Design and Synthesis of a Novel Ag2o/Bivo4/Diatomite Functional Composite with P-N Heterojunction for Imidacloprid Degradation

In this study, a kind of Ag2O/BiVO4/diatomite composite with p-n heterojunction structure was synthesized by simple hydrothermal method with diatomite as carrier. It is found that imidacloprid (IMD) was efficiently degraded under the action of hydrogen peroxide (H2O2). The effects of pH value, catalyst dosage, H2O2 concentration, initial IMD concentration and anion on degradation efficiency of IMD by this new photocatalytic composite were systemically evaluated. The results show that the p-n heterojunction formed between the two contact surfaces of Ag2O nanoparticle and BiVO4 promotes the charge transfer between the interfaces, inhibits electrons and holes recombination, and thus significantly improves the catalytic performance. The stability and reusability of Ag2O/BiVO4/diatomite composites were tested with ICP experiment and cyclic experiment. Active substance capture experiment and ESR reveal the photocatalytic reaction mechanism and confirm that superoxide radical (•O2-), hydroxyl radical (•OH), and h+ can promote the degradation of IMD. The degradation products and the intermediates of IMD were identified through LC-MS, on a basis of which the possible transformation pathway was proposed. Ional composite with p-type Ag2O and n-type BiVO4 heterojunction structures in-situ formed via cost effective synthesis approach open up a new direction in photocatalytic degradation of organic pollutants.