Adsorption of diethylether on single-crystal gold electrodes: Calculation of adsorption parameters

Abstract

In this paper quantitative studies of the adsorption of diethylether on the three low-index faces (111), (100) and (110) of the gold electrode are presented. The equilibrium charge densities at the gold electrode were determined from combined chronocoulometric and admittance measurements. The adsorption parameters such as free energy of adsorption Δ G A, limiting Gibbs excess Γ max, lateral interaction constant a, etc. were calculated and compared with earlier results relative to the mercury electrode surface. These adsorption parameters were next discussed in terms of the properties characteristic for the nature (liquid, solid) and the structure (crystallographic orientation) of the surfaces investigated. Under the assumption that: (1) diethylether adsorption is a water-substitution process, and (2) the ether-metal interactions are weak and change slightly with the nature and the structure of the surface, the free energies of adsorption Δ G A 0 were used as a probe of the surface hydrophilicity. The following series of increasing hydrophilicity was proposed: Au(111)≦Hg≦Au(100)<Au(110) and the earlier literature estimations of gold hydrophilicity were critically discussed.