UV-Induced Photocatalytic Degradation of Methyl Green Dye by ZnO Nanowires and Nanorods Obtained by Spray Pyrolysis

Abstract

ZnO nanorods and ZnO nanowires were obtained using solutions of zinc chloride and zinc acetate dihydrate, respectively, as precursors. The thin films were deposited by ultrasonic spray pyrolysis onto glass substrates at 350 °C and their morphological, structural, and optical properties were investigated. ZnO nanostructures morphologies were observed by SEM and images showed that a large amount of ZnO nanorods and nanowires were deposited onto the full substrates surfaces. The films have polycrystalline nature and hexagonal wurtzite structure with (002) and (101) preferential orientations for ZnO nanorods and nanowires, respectively. The crystallite size was found to be in the range of 30 nm. The films exhibit an optical transparency in the visible region of about 60 % for ZnO nanowires and 30 % for ZnO nanorods. The different ZnO films were used as photocatalysts to study the photodegradation of methyl green dye induced by UV light. ZnO nanorods exhibited higher photodegradation efficiency and a larger rate constant than ZnO nanowires leading to an improvement from 60 % to 80 % of the degradability of the dye.