三维石墨烯的可控生长、在超级电容器领域的应用以及初步电学输运研究

Graphene is one of the most widely attractive projects nowadays because of its abundance of properties and applications to be explored. As 1D and 2D systems of graphene are investigated, recently, 3D graphene (vertically standing, curved and bushlike), namely floating graphene systems are attracting more and more attention. They have promising future and wide application fields in fuel cells, field emission and supercapacitors. Nevertheless, there are rare reports devoted to the systematic investigations in to the growth mechanism, controllable production of these 3D graphene systems, the influences of the size, morphologies, number of layers and sterical configurations on the performance of the supercapacitors and other devices so far. In this project we are proposing to grow the floating graphene systems on kinds of substrates after treated by physical, chemical and electrochemical methods adjusting the experimental parameters using updated MPCVD equipment. The growth mechanism will be systematically studied and controllable production will be achieved. Then the influence of the kinds of 3D graphene systems on the supercapacitors will be investigated and the performance indexes will be improved. At last the electric transport properties by 2-terminal method using substrates as one terminal will be explored to underlie the applications in electrical fields.

石墨烯是当前科学界最受瞩目的研究目标之一，有丰富的物理内涵和实际应用尚待探索。一维和二维石墨烯被广泛研究的同时，三维石墨烯（暨悬浮石墨烯，悬浮部分呈现包括直立、弯曲以及灌木丛状等形貌）以独特的结构和性质受到越来越多的关注。三维石墨烯在燃料电池、场发射和超级电容器领域具有光明的前景和广阔的应用空间。然而目前对这种三维结构的生长机制和可控生长，其尺寸、形貌、层数和空间构型对于在超级电容器等领域的应用的影响等方面的研究仍很匮乏。本项目拟采用改进的微波CVD系统在经过物理、化学方法处理的多种基底上通过调节实验参数来系统的研究三维石墨烯的生长机理以期实现这类石墨烯的可控生长。进而对不同尺寸、形貌以及层数的三维石墨烯作为电极对超级电容器性能的影响进行深入研究以提高现有性能指标。最后以生长基底为两端法的一极对此类石墨烯的电学输运做初步的探索为其在电子学领域的应用打下基础。

直立石墨烯在实际的物理化学应用中有着极为重要的意义。石墨烯基超级电容器、柔性能源器件和光探测器是近年来相当活跃的热点领域。我们利用自制的微波化学气相沉积系统，成功的在碳纤维等材料上生长出了尺寸形貌可控的直立石墨烯。并深入研究了实验条件对样品形貌的影响。我们利用生长的直立石墨烯作为超级电容器的电极，并将其与碳纤维相结合，得到了良好的结果。超级电容器表现良好，并实现了超高速的充、放电。进而我们把石墨烯、碳纤维和PDMS结合成功制成了柔性能源器件。该柔性器件展现了良好的比电容和充放电速度。而且该器件在经历了2万个循环后依然展现了优异的性能。该结果对于超级电容器以及柔性能源器件的研发有重要意义。同时我们还利用所生长的直立石墨烯进行了光电探测方面的研究。本项目直接在硅上生长了直立石墨烯，直接形成了石墨烯和硅的异质结光探测器。这样做的好处是避免了库伦阻塞。与其他石墨烯/硅器件相比，我们的探测范围扩展到了400到1700纳米。该器件灵敏度达到了0.241 A/W 而响应时间短于240微秒。理论计算表明我们的探测器消除了其他器件中的库伦阻塞，该成果表明此种原位制备的光探测器具有广泛的应用前景。