Construction of Z-Scheme Heterojunction Bi2MoO6/UiO-66-NH2 and Photocatalytic Degradation of OTC

Abstract

The extensive use of oxytetracycline (OTC) poses significant threats to aquatic ecosystems, necessitating efficient removal strategies. While photocatalytic technology is a promising approach, single catalysts, like UiO-66-NH2 and Bi2MoO6, suffer from rapid photogenerated carrier recombination and narrow light absorption. To address this, a Z-scheme heterojunction photocatalyst, Bi2MoO6/UiO-66-NH2, was synthesized via a solvothermal method to enhance OTC degradation. Characterization results showed that the composite expanded visible-light absorption and improved electron-hole separation. Under simulated sunlight, the optimized composite (BUN80) achieved an OTC removal efficiency of 87.68% within 120 min under optimized conditions. The catalyst retained photocatalytic activity over five consecutive cycles, although a decrease in removal efficiency was observed. Radical trapping experiments indicated that h+ and •O2− were the main reactive species, and a proposed Z-scheme charge transfer pathway was suggested based on band structure analysis and photoelectrochemical results. LC-MS analysis identified 17 intermediate products, and ECOSAR-based toxicity prediction suggested a decreasing trend in aquatic toxicity during the degradation process. These findings indicate that Bi2MoO6/UiO-66-NH2 is a promising photocatalyst for OTC degradation in water.