MBOClxBr1-x microspheres derived from Bi-MOF for efficient degrade tetracycline hydrochloride under visible light irradiation

Abstract

Through the halogenation reaction and employing metal-organic framework microspheres (Bi-MOF-M) as a sacrificial template, interleaved BiOCl_xBr_1-x nanosheet layers were grown on its surface. In contrast to Bi-MOF-M, the acquired MBOCl_xBr_1-x not only extends the visible light absorption range but also facilitates the effective separation of photogenerated carriers. Furthermore, based on Density Functional Theory simulation, the band gap structure of MBOCl_xBr_1-x could be effectively adjusted by changing the molar ratio of Cl/Br, which aligned with the results of Tauc plots. Taking tetracycline hydrochloride (TCH) as the target pollutant, we evaluated the photocatalytic degradation activity, stability, and recyclability of the sample under visible light. It was observed that materials with varying Cl/Br molar ratios significantly influenced the photocatalytic degradation of TCH, with MBOCl_0.25Br_0.75 exhibiting the highest photocatalytic activity, the degradation efficiency reached 83.16%, and the kinetic constants for TCH degradation were found to be 5.7 times and 1.5 times greater than those of Bi-MOF-M and BiOCl_0.25Br_0.75, respectively. Additionally, Rhodamine B (RhB), oxytetracycline (OTC), ciprofloxacin hydrochloride (CIP·HCl), methylene blue (MB), and malachite green (MG) were employed as extended contaminants to further assess the catalytic activity of the samples. We also investigated the effects of pH, inorganic anions, and temperature on the degradation of TCH by MBOCl_0.25Br_0.75. The potential pathways for the photocatalytic degradation of TCH by the catalyst were elucidated through high-performance liquid chromatography-mass spectrometry analysis. Meanwhile, a rational mechanism for the photocatalytic degradation of TCH by the MBOCl_0.25Br_0.75 catalyst with ·OH and ·O₂^- as the predominant active species was proposed. A green synthesis method had been proposed that not only preserves the exceptional structural properties of metal-organic frameworks (MOFs) but also modulated the energy band structure and enhances photocatalytic performance.