Fabrication of ternary ZnO–Cu2O-chitosan nanocomposite for efficient photocatalytic degradation of organic pollutants

Persistent organic contaminants in wastewater pose serious environmental and public health risks due to their toxicity and persistence. In this work, ZnO, Cu 2 O, ZnO-Cu 2 O, and ZnO-Cu 2 O-chitosan (ZCC) photocatalysts were synthesized via a green-assisted co-precipitation route and characterized by XRD, SEM, EDS, HRTEM, and UV-vis DRS. The photocatalytic activity of the synthesized samples was studied by conducting degradation experiments under visible light irradiation using Rhodamine B (RhB), Methyl Orange (MO), and p-nitrophenol (PNP) as pollutants. Degradation studies, TOC analysis, and recycling tests were used for evaluating their degradation kinetics, mineralization ability, and stability respectively. Of the synthesized samples, ZCC nanocomposite showed the highest photocatalytic efficiency with nearly complete degradation of RhB and MO within 160 minutes and efficient degradation of PNP within 200 minutes under visible-light illumination. Good removal of TOC and reusability after repeated cycles were also noted. The high efficiency of the ZCC nanocomposite can be attributed to efficient absorption of visible light, effective charge transfer at the ZnO-Cu 2 O heterostructure interface, and chitosan's role in promoting adsorption. Overall, the green-synthesised ZCC nanocomposite exhibited excellent visible-light-induced photocatalytic activity and reusability for water purification.