The interfacial capacitance of Au(100) in an ionic liquid, 1-butyl-3-methyl-imidazolium hexafluorophosphate

Impedance spectra for Au(100) in 1-butyl-3-methyl-imidazolium hexafluorophosphate are presented. The derived spectra of interfacial capacitance exhibit two arcs, a finding which is inconsistent with current theories on metal/ionic liquid double layers as well as previous measurements on similar systems. The two-arcs behaviour is most probably due to the kinetics of anion/cation replacement in the innermost part of the double layer. (C) 2011 Elsevier B.V. All rights reserved.