Fabrication of Cu doped ZnO nanocrystals hybridised with Graphene oxide nanosheets as an efficient solar light driven photocatalyst for the degradation of Quinalphos pesticide in aqueous medium

This present study involves the sonochemical and microwave synthesis of an efficient light harvesting nanocomposite, copper doped zinc oxide nanocrystals hybridised with graphene oxide nanosheets (ZnO/Cu/GO). The synthesised nanocomposite was characterised through various spectroscopic methods like XRD, SEM, EDX, FT-IR, UV-DRS and fluorescence analysis. This nanocomposite was employed to degrade; an organophosphorous pesticide, Quinalphos and its percentage efficiency of degradation was studied. The results have revealed that, 99 % of 40 ppm of Quinalphos pesticide could be degraded using ZnO/Cu/GO nanocomposite (3 mg/L) under visible light radiation within20 minutes at neutral pH. The presence of an intrinsic defects and the fluorescence property of the prepared nanocomposite were also detected. Finally, mineralisation of 98% was confirmed by COD and TOC analysis. The reaction rate followed pseudo - first order kinetics with a rate constant of 4.24 x 10­³min^-1. Furthermore, the composite has demonstrated a reusable feature and was utilised for eight cycles without any change in its activity. These findings have illustrated an enhanced Photocatalytic activity of ZnO/Cu/GO nanocomposite due to decrease in the rate of electron hole recombination reaction. Moreover, the nanocomposites eco-friendly, more stable, and well organised, which could be preferred for the treatment of industrial and agricultural waste water containing organic contaminants relatively in shorter period under irradiation using sunlight. Henceforth, ZnO/Cu/GO nanocomposite was developed as a significant tool for the treatment of effluents in many environmental applications.