Synthesis of p-n heterojunction photocatalyst from ZnO nanorod and Cu2O nanoparticles for visible light photocatalytic degradation of Paraoxon insecticide

In the current work, a novel ZnO-Cu2O heterojunction was synthesized from ZnO nanorods and Cu2O nanoparticles via a hydrothermal route and was applied for the first time as a visible light-active photocatalyst for the Paraoxon insecticide decomposition. Crystallinity, shape, and size of the particles and optical properties of the synthesized heterojunction nanocomposites were evaluated by XRD, FESEM, EDS, Mott-Schottky, photocurrent analysis, and UV-Visible spectroscopy analyses. Based on the obtained results, the ZnO-Cu2O heterojunction nanocomposite was successfully synthesized and compared to pure ZnO semiconductor has enhanced photocatalytic efficiency. The nanocomposite with a 40% weight percentage of Cu2O has the best photocatalytic activity of 0.0201 min-1, which could be related to the improvement of optical properties (the increase in the visible light harvesting ability) and the recombination reduction of the photoinduced electron-hole pairs. In addition, according to the radical trapping tests and Mott-Schottky experiments, superoxide radical was determined as the main oxidizing species for the photocatalytic degradation of Paraoxon, and a type II charge transfer process was proposed for the improved photocatalytic activity.