title: Effect of noncovalent basal plane functionalization on the quantum capacitance in graphene.
abstract: The concentration-dependent density of states in graphene allows the capacitance in metal-oxide-graphene structures to be tunable with the carrier concentration. This feature allows graphene to act as a variable capacitor (varactor) that can be utilized for wireless sensing applications. Surface functionalization can be used to make graphene sensitive to a particular species. In this manuscript, the effect on the quantum capacitance of noncovalent basal plane functionalization using 1-pyrenebutanoic acid succimidyl ester and glucose oxidase is reported. It is found that functionalized samples tested in air have (1) a Dirac point similar to vacuum conditions, (2) increased maximum capacitance compared to vacuum but similar to air, (3) and quantum capacitance "tuning" that is greater than that in vacuum and ambient atmosphere. These trends are attributed to reduced surface doping and random potential fluctuations as a result of the surface functionalization due to the displacement of H2O on the graphene surface and intercalation of a stable H2O layer beneath graphene that increases the overall device capacitance. The results are important for future application of graphene as a platform for wireless chemical and biological sensors.
authors.affiliation: University of Minnesota-Twin Cities , 200 Union Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Mona A
authors.initials: MA
authors.lastname: Ebrish
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Olson
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Koester
mesh_terms: D006108:Graphite / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D006108:Graphite