BiOBr Nanosheets Supported on a Bi-MOF as an S-Scheme Heterojunction for Visible-Light Photodegradation of Tetracycline

Abstract

The persistent contamination of water by tetracycline (TC) antibiotics poses serious ecological and health risks, yet single-component photocatalysts like BiOBr and Bi-MOF are limited by rapid charge recombination and poor redox capability. Herein, we report the in situ construction of an S-scheme heterojunction by directly growing BiOBr nanosheets onto a Bi-MOF platform. This in situ strategy creates an atomically intimate heterointerface, which can generate a robust built-in electric field that drives directional charge transfer along the S-scheme pathway. The optimized BiOBr/Bi-MOF-45 achieves 96% TC removal within 60 min under visible-light, with a rate constant 17.6 times that of pristine BiOBr. EPR, radical trapping, in situ XPS, and band structure analysis validate the S-scheme mechanism, which preserves strongly reductive electrons for •O2− generation and strongly oxidative holes for •OH generation. This work provides insights into the mechanism and design of Bi-MOF-based S-scheme heterojunctions, demonstrating their potential application value in solar-driven antibiotic wastewater remediation.