The Design,Preparation And Feasibility Research Of In Situ Electrochemical-Nuclear Magnetic Resonance Cell Based On Graphene Electrode

In order to enhance the utilization efficiency of new energy resources,it's important to design catalysts with high reactivity and stability.With the development of spectroelectrochemistry,research about the structure and property of catalysts has been getting results at a level of molecule.Nuclear Magnetic Resonance(NMR)has the advantages of high resolution and strong ability for quantifying and chemical structure elucidation.Combined with electrochemistry,in situ EC-NMR is a powerful coupling technique in the analysis of electrochemical adsorption,electrocatalytic processes and mechanism research.In this thesis,we have designed and prepared a new EC-NMR cell,in which an in situ reaction can be detected without any magnetic interference from electrodes or potentiostat.The main results and conclusions are as follows:1.With the advantages of good conductivity,large surface area,stability in both chemical properties and mechanical capacity and specific two-dimensional structure,graphene has received much attention on energy conversion and storage.Up to now,graphene growth on Cu foil with Chemical Vapor Deposition(CVD)is the primary method for graphene preparation.It remains a serious problem to transfer graphene from Cu foil to target substrates.We have compared the transfer process with PMMA and PDMS and applied SEM,HRTEM and Raman Spectrum to characterize the quality of graphene.As for the well transferred graphene,there is a raio of IG/IG' 1/2 and noobvious D peak(1350 cm-1)in Raman spectrogram.We have also obtained SEM and HRTEM images with flat surface structure,uniform color and fringe contrast,which means the graphens is clean and intact.Besides,the Selected Area Electron Diffraction(SEAD)image demonstrated a hexagonal flat sheet structure of graphene By using the Si-graphene as working electrode,we obtained a CV curve with proper current density and no impurity peaks,which indicates graphene is an excellent electrode material.2.In this thesis,we have designed and prepared a new EC-NMR cell:The Reference Electrode(RE)is made by inserting a silver wire into aqua regia.Then put the Ag/AgCl electrode into the RE compartment with 1.0 M KCI electrolyte;The Counter Electrode(CE)is made by electrodeposition of Pt black onto the surface of helical Pt wire.There is also an independent CE compartment to avoid contamination from the parallel reaction on CE.The Si-based graphene is used as Working Electrode(WE)stretching into the NMR detection area.For the ferrocene/ferrocenium system,we have studied the electrochemical behavior with CV curves on glassy carbon electrode,with catalyst of Pt/C and pure graphene,respectively.And we also conducted ex-situ and in-situ EC-NMR test for the reaction.We find the characteristic peak of ferrocene at 4.2 ppm is disappear gradually in oxidation process and recover increasingly.We can draw a conclusion that the graphene electrode can be a successful application in EC-NMR cell and we have developed a new EC-NMR technique with good performance and repeatability.