Synergistic non-metal doping and heterojunction engineering in B-doped Bi2MoO6/MIL-88B(Fe) for efficient photocatalytic tetracycline degradation under visible light.

Among diverse photocatalytic materials, Bi2MoO6 (BMO) has attracted significant attention by virtue of its unique layered structure, narrow bandgap, and tunable energy band configuration. However, its practical application was hindered by inefficient separation of photogenerated carriers and inadequate visible-light utilization. To overcome these limitations, synergistic modification through elemental doping and heterojunction construction was implemented in this study. Herein, boron-doped Bi2MoO6 (B-BMO)/MIL-88B(Fe) composites with Z-scheme heterojunctions were fabricated via a facile solvothermal method. Boron doping effectively modulated the energy band structure, reduced the bandgap, enhanced the light absorption capacity, and induced lattice distortion. Meanwhile, the staggered energy band alignment between MIL-88B(Fe) and B-BMO facilitated Z-scheme heterojunction formation, which strengthened charge carrier separation while maintaining a strong redox capability. Under visible-light irradiation, the B-BMO/MIL-88B(Fe) composite achieved 91.26% degradation efficiency for tetracycline hydrochloride (TCH) within 120 min, with a reaction rate constant of 0.0129 min-1. Compared to pristine B-BMO, the degradation rate improved by 10.2%. The composite maintained over 80% degradation efficiency after three consecutive cycles and retained favorable activity after five successive cycles. Sacrificial agent experiments identified superoxide anion radicals (˙O2-) as the dominant reactive species during the degradation process. Liquid chromatography-mass spectrometry (LC-MS) analysis enabled identification of degradation intermediates, leading to the proposal of a plausible TCH degradation pathway. This study provides insights into subsequent non-metallic element doping and heterojunction engineering strategies for BMO-based photocatalysts.