Multivalent regulation of cerium metal-organic framework for photocatalytic degradation of tetracycline

Cerium-based metal-organic frameworks (Ce-MOFs) are emerging as hierarchical photocatalysts with tunable electronic structures, demonstrating significant potential for tetracycline (TC) degradation. In this work, mixed-valence cerium metal-organic framework (MVCM) was synthesized by a one-step partial oxidation strategy. Various characterization techniques were systematically employed to investigate the morphology, structure and optical properties of MVCM. It was found that multivalent regulation could enhance the visible light response and inhibit the recombination of photoinduced charges, thus overcoming the drawback of conventional Ce-MOF. When tetracycline was used as the target pollutant, the degradation rate of MVCM-1.0 reached 95 % after 80 min of illumination, which was ninefold higher than that of the pristine Ce-MOF. Moreover, the MVCM-1.0 exhibite excellent stability and recyclability. The degradation mechanism was analyzed through various approaches, including active species trapping experiments, electron paramagnetic resonance measurements, and relevant electrochemical analyses. In addition, the main degradation products and the possible decomposition routes of TC were inferred by combining liquid chromatography-mass spectrometry (LC-MS). This work deepens the understanding of the internal relationship between the structure and performance of photocatalysts.