Construction of Bi2MoO6 sheets/NH2-UiO-66(Zr) heterojunction photocatalysts toward enhanced degradation of tetracycline under visible light

Abstract

The application of photocatalysts in environmental field has emerged as a prominent research topic. Nevertheless, the efficiency of photocatalysts is reduced as the recombination of photogenerated chargers significantly, restricting their extensive use in this domain. In the present study, photocatalysts composed of bismuth molybdate/NH2-UiO-66(Zr) (Bi2MoO6/NH2-UiO-66(Zr)) featuring Z-scheme heterojunctions were effectively synthesized using a two-step hydrothermal technique. These photocatalysts exhibit remarkable photocatalytic degradation under visible light conditions. Notably, the broad planar configuration of Bi2MoO6 sheets improves the separation of the photogenerated charge carriers. NH2-UiO-66(Zr) layered atop Bi2MoO6 sheets enhances the availability of catalytically active sites, reduces charge recombination, and promotes charge transfer through the interface. The kinetic rate constant for Bi2MoO6/NH2-UiO-66(Zr) is around 0.00329 L mg−1 min−1, indicating the increase of 3.78 and 41.13 times compared with pure Bi2MoO6 and NH2-UiO-66(Zr), respectively. The efficiency for photocatalytic degradation of tetracycline using Bi2MoO6/NH2-UiO-66(Zr) reaches 81.72 % under visible light. Importantly, this efficiency exhibits a reduction of 10 % after five recycling cycles, demonstrating notable stability. The photocatalytic mechanism involved in tetracycline degradation was uncovered through trapping experiments and EPR, indicating that it is predominantly facilitated by the active oxidation of ·O2- and ·OH. The intermediates of the photocatalytic process as well as the possible degradation pathways were discussed. The creation of Bi2MoO6 sheets/NH2-UiO-66(Zr) heterojunction photocatalysts provides a fresh approach to the development of novel catalysts, which may lead to significant advancements in environmental remediation efforts.