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

Abstract

A series of β-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 (OⁱPr)₄ and a β-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 β-SiC is p-type semiconductor. The XRD, TEM and XPS studies confirm the formation of a heterojunction between the β-SiC and TiO₂. The photocatalytic activities of all the β-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% β-SiC–TiO₂ exhibits a significant activity of 87% dye degradation in the presence of solar light. The high activity of 20 wt% β-SiC–TiO₂ is ascribed to high surface area, low crystallite size, high generation of OH radicals and COD efficiency.