Preparation And Application Of Multi-walled Carbon Nanotubes And Ionic Liquid Composite Film Modified Electrode

Carbon nanotubes exhibit many extraordinarily attractive physical and chemical properties, such as the large surface area, the good ability to promote electro-transfer reactions, remarkable catalysis towards biomolecules, good biocompatibility, accumulating many kinds of molecules and etc. Room temperature ionic liquids can be used as electrolyte as well as solvent. They also have attracted considerable attention due to their unique physical and chemical properties, such as high thermal and chemical stability, high conductivity, the ability to dissolve a wide range of organic and inorganic molecules, wide electrochemical potential window, ability to facilitate direct electron-transfer reactions, good biocompatibility and etc. Since the introduction, carbon nanotubes and room temperature ionic liquids have received enormous attention in the fields of electrochemistry. Moreover, it's attractive that the combined application of them has more promising prospects in many fields of electrochemistry, for example, the fabrication of chemical modified electrode.A novel modified electrode (MWNTs-IL-Gel/GCE) was prepared with multi-walled carbon nanotubes (MWNTs) and ionic liquid, 1-butyl-3-Methylimidazolium hexafluorophosphate, to modify glassy carbon electrode. A three-electrode system where a MWNTs-IL-Gel/GCE served as the working electrode, a saturated calomel electrode served as the reference electrode and a platinum wire electrode served as the auxiliary electrode was used to studied the electrochemical behaviors of dihydroxy-benzene and guaninein. The effect of ionic liquid on the MWNTs-IL-Gel/GCE was studied with cyclic voltammograms, scanning electronic microscopy, electrochemical impedance spectroscopy and UV–vis absorption spectra. The main research work was as follows:1. Electrochemical behavior of hydroquinone at multi-walled carbon nanotubes and ionic liquid composite film modified electrode.A novel modified electrode (MWNTs-IL-Gel/GCE) was prepared with multi-walled carbon nanotubes and ionic liquid. The SEM and EIS showed the superiority of MWNTs-IL-Gel/GCE to MWNTs/GCE and GCE in terms of promoting electron transfer and enhancing sensitivity. Electrochemical behavior of hydroquinone at the modified electrode was studied. Owing to the higher electroactive surface area of MWNTs and the solvent effect of RTIL, MWNTs-IL-Gel/GCE appeared a remarkable increase in the peak current of hydroquinone. The MWNTs-IL-Gel/GCE was used for the voltammetric determination of hydroquinone with the advantages of simple preparation, fast response, and high sensitivity.2. Electrocatalytic oxidation of catechol and separation of isomers at carbon nanotubes-ionic liquid gel modified glassy carbon electrodeThe effect of ionic liquid on the MWNTs-IL-Gel/GCE was studied with electrochemical impedance spectroscopy (EIS) and UV–vis absorption spectra (UV). Electrochemical behavior of catechol was demonstrated at MWNTs-IL-Gel/GCE. The modified electrode showed a magic electrocatalytic activity and reversibility towards oxidation of catechol. The oxidation and reduction peak separation (?E) has been decreased from 103 to 67 mV for catechol at MWNTs-IL-Gel/GCE. The peak current increased for about 100-fold larger than that on the bare GCE. In a mixture solution, oxidation peaks of catechol and hydroquinone are separated by about 119 mV, which achieved the separation of isomers.3. Electrochemical behavior of guaninein at multi-walled carbon nanotubes and ionic liquid composite film modified electrodeA novel modified electrode (MWNTs-IL-Gel/GCE) was prepared. The interactions between MWNTs and IL was estimated by scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Owing to the higher electroactive surface area of MWNTs and the solvent effect of RTIL, the peak current of guaninein at MWNTs-IL-Gel/GCE increased for about 148-fold larger than that at the bare GCE. The effect of buffer pH and scan rate were studied. In future research, MWNTs-IL-Gel/GCE is expected to be used to determine the guanine.