Photocatalytic degradation of dyes over Au decorated SrTiO<sub>3</sub> nanoparticles under simulated sunlight and visible light irradiation

Abstract

Au–SrTiO3 nanocomposites were prepared using a photocatalytic reduction method by which the Au nanoparticles with particle size of 7–26 nm were deposited on the surface of SrTiO3 particles with an average diameter of ∼55 nm. The structure, morphology and optical properties of products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Transmission electron microscopy and UV–visible diffuse reflectance spectroscopy. It is found that the loaded Au nanoparticles on SrTiO3 particles exist in the metallic state, and the surface plasmon resonance absorption band centered around 557 nm is obviously detected in the diffuse reflectance spectra of Au–SrTiO3 nanocomposites. The photocatalytic activities of samples toward the degradation of dyes (acid orange 7 and methyl orange) were evaluated under simulated sunlight and visible light irradiation. The results indicate that the decoration of Au nanoparticles can effectively improve the photocatalytic activity of SrTiO3, and the catalytic efficiency of composites is related to the content of Au. More importantly, the Au–SrTiO3 nanocomposites exhibit much higher photocatalytic activity under simulated sunlight than under visible light. In addition, a possible promotion mechanism of Au nanoparticles on the photocatalytic activity of SrTiO3 was proposed.