Construction of hierarchical S-scheme MgIn₂S₄/CeO₂ heterojunction for boosted photocatalytic oxidation of tetracycline and reduction of Cr(VI)

This study explores the photocatalytic performance of a hierarchical MgIn₂S₄/CeO₂ S-scheme heterojunction, emphasizing its structural, morphological, and electronic features. The heterojunction was synthesized in situ by integrating a porous MgIn₂S₄ framework with CeO₂ nanorods. Comprehensive characterization techniques such as XRD, XPS, FE-SEM, TEM, and BET confirm the heterojunction's formation and reveal its enhanced surface area, hierarchical porosity, and interfacial electronic interactions. Furthermore, the optical and photoelectrochemical properties were investigated through UV-Vis DRS, photoluminescence spectroscopy, photocurrent response, and EIS, thus demonstrating enhanced visible light absorption, reduced charge recombination, and efficient charge transfer. The photocatalytic tests show that MgIn₂S₄/CeO₂ has a degradation efficiency of 86 % for the photooxidation of tetracycline and 96 % for the photoreduction of Cr(VI) after 120 min. The enhanced properties can be attributed to the S-scheme heterostructure, which facilitates better charge transfer and separation and preserves the high redox potential photogenerated carriers for photocatalytic reactions. The degradation products of tetracycline were confirmed using HPLC–MS analysis. This work provided a systematic approach to designing advanced photocatalysts with promising applications in environmental remediation, and the findings contribute to the development of sustainable technologies for wastewater treatment.