Defect-controlled growth of ZnO nanostructures using its different zinc precursors and their application for effective photodegradation

Abstract

Various zinc precursors, such as zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride, have been used to control the formation of zinc oxide (ZnO) nanostructures onto aluminum substrate by chemical means. FESEM images of the ZnO nanostructures showed the formation of different morphologies, such as flakes, nanowalls, nanopetals, and nanodisks, when the nanostructures were synthesized using zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride precursors, respectively. The TEM image of disk-like ZnO nanostructures formed using zinc chloride as a precursor revealed hexagonally shaped particles with an average diameter of 0.5 μm. Room-temperature photoluminescence (PL) spectra revealed a large quantity of surface oxygen defects in ZnO nanodisks grown from zinc chloride compared with those using other precursors. Furthermore, the ZnO nanostructures were evaluated for photocatalytic activity under ultraviolet (UV) light illumination. Nanostructures having a disk-like shape exhibited the highest photocatalytic performance (k = 0.027 min−1) for all the ZnO nanostructures studied. Improved photocatalytic activity of ZnO nanodisks was attributed to their large specific surface area (4.83 m2 g−1), surface oxygen defects, and super-hydrophilic nature of their surface, which is particularly suitable for dye adsorption.