課題番号                ：S-19- NI-0037

利用形態                ：技術相談

利用課題名（日本語）    ：新規グラフェン合成触媒の探索

Program Title (English) ：Investigation on the catalytic property of novel catalysts in graphitization

Username (English)     ：Amr Attia Abuelwafa Qenawe ¹⁾

所属名（日本語）        ：1) 南谷大学

Affiliation (English)  ：1) South Valley University, Egypt

１．概要（Summary ）

Graphene attracts much interest as the promising nanomaterial for a variety of devices of next generation. For the practical appications, its controllable synthesis is important.  Thus, the the catalyst and the technique to achiev this goal should be exploered [1-3].  Here, the catalytic property for Ga was investigated using in-situ transmission electron microscopy (TEM) specific to Nagoya Institu of Technology.

２．実験（Experimental）

Ga-incorporated carbon nanofibers (Ga-CNFs) were synthesized usin a room temperature CNF synthesis system.  The overall morphology of the samples and the graphitization process of amorphous CNF was observed by scanning electron microscopy (SEM; JSM-5600) and in-situ TEM (JEM ARM 200F), respectively.

３．結果と考察（Results and Discussion）

Although Ga is easy to melt (melting point: 29.76^oC), Ga-CNFs could be synthesized on carbon foils by the ion-irradiation method with a simultaneous Ga supply, similar to other metals. They were characterized with CNF-tipped cones in morphology and with an amorphous C matrix and metallic Ga nanoparticles dispersing therein in crystalline strucuture.

The structural change induced by resistive Joule heating with an application of increasing voltage between Ga-CNF and a counter electrode in TEM was as follows: The small Ga nanoparticles gradually evaporated due to Joule heating, and suddenly all the Ga nanopartilces disappeared.  Further increase in applied volgtage led to the breakdown of the CNF at about its middle.  From the current-voltage (I-V) measurement, the non-linear increase with applied voltage is observed, suggesting the conductivity increase due to the structural change of the CNF-tipped cone.  The maximum current reached 15.4 µA just before the breakdown of the CNF.  A high resolution TEM taken at the broken part of the CNF clearly showed the lattice fringes with the inter layer distance of 0.337 nm which certainly corresponds to that of graphene (002), confirming the formation of long-ranged graphitized layer at the surface region of the CNF similar to the tip-closed carbon nanotube. The catalytic property of Ga was thus observed in atomic dimension.

４．その他・特記事項（Others）

[1] R. Vishwakarma, M. S. Rosmi, K. Takahashi, Y. Wakamatsu, Y. Yaakob, M. I. Araby, G. Kalita, M. Kitazawa, M. Tanemura, Scientific Reports, 7 (2017) 43756

[2] S. Sharma, M. S. Rosmi, Y. Yaakob, M. Z. M. Yusop, G. Kalita,  M. Kitazawa, M. Tanemura, Carbon 132 (2018) 165-171.

[3] S. Sharma, B. P. Jaisi, M. I. Araby, S. Elnobi, M. E. Ayhan, G. Kalita,  M. Tanemura, RSC Advances 9 (2019) 34377-34381.

５．論文・学会発表（Publication/Presentation）

None

６．関連特許（Patent）

None