Structural control and applications of carbon nanowalls

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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.