Synthesis Of Carbon Nanotubes By Low Pressure Chemical Vapor Deposition And Their Applications

Since Japanese scientist Iijima found multi-wall carbon nanotubes(CNTs)in 1991,CNTs has aroused great interest from researchers due to their unique structure, mechanical and electrical properties.The main preparation methods of CNTs are:Arc discharge,laser evaporation,and chemical vapor deposition.CNTs had been widely used in the flat panel displays,supercapacitors,biosensors,etc.because of their small size,high mechanical strength,large specific surface area,high electrical conductivity and interface effects,as well as chemical and thermal stability.In this paper,we use low-pressure chemical vapor deposition system to synthesize highly vertically aligned CNTs and non-aligned CNTs respectively,and apply them successfully in super-capacitors,field-emission cathode,as well as biological sensors.This paper is divided into five chapters and introduced as follows:In chapter one,the discovery,classification,property as well as the main preparation methods of CNTs are described.An overview of the applications of CNTs in supercapacitors,field emission display devices,as well as biological sensors is introduced.In chapter two,two differrent low-pressure chemical vapor deposition systems are used to synthesize highly vertically aligned CNTs and non-aligned CNTs.Metal organic compounds-iron phthalocyanine(phthalocyanine,FePc,FeC₃₂N₈H₁₆)is used as carbon source for highly vertically aligned CNTs grown on silicon film or quartz substrate with argon and hydrogen as carrier gas.Non-aligned CNTs,with acetylene (C₂H₂)as carbon source and hydrogen as carrier gas,are synthesized on the nickel films and graphite substrates.The influence of different substrates and the gas flow ratios to the morphology of CNTs are investigated.In chapter three,we employ as-grown CNTs as electrodes,polyvinyl alcohol-potassium chloride gel as the electrolyte,respectively.A very ideal capacitor performance is obtained using PVA-potassium chloride electrolyte.Furthermore, polyacrylamide hydro-gel has been used successfully as supercapacitor electrolyte.In chapter four,CNTs field emission cathode on the ITO glass which conductive silver paste was printed on using electrophoresis technology is prepared and the influence of different CNTs,different oxidation methods to the field emission performance is studied.It is found that CNTs with a suitable density,greater aspect ratio possess better field emission properties.Compared to CNTs oxidated by hydrogen peroxide,CNTs oxidated by nitrate exhibit better field emission performance.Chapter five focuses on the detection of hemoglobin(Hb)using CNTs and 1-pyrenebutanoic acid,succinimidyl ester nanocomposites modified electrode. UV-visible adsorption spectra,Fourier transform infrared spectra,scanning electron microscope and electrochemical impedance spectroscopy have been used to characterize the film.The proposed method has succeeded for Hb detection.