Rational design and statistical optimization of MIL-53(Fe)/BiOI heterojunctions for efficient solar-driven photocatalytic dye degradation

초록

Water contamination by synthetic dyes poses severe environmental and health risks, necessitating efficient solardriven remediation technologies. Herein, we report the rational design and synthesis of MIL-53(Fe)@BiOI heterojunctions via a facile solvothermal approach, achieving intimate interfacial contact between the porous ironbased MOF and visible-light-active BiOI nanosheets. Comprehensive characterization (XRD, FT-IR, SEM, EDX, UV-Vis spectroscopy) confirmed successful heterostructure formation, significant bandgap narrowing (from 2.65 eV in pristine MIL-53(Fe) to 2.06 eV in the 5 wt% BiOI composite), and enhanced charge separation. The MIL-53(Fe)@BiOI-5% composite exhibited superior photocatalytic activity, degrading 97% of methylene blue under natural sunlight within 120 min, far outperforming the pristine MOF. Response surface methodology coupled with Box-Behnken design (RSM-BBD) systematically optimized key operational parameters (catalyst dosage, irradiation time, pH), revealing strong synergistic interactions, particularly the dominant role of acidic conditions (pH 3). Under optimized conditions (0.05 g catalyst, 120 min, pH 3), complete MB degradation (100%) was achieved with excellent model fidelity (R2 = 0.9796, adjusted R2 = 0.9533). This work reports the rational design and RSM-BBD optimization of a pristine MIL-53(Fe)@BiOI heterojunction for efficient solardriven (natural sunlight) photocatalytic dye degradation, providing new insights into interfacial charge transfer and a scalable pathway for real-world wastewater treatment.

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