Photocatalytic Performance of MIL‐88B(Fe)/BiOCl Heterojunction and Mechanism of Organic Dye Degradation

Abstract This study successfully synthesized MIL‐88B(Fe)/BiOCl heterojunction materials (designated as MLB‐X) with varying metal molar ratios via a hydrothermal method and systematically investigated their photocatalytic degradation performance and mechanisms towards two dyes, Neutral Red and Basic Fuchsia. A series of characterization techniques, including X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy‐dispersive X‐ray spectroscopy (EDS) were employed to analyze the micromorphology, elemental composition, and crystal structure of the synthesized materials. Photocatalytic experiments systematically examined the effects of catalyst dosage, solution pH, and coexisting inorganic anions on dye removal efficiency. MLB‐50 achieved degradation efficiencies between 95% and 90% for 30 mg/L neutral red and basic fuchsia, respectively. Moreover, it maintained approximately 80% degradation efficiency after four consecutive recycling tests, demonstrating favorable stability and reusability. Through photoluminescence (PL) spectroscopy, ultraviolet‐visible diffuse reflectance spectroscopy (UV–vis DRS), and active species trapping experiments, the electron transfer pathway was elucidated. The formation of a Z‐scheme heterojunction between MIL‐88B(Fe) and BiOCl significantly enhanced the material's light absorption capacity and the separation efficiency of photogenerated charge carriers. The mechanistic roles of hydroxyl radicals (·OH), superoxide radicals (•O 2 − ), and photogenerated holes (h⁺) in the degradation process were clarified, and a plausible dye degradation pathway was proposed. These results indicate that MLB‐50 demonstrates promising potential for application in the treatment of printing and dyeing wastewater.