Photocatalytic Activity of TiO₂ Nanoparticles Sensitized by CuInS₂ Quantum Dots

Abstract

In this paper, <i>p</i>-type CuInS₂ quantum dots are synthesized by a solvothermal route and incorporated with <i>n</i>-type TiO₂ nanoparticles by a thermal treatment process. Transmission electron microscopy (TEM) results indicate that the CuInS₂ quantum dots distribute uniformly and the size is ∼3.4 nm. Photocatalytic activities of the TiO₂ nanoparticles sensitized with the CuInS₂ quantum dots are evaluated by the degradation of the methyl orange aqueous solution under ultraviolet (UV) and visible (vis) light irradiation and show an enhanced performance, compared with the pure TiO₂ nanoparticles and the pure CuInS₂ quantum dots. Microstructural, morphological, and optical properties of the TiO₂ nanoparticles sensitized with the CuInS₂ quantum dots are characterized by X-ray diffraction (XRD) analysis, TEM, and UV–vis absorption spectroscopy. Results indicate that the CuInS₂ quantum dots greatly enhance the absorption of UV and visible light due to the <i>p</i>–<i>n</i> heterojunction being constructed between <i>p</i>-type CuInS₂ quantum dots, and <i>n</i>-type TiO₂ nanoparticles. Effects of the mass ratio of the TiO₂ and CuInS₂ and the thermal treatment temperature on the photocatalytic activities of the TiO₂ nanoparticles sensitized with the CuInS₂ quantum dots are also investigated.