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

In the current work, a novel ZnO-Cu2O heterojunction was synthesized from ZnO nanorods and Cu2O nanoparticles via hydrothermal route and was applied for the first time as a visible light active photocatalyst for decomposition of Paraoxon insecticide. Crystallinity, shape and size of 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 the enhanced photocatalytic efficiency. The nanocomposite with 40% weight percentage of Cu2O has the best photocatalytical activity of 0.0201 min-1, which could be related to the improvement of optical properties (increasing of the visible light harvesting ability) and the reduction of the recombination 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 photocatalytic degradation of Paraoxon, and a type II charge transfer process was proposed for the improved photocatalytic activity.