Preparation of BiVO4/RGO-TNT Nanomaterials for Efficient and Recyclable Photocatalysis of Imidacloprid Insecticide

The photocatalytic composites based on BiVO4, TiO2 nanotubes (TNT) and reduced graphene oxide (RGO) were synthesized by a one-step hydrothermal synthesis method. The properties and structures of the samples were characterized by SEM, XRD, UV-Vis DRS, Raman spectroscopy, photoluminescence spectroscopy and XPS. The effects of RGO-TNT loading, pH, and dosage of catalysts on degradation efficiency were tested. The best removal results were occured on the condition that loading amount of RGO-TNT was 10 %, solution pH 10, and catalyst dosage was 1.4 g L-1. The obtained ternary composite with 10 wt% RGO-TNT exhibited a significant enhancement in photocatalytic efficiency due to the lower band gap with enhanced light absorption and a suppression in the recombination rates of the photogenerated charge carriers, and about 73 % of imidacloprid was degraded within 30 min under UV irradiation. Furthermore, BiVO4/RGO-TNT-10 can be reused for 6 times without obvious catalysis loss. Trapping experiments showed that hydroxyl radicals were the main active species in the imidacloprid photocatalytic degradation, and a possible photocatalytic mechanism was proposed based on the results of trapping experiments.