Construction Of Z-type Heterostructures （Zr/Ce）UiO-66（NH₂）@ Organic Polymers And Their Photocatalytic Properties

Tetracyclines have become one of the most widely used drugs in human and animal disease control due to their low cost,broad spectrum and high activity,becoming the second most commonly used antibiotic worldwide in 2020.Tetracycline hydrochloride（TC）that is not metabolized by organisms are released into nature,thus threatening human health and ecological safety.Non-homogeneous photocatalysis is expected to be a novel wastewater treatment technology due to its green energy,low cost,high mineralization capacity,and almost harmless degradation products.In this paper,a series of research works based on the dual modification of UiO-66 and the construction of Z-system heterojunctions were carried out with the goal of efficient removal of TC,and the main conclusions obtained are as follows:（1）The（Zr/Ce）U（NH₂）@CN Z-system heterojunction photocatalysts were prepared by the solvothermal method by mixing the precursors of g-C₃N₄ and double-modified（Zr/Ce）U（NH₂）in proportion,and the optimum mass ratio was determined to be 0.2.Structural and performance characterization demonstrated that the modification of UiO-66 by-NH₂ and Ce improved the catalytic activity of MOFs.Among them,the modification of-NH₂ enhanced the visible light utilization of MOFs,and the introduction of metal Ce promoted electron transfer from organic ligands to metal clusters（LMCT）.In addition,XRD,XPS,FTIR,SEM and TEM results showed that g-C₃N₄ had an irregular muslin structure,while（Zr/Ce）U（NH₂）showed a regular and homogeneous size octahedral structure.Meanwhile,the muslin-like structure of g-C₃N₄ promoted the dispersion of MOFs particles,thus achieving an increase in the specific surface area of the composites.the results of PL and TRPL showed that the carrier separation ability of the composites was significantly enhanced.In the photocatalytic degradation experiments of TC,the degradation rate constant of 0.2-（Zr/Ce）U（NH₂）@CN for TC after 120 min of light was 0.0261 min^-1,which was 23.73 and 5.89 times higher than that of UiO-66 and CN,respectively.ISI-XPS results demonstrated the existence of Z type of electron transfer path.The degradation of TC by（Zr/Ce）U（NH₂）@CN was demonstrated to achieve a simultaneous reduction in toxicity using the ECOSAR technique.In addition,repeated experiments demonstrate the excellent stability and reusability of the photocatalyst.（2）To further enhance the catalytic performance of UiO-66-based photocatalysts,（Zr/Ce）U（NH₂）@N-PDI Z system heterojunction photocatalysts were successfully prepared using self-assembled Perylenimine（Nano PDI）as the carrier,and the optimum mass ratio was determined to be 0.5.The results of XRD,FTIR,Raman and DRS indicated that the self-assembled Nano PDI has a strongerπ-πstacking structure,which will facilitate the electron transfer and separation within PDI and between binary materials,and the PL,I-t and EIS results demonstrate this performance enhancement.In addition,SEM,TEM and BET results show that the nanosizing of PDI contributes to its size reduction and specific surface area increase,with the diameter of PDI reduced from 1μm to 50 nm after nanosizing.DRS results show that the composite maintains a high visible light absorption similar to that of Nano PDI,which allows more photogenerated carriers to be generated.PL,I-t and EIS demonstrate that the composite catalyst The construction of the composite catalysts effectively promoted the transfer and separation of photogenerated carriers.The photocatalytic degradation experiments demonstrated that 0.5-（Zr/Ce）U（NH₂）@N-PDI had the best degradation performance for TC with a degradation rate constant of 0.116 min^-1 after 60 min of light exposure,which was 1.93times higher than that of Nano PDI and 4.46 times higher than that of（Zr/Ce）U（NH₂）.The results of mineralization experiments and the ECOSAR technique proved that 0.5-（Zr/Ce）U（NH₂）@N-PDI also had excellent mineralization and detoxification ability for TC.The good stability and reusability of（Zr/Ce）U（NH₂）@CN were demonstrated by degradation repetition experiments.