Mesocrystals usually assume properties differing from that of nanocrystals with the same compositions due to their unique morphologies and size region. In the work, a simple wet chemical procedure was developed for the preparation of mesocrystals consisting of ZnO nanoparticles. By simply mixing the aqueous solutions of zinc acetate [Zn(Ac)2], sodium hydroxide (NaOH), and tartaric acid (TA) at certain temperatures, composites of zinc hydroxide nanoparticles and tartaric acid, Zn(OH)2–TA, with rod-like morphology were obtained. After being annealed in air at certain temperatures, the mesocrystals composed of ZnO nanoparticles were generated, which inherited the rod-like morphology of the Zn(OH)2–TA composites. The chemical composition, crystalline structure and morphology of as-prepared ZnO mesocrystals were characterized using scanning electron microscopy, X-ray powder diffraction, FT-IR, and thermogravimetric analysis. Their photocatalytic properties were also investigated. It was illustrated that, in comparison with the individual ZnO nanoparticles, the ZnO mesocrystals show decent photocatalytic performance to the photodegradation of methyl orange and the photoreduction of Cr6+.
