Synergistic Photocatalysis: Exploring MIL-۵۳(Al)-(NH۲)@BiOBr Nanocomposites for Enhanced Degradation of Methylene Blue

This study evaluated the photocatalytic degradation of Methylene Blue (MB) using MIL-۵۳(Al)-NH۲@BiOBr composites as a staggered-gap (type II) heterojunction under visible light for the first time. Various composites (BM-۱۰, BM-۱۵, and BM-۲۰) with different MIL-۵۳(Al)-NH۲ loadings are tested to evaluate their Removal Efficiency (RE) of MB over time. The results show that the MOF@BiOBr composites significantly enhance photocatalytic performance compared to MIL-۵۳(Al)-NH۲ alone, achieving complete degradation within ۴۰–۵۰ minutes, with BM-۲۰ exhibiting the fastest and most efficient degradation. The unique band structure of MIL-۵۳(Al)-(NH۲)@BiOBr has several advantages, such as efficient charge separation and visible light absorption that enhance its photocatalytic degradation performance. The study further explores the effect of pH, finding optimal performance at pH ۸ due to favorable electrostatic interactions and enhanced generation of reactive oxygen species. While all samples maintain high degradation efficiency (above ۸۰%), the performance gap between BM-۲۰ and the other samples widens slightly as the concentration of MB increases, especially at higher concentrations (۷۰ mg/L and ۸۰ mg/L). Photocatalyst dosage was also examined, indicating that an optimal catalyst concentration of ۰.۰۷ g/L maximizes degradation efficiency, while higher pollutant concentrations slightly reduce performance due to active site saturation. Reusability tests over five cycles reveal that BM-۲۰ maintains high stability and efficiency, demonstrating its potential for practical applications in environmental remediation. The enhanced performance arises from the synergistic interaction between MIL-۵۳(Al)-(NH₂) and BiOBr, where the MOF contributes electron-donating amino groups to facilitate charge transfer, while BiOBr provides visible-light-active layered structures. This type II heterojunction design distinguishes the composite from previously reported photocatalysts and offers a promising new strategy for solar-driven dye degradation.

کلیدواژه ها:

MIL-۵۳(Al)-NH۲ ، BiOBr ، Type II heterojunction ، Photocatalysis