A New Form of Electrochemical Kinetics, at the Single Layer Graphene – Electrolyte Interface

Abstract

The “all-surface” characteristic of single–layer graphene (SLG) offers a remarkable paradigm for the exploration of novel physical and chemical phenomena. However, in many cases it is unclear as to how a graphene surface manifests clearly different chemical characteristics compared to any other surface. In this work, we report on a characteristic, experimentally demonstrated, that is unique to the two-dimensional nature of SLG in terms of a completely new type of electrokinetics in stark contrast to the accepted Marcus-Hush-Chidsey (MHC) formalism. We will indicate that the specific consideration of the unusual linear variation of the two-dimensional density of states (DOS) in SLG, would cause a deviation from both Arrhenius activation relation based Butler-Volmer kinetics as well as the MHC kinetics, which assumes a constant DOS. Consequently, we propose a new lower-dimensional DOS based reaction rate constant and experimentally show that aspects related to a non-ideal DOS were explained through electron and hole puddles formed in wrinkled graphene. Our experiments and related fitting of the data considerably supplements the presently used standard models to analyze the variation of the reaction rate constants and has significant implications wherever nanoscale electrodes are utilized in energy storage and transduction.