Effects of morphology, surface area, and defect content on the photocatalytic dye degradation performance of ZnO nanostructures

ZnO nanostructures of different morphologies were fabricated through ultrasound-assisted hydrolysis of zinc acetate at room temperature, by controlling the pH of the reaction mixture. It has been observed that the pH of the reaction solution affects both the morphology and defect content of the nanostructures. To study the effects of morphology and other parameters like specific surface area, defect content, and surface contamination on photocatalytic activity, both the as-grown and air-annealed nanostructures were tested for methylene blue (MB) degradation under UV light. While all the above mentioned parameters have been seen to affect the photocatalytic performance of ZnO nanostructures, specific surface area, defect content, and carbon contamination at the surface have been seen to be the most important parameters, and should be controlled for their application in photocatalysis. Therefore, for photocatalytic applications of ZnO nanostructures, not only their morphology or the specific surface area are important, but care should be taken to control their defect contents and surface contaminants.