Enhancement of Photocatalytic Activity of ZnO/SiO2 by Nanosized Pt for Photocatalytic Degradation of Phenol in Wastewater

ZnO-SiO2 nanoparticles were synthesized by a sol-gel technique from Zn(NO3)(2) . 6H(2)O and tetraethyl orthosilicate (TEOS). The synthesized samples were further modified by nanosized Pt from H2PtCl6 solution through photoassisted deposition PAD) and impregnation (Img) routes. The obtained samples were characterized by a series of techniques including X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, N2 adsorption, extended X-ray absorption fine structure (EXAFS), and transmission electron microscopy (TEM). The photocatalytic activity of the Pt-ZnO/SiO2 was evaluated by photocatalytic degradation of phenol in synthetic wastewater under UV-irradiation. Results obtained revealed that the surface area and the photocatalytic activity of the prepared samples were increased in the order ZnO/SiO2 < PAD: Pt-ZnO/SiO2 < img: Pt-ZnO/SiO2. The surface area decreased from 480 to 460 and 450 m(2)/g, while the efficiency of the phenol degradation increased from 80 to 85 and 100%, with the ZnO/SiO2, Img: Pt-ZnO-SiO2, and PAD: Pt-ZnO-SiO2 samples, respectively.