Covalent Functionalization by Cycloaddition Reactions of Pristine Defect-Free Graphene

详细信息    查看全文

• 作者：Lakshya Daukiya ; Cristina Mattioli ; Dominique Aubel ; Samar Hajjar-Garreau ; François VonauEmmanuel Denys ; Günter Reiter ; Jonas Fransson ; Elsa Perrin ; Marie-Laure Bocquet ; Cristina BenaAndré Gourdon ; Laurent Simon
• 刊名：ACS Nano
• 出版年：2017
• 出版时间：January 24, 2017
• 年：2017
• 卷：11
• 期：1
• 页码：627-634
• 全文大小：510K
• ISSN：1936-086X

文摘

Based on a low-temperature scanning tunneling microscopy study, we present a direct visualization of a cycloaddition reaction performed for some specific fluorinated maleimide molecules deposited on graphene. Up to now, it was widely admitted that such a cycloaddition reaction can not happen without pre-existing defects. However, our study shows that the cycloaddition reaction can be carried out on a defect-free basal graphene plane at room temperature. In the course of covalently grafting the molecules to graphene, the sp² conjugation of carbon atoms was broken, and local sp³ bonds were created. The grafted molecules perturbed the graphene lattice, generating a standing-wave pattern with an anisotropy which was attributed to a (1,2) cycloaddition, as revealed by T-matrix approximation calculations. DFT calculations showed that while both (1,4) and (1,2) cycloadditions were possible on free-standing graphene, only the (1,2) cycloaddition could be obtained for graphene on SiC(0001). Globally averaging spectroscopic techniques, XPS and ARPES, were used to determine the modification in the elemental composition of the samples induced by the reaction, indicating an opening of an electronic gap in graphene.