The composite of graphene and carbon nanotubes (CNTs) can increase the electrical conductivity and the electrochemical active sites in favor of the application in energy storage and conversion. However, the fabrication of graphene/CNT hybrid material requires multiple steps to introduce two kinds of catalysts for separate growth of graphene and CNTs. Here, we report a one-step process to in situ grow a seamless graphene/CNT heterojunction using a single catalyst of copper foil. Through precise tuning of the evaporation temperature of ethanol, creation of a method for seamlessly bonding CNTs on the graphene surface without assistance of metal particles has been realized. A study of the growth mechanism shows that the self-limited surface reaction of copper foil leads to many defects in multilayer graphene films, which provides the nucleation sites for the seamless growth of CNTs. The as-grown graphene/CNT heterojunctions have a higher electrical conductivity than the single graphene film, and its optical transmittance is almost equal to that of graphene film.

中文翻译：

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化学气相沉积一步法合成无缝石墨烯-碳纳米管异质结

石墨烯和碳纳米管（CNT）的复合材料可以增加电导率和电化学活性位，有利于在能量存储和转换中的应用。然而，石墨烯/ CNT杂化材料的制造需要多个步骤来引入两种催化剂以分别生长石墨烯和CNT。在这里，我们报告了一个就地步骤使用单一的铜箔催化剂生长无缝的石墨烯/ CNT异质结。通过精确调节乙醇的蒸发温度，已经实现了一种无需金属颗粒的辅助即可无缝结合碳纳米管在石墨烯表面的方法。对生长机理的研究表明，铜箔的自限表面反应会导致多层石墨烯薄膜中出现许多缺陷，从而为CNT的无缝生长提供了成核位点。所生长的石墨烯/ CNT异质结具有比单个石墨烯膜更高的电导率，并且其光学透射率几乎等于石墨烯膜的光学透射率。