Preparation of Cu-doped ZnS QDs/TiO2 nanocomposites with high photocatalytic activity

Abstract Cu-doped ZnS quantum dots (QDs) were synthesized in aqueous solution using 3-mercaptopropionic acid (MPA) as stabilizer. Transmission electron microscopy (TEM) results indicate that the Cu:ZnS nanocrystals distribute uniformly and the size is ca. 2.9 ± 0.5 nm. These nanocrystals were successfully associated to anatase TiO 2 nanoparticles to yield TiO 2 /Cu:ZnS photocatalysts. Morphological and optical properties of TiO 2 /Cu:ZnS nanocomposites were characterized by X-ray diffraction (XRD) analysis, TEM, and UV–vis and fluorescence spectroscopies. Photocatalytic activities of TiO 2 /Cu:ZnS nanocomposites were evaluated by the oxidation of salicylic acid aqueous solutions under UV light irradiation. Enhanced performances compared either to pure TiO 2 nanoparticles or to undoped TiO 2 /ZnS nanocomposites were observed. Effects of the mass ratio of the TiO 2 and Cu:ZnS and of the pH of the aqueous solution containing salicylic acid on the photocatalytic activities of TiO 2 nanoparticles sensitized with Cu:ZnS QDs were also investigated.