Green fabrication of zinc oxide supported carbon dots for visible light-responsive photocatalytic decolourization of Malachite Green dye: Optimization and kinetic studies

Abstract A succession of zinc oxide supported carbon dots (CZnO-dots) was fabricated from gum ghatti via a single-pot and straightforward microwave process. The as-fabricated CZnO-dots were employed as the visible-light responsive photocatalyst for the effectual decolourization of Malachite Green dye (MG). The optical band gap was evaluated using a tauc plot in which integration of ZnO to Carbon dots (C-dots) reduces the bandgap compared to bare C-dots and pure ZnO nanoparticles. The increased photocatalytic efficacy was observed in 1 wt% ZnO of CZnO-dots amongst all samples. By the influence of different operating conditions, the CZnO-dots show a degradation efficiency of about 94.8% with an irradiation time of 60 min. Besides capturing the active species in photodegraded products, the possible mechanism behind the photocatalytic degradation of MG dye has been discussed. Notably, the environmental assessment has been measured to develop mung bean plants using treated dye water. The growth of mung bean plants in the treated dye water was almost the same as that found in the control group, while the retarded growth was seen in the MG dye solution. Thus, the as-prepared CZnO-dots can be effectively used for the practical application related to environmental remediation.