Photocatalytic degradation of stearic acid by ZnO thin films and nanostructures deposited by different chemical routes

Abstract

The structural, morphological and photocatalytic properties of ZnO thin films and nanostructures deposited on Corning glass substrates via various chemical routes were investigated. It is demonstrated that the structural and morphological characteristics of the samples depend drastically on deposition technique and parameters. ZnO nanostructured films, nanopetals and nanowires were systematically obtained by varying the experimental conditions. Sol–gel method leads to the formation of dense ZnO nanostructured thin films with a preferred growth orientation along the (0 0 2) crystallographic direction, while ultrasonic spray pyrolysis results in ZnO nanopetals, their dimensions increasing with spraying time. On the other hand, highly oriented ZnO nanowires were obtained via aqueous solution growth on seeded Corning substrates. All ZnO samples show remarkable photocatalytic activity regarding the degradation of stearic acid, which is attributed to their good crystallinity and large surface area. In particular, ZnO nanowires exhibit an outstanding photocatalytic activity, degrading stearic acid by almost 93% in 30 min. This behaviour is mainly due to their high surface-to-volume ratio.