Development of Hydrogen Storage Technique by Using Carbon Nanotubes

单壁碳纳米管和掺杂金属的石墨纳米纤维具有很高的储氢能力。由于其在燃料电池汽车应用中的影响，已经进行了大量的实验和理论工作。一些最引人注目的报告是值得怀疑的，在这个研究项目中的分子动力学模拟不能解释单壁碳纳米管的储氢能力超过1重量%。因此，制备高纯度的单壁碳纳米管是解决这一矛盾的关键。除了激光炉技术，我们开发了一种新的CVD技术，用于批量高纯度的单壁碳纳米管的产生。以乙醇、甲醇等醇类化合物为碳源，在600 ~ 800 ℃的较低反应温度下，可以合成出不含金属颗粒、无定形碳或MWNTs的高纯单壁碳纳米管。通过共振拉曼散射和近红外荧光光谱研究，在较低的CVD温度下，直径和手性分布可以相当窄。结合对纳米管生长过程的分子动力学模拟，论证了纳米管帽状结构决定手性的机理。除了通过使用沸石的本体生成之外，通过浸渍涂覆直接位于石英或硅基底上的Fe/Co或Co/Mo纳米颗粒可以用作有效的催化剂。使用后一种系统，详细表征了催化剂和在石英衬底上垂直排列的SWNTs垫的生长。使用后一种系统，产生了几乎不含金属的SWNT，用于进一步澄清储氢检查。

The high hydrogen storage capacity of carbon nanotubes has been reported for single-walled carbon nanotubes (SWNTs) and metal-doped graphite nanofibers. Because of its impact in applications in fuel cell vehicles, intensive experimental and theoretical works have been performed. Some of the most striking reports are questionable and molecular dynamics simulations in this research project cannot explain the hydrogen storage capacity of SWNTs more than 1 wt %. Hence, the generation of high-purity SWNTs is the key issue to solve this discrepancy. In addition to the laser-furnace technique, we developed a new CVD technique for bulk high-purity generation of SWNTs. By using alcohols such as ethanol and methanol as the carbon sources in catalytic CVD, high-purity SWNTs without metal particles, amorphous carbon or MWNTs can be synthesized at relatively low reaction temperatures of 600 -800 For the bulk generation of SWNTs, Fe/Co bimetal catalysts supported on USY zeolite was employed. The diameter and chirality distributions, which were examined by resonant Raman scatterings and near infrared fluorescence spectroscopy, could be quite narrow at lower CVD temperatures. Combined with the molecular dynamics simulation of the nanotube growth process, the determination mechanism of chirality by the nanotube cap structure was demonstrated. In addition to the bulk generation by using zeolite, Fe/Co or Co/Mo nano-particles directly located on quartz or silicon substrate by dip-coating can be used as efficient catalysts. With this latter system, detailed characterization of catalysts and the growth of vertically aligned SWNTs mat on a quartz substrate were demonstrated. With this latter system, virtually metal-free SWNTs were generated for the further clarifications of hydrogen storage examinations.