Cycloaddition reactions on epitaxial graphene

Abstract

By means of first principles calculations we investigated the occurrence of cycloaddition reactions on a buffer layer of graphene on silicon carbide. We found that there is a strong correlation between the number and position of the interface bonds and the cycloaddition products. In contrast with results obtained for freestanding graphene, we found that for a buffer layer of epitaxial graphene, the unusual 1,3 cycloaddition of benzynes was preferred over the [4+2] and [2+2] paths. We show that the bonds formed between graphene and the substrate guide the chemical processes occurring on graphene. In turn, the chemical reactivity of supported graphene can be completely different as compared with freestanding graphene, making unfavorable processes the preferred ones. We expect that the results presented open a new direction to attain chemical functionalization of graphene.