Construction of petal-like MOF-derived C-TiO₂/Caln₂S₄ with S-scheme heterojunction for boosted photocatalytic of antibiotics and organic pollutants

From the perspective of environmental protection, the highly efficient degradation of antibiotics and organic dyes in wastewater need to be tackled as soon as possible. Fortunately, the utilization of semiconductor photocatalysts with the Step-like scheme heterojunction (S-scheme) for their degradation has been currently considered as a very effective approach. In this paper, a novel S-scheme MOF-derived C-TiO₂/Caln₂S₄ composites were synthesized to degrade antibiotics and organic pollutions. The FESEM and HRTEM images of as-fabricated samples indicated that the C-TiO₂ nanoparticles were intimately grown on Caln₂S₄ surface and the morphology of C-TiO₂/Caln₂S₄ exhibited petal-like structure. The experimental characterizations and density functional theory (DFT) calculation were utilized to expound the existence of S-scheme heterojunction. Additionally, the degradation rates of tetracycline hydrochloride (TC) and rhodamine B (RhB) solution catalyzed by 40 wt% C-TiO₂/Caln₂S₄ (40 wt% TCLS) under 300 W Xenon lamp irradiation ran up to 83.4% and 95.1%, respectively. Moreover, the mineralizations of TC and RhB solutions were proved via total organic carbon (TOC) tests. The possible degradation pathway of TC was also conjectured via liquid chromatograph mass spectrometer (HPLC-MS). Response surface methodology (RSM) was applied to analyze the degradation condition of RhB over 40 wt% TCLS. Once more, the toxicity of TC and RhB solution catalyzed by 40 wt% TCLS were also assessed via biotoxicity tests. This work provides a new way for preparing novel S-scheme heterojunction photocatalysts to solve environmental pollution in the future.