Facile Fabrication of S-TiO2/beta-SiC Nanocomposite Photocatalyst for Hydrogen Evolution under Visible Light Irradiation

Abstract

A series of sulfate modified TiO2/beta-SiC nanocomposite photocatalysts has been fabricated by sol-gel and wetness impregnation method by varying amount (5-20 wt %) of sulfate contents. The photocatalysts has been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS), Brunauer-Emmett-Teller (BET) surface area, high resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), photoelectrochemical (PEC) measurement and photoluminescence (PL) florescent spectra study. The finding confirms that type (II) heterojunction exists between the crystal lattice of beta-SiC and TiO2; alternatively, sulfate (S6+) is bidentately coordinated on the surface of TiO2. The existence of sulfate maintains the morphology as well as enhances the surface area, decreases the crystallite size, shifts the optical absorption toward the red end, enhances the generation of OH radical, acts as cocatalyst, and facilitates the photogenerated charge carriers. The photocatalytic activity of the synthesized catalysts has been evaluated toward hydrogen energy production in the presence of visible light. The excellent photocatalytic activity (1254 mu mol in 3 h) for 15 wt % S doped TiO2/beta-SiC has been attributed to the synergistic interaction of ternary species, and establishment of heterojunction, which decreases the charge recombination rate, makes easy channelization of electron for effective surface charge transfer, and enhances the photocatalytic properties of the catalyst.