Structural control and applications of carbon nanowalls

我们得到了如下所述的三个主要结果。(1)研究了CNWs的生长过程。研究发现，构成碳纳米墙（CNWs）的石墨烯层的优先取向是垂直于衬底表面。需要注意的是，在垂直生长之前，石墨烯层是水平取向的。此外，还发现在生长初期，纳米金刚石颗粒在衬底上形成。这种对基板和CNWs之间的界面层的理解不仅对生长控制有用，而且对器件应用也有用。(2)对其输运、吸氢等理化性质进行了研究。研究发现CNW具有Anderson弱局域性，这可以从CNW的域结构来解释。利用量子化学计算表征了CNWs在畴边界和平台处的吸氢特性。(3)采用溶液还原法制备了碳纳米壁负载铂催化剂（Pt/CNW）。结果表明，在每个CNW中，平均直径为3.5 nm的Pt纳米颗粒沿畴边界分布良好。此外，Pt/CNW具有较高的电化学活性表面积和利用率，可与市售的T？Pt/CB性能良好。如此高的电催化活性可以归因于CNW的高导电性和Pt纳米粒子在畴边界上的电子性能的改善，以及Pt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.