Study On Electron Transfer On Carbon Nanotubes By Probe Moleculas And The Effect On Glycerol Electrooxidation On Platinum Supported On Carbon Nanotubes

The electronic structure of carbon nanotubes(CNTs)owns a special delocalized ? electron system.Chemical modification or doping can modulate the electronic structure of CNTs.Because of the unique and tunable electronic properties,CNTs have a wide range of applications in the field of electrocatalysis or heterogeneous catalysis as catalysts or supports.Only by accurately understanding the electron transfer behavior of CNTs,can we better design the catalysts for superior catalytic performance.In most of the current researches,the electron transfer between CNTs and reactants can be qualitatively and indirectly evaluated.It is still lack of quantitative method to mearsure the electron transfer ability of CNTs.This thesis introduces that a probe molecula,7,7,8,8-tetracyanoquinone dimethane(TCNQ),can be used to develop a qualitative and quantitative method to characterize the electron transfer ability of CNTs.Using CNTs as supports of Pt catalysts,the gycerol electrooxidation was employed as a model reaction to study the effect of the electron transfer ability of CNTs on the catalytic performance of supported Pt catalysts.The main research contents are as follows:(1)It was found that electrons are transferred from CNTs to TCNQ,and TCNQ accepts electrons to form different anions.The free radical anionic products of TCNQ was prepared by electrolytic synthesis.By this means,the electron transfer behavior between CNTs and TCNQ was quantitatively analyzed in combination with UV-Vis.It was proposed that the numbers of elctrons tranfered from CNTs to TCNQs can be an index for evaluating the electron transfer ability of CNTs.The kinetics of the electron transfer reaction was investigated.(2)By changing the defectiveness degree and performing nitrogen doping,a series of CNTs were prepared,thereby modulating their electron transfer ability.It was found that the electron transfer ability of defective CNTs is correlated with the defectivness.The electron transfer ability of nitrogen-doped CNTs had no obvious relationship with the gross amount of nitrogen dopants,while the distribution of nitrogen dopants would significantly change the electron transfer ability.(3)A series of defective and nitrogen-doped CNTs were used as supports for Pt catalysts.The Pt catalysts supported on nitrogen-doped CNTs are more electron-rich than those on the undoped CNTs.The CNTs with the higher defectiveness degree tend to transfer more electrons to Pt.Taking the electrocatalytic oxidation reaction of glycerol as a model reaction,it was found that the increasing electron transfer ability of CNTs is beneficial to improve the glycerol electrooxidation performance of the Pt catalyst,because the more electron-enrich Pt is more conducive to glycerol electrooxidation.