One pot synthesis of Ag-SnO2 quantum dots for highly enhanced sunlight-driven photocatalytic activity

Abstract

Herein, we reported a plasmonic photocatalyst, Ag-SnO2 quantum dots (QDs) for the abatement of water pollution by a simple and one pot synthesis in water. The Ag-SnO2 QDs were prepared with various concentrations of Ag loading. The as synthesized plasmonic photocatalysts were systematically investigated by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and nitrogen adsorption-desorption isotherm, diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL). The average crystallite size of pristine SnO2 QDs was achieved below 3 nm. The band gap of Ag-SnO2 QDs plasmonic photocatalyst was shifted from UV to visible region i.e. from 3.02 to 2.54 eV. The surface plasmon resonance (SPR) band of Ag-SnO2 QDs is blue shifted in the visible region and the PL intensity of Ag-SnO2 QDs composites decreases with the increase of Ag loading. The sunlight driven photocatalytic activity of Ag-SnO2 QDs composites was carried out by the degradation of Rhodamine B (RhB) solution and the optimized amount of Ag was significantly enhances the photocatalytic activity. The Ag-SnO2 QDs composite with optimized Ag amount showed the highest photocatalytic performance with 98% degradation of the dye under sunlight within 180 min. The improved photocatalytic activity under sunlight is attributed to the tuning of band gap to visible region, SPR of Ag and its synergetic effect of metal and semiconductor quantum dot. The plausible photocatalytic mechanism was suggested for the degradation of the pollutant under sunlight irradiation.