Electrochemical SERS And SHINERS Study Of Electrode/Solution Interfaces

Surface enhanced Raman spectroscopy(SERS)is widely used in the adsorption behavior and kinetic reaction of metal electrode/solution interfaces because of its extremely high surface sensitivity,especially the appearance of shell isolated nanoparticle enhanced Raman spectroscopy(SHINERS)was greatly extended to the atomic single crystal surface,which opens a new method for electrochemical system.In present work,the traditional electrochemical method.SERS and SHINERS were used to study the electrochemical behaviors of aromatic alkynes on the roughened polycrystalline gold electrode(ORC-Au(poly))and Au(111)single crystal electrode surfaces.Moreover,the effects of solvent on the interfacial catalytic reaction were compared.The main results were listed below:1.The adsorption and reaction behavior of p-amino phenylacetylene(PEAN)on ORC-Au(poly)and Au(111)single crystal electrode were investigated.Combined with DFT,the results revealed that the adsorption configurations of PEAN on ORC-Au(poly)and Au(111)single crystal electrodes are different.Great differences in triple bond region are related to the order of surface atoms,the chemical state on electrodes’ surface,and the most important factor is the Gibbs free energies of adsorption configurations.PEAN was tilted adsorbed on ORC-Au(poly)electrode surface through carbon carbon triple bond end;while a flat geometry adsorption via two carbon atoms of PEAN which broke π of triple bond formed preferentially at the Au(111)electrode surface.2.The mechanism of electrochemical catalytic hydrogenation of PEAN on the ORC-Au(poly)interface at extreme negative potentials was discussed.The research shows that the electrochemical catalytic hydrogenation of PEAN on ORC-Au(poly)in methanol solvents occured at extreme negative potentials,but no obvious Raman spectra in acetonitrile are not observed.The catalytic hydrogenation is mainly due to the large electromagnetic field enhancement effect from the nanostructure of the electrode surface.3.The electrochemical reduction of nitrobenzene derivatives(p-nitrophenylacetylene(PNPA)on ORC-Au(poly)and Au(111)single crystal electrodes was studied and the intermediate products were initially evaluated.The process of the reaction was effectively controlled by changing the pH value of the solution,replacing the metal substrate and selecting the crystal appearance.The results display that the main reduction product of PNPA is PEAN in acidic solution,while in the alkaline or neutral solution,the coupling reaction of PNPA can be happened to produce azo or azoxy derivatives.