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

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.

Automated summary

Small size AuAg colloidal nanoparticles are prepared using a mild decomposition method and directly deposited on TiO2 NPs or integrated with reduced graphene oxide (rGO) under hydrothermal conditions. Characterization of the nanomaterials was conducted using various techniques. The localized surface plasmon resonance displayed by AuAg nanoparticles and the efficient charge carrier separation provided by graphene nanosheets contribute to the enhanced performance of the photocatalysts.