Synthesis of Platelet Carbon Nanofiber/Carbon Felt Composite on in Situ Generated Ni鈭扖u Nanoparticles
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- 作者：Tiejun Zhao ; Ingvar Kvande ; Yingda Yu ; Magnus Ronning ; Anders Holmen ; De Chen
- 刊名：Journal of Physical Chemistry C
- 出版年：2011
- 出版时间：February 3, 2011
- 年：2011
- 卷：115
- 期：4
- 页码：1123-1133
- 全文大小：724K
- 年卷期：v.115,no.4(February 3, 2011)
- ISSN：1932-7455
文摘
A platelet carbon nanofiber/carbon felt composite with a high surface area (>250 m2/g) is synthesized over a carbon felt supported Ni鈭扖u catalyst using ethane鈭抙ydrogen mixtures at 923 K. A uniform layer of carbon nanofibers is thus achieved via an in situ generation and dispersion of Ni鈭扖u nanoparticles induced by the surface reaction of hydrocarbon decomposition. This represents a cost-effective and flexible method without the requirement for presynthesis of uniformly distributed nanoparticles. Both thermodynamic analysis and experimental observation reveal that, in the initial growth period, formation of a molten phase of the nanosized Ni鈭扖u鈭扖 phase promotes the fragmentation of Ni鈭扖u parent particles of micrometer size. A unique octopus-like growth mode is observed during the formation of graphene layers from this liquid-like Ni鈭扖u鈭扖 system. A comparative study between Ni and Ni鈭扖u catalysts is performed. It is found that the addition of Cu in the Ni鈭扖u catalysts can enhance the fragmentation ability of the parent Ni鈭扖u particles when contacting with hydrocarbon. A treelike growth mode of carbon nanofibers grown on Ni鈭扖u catalysts is observed due to the further fragmentation of Ni鈭扖u particles during carbon nanofiber growth. In contrast to Ni鈭扖u catalysts, two different growth mechanisms on the Ni catalyst are found: a governing tip-growth mechanism by particles smaller than 50 nm and an octopus-like growth mechanism by larger particles (50鈭?00 nm). The graphene sheet orientation in the carbon nanofibers depends on the composition of the metal particle; fishbone carbon nanofibers are obtained with carbon felt supported Ni catalysts, while platelet carbon nanofibers were obtained with Ni鈭扖u catalysts. The formation of platelet carbon nanofibers from the Ni鈭扖u catalysts is ascribed to a higher degree of interface wetting between the Ni鈭扖u particle and the produced graphene sheets.