| 研究実績の概要 |
One of the major challenges in realization of graphene-based technology is to tailor its properties through chemical or mechanical means. Hence the present research project is focused on exploring a new chemical approach for direct binding of transient radical species formed in a reaction mixture onto graphene.
According to the initial plan, I have performed the direct binding of fluoro substituted aryl and chloro substituted alkyl group on EG on SiC. Using two different kinds of typical organic halides (bromopentafluorobenzene and bromodichloromethane), I have found that transient substituted aryl or alkyl radical generated during the preparation of Grignard reagent chemisorbed onto the surface of graphene sample preloaded into the reaction vessel. It should be noted that the corresponding aryl or alkyl bromide and Grignard reagent itself do not react with pristine graphene. The chemisorbed species on graphene are characterized by x-ray photoelectron spectroscopy (XPS), scanning tunnelling microscopy and spectroscopy (STM/STS) and Raman spectroscopy. Since there are large number of organic bromides commercially available, the present approach can be utilized for chemical grafting of functional organic molecules on graphene and other two dimensional materials, which is highly desirable for realization of graphene based devices including chemical and biosensors.
Based on the results obtained for binding of substituted aryl and alkyl groups on graphene, I have published a paper in Chem. Commun. and presented oral presentation in different international conferences.
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| 今後の研究の推進方策 |
As we know that thiol(SH) and amine (NH2) functionalized surface is technologically more important because of its higher affinity toward nano-particles and bio-moelcules. As planned initially I will be focused on the functionalization of graphene with SH, NH2 and COOH groups using either Grignard procedure as succeeded in the first year of the project or ‘diazotization’ procedure. Diazonium salt is known to undergo spontaneous reduction onto a solid surface resulting into the chemisorption of organic part of the molecule on the solid surface. However, commercially available pre-prepared diazonium salts are very few in number. But there are large numbers of amines that can give unstable diazonium salt upon diazotization reaction. Hence, in the case of ‘diazotization’ procedure, the graphene sample will be treated with in-situ prepared diazonium salt from a desired primary amine without separating the salt from the reaction mixture. The chemically modified surface will be characterized by various surface probe techniques as performed in the first year of the project.
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