Two novel sets of UiO-66@ metal oxide/graphene oxide Z-scheme heterojunction: Insight into tetracycline and malathion photodegradation

Nowadays, widespread researches have been focused on the development of effective photocatalysts to remove pollutants of the aquatic system. In accordance with the universal studies, two new sets of UiO-66@ metal oxide (including ZnO and TiO2)/graphene oxide heterojunctions were synthesized for photodegradation of aromatic (tetracycline) and nonaromatic (malathion) pollutants which are challenging cases in the environment. The dosage of the photocatalyst, pH of the solution, the type of metal oxide, and the presence of various scavengers are assayed parameters in this work. In the optimum condition, maximum photodegradation efficiency is achieved in 90 min for tetracycline (81%) and malathion (100%) by the UiO-66@ZnO/graphene oxide. The superior separation of charge carriers by Z-scheme mechanism, excellent electron mobility on layers of graphene oxide and high surface area are factors that enhanced the efficiency. Furthermore, in comparison with pure UiO-66, the band gaps belong to heterojunctions revealed a red shift in the absorption edge, which can be responsible for more expand adsorption of the solar spectrum. Total organic carbon analysis verified the decontamination of these pollutants in the solution. The produced main intermediates during the photocatalytic process were identified and the possible degradation pathway proposed. In general, the superior photocatalytic activity suggests that these designed photocatalysts can be a promising choice for having a clean future. (C) 2020 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.