A novel Au-SnO2-rGO ternary nanoheterojunction catalyst for UV-LED induced photocatalytic degradation of clothianidin: Identification of reactive intermediates, degradation pathway and in-depth mechanistic insight

Herein, we have developed Au-SnO2-rGO ternary nanoheterojunction catalyst for photocatalytic degradation of dothianidin under UV-LED irradiation. Au nanoparticles (Au NPs) were decorated with quantum sized SnO2 nanoparticles (SnO2 NPs) and embedded in the reduced graphene oxide (rGO) matrix. The synthesized photocatalyst was characterized using common instrumentation techniques to evaluate the morphological, structural and surface chemical properties of the catalyst. The photocatalytic property of the as-synthesized nanocomposite was investigated by studying the degradation of clothianidin under UV-LED irradiation. Approximately 97% of the degradation was achieved in 120 min with pseudo first-order reaction rate of 0.0309 min(-1). The effect of various parameters like contact time, catalyst dose, initial concentration, pH, irradiation source and interfering ions on the degradation performance has also been investigated. Identification of various intermediates in the degradation process was done with high performance liquid chromatography- mass spectral (LC/HRMS) technique. The reactive intermediates responsible for the degradation have also been identified with electron spin resonance (ESR) technique and complete mechanism of the degradation process has been proposed with the help of photo luminescence (PL) quenching studies.