| Metal-Organic Frameworks?MOFs?,as a new class of three-dimensional porous materials,have large specific surface area,rich metal sites,high porosity,etc.,but the weak conductivity of MOFs materials limits it's application in the field of electrochemical sensing.In this paper,four kinds of MOFs,MOFs derivatives and graphene?GO?composites with good electrocatalytic properties were prepared by simple and easy control method.Four novel electrochemical sensors were constructed based on the nanocomposites.A new electrochemical method for the determination of hydrazine hydrate,formaldehyde,phenol and nitrite was established by electrochemical and electrocatalytic behavior of the sensor.The sensor enriches the research content of electrochemical sensors and expands the application of MOFs materials in food,pesticide and environmental analysis.The main research contents are as follows:?1?Cu3?BTC?2/GO composites were prepared by simple in situ chemical method.The materials were characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and energy dispersive X-ray spectroscopy?EDS?.The electrochemical behavior and Electrocatalytic Performance of Cu3?BTC?2/GO composites for hydrazine hydrate were studied.The experimental results show that the sensor has significant electrochemical signal enhancement effect on hydrazine hydrate based on the synergistic effect between Cu3?BTC?2 and GO.Under the optimum conditions,the linear detection range was1.0×10-3 to 5.0 mM and the detection limit was 0.5×10-3 mM.The sensor can be used for the analysis and detection of hydrazine hydrate in practical samples.?2?Ni-MOF/rGO composites were prepared by solvothermal method using Ni?NO3?2·6H2O,PTA and reduced graphene oxide?rGO?as raw materials.Then a green and easily controlled derivatization of Ni?OH?2/rGO composites in NaOH solution was carried out.The morphology and structure of the composites were characterized by means of SEM,TEM,EDS and element mapping.Due to the synergistic effect between petal-shaped nickel Ni?OH?2and highly conductive rGO,Ni?OH?2/rGO exhibits higher catalytic activity for formaldehyde than bare glassy carbon electrodes,rGO and Ni-MOF and Ni-MOF/rGO.The analytical performance of the sensor for formaldehyde was investigated by linear sweep voltammetry?LSV?.The results showed that the sensor exhibited strong electrocatalytic performance for formaldehyde in the linear analysis range of 0.1 to 100 mM,and the detection limit was 0.06mM.In addition,the sensor has been applied to the determination of formaldehyde in real water samples with recovery ranging from 97.9%to 110.4%.?3?Using Fe-MOF as precursor,a rod-shaped Fe2O3/Fe-MOF/rGO composite was prepared by partial calcination.The morphology,composition and thermal stability of the composites were characterized by SEM,TEM,EDS,X-ray diffraction?XRD?,thermogravimetric analysis and element mapping.The Fe2O3/Fe-MOF/rGO/GCE modified electrode was prepared by dropping the material onto the surface of bare glassy carbon electrode.The electrical sensing properties of Fe2O3/Fe-MOF/rGO on phenol were studied.The experimental results show that the Fe2O3/Fe-MOF/rGO electric sensor exhibits high electrocatalytic activity and anti-interference ability to phenol.In addition,the Fe2O3/Fe-MOF/rGO composites showed good stability and reproducibility for the determination of phenol.The corresponding linear detection range was 0.5 to 180?M and 180to 600?M,and the detection limit was 0.1?M.?4?Cu3?BTC?2 prepared by solvothermal method was used as precursor.Ag/CuS/rGO composites were obtained by simple two-step transformation at room temperature.The phase,surface morphology and electrocatalytic performance of the composites were characterized by SEM,TEM,EDS,elemental mapping analysis,CV and LSV.The results show that the sensor assembled by Ag/CuS/rGO composite has good electrocatalytic performance for NO2-ions.The detection linearity ranges from 1 to 50?M and 50 to 550?M,and the detection limit was0.4?M?S/N=3?.In addition,the effective specific surface area of the composite modified electrode is much higher than that of the bare glassy carbon electrode.Therefore,Ag/CuS/rGO composite material has a certain practical value in the detection of NO2-ions. |
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