title: Free energy relationships in the electrical double layer over single-layer graphene.
abstract: Fluid/solid interfaces containing single-layer graphene are important in the areas of chemistry, physics, biology, and materials science, yet this environment is difficult to access with experimental methods, especially under flow conditions and in a label-free manner. Herein, we demonstrate the use of second harmonic generation to quantify the interfacial free energy at the fused silica/single-layer graphene/water interface at pH 7 and under conditions of flowing aqueous electrolyte solutions ranging in NaCl concentrations from 10(-4) to 10(-1) M. Our analysis reveals that single-layer graphene reduces the interfacial free energy density of the fused silica/water interface by a factor of up to 7, which is substantial given that many interfacial processes, including those that are electrochemical in nature, are exponentially sensitive to interfacial free energy density.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Achtyl
authors.forename: Ivan V
authors.initials: IV
authors.lastname: Vlassiouk
authors.forename: Pasquale F
authors.initials: PF
authors.lastname: Fulvio
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Mahurin
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.forename: Franz M
authors.initials: FM
authors.lastname: Geiger