Enhanced Chemical Reactivity of Graphene by Fermi Level Modulation

Abstract

Among various approaches to modify the electronic and chemical properties of graphene, functionalization is one of the most facile ways to tailor these properties. The rearranged structure with covalently bonded diazonium molecules exhibits distinct semiconducting property, and the attached diazonium enables subsequent chemical reactions. Notably, the rate of diazonium functionalization depends on the substrate and the presence of strain. Meanwhile, according to the Gerischer-Marcus theory, this reactivity can be further tuned by adjusting the Fermi level. Here, we precisely controlled the Fermi level of graphene by introducing the self-assembled monolayer (SAM) and investigated the degree of chemical reactivity of graphene with respect to the doping types. The n-doped graphene exhibited the highest reactivity not only for diazonium molecules but also for metal ions. The increased reactivity is originated from a remarkable electron donor effect over the entire area. In addition, the n-doped graphene enabled spatially patterned functionalization of diazonium molecules, which was further utilized as a growth template for gold particles that would be advantageous for enhanced electrochemical reactivity.