title: Differential capacitance of the double layer at the electrode/ionic liquids interface.
abstract: The differential capacitance of the electrical double layer at glassy carbon, platinum and gold electrodes immersed in various ionic liquids was measured using impedance spectroscopy. We discuss the influence of temperature, the composition of the ionic liquids and the electrode material on the differential capacitance/potential curves. For different systems these curves have various overall shapes, but all include several extremes and a common minimum near the open circuit potential. We attribute this minimum to the potential of zero charge (PZC). Significantly, the differential capacitance generally decreases if the applied potential is large and moving away from the PZC. This is attributed to lattice saturation [A. A. Kornyshev, J. Phys. Chem. B, 2007, 111, 5545] effects which result in a thicker double layer. The differential capacitance of the double layer grows and specific adsorption diminishes with increasing temperature. Specific adsorption of both cations and anions influences the shapes of curves close to the PZC. The general shape of differential capacitance/potential does not depend strongly on the identity of the electrode material.
authors: Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia. vera.lockett@gmail.com
authors: Vera
authors: V
authors: Lockett
authors: Mike
authors: M
authors: Horne
authors: Rossen
authors: R
authors: Sedev
authors: Theo
authors: T
authors: Rodopoulos
authors: John
authors: J
authors: Ralston
mesh_terms: D002244:Carbon / Q000737:chemistry*; D058266:Dielectric Spectroscopy; D025802:Electric Capacitance; D004563:Electrochemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D013696:Temperature
chemical_list: D052578:Ionic Liquids; D010984:Platinum; D002244:Carbon; D006046:Gold