Study On Electrochemical Sensors Based On Metal-orgnic Framework Derived Carbon

Metal-organic framework（MOF）is a kind of crystalline porous material with periodic structure formed by coordination interaction between inorganic metal ions and organic ligands.MOF materials have the advantages of high surface area,adjustable pore size and open metal sites.They have great potential in applications such as sensors,gas storage/separation,catalysis and energy,and have attracted widespread attention in recent years.However,MOF materials generally have shortcomings such as low stability and poor conductivity,which greatly limits their application in the above fields.In contrast,MOF derived carbon materials have the advantages of large specific surface area,high porosity,high catalytic sites,high conductivity and high stability of MOF materials,and tend to exhibit more excellent performance in the above applications.In this paper,MOF derived carbon materials were combined with graphene materials,and in-situ growth of MOF nanocrystals and high temperature carbonization reduction on graphene oxide（GO）sheets,two kinds of MOF derived carbon modified reduced graphene oxide（rGO）with"sandwich"structure were obtained.And based on these two composite materials,electrochemical sensors for the detection of typical environmental pollutants such as heavy metal ions and antibiotics were constructed.The main work of this thesis are:Construction of metronidazole（MNZ）sensor based on ZIF-67C@rGO:Through the one step room temperature solvothermal method,GO is used as a substrate for in situ synthesis of the zeolite imidazolate framework compound ZIF-67（Zeolitic imidazole framework-67）.Subsequently,it was converted into a composite material of ZIF-67 derived porous carbon and rGO（ZIF-67C@rGO）by pyrolysis at a high temperature.ZIF-67C@rGO-0.06 is used as an electrode modification material for electrochemical detection of MNZ because of its large specific surface area,fractional pore size,and Co/N co-doped active sites.It exhibits excellent sensing properties:wide linear range（0.5 to 1000μM）and low detection limit（0.05μM）.Construction of catechol（CC）and hydroquinone（HQ）sensors based on ZIF-8C@rGO:In order to improve the dispersibility of MOF nanocrystal particles on GO matrix,and to expand the application of MOF and rGO composites as electrochemical sensor modified electrodes.In this work,combined with the advantages of ZIF-8 derived carbon and rGO,ZIF-8 derived carbon embedded in rGO composites（ZIF-8C@rGO）were synthesized via an in-situ growth of ZIF-8 on GO and a follow up simultaneous carbonization/reduction.For the electrochemical determination of catechol（CC）and hydroquinone（HQ）,the sensor based on ZIF-8C@rGO exhibits a linear range of 0.5 to 70μM,and the detection limit of HQ and CC were 0.073μM and0.076μM,respectively.Construction of lead ion and cadmium ion sensors based on N-PC@rGO:Screen printed electrode（SPE）based microsensors are an emerging tool that is fast,simple,and economical.Unmodified SPE has disadvantages such as poor sensitivity,stability and reproducibility,but modification of SPE can improve its detection performance for heavy metal ions.In this chapter,the electrochemically optimal material prepared in the previous chapter was used as a SPE modification,which combines the synergistic effect of strontium ions and Nafion membrane to improve the electrochemical performance of the sensing electrode for cadmium ions and lead ions.Nafion/Bi/N-PC@rGO/SPE constructed under optimized experimental conditions enables simultaneous detection of cadmium and lead ions with a linear range of 1 to 70μg L^-1 and low detection limits 0.382μg L^-1for of cadmium ions and 0.648μg L^-1 for lead ions.