Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Floating method and anodic alumina template - assisted CVD carbon nanotubes prepared

Author HuXiaoYang
Tutor ZhangYingJiu
School Zhengzhou University
Course Condensed Matter Physics
Keywords Floating-catalyst method cobaltocene anodic aluminum oxide templates (AAO) Aligned CNT arrays amorphous carbon nanotubes Ag/CNT heterojunction arrays
CLC TB383.1
Type Master's thesis
Year 2009
Downloads 36
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Due to perfect one-dimension structure,excellent mechanical,thermal,optical and electrical properties,increasingly extensive application prospects in nano-eletronics, nano-medicine and medicament transfer,sensor,high strength composite materials,field emission devices and supercapacitor etc,carbon nanotubes(CNTs) have attracted high attention and great research interest.Although in the recent twenty years,deep and comprehensive successes in synthesis,properties and application research of carbon nanotubes have been achieved,there still presents a challenge to synthesize large-scale aligned single-walled carbon nanotubes(SWNTs).Moreover,there are also many questions to be solved in orientated growth,assembly and application of carbon nanotubes.The floating-catalyst method,which is regarded as the most promising approach for mass CNTs production,is chosen to study separately the effects of ferrocene,cobaltocene, cobaltocene-ferrocene mixture,ferric nitrate,cobaltous nitrate used as catalyst,ambience, sulfur,the addition of water and so on during the synthesis process on the growth of carbon nanotubes when ethanol is used as the carbon source.The research reveals that cobaltocene-ferrocene mixture is the most superior catalyst choice when alcohol is taken as a carbon source system.The proper addition of sulphur can not only enhance quality and yield of carbon nanotubes when use ferrocene as catalyst,but also has obviously effect on quality and yield when use cobaltocene or cobaltocene-ferrocene mixture as catalyst.The possible reason may relate to that sulphur can activate the iron and cobalt catalyst.It is also found that the water introduction can reduce dependence on hydrogen and thus increase output during SWNTs synthesis process.In order to obtain highly aligned CNTs array and carry out the effective assembly,an anodic aluminum oxide templet(AAO) assisted CVD approach which takes acetylene and athylene as the carbon sources is introduced to grow CNTs and result shows that the highly orientated CNTs arrays can be gotten by this method based on the self-catalyst function of AAO.By characterizing morphologies of CNTs synthesized at different temperature and reaction duration,growth mechanism is discussed and a possible growth mode is proposed then.Ag nanowires are grown at the speed of 200nm/min by an electrochemical deposition method at a constant voltage of 0.4V-0.3V.Combined with CVD carbon nanotubes synthesis,the Ag/CNT heterojunction arrays are synthesized and assembled.This kind of heterjunction structure is expected to be able to debase the high impedance between the CNTs and the electrode connection in supercapacitor or field emission device and let these devices perform outstanding capabilities.As the prepared Ag nanowires dissipate alone the walls of AAO holes at high temperature,a special CNTs structure is formed and its corresponding growth mechanism is proposed simply.The appearance of this structure possibly will provide some new source materials for the research of CNTs application.

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