H. Matsui et A. Kunugi, EFFECTS OF SURFACE MODIFICATION ON DOUBLE-LAYER IMPEDANCE OF PLATINUM-ELECTRODES IN AN ACID-SOLUTION .1. ADSORPTION OF CARBON-MONOXIDE, Journal of electroanalytical chemistry [1992], 372(1-2), 1994, pp. 225-231
The double-layer impedance of Pt electrodes with and without adsorbed
CO was investigated in 0.5 M H2SO4 by a fast Fourier transform method.
The complex impedance plot for a smooth bare Pt electrode was a strai
ght line at an angle of 4-degrees-6-degrees to the vertical. This was
explained in terms of atomic-scale surface unevenness, considering the
distributed pore model of a flat surface coupled with the solution re
sistance. However, when the Pt electrode was modified by adsorbed carb
on monoxide. the observed impedance behavior was purely capacitive at
frequencies above 10 kHz. This was explained in terms of the hydrophob
ic nature of the adsorbed CO.