregnation in solution at RT or under hydrothermal conditions. AuAg–TiO₂–rGO (rGO = reduced graphene oxide) hybrid nanostructures are also prepared under hydrothermal reduction of graphene oxide. The obtained nanomaterials have been characterized through XRD, TEM, HRTEM, solid state UV/vis, Raman and XPS. The use of the nanomaterials as plasmonic photocatalysts under visible white LED light and sunlight is studied and the possible mechanisms of the catalytic degradation of methylene blue (MB) are proposed. The localized surface plasmon resonance (LSPR) displayed by the spherical AuAg nanoparticles enhances their ability of visible light absorption, whereas graphene nanosheets provide a very efficient charge carrier separation, allowing a good performance of the photocatalysts under low-power white LED sources or sunlight.