Few theories have proven useful for as long a period as that of Gouy, Chapman, and Stern (GCS) for an electrochemical interface. It seems amazing that a theory that assumes that the solvent is a continuum, the ions are points, and neglects inter-particle correlations, would be useful. However, the GCS theory is a description rather than a theory. Its application requires parametrization. GCS results may be useful but provide no fundamental insight into the structure of the interface. The inadequacy of the GCS description became apparent as a result of the seminal simulations of Torrie and Valleau (TV) in 1980. Their simulations allowed a test of the GCS description that parametrization cannot conceal. Rather than a well that becomes a plateau at large concentration and electrode charge, as the GCS description suggests, the differential capacitance really has a double hump shape at low ion concentrations that transforms into a single hump at large concentrations. However, the acceptance of the TV insights has been slow because of experimental difficulties with aqueous systems at high concentrations and electrode charge. In contrast, ionic liquids exist at high concentrations and are particularly well suited for exposing the shortcomings of the GCS description. The TV results, as well the results of recent simulations and theory of the electrochemical interface for model ionic liquids, are discussed.

Computer simulations provide an understanding of the electrochemical interface

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.