In-situ Electrochemical Nuclear Magnetic Resonance:a Study In Detection Device And Acquisition Technology

The electrochemical reaction process is often accompanied by the formation of chemically active intermediate products,and the study of these intermediate products is essential to understand the mechanism of the electrochemical reaction.Nuclear magnetic resonance(NMR)is a non-invasive detection technique,which is powerful in structure analysis and quantitative analysis of soluble organic small molecules.Combination between NMR technology and electrochemical technology,namely in situ electrochemical nuclear magnetic resonance(EC-NMR)technology,has been recently proposed.Through EC-NMR technology,one can monitor the whole electrochemical reaction process,observe the changes of reactants,the appearance of products and reaction intermediates,and infer the electrochemical reaction mechanism.Moreover,the EC-NMR technology can also be used to perform quantitative analysis on the substances that appear in the reaction process and calculate the reaction rate.For the substance with complex molecular structure,the two-dimensional NMR spectrum can spread out the crowded peaks on the spectrum and obtain more information about the molecular structure than the one dimensional NMR spectrum.However,due to the limitation of its long acquisition time,the traditional twodimensional NMR spectrum is difficult to be applied to real-time dynamic system monitoring,so it is necessary to develop faster NMR technology.The ultra-fast twodimensional technique based on space-time coding can obtain the complete twodimensional spectrum in only one scan,and the sampling time is only a few seconds.It is very suitable for monitoring the chemical reaction process of substances with overlapping spectral peaks.The main results are as follows:1.In this study,we designed a liquid EC-NMR system that is easy to construct and has good compatibility between NMR and electrochemical technique.In order to determine the capability of this system for liquid in-situ NMR study,we conducted a model experiment of methanol electrooxidation.1H NMR was used to monitor the electrochemical oxidation process of methanol with Pt and Pd under different voltages.The catalytic properties of the two catalysts were compared,and the reaction mechanism and kinetic process of methanol electrooxidation were thoroughly understood.2.In this study,we applied the ultrafast COSY technology to study electrooxidation of glucose and monitor the whole reaction process.The reaction products were identified by the spectra,and the whole reaction mechanism of the electrocatalytic oxidation of glucose was studied.