Double layer capacitance of the platinum group metals in the double layer region

Abstract The interfacial impedance for the platinum-group metals, in simple binary electrolytes, in their so-called double layer region, is generally assumed to be ideally capacitive. In this communication, mainly addressing the Ir(1 0 0) / 0.1 M HCl system, we demonstrate that this is not necessarily the case when the anion of the solute is specifically adsorbed on the electrode. The frequency dependence is attributed to the relatively slow exchange of anions at the outer Helmholtz plane with the adsorbed ones (i.e. those at the inner Helmholtz plane).

[1]  H. Nozoye,et al.  Note on the hydrogen adsorption-desorption voltammogram on Pt(111) in sulfuric acid solution , 1994 .

[2]  R. Durand,et al.  High frequency impedance measurements on Pt(111) in sulphuric and perchloric acids , 2001 .

[3]  H. Baltruschat,et al.  The rate of anion and hydrogen adsorption on Pt(111) and Rh(111) , 1998 .

[4]  D. Grahame.  The electrical double layer and the theory of electrocapillarity. , 1947, Chemical reviews.

[5]  H. Baltruschat,et al.  On the rate of hydrogen and iodine adsorption on polycrystalline Pt and Pt(111) , 1994 .

[6]  T. Pajkossy,et al.  Measurement of adsorption rates of anions on Au(111) electrodes by impedance spectroscopy , 2002 .

[7]  T. Pajkossy,et al.  Impedance aspects of anion adsorption on gold single crystal electrodes , 1996 .

[8]  B. Conway,et al.  Evaluation of the effect of two-dimensional geometry of pt single-crystal faces on the kinetics of upd of h using impedance spectroscopy , 1996 .

[9]  T. Pajkossy,et al.  Voltammetry and impedance measurements of Ir(1 1 1) electrodes in aqueous solutions , 2005 .

[10]  R. Durand,et al.  Pt(111) electrosorption impedance in mixed electrolyte , 2002 .

[11]  Dieter M. Kolb,et al.  Double layer capacitance of Pt(111) single crystal electrodes , 2001 .

[12]  B. Conway,et al.  Comparative evaluation of surface structure specificity of kinetics of UPD and OPD of H at single-crystal Pt electrodes 1 Presented at the Surface Electrochemistry Conference, Alicante, Spain, September 1997. 1 , 1998 .

[13]  R. Durand,et al.  Preparation of monocrystalline Pt microelectrodes and electrochemical study of the plane surfaces cut in the direction of the {111} and {110} planes , 1980 .

[14]  E. Sibert,et al.  Electrosorption impedance on Pt(111) in sulphuric media and nature of the “unusual” state , 2001 .

[15]  H. Thirsk,et al.  The kinetics of adsorption of sulphide ions at a mercury electrode , 1970 .

[16]  T. Pajkossy.  Voltammetry and Impedance of Pt(111) Electrodes in Aqueous KClO4 Solutions , 2003 .