Crs. Silva et al., PARTIALLY BLOCKED SURFACE STUDIED BY THE ELECTROHYDRODYNAMIC IMPEDANCE, Journal of electroanalytical chemistry [1992], 365(1-2), 1994, pp. 133-138
The mass transport to a partially blocked surface on a rotating disc e
lectrode when its angular velocity is submitted to small sinusoidal os
cillations around a mean value has been analysed. From the quantitativ
e treatment of the response of a single active site embedded in an oth
erwise conducting surface, it was inferred that the high frequency res
ponse of a partially blocked surface with active sites of the same siz
e can be estimated. The response contains two time constants and its f
requency analysis can provide the average size site and the active fra
ction of the interface. These predictions were compared with an experi
mental investigation using a photolithographic model of a partially bl
ocked electrode. Good agreement between theory and experiment was obta
ined when the high frequency response was corrected for kinetic effect
s due to the finite rate of the chosen redox reaction and double-layer
charging.