Study on the fabrication of diazonium molecular monolayer material on graphite substrate viaelectrochemical grafting approach

Abstract

Surface denaturation of carbon surfaces with molecular monolayer is appointed as one of the most effective bottom-up techniques to enlarge the applicability of the carbon-based electrodes in the electrochemical sensor field. Diazonium molecules have been often employed to denature the surface of materials such as graphite and graphene through the formation of C-C chemical bonds between them. However, the layered formation of these molecules is not well controlled yet due to their intrinsic high reactivity. This report demonstrated a practical approach for covalent functionalisation of the highly oriented pyrolytic graphite (HOPG) surface, a model system of multilayered graphene, by using 3,5-bis-tert-butylbenzenediazonium molecules. Due to the substituents at the 3,5 positions the aryl radicals prefer bonding directly to the HOPG surface than attacking the grafted aryls towards the monolayered formation. The efficiency of this approach was determined by the combined cyclic voltammetry, atomic force microscopy and scanning tunnelling microscopy.