Studies On The Multiwall Cabon Nanotubes In The Solid-state Electrochemiluminescence

Electrochemiluminescence(ECL)is a new kind of detection approach,which has been widely used in biological,pharmic,chemical and environmental applications due to its continuance,sensitivity,reproducibility and relative easiness to be automatically controlled. In ECL research,ruthenium complexes have been widely applied well.Solid-state ECL, which immobolizes ruthenium(â…¡)complexes onto a modified electrodes,became attractive in ECL studies and applications.Since the discovery of carbon nanotubes(CNTs),much attention has been paid to them.The one-dimensional tubular structure of CNTs has greatly stimulated studies of this novel material in the field of physics,chemistry and material science.Depending on their atomic structure,CNTs behave electronic properties suggest that CNTs have the ability to promote electron-transfer reactions.In a recent review,attention has been paid that the CNTs composite material has electronic,adsorption,mechanical and thermal properties.In this thesis,two kinds of CNTs and the CNTs composite material modified electrodes have been fabricated to immobilize ECL active species of ruthenium(â…¡) complexes.Then,their applications in solid-state ECL have been studied in details,and sensitive methods based on the study results for the determination of some samples have been made.This thesis includes three chapters,and the main research work is summarized as follows:In chapterâ… ,the principle of ruthenium(â…¡)complexes being used as ECL reagent and the development of approaches of solid-state ECL on tris(2,2'-bipyridine)ruthenium(â…¡) [Ru(bpy)₃²⁺]modified electrodes were reviewed.Furthermore,the structure of CNTs and their modification as well as their applications were described in detail.In chaperâ…¡,tetramethoxysilane and dimethyldimethoxysilane were selected as co-precursors to form an organically modified silicate film for the immobilization of multiwall carbon nanotubes wrapped by poly(p-styrenesulfonate)(PSS),then Ru(bpy)₃²⁺ was successfully immobilized on glassy carbon electrode via ion-exchange.PSS was employed to increase the conductivity of the composite material film and disperse the cut MWNTs,which were cut and shortened in a mixture of concentrated sulfuric and nitric acids, in the film.It was found that MWNTs could adsorb Ru(bpy)₃²⁺and acted as conducting pathways to connect Ru(bpy)₃²⁺sites to the electrode.MWNTs also played a key role as materials for the mechanical and thermal properties.The ECL detection limit(S/N=3)for methamphetamine by the modified electrode was 1.5×10^-8mol L^-1,which indicated a suitable sensitivity for practical applications.In addition,the ECL sensor presented excellent characteristics in terms of stability,reproducibility and application life.In chapterâ…¢,immobilization of bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(â…¡)(Ruâ…¡)was carried out by functionalizing the multiwall carbon nanotubes (f-MWNTs).Treatment with nitric acid and sulfuric acid mixture(1:3)leads to the functionalization of nanotubes as observed from Fourier transform infrared absorption spectroscopy(FTIR)measurements and transmission electron microscope(TEM).The strong hydrophobic interaction between f-MWNTs and the surface of glassy carbon electrode could make f-MWNTs immobilize on the electrode firmly.Ruâ…¡was coupled with the solution of N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride and then immobilized on nanotubes.The reaction of complex containing Ruâ…¡can form a covalent bond with f-MWNTs as observed from FTIR and energy-dispersed spectroscopy(EDS)measurements.Because the f-MWNTs on the electrode surface had open structures,large surface area and excellent conductivity,the modified electrode exhibited good electrochemistry activity and sensitivity with ECL detection limits of 8.8×10^-7mol L^-1tripropylamine.