In situ conversion of ZnO microsphere from ZnS complex microstructure and photocatalytic study

Precursor ZnS complex microstructure, synthesized under concentrated NaOH solution, was annealed at different temperatures to fabricate self-supported ZnO microstructure with large-scale yield. The crystal structure, morphology and chemical compositions of the as-prepared ZnO nanoparticles were examined by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller specific surface area (BET). The experimental results show that the obtained ZnO microsphere keeps an intact self-supported structure even after high temperature annealing and the XRD observation indicates that the crystal lattice becomes more integrated along with the elevation of annealing temperature. We further investigated the photocatalytic property towards eosin B and found that the photocatalytic property seems to be closely related to crystallinity of the lattice. As the crystallinity enhances, the photocatalytic performance of the ZnO self-supported microsphere becomes significantly better. Overall, the investigation indicates that we have prepared a novel kind of self-supported ZnO microsphere photocatalyst with the merit of mass production and high catalytic efficiency.