Structural control and applications of carbon nanowalls

主要取得了以下三方面的结果：(1)研究了碳纳米管的生长过程。研究发现，构成碳纳米墙(CNW)的石墨烯层的择优取向垂直于衬底表面。应该注意的是，在垂直生长之前，石墨烯层是水平取向的。此外，还发现在生长的初始阶段，在衬底上形成了纳米金刚石颗粒。了解衬底和碳纳米管之间的界面层不仅对生长控制有帮助，而且对器件的应用也很有帮助。(2)研究了碳纳米管的物理和化学性质，如输运性质和吸氢性能。研究发现，CNW具有Anderson弱局域化现象，这可以从CNW的磁区结构中得到解释。通过量子化学计算表征了碳纳米管在晶界和平台上的吸氢性能。(3)采用溶液还原法制备了碳纳米管负载铂催化剂。结果表明，铂纳米粒子的平均直径为3.5 nm，沿晶界均匀分散在每个碳纳米管中。结果表明，该催化剂具有较高的电化学活性比表面积和较高的利用率，可与工业上生产的T？性能良好的PT/CB共混物。这种高的电催化活性可以归因于CNW的高导电性和铂纳米粒子在电畴边界的电子性质的改善，以及铂粒子的高分散性。

We obtained main three results as mentioned below.(1) The growth process of CNWs was investigated. It was found that the preferred orientation of graphene layers constituting carbon nanowalls(CNWs) is perpendicular to the substrate surface. It should be noted that, before the vertical growth, the graphene layers are horizontally oriented. Furthermore, it was found that nanodiamond particles are formed over the substrate at the initial growth stage. Such understanding of the interface layers between the substrate and CNWs will be useful for not only the growth control but also device applications.(2) The physical and chemical properties such as transport properties and hydrogen absorption were investigated. It was found that CNWs exhibit Anderson weak localization which can be explained from domain structure of CNW. The hydrogen absorption properties at domain boundary and terrace of CNWs were characterized by quantum chemical calculation.(3) Platinum catalysts supported on carbon nanowalls(Pt/CNW) were prepared by a solution-reduction method. It was found that Pt nanoparticles with a mean diameter of 3.5 nm are well dispersed along domain boundaries in each CNW. In addition, it was shown that the Pt/CNW has high electrochemical active surface area and utilization, comparable to those for commercially available T? Pt/CB with good performance. Such high electrocatalytic activity could be attributed to the high electric conductivity of CNW and the improvement of electronic properties of Pt nanoparticles on the domain boundaries, in addition to the high dispersion of Pt particles.