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

• Cu-doped ZnS QDs were associated to TiO2 using a simple wet chemistry route.
• A strong photocatalytic activity of TiO2/Cu:ZnS nanocomposites was observed.
• Effective electron–hole pairs separation by the heterojunction constructed by TiO2 and Cu:ZnS.
• A synergistic effect was observed between Cu:ZnS dots and TiO2 for the production of hydroxyl radicals.

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 TiO2 nanoparticles to yield TiO2/Cu:ZnS photocatalysts. Morphological and optical properties of TiO2/Cu:ZnS nanocomposites were characterized by X-ray diffraction (XRD) analysis, TEM, and UV–vis and fluorescence spectroscopies. Photocatalytic activities of TiO2/Cu:ZnS nanocomposites were evaluated by the oxidation of salicylic acid aqueous solutions under UV light irradiation. Enhanced performances compared either to pure TiO2 nanoparticles or to undoped TiO2/ZnS nanocomposites were observed. Effects of the mass ratio of the TiO2 and Cu:ZnS and of the pH of the aqueous solution containing salicylic acid on the photocatalytic activities of TiO2 nanoparticles sensitized with Cu:ZnS QDs were also investigated.

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