Synthesis and Characterization of ZnO/TiO2 Photocatalyst Decorated with PbS QDs for the Degradation of Aniline Blue Solution

Abstract

A ZnO/TiO2 photocatalyst decorated with PbS quantum dots (QDs) was synthesized to achieve high photocatalytic efficiency for the decomposition of dye in aqueous media. A TiO2 porous layer, as a precursor photocatalyst, was fabricated using micro-arc oxidation, and exhibited irregular porous cells with anatase and rutile crystalline structures. Then, a ZnO-deposited TiO2 catalyst was fabricated using a zinc acetate solution, and PbS QDs were uniformly deposited on the surface of the ZnO/TiO2 photocatalyst using the successive ionic layer adsorption and reaction (SILAR) technique. For the PbS QDs/ZnO/TiO2 photocatalyst, ZnO and PbS nanoparticles are uniformly precipitated on the TiO2 surface. However, the diameters of the PbS particles were very fine, and their shape and distribution were relatively more homogeneous compared to the ZnO particles on the TiO2 surface. The PbS QDs on the TiO2 surface can induce changes in band gap energy due to the quantum confinement effect. The effective band gap of the PbS QDs was calculated to be 1.43 eV. To evaluate their photocatalytic properties, Aniline blue decomposition tests were performed. The presence of ZnO and PbS nanoparticles on the TiO2 catalysts enhanced photoactivity by improving the absorption of visible light. The PbS QDs/ZnO/TiO2 heterojunction photocatalyst showed a higher Aniline blue decomposition rate and photocatalytic activity, due to the quantum size effect of the PbS nanoparticles, and the more efficient transport of charge carriers.