Synthesis and characterization of activated carbon-coated SiO2/TiO2−xCx nanoporous composites with high adsorption capability and visible light photocatalytic activity

Abstract

High thermal stability C-doped SiO2/TiO2 coated with activated carbon (AC) nanoporous composites that exhibit high absorption capability and efficient visible light photocatalytic activity were synthesized. The silica particles serve as the cores, glycerol used as the carbon source and pore-forming promoter, and TiCl4 used as the source of TiO2. The structure, crystallinity, morphology and other physical–chemical properties of the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT–IR), N2 adsorption–desorption isotherms and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Composition of the composites was also analyzed by energy dispersive x-ray spectra (EDX). The formation mechanism of the nanoporous composites was extensively discussed. Methylene blue (MB) solution was used as a pollution model to evaluate the adsorption capability and photocatalytic activity of the samples under visible light. The as-synthesized nanoporous composites exhibit both much higher absorption capability and better photocatalytic activity for the photooxidation of MB than pure titania. The higher absorption capability and better photocatalytic activity of as-synthesized nanoporous composites are attributed to their high surface area, well conductivity and higher visible light absorption intensity.