Sustainable visible-light-induced degradation of antibiotic and dye pollutants in water bodies using a 2D Ti3C2 MXene-supported CoAl-LDH/Bi2MoO6 ternary heterostructure with a synergistic 2D/2D/2D hybrid configuration and S-scheme charge transfer

Abstract

Environmental remediation requires the development of advanced photocatalysts for the removal of persistent organic pollutants, including antibiotics and dyes. In the present study, we report the design and fabrication of a novel ternary hybrid photocatalyst consisting of a CoAl layered double hydroxide (LDH), Bi₂MoO₆ (BMO), and the MXene Ti₃C₂ (TC) for the effective degradation of the antibiotic sulfamethoxazole (SLF) and the organic dyes Congo red and indigo carmine under visible light illumination. Characterization of the ternary photocatalyst revealed a well-integrated 2D/2D/2D heterostructure with optimized interfacial interactions, enhanced light-harvesting capabilities, and superior charge-carrier dynamics. The optimized LDH/BMO20/TC photocatalyst achieved exceptionally high degradation rates for the antibiotic and dyes with high mineralization rates, significantly outperforming the binary photocatalyst and individual components. This enhanced photocatalytic activity was attributed to an S-scheme mechanism that promoted selective recombination at the interface while preserving the strong reducing ability of CoAl-LDH and the strong oxidizing capacity of BMO. Electron spin resonance analysis confirmed the production of O₂^•− and ^•OH radicals, while in-situ light-irradiated X-ray photoelectron spectroscopy identified charge redistribution, providing compelling evidence for the proposed S-scheme mechanism. Ti₃C₂ also served as an electron mediator, enhancing charge separation, accelerating electron transport, and stabilizing the heterostructure. The developed ternary catalyst exhibited exceptional reusability and robust activity across varying pH conditions and water matrices, demonstrating its potential as a versatile and sustainable photocatalyst for advanced environmental remediation and wastewater treatment.