Enhancement of photocatalytic activity of ZnO/SiO2 by nanosized Pt for photocatalytic degradation of phenol in wastewater

Abstract

ZnO- SiO 2 nanoparticles were synthesized by a sol-gel technique from Zn (NO 3) 2 6 H 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/ SiO 2 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/ SiO 2 PAD: Pt-ZnO/ SiO 2 img: Pt-ZnO/ SiO 2. The surface area decreased from 480 to 460 and 450m 2/g, while the efficiency of the phenol degradation increased from 80 to 85 and 100, with the ZnO/ SiO 2, Img: Pt-ZnO- SiO 2, and PAD: Pt-ZnO- SiO 2 samples, respectively. Copyright © 2012 R. M. Mohamed and M. A. Barakat.