Effect Of Surface Chemical Structure On The Electrochemical Performance Of CNT

Since the discovery of carbon nanotubes(CNTs) in 1991, it has recently been become to one of the forefront of researches in the world due to their attractive mechanical,electronic and chemical properties. CNT is an excellent electrode material because of it's conductivity and ideal surface structure. Some report suggested that CNT electrode could enhance electro-transfer of biology molecule greatly, so it can become a kind of potential material for biology sensor. Also CNT is considered as a promising electrode material for electrochemical capacitor due to it's special structure. This paper studies the influence of the surface chemical structure of CNTs on electrochemical performance, and emphasizes the effects of the surface chemical structure on basic electrode performance and capacitance.The surface defects and oxygenated group functionalities of MWNT are increased after electrochemical oxidation, which were confirmed by HRTEM,Roman and XPS. The Fe(CN)64- redox reaction is used as the benchmark in investigating electrochemical performance of different carbon nanotubes electrode. The anodic,cathodic peak on cyclic voltametric curve is from Fe(CN)64-/3- (peak potential separation:ΔEp), and we mainly pay attention toΔEp in this system. We presumed that the electrode reaction was dominated by diffusion and absorption according toΔEp obtained in experiment and theoretical deduce. We prove, through FTIR experiments, that Fe(CN)64- can be absorbed by CNTs, and SWNT oxidized for 80 cycles have stronger absorbability than MWNT activated in air. It is shown in the experiments that the absorption is proportional to the concentration of K4Fe(CN)6. In order to find the factors of leading to decrease onΔEp value of CNTs after electrochemical oxidation, >C-O or >C=O bonds of CNT surface were changed into >C-H by H2 reaction heat treatment. At last we obtain that the defects of CNT, rather than the oxygenated group functionalities mentioned in some references, lead to decrease onΔEp value of CNTs.>C-O or >C=O,>C-Cl bonds are formated on MWNT surface after oxidation is conducted in KOH solution and KCl solution respectively. The...