Enhanced photocatalytic activity of ZnO microspheres via hybridization with CuInSe₂ and CuInS₂ nanocrystals.

ZnO microspheres sensitized by CuInSe(2) and CuInS(2) nanoparticles, which were synthesized by a solvothermal method and have a size about 20 and 3.5 nm, respectively, were used to a photodegradation of rhodamine B under an irradiation of mercury lamp. Results show that the photocatalytic activities of the ZnO/CuInSe(2) and the ZnO/CuInS(2) are much higher than that of the ZnO microspheres because of a formation of the heterojunction in two systems. It is also noted that the ZnO/CuInS(2) exhibits a higher photocatalytic activity than the ZnO/CuInSe(2), which is probably related to more suitable band gap to sunlight for CuInS(2) nanocrystals and the larger specific surface due to a small size. Particularly, the ZnO/CuInSe(2)/CuInS(2) shows the highest photocatalytic activities in all measured photocatalysts, which should be attributed to the formation of double heterojunctions among ZnO, CuInSe(2), and CuInS(2).