The Studies Of The Hydrogen Storage Properties Of Multi-walled Carbon Nanotubes (MWNTs) And Single-walled Carbon Nanotubes (SWNTs)

In this thesis, previous works on hydrogen storage in carbon nanotubes have been comprehensively reviewed. In this basis: the following works have been carried out: Firstly, single-walled carbon nanotubes(SWNTs) and multi-walled ones were selected for the hydrogen storage experiments. The theory of the hydrogen uptake on carbon nanotubes has been discussed. Secondly, for the purpose of improving the activities of the carbon nanotubes' surface, MWNTs were treated by oxygenation in the air and surface treatment. Thirdly, MWNTs were modified by mechanical grinding. A new method-MWNTs was modified by mechanical grinding in the air was carried out. The positions of hydrogen uptake in carbon nanotubes were studied. By means of TEM, FTIR and Raman spectra methods, the morphology and micro-structure, the surface information have been investigated.It is indicated that the process of absorption and desorption of hydrogen in carbon nanotubes is a kind of physical process. The amount of hydrogen uptake was influenced intensively by the temperature and pressure. The experimental results show that high pressure and low temperature were benefit to hydrogen storage in carbon nanotubes.Modification by mechanical grinding get shorter and tip-opening carbon nanotubes in which hydrogen can access more easily. We draw a conclusion about the hydrogen uptake position: SWNTs usually get together in band. The cavities inside the SWNTs and the space between the SWNTs in band can be the storage positions; As far as the MWNTs, there is a little difference, the storage positions include inside cavities, the space of inter-layer as well as the outer surface of carbon nanotubes' wall. We found that modification by mechanical grinding in the air not only made the shorter opening MWNTs but also got more purified MWNTs in reason of oxygenation. The properties of absorption was improved remarkably. After lOh's milling, the hydrogen absorption was up to 1.81wt% at 12MPa under room temperature. More works such as effort on the syntheses of carbon nanotubes, the mechanical ofhydrogen storage on carbon nanotubes and how to improve the weight & volume storage must be done in order to practical applications.