The Preparation And Its Application Of Electrodes Modified With Ionic Liquids

Room temperature ionic liquids have many special characters such as thermal stability, good ionic conductivity, and wide electrochemical windows. Due to their unique physical and chemical properties,ionic liquids have been attracted more and more attention in the fabrication of modified electrodes. The ionic liquids modified electrodes can notably improve sensitivity and lower background response. Electroactive substance and biomacromolecule are used as a study system. The fabrication of electrodes based on ionic liquid and nanomaterial was studied, and the experimental conditions were also investigated by electrochemical methods. The modified electrodes can be also applied to the determination of sample. The thesis includes four parts:In the first chapter, the physical and chemical characteristics of ionic liquids are introduced in a simply way, and the preparation of electrodes modified with ionic liquids and their applications in electroanalytical fields are reviewed. We mainly summarized its recent progress and applications of ionic liquids as a binder, modifier and electrolyte. At the same time, it is pointed out that the research about ionic liquids is extensive at home and abroad, and one of hot topics in future.In the second chapter, the ionic liquid N-octylpyridinum hexafluorophosphate (OPFP) was used as a binder combining with ferrocene (Fc) and carbon graphite to make a Fc-OPFPE modified carbon paste electrode. The electrochemical behavior of dopamine at this electrode had been investigated by cyclic voltammetry and chronoamperometry. The experimental results suggested that the proposed electrode exhibited an electrocatalytic activity toward the redox of dopamine. Compared with traditional paste electrode, the ionic liquid modified electrode can lower loss of ferrocene and improve the sensitivity.In the third chapter, a new composite electrode of multiwall carbon nanotubes (MWNTs) and the ionic liquid 1-dodecyl-3-methylimidazolium hexafluorophosphate (DDMIMPF6) was fabricated to determine rutin. The morphologies of the MWNTs/DDMIMPF6 composite electrode is characterized by scanning electron microscopy observation. Potassium ferricyanide was selected as a probe to evaluate the electrochemical performance of the composite. Compared with other electrodes modified with ionic liquids, the MWNTs/DDMIMPF6 composite electrode has low background currents. The experimental results suggested that the composite electrode exhibited an electrocatalytic activity toward the redox of rutin, and facilitated the electron transfer between rutin and electrode, notably improved sensitivity and stability. We successfully applied to the determination of rutin content in samples without the influence of the coexisting substances.In the fourth chapter, a novel glassy carbon electrode modified with the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][CF3SO3]) was prepared by casting method. Hemoglobin was immobilized on the surface of it with the help of chitosan, which direct electrochemical behaviors was also investigated. UV—Vis spectra indicated that Hb could keep its original secondary structure well in the film.Cyclic voltammogram of the Chi-Hb-IL-GCE in phosphate buffer solution showed a pair of well-defined and quasi-reversible redox peaks for Hb Fe(Ⅲ)/Fe(Ⅱ), indicating that a direct electron transfer between Hb and GC electrode occurred. The Chi-Hb-IL-GCE also exhibited excellent electrocatalytic behaviors to the reduction of hydrogen peroxide, and a lower detection limit was obtained.