Enhanced electrochemical expansion of graphite for in situ electrochemical functionalization.

An all electrochemical route to functionalized graphene directly from a graphite electrode is described herein obviating the need for defect inducing oxidative or prolonged sonication treatments. Enhanced electrochemical expansion of graphite is achieved by sequential treatment, beginning with the established method of expansion by electrolysis in a Li(+) containing electrolyte, and then with the much larger tetra-n-butylammonium. The result is a hyperexpansion of the graphite basal planes. As a demonstration of the utility of this method, we successfully performed a subsequent in situ electrochemical diazonium functionalization of the hyperexpanded graphite basal planes to give functional graphene sheets. This potential controlled process is more effective than chemical processes and also provides a means of controlling the degree of functionalization. We have further demonstrated that the functionalized graphene could be converted to a pristine low defect form via laser ablation of the funtional groups. As a result, this method presents a potentially scalable approach for graphene circuit patterning.