Preparation, Characterization And Electrochemical Properties Of Metal Organic Framework Compounds (MOF)

Recently,Metal-Organic Framework(MOF)compounds,which are new type of porous material in which the organic ligands coordinate to the metal ion centers in a bridging model,were received considerable attention due to their own structure,large specific surface area,regular adjustable pore size and removable properties,applied in the field of gas storage and seperate,fluorescence sensing,heterogeneous catalysis,drug delivery and other aspects of the great potential of the application.Although MOF have been regarded as excellent catalytic materials,there have been very few reports on the use of MOF as electrocatalysts.In the early of 2014,few reports were reported on that less MOF compounds has been applied in electrochemical applications.As human society is increasingly concerned about the field of life sciences,information technology and energy,during this stage,more research articles which related with MOF compounds were published on professional journals,which means MOF became play an important role on the above field.Nowadays,researchers focued their attention on MOF and made their full use in the field of biomedical,semiconductor technology and energy.In this dissertation,we used the upgraded method to prepare the target samples that HKUST-1,ZIF-8 and ZIF-67 and applied them into Hydrogen Evolution Reaction(HER),Electrochemical Sensor and Energy Storage and Conversion(ESC).Actually,those samples were modified onto the electrode surface to achieve functional electrode.MOF,has some drawbacks in the above fields because of its conductivity,whereas also provide a possible opportunity on electrochemical application.The main research results are summarized as follows:MOF has few applications in electrochemical hydrogen evolution.The simplest MOF as HKUST-1 was prepared through solvothermal method using Cu(OAc)2H2O and H3 BTC in each solution,then activated via organic solutions,and it was used in working electrode for electrochemical test,as catholic polarization linear sweep voltammetry(LSV)and Tafel polarization curves.Electrochemical test results exhibit that compared with glassy carbon(GC)electrode,the hydrogen evolution potential of HKUST-1 catalytic layer of the electrode positive shift of 532 mV,the hydrogen evolution potential of activated one positive shift reaches 658 mV.Then the structure and morphology of the samples were physical characterization results indicate that: HKUST-1 has good stability and large specific surface area,the activation treatment can improve HKUST-1 ratio of surface area.This process improves its conductivity and enhances its electrochemical stability after HKUST-1 modified with Nafion solution.Zeolitic imidazolate frameworks(ZIF-8)was obtained rapidly within 30 min via ultrasonic-assisted solvothermal method.The structural,elemental composition and morphology were investigated by X-ray diffraction(XRD),Energy-Dispersive X-ray Spectrometer(EDS),Scanning Electron Microscopy(SEM),Transmission electron microscopy(TEM)and Brunauer-Emmett-Teller(BET).The results showed that ZIF-8 nanocrystals possess cubic sodalite-related(SOD)structure and provide more active sites for adsorption.Further,the prepared ZIF-8 nanocrystals have been examined for the electrochemical sensor of dopamine(DA)using cyclic voltammetry(CV)and differential pulse voltammetry(DPV)techniques.The electrochemical studies demonstrated that the modified electrode displayed enhanced catalytic activity in the process of oxidation of DA when the working potential is-100 mV(vs.SCE).Additionally,the sensor detected DA linearly over a concentration range of 5.0 × 10-8 to 2.0 × 10-5 M with a lower detection limit of 1.95 × 10-7 M(S/N=3).Importantly,ZIF-8 nanocrystals modified electrode showed a favorable anti-interference ability and long-term stability.On the basis of the quick synthesis of ZIF-8,we used the ZIFs as template to change the metal source in order to synthesize(Co-)ZIF-67.Due to the structural properties of the MOF material,some MOFs which lack of conductivity,are difficult to be applied in the field of electrochemistry.Carbonization is an effective conductive method.C-67 was obtained when carbonization treatment on ZIF-67.The morphology and structure of C-67 was characterized by XRD,SEM and TEM,CV and other electrochemical tests,and then applied to the direct methanol fuel cell cathode catalyst,through the CV,LSV and i-t tests.We found that C-67 has achieved the structural characteristics of ZIF-67 and has improved its conductivity on the other hand.The results of CV and RRDE tests show that C-67 has better catalytic properties and anti-methanol oxidation.