Investigation Of Electrochemical Sensing Based On Two Types Of Metal-organic Framework Materials Of MIL And ZIF

The metal organic frameworks have developed rapidly due to its structural diversification,porosities,high specific area,and many metal unsaturated sites,etc.,and have provided rich and diverse sensitive materials for electrochemical sensing study.In this paper,nine different composite materials were prepared around two types of metal organic framework materials of MIL and ZIF,nine electrochemical sensors based on the two types of materials of MIL and ZIF were constructed,and new electrochemical sensing methods for detecting N₂H₄,NO₂^-,H₂O₂and DA were established.This research can provide new ideas for electrochemical sensing study and can expand the application range of metal-organic framework materials.The dissertation is divided into three chapters,and the author’s main contributions are as follows.1.Electrochemical sensing research based on MIL series materialsF-MIL-53（Fe）/Fe₂O₃,Fe-MIL-101（Cr）,Au/MIL-101（Cr）-NH₂ and MIL-101（Cr）-SO₃H/PEI-r GO were prepared by template method,impregnation method and in-situ synthesis method,respectively.And four new electrochemical sensing methods for N₂H₄,NO₂^-and DA were constructed based on these four composite materials.The results showed that four materials with different morphologies can be obtained by changing the amount of HCl,among which the fusiform F-MIL-53（Fe）/Fe₂O₃ showed the best electrochemical performance;the N₂H₄electrochemical sensing method based on F-MIL-53（Fe）/Fe₂O₃ showed two linear ranges,0.3-380 and 380-8400μmol·L^-1,the sensitivities were 212.2 and 61.9μA(mmol·L^-1)^-1 cm^-2,the detection limit（LOD）was 0.03μmol·L^-1.The iron species was successfully incorporated into MIL-101（Cr）by the impregnation method to prepare an octahedral Fe-MIL-101（Cr）composite material;the NO₂^-electrochemical sensing method based on Fe-MIL-101（Cr）had a proportional band of 2.5-11400μmol·L^-1,sensibility of 179.9μA(mmol·L^-1)^-1 cm^-2 and LOD of 0.2μmol·L^-1.Au nanoparticles had been uniformly supported on the surface of MIL-101（Cr）-NH₂ by in-situ reduction;the DA electrochemical sensing method based on Au/MIL-101（Cr）-NH₂ had a proportional band of 0.3-288.8μmol·L^-1,sensibility of 251.6μA(mmol·L^-1)^-1 cm^-2,LOD of 9.6 nmol·L^-1.MIL-101（Cr）-SO₃H had been generated on the surface of r GO in situ through electrostatic interaction,and presented a perfect sphere with obvious boundaries;the DA electrochemical sensing method based on MIL-101（Cr）-SO₃H/PEI-r GO had a proportional band of 0.3-238.8μmol·L^-1,sensibility of 327.7μA(mmol·L^-1)^-1 cm^-2,LOD of 0.07μmol·L^-1.Compared with the related sensing methods in the literature,the linear range of the former sensing method had been expanded by 25.9 times,and the detection limit had been reduced by 60 times;the detection limit of the second sensing method had been reduced by 2 times;the third and fourth sensing materials prepared by the in-situ method had the advantages of good dispersion,while the detection limit of the third sensing method was 7.3 times lower than that of the fourth,and the sensitivity of the fourth sensing method was increased by 1.3 times.2.Electrochemical sensing research based on ZIF series materialsFive materials,Ag@ZIF-67,H-Au@ZIF-67,H-Zn/Co-ZIF and C-ZIF-67,T-ZIF-67/r GO were prepared with methanol and water as solvents respectively.The H₂O₂ electrochemical sensing methods based on Ag@ZIF-67 and C-ZIF-67,the DA electrochemical sensing methods based on H-Au@ZIF-67 and H-Zn/Co-ZIF,and the H₂O₂ and DA electrochemical sensing methods based on T-ZIF-67/r GO were constructed.The research results showed that the synthesized Ag@ZIF-67 had a rhombic dodecahedral core-shell structure,and the H₂O₂ electrochemical sensing method based on Ag@ZIF-67 exhibited three linear ranges,which were 5-275μmol·L^-1,775-2775μmol·L^-1 and 4775-16775μmol·L^-1,the corresponding sensitivities were27,13 and 5.3μA(mmol·L^-1)^-1 cm^-2,respectively,and the LOD was 1.5μmol·L^-1;the synthesized H-Au@ZIF-67 was a hollow material assembled from ZIF-67 particles with Au nanoparticles attached inside,and the DA electrochemical sensing method based on H-Au@ZIF-67 had a linear range of 0.3-438.8μmol·L^-1,sensitivity of 332.1μA(mmol·L^-1)^-1 cm^-2,LOD of 0.04μmol·L^-1;the synthesized H-Zn/Co-ZIF had an internal cavity with a diameter of 450 nm and a shell with a thickness of 110 nm,and the DA electrochemical sensing method based on H-Zn/Co-ZIF had linear range of 0.3-588.7μmol·L^-1,sensitivity of 316μA(mmol·L^-1)^-1 cm^-2,LOD of 0.01μmol·L^-1;the H₂O₂electrochemical sensing method based on the C-ZIF-67 had three linear ranges,which were2.5-212.5,212.5-1662.5 and 1662.5-6662.5μmol·L^-1,respectively,the corresponding sensitivities were 12,5.3 and 2.4μA(mmol·L^-1)^-1 cm^-2,respectively,and the LOD was 0.7μmol·L^-1;the H₂O₂ electrochemical sensing method based on the T-ZIF-67/r GO had two linear ranges,5-2150 and 2150-11150μmol·L^-1,the corresponding sensitivities were 51.86 and 19.44μA(mmol·L^-1)^-1 cm^-2 respectively,LOD was 1.5μmol·L^-1.In addition,T-ZIF-67/r GO can also be used to construct DA electrochemical sensing method with linear ranges of 0.3-66.3 and66.3-1216.3μmol·L^-1,sensitivities of 93.7 and 57μA(mmol·L^-1)^-1 cm^-2,detection limit of 0.05μmol·L^-1.Among the three H₂O₂ sensing methods,the sensing method based on T-ZIF-67/r GO which was synthesized with water as solvent was more economical to construct,and the sensitivity was increased by 1.9 times;among the three DA sensing methods,the detection limit of the sensing method based on hollow H-Zn/Co-ZIF synthesized with methanol as solvent was reduced by 4.0 times,and the linear range of the DA sensing method based on T-ZIF-67/r GO synthesized with water as solvent was broadened by 2.1 times;among the six sensors,only the sensor based on T-ZIF-67/r GO synthesized with water as solvent can be used not only for the measurement of H₂O₂,but also for the measurement of DA.