Effect of Sn Doping on the Photocatalytic Properties of ZnO

Abstract

: In this work, we synthesized solutions of un-doped ZnO and ZnO doped with tin (Sn) by the sol-gel method. From these solutions, we deposited thin layers on glass substrates by the spin-coating technique. The main purpose of this work is to study the influence of the incorporation of Sn into the ZnO matrix on the photocatalytic properties of the latter. The crystal structure is hexagonal with a preferential orientation of the crystallites (002), and the reduction in the size of the grains is observed from 21 nm for the un-doped ZnO to 15 nm for the doped ZnO. For both samples, the transparency in the visible region is high and exceeds 75%, and a slight change in the band gap is from 3.22 to 3.23 eV, i.e., it is attributed to a combination of the Burstein–Moss effect and electron-impurity scattering. The methylene blue UV photocatalysis test gives a degradation rate of 40% for un-doped ZnO and 60% for Sn-doped ZnO (2%). This study confirms the remarkable influence of Sn doping on the photocatalytic properties of ZnO and also on its morphological and optical properties.