Fabrication of ZnS/ZnO composite photocatalysts by spin-coating ZnS nanoparticles on ZnO thin film

ZnS/ZnO nanocomposites were fabricated by a simple coating method. ZnO thin film (TF) and ZnS nanoparticles were prepared separately by a sputtering technique and wet chemistry approach, respectively. Finally, those were combined together via the spin-coating of ZnS nanoparticles on a ZnO TF. The ZnS/ZnO products were characterized by X-ray diffraction and photoluminescence spectroscopy, which demonstrated the electrical contact between ZnO and ZnS. Compared with ZnS nanoparticles and ZnO TFs, the composite exhibited higher photocatalytic activity toward the decomposition of methylene blue, which could be explained by the separation and transfer of the photoexcited carriers at the contact. Moreover, by applying thermal pre-treatment to ZnO TFs, the crystallinity of the film was observed to be improved, which further enhanced the photocatalysis owing to the longer lifetime of the photoexcited carriers.