Synthesis,Structure And Photocatalytic Properties Of Coordination Polymers Containing Acylhydrazidate Molecules Or Oxalic Acid

With the rapid development of industrial technology,large-scale discharge of organic wastewater with toxic and bioaccumulate has become a serious worldwide issue.Conventional methods for wastewater treatment have barriers such as high operating cost and so on.Photocatalysis technology combines photochemistry and catalytic chemistry,which can utilize solar energy to eliminate the organic pollutants and provide new ideas for wastewater treatment.Coordination polymer materials are not only diverse in types and have regular crystal structures;they also exhibit semiconductor properties,which are crucial for driving photocatalytic reactions.This opens up new avenues in the field of photocatalysis.Three coordination polymers were synthesized under the hydrothermal conditions and applied to photocatalytic degradation on organic dyes.The specific research contents and main achievements are as follows:（1）A new oxalate-bridged 1-D chained Mn（II）coordination polymer[Mn₂（ox）₂（bim）₄]_n（CP-Mn）(ox=C₂O₄^2-,oxalate dianion,bim=benzimidazole)was synthesized by the simple hydrothermal self-assembly of Mn SO₄·H₂O,H₂ox and bim.It has been characterized through many tests,and the band gap width has been calculated.At the same time,the intermolecular interactions of each complex unit were quantitatively analyzed by Hirshfeld surface analysis.The results of photocatalytic activity toward methylene blue degradation showed that the highest degradation rate reached 89.9%at p H=4.The degradation rate of MB with H₂O₂ was higher than that without H₂O_2.The degradation rate of MB over CP-Mn increased under more acid solutions.The photocatalytic reaction followed a pseudo-first-order kinetics character.The CP-Mn catalyst was very stable and could be used for repeated treatment of MB dye.The photocatalytic degradation mechanism has been proposed through photoelectron-chemical and trapping radical experiments.It turned out that the·OH was active species in the catalytic reaction and the band positions were elucidated via UV-vis absorbance spectra and Mott-Schottky plots.The underlying mechanism for MB decomposition were proposed.（2）Two novel visible-light-driven coordination polymers photocatalysts[Zn（FDPTH）（bpy）]（CP-Zn）and[Pb（FDPTH）（phen）]（CP-Pb）（FDPTH=4,4’-hexafluoroisoprorylidene-diphthalhydrazidate,bpy=2,2’-bipyridine,phen=1,10-phenanthroline）were obtained under the hydrothermal ligand in situ reaction,the 4,4’-（hexafluoroisopropylidene）-diphthalic anhydride（6-FDCA）was selected to serve as the acidic precursor,and Zn（II）,Pb（II）as the metal ion,respectively.The two coordination polymers have been characterized through many tests,and the band gap width has been calculated.At the same time,the intermolecular interactions of each complex unit were quantitatively analyzed by Hirshfeld surface analysis.Photocatalytic experiment indicated that the degradation rate of MB over CP-Zn and CP-Pb increased under alkaline or neutral conditions（84.5%for CP-Zn,71.4%for CP-Pb in 70 min at p H=10）.The degradation rate of MB with H₂O₂ for CP-Pb was higher than that without H₂O_2.Contrary to CP-Pb,in the presence of H₂O₂,the photodegradation efficiency on MB for CP-Zn decreased slightly.The photocatalytic reaction followed a pseudo-first-order kinetics character.Both two ctatalysts were very stable and could be used for repeated treatment of MB dye.The photocatalytic degradation mechanisms have been proposed through photoelectrochemical and trapping radical experiments.It turned out that the·OH was active species in the catalytic reaction and the band positions were elucidated via UV-vis absorbance spectra and Mott-Schottky plots.The underlying mechanism for MB decomposition were proposed.