Construction of Z-scheme NiO/BiOBr heterojunction for facilitating photocatalytic degradation of oxytetracycline and 2-mercaptobenzothiazole

Abstract

Z-scheme NiO/BiOBr heterojunction was prepared by mechanical ball milling method and applied for the photodegradation removal of oxytetracycline (OTC) and 2-mercaptobenzothiazole (MBT). The Z-scheme electron transport pathway optimizes the separation of photogenerated carriers, thereby significantly increasing the generation capacity of reactive oxygen species (ROS). The photocatalytic degradation experiments demonstrate that the optimized OTC and MBT removal efficiency of NiO/BiOBr (NBOB) composites could reach 72.6% (120 min) and 97.7% (9 min), respectively. Photoluminescence (PL) spectra and PL decay curves indicate that NBOB-2 composites exhibit low photoinduced electron-hole recombination rate and accelerated electron separation efficiency. In addition, ESR spectra confirm that the Z-scheme NiO/BiOBr heterojunction can generate a larger quantity of ROS species. The possible photodegradation pathways and toxicity analysis for the OTC and MTB photodegradation intermediates are elucidated by HPLC-MS measurement and T.E.S.T. application. The manuscript provides a reference for the macro-preparation of bismuth-based photocatalysts with superior performance and high stability.