Visible light-driven mesoporous Au–TiO2/SiO2 photocatalysts for advanced oxidation process

Au–TiO2/SiO2 heterogeneous catalysts with different Au contents were successfully synthesized by a facile hydrothermal process and their photocatalytic activity towards reduction of Rose Bengal (RB), Methyl Blue (MB), Rhodamine B (RhB) and Congo Red (CR) was investigated in the presence of sodium borohydride (NaBH4) for advanced oxidation process (AOP). The results reveal that 3 wt% Au loaded in TiO2/SiO2 can significantly degrade high RB concentration dye (>95%, 0.3 g/L, 12 pH) within 20 min of irradiation time. All catalysis reaction followed the pseudo-first order rate reaction with high correlation coefficient. The effect of loading of Au nanoparticles (1–5 wt%) along with variation in dye concentration (100–500 ppm), pH of solution (2–12), catalysts dosage (0.1–0.5 g/L), and reaction temperature (30–80 °C) were also studied. The present works shows the superior performance of Au–TiO2/SiO2 heterogeneous catalysts to be related to the high dispersion of Au nanoparticles in the TiO2/SiO2 and to the catalytic effect between gold and TiO2.

Graphical abstractA schematic illustrating the synthesis of Au–TiO2/SiO2 nanocomposite and the mechanism of photodegradation under sunlight irradiation.Figure optionsDownload full-size imageDownload as PowerPoint slide