| Metal organic frameworks(MOFs)are a new type of functional materials with porosity,large specific surface area and adjustable structure.However,many MOFs have poor conductivity or selectivity.In order to compensate for these defects,they are often combined with other materials to form of better performance MOFs composite materials to improve conductivity and selectivity.Based on this,this paper prepared three metal-organic framework composite materials and used them for the electrochemical detection of atrazine,bisphenol A and 2-naphthylamine.The research content is as follows:(1)The cobalt-based conductive MOF material Co3(HHTP)2(Co-CMOF)with the ligand 2,3,6,7,10,11-hexahydroxytriphenyl(HHTP)was synthesized and carbonized at high temperature to obtain Co-CMOF derived carbon materials(Co-CMOF@C),and then Co-CMOF@C-PEI-Au NPs nanocomposites was formed by combining PEI and Au NPs on Co-CMOF@C.The Co-CMOF@C-PEI-Au NPs was characterized by infrared spectroscopy,scanning electron microscopy,transmission electron microscopy and other methods.Co-CMOF@C-PEI-Au NPs was used as a biosensing substrate for signal amplification,an electrochemical aptamer sensor for the specific detection of atrazine was successfully constructed.Cyclic voltammetry,chronocoulomb method,and differential pulse voltammetry were used as characterization methods to determine the electrochemical performance of modified electrodes.The cyclic voltammetric current response of Co-CMOF/GCE was lower than that of bare glassy carbon electrode(GCE).After the Co-CMOF was carbonized,the current response of Co-CMOF@C/GCE was 2.1 times that of bare GCE,and 3.0 times that of Co-CMOF/GCE,indicated that the excellent conductivity of Co-CMOF@C,and after PEI and Au NPs were compounded,the conductivity of Co-CMOF@C-PEI-Au NPs/GCE was further improved.Compared with simazine,propanil and the like,the response current attenuation value of Co-CMOF@C-PEI-Au NPs/GCE sensor to atrazine was 10 times that of them,indicated that it had better selectivity.The response of the aptamer sensor to atrazine showed a good linear relationship from the concentration of 5×10-13 to 1×10-7 M,and the detection limit was 3.5×10-13 M(S/N=3).The electrochemical aptamer sensor had the characteristics of high sensitivity and good selectivity,and had been successfully used for the detection of atrazine in wastewater samples,with a standard addition recovery rate of 98.1%?104.6%.(2)Zr-MOF(PCN-223(H))was used as the carrier material,combined with the self-polymerization of dopamine(DA)in an alkaline environment,a polydopamine-coated Zr-MOF composite material(Zr-MOF-PDA)was synthesized.Zr-MOF-PDA was characterized by infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy and other methods.Based on Zr-MOF-PDA,an electrochemical sensor(Zr-MOF-PDA/GCE)for high-sensitivity detection of bisphenol A was constructed.Cyclic voltammetry,chronocoulomb method,and differential pulse voltammetry were used as characterization methods to determine the electrochemical performance of modified electrodes.From the experimental results,it could be seen that Zr-MOF-PDA/GCE had better conductivity and larger effective surface area,and the response current value of Zr-MOF-PDA/GCE to bisphenol A was 2.0 of Zr-MOF/GCE,and 2.8 times that of bare GCE.This was because Zr-MOF had excellent conductivity and large specific surface area,and polydopamine had a better recognition and adsorption effect on bisphenol A.The synergistic effect of the two improved the sensitivity of the sensor.Compared with2-naphthylamine,hydrogenated bisphenol A and the like,the Zr-MOF-PDA/GCE sensor had 8 times the current response value of bisphenol A,indicated that it had better selectivity.When the concentration of bisphenol A was 0.01-1.4?M,the response current value of Zr-MOF-PDA/GCE sensor to bisphenol A had a good linear relationship with its concentration,and 0.004?M was the lowest detection limit(S/N=3).The Zr-MOF-PDA/GCE sensor had the characteristics of high sensitivity and fast response,and it had been successfully used in the detection of river water,milk and plastic bottles,with a standard recovery rate of 98.4%-103.1%.(3)A molecular-imprinted material(Zr-MOF-MIP)was synthesized using Zr-MOF(PCN-224(H))as carrier material(four-coordinate zirconium MOF with4-carboxyphenylporphyrin as the ligand),2-naphthylamine(2-NA)as template molecule,methacrylic acid as functional monomer,N,N'-methylene bisacrylamide as crosslinking agent and azodiisobutyronitrile as initiator.Zr-MOF-MIP was characterized by infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy and energy spectrum.A molecular-imprinted electrochemical sensor(Zr-MOF-MIP/GCE)for the detection of 2-NA was successfully constructed by dropping Zr-MOF-MIP on the surface of glassy carbon electrode(GCE)and drying it.Cyclic voltammetry,chronocoulomb method,and differential pulse voltammetry were used as characterization methods to determine the electrochemical performance of modified electrodes.As a result,Zr-MOF-MIP/GCE has good electrical conductivity and large effective surface area,and has good adsorption property for 2-NA.The current response of Zr-MOF-MIP/GCE was3.0 times that of Zr-MOF-NIP/GCE.Compared with o-phenylenediamine,aniline and the like,the current response value of the Zr-MOF-MIP/GCE sensor to 2-naphthylamine was12 times that of them,indicated that it had better selectivity.The DPV response current of the Zr-MOF-MIP/GCE sensor to 2-NA showed a good linear relationship with its concentration when the 2-NA concentration was 1.0-100?M,and the lowest detection limit was 0.35?M(S/N=3).Zr-MOF-MIP/GCE molecularly imprinted sensor had the characteristics of high sensitivity and fast response,and it had been successfully applied in the detection of environmental water samples,with a standard recovery rate of98.2%-103.2%. |
PDF Full Text Request