Solar light driven Rhodamine B degradation over highly active beta-SiC-TiO2 nanocomposite

Abstract

A series of beta-SiC-TiO2 nanocomposites were successfully fabricated by a sol-gel process with the purpose of efficient charge (e(-), h(+)) separation and the enhancement of the photocatalytic performance under solar light irradiation. A pristine anatase state of TiO2 was prepared by the acid hydrolysis of Ti((OPr)-Pr-i)(4) and a beta-SiC powder was synthesized by a thermal plasma process from rice husks. The physicochemical characteristics of the nanocomposites were surveyed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS), BET surface area, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and photoelectrochemical (PEC) measurement. The PEC study confirms that TiO2 is n-type semiconductor, whereas the beta-SiC is p-type semiconductor. The XRD, TEM and XPS studies confirm the formation of a heterojunction between the beta-SiC and TiO2. The photocatalytic activities of all the beta-SiC-TiO2 nanocomposites were studied for aqueous Rhodamine B (Rh-B) dye degradation under solar light irradiation. The photodegradation mechanism of all the synthesized catalysts were further confirmed through chemical oxygen demand (COD) analysis and trapping of hydroxyl radicals by a fluorescence probe technique. Among all the samples, 20 wt% beta-SiC-TiO2 exhibits a significant activity of 87% dye degradation in the presence of solar light. The high activity of 20 wt% beta-SiC-TiO2 is ascribed to high surface area, low crystallite size, high generation of OH radicals and COD efficiency.