Effect of Ag Content on Photocatalytic Activity of Ag@TiO2/rGO Hybrid Photocatalysts

In this study, silver (Ag)-doped titanium dioxide/reduced graphene oxide (Ag@TiO2/rGO, TGA) hybrid photocatalysts were synthesized for enhanced photocatalytic properties. TGA hybrid photocatalysts were synthesized through a facile sol-gel method. Synthesis of graphene oxide (GO) nanoparticles were obtained by Hummer's method followed by chemical reduction to obtain rGO nanoparticles. Ag doping was carried out at the sol stage of the sol-gel synthesis. Increasing amounts of Ag nanoparticles from 0.5 wt.% to 4 wt.% were added to increase the degradation effect of methylene blue (MB) under UV light irradiation. X-ray diffractometry (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), UV-vis spectrophotometry, photoluminescence spectroscopy (PL), and diffuse reflectance spectroscopy (DRS) were used to investigate the crystal structure, topography, morphology, chemical and optical properties of the samples, respectively. Samples were calcined in order to obtain the anatase phase at 500 degrees C with a heating rate of 10 degrees C/min for 2 h in air atmosphere. The effect of Ag content on the photocatalytic properties of TiO2 based nanocomposite material was observed by keeping the weight ratio of rGO constant at 4 wt.%. Ag addition into the TiO2/rGO matrix exposed an excellent photocatalytic activity under UV light irradiation than that of undoped TiO2/rGO photocatalyst. The absorbance value of MB was degraded from 0.683 to 0.011 at 664 nm by TGA1 sample for 240 min. This demonstrated that the TGA1 hybrid photocatalyst containing 1 wt.% of Ag exhibited the highest degradation efficiency of 98.4%. This paper indicates the potential photocatalytic application of Ag-doped TiO2/rGO photocatalysts on the removal of dissolved organic pollutants in water.