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Electrochemical impedance spectroscopy (EIS) and cyclic
voltammetry were used to investigate the oxide layer formed on a
copper disc electrode and the changes that took place when treated
potentiostatically in the range of -0.3 V to 0.9 V in aqueous buffer
solution of pH 9.2. Equivalent circuits were used to model the
response of the electrode, initially at equilibrium to an applied
potential. These circuits were proposed for different potential
ranges in order to illustrate the Cu/oxide/electrolyte system and its
properties in terms of 2 interfaces. A criterion for the
applicability of equivalent circuit models was discussed. Changes in
the film/metal interface as a function of potential were probed at 30
mHz from Nyquist plots. Diffusion coefficient calculated for the
ionic movement in the film at 2 potential values using EIS data was of
the order of 10-9 cm2 s-1.
Electrochemical impedance spectroscopy (EIS) and cyclic
voltammetry (CV) were used to investigate the oxide layer formed on a
copper disc electrode and the changes that took place when treated
potentiostatically in the range of -0.3 V to 0.9 V in buffer of pH
8.5. The response of an electrode using EIS, initially at
equilibrium, to an applied potential was then modeled with equivalent
circuits, proposed for different potential regions that completely
illustrated the Cu/oxide/electrolyte systems and their properties in
terms of 2 interfaces. Criterion for the applicability of equivalent
circuit models was discussed. Changes in the film/metal interface as
a function of potential were also probed at 30 mHz using Nyquist
plots. Diffusion coefficient and concentration of mobile ions in the
film calculated from the EIS data came out of the order of 10-6
cm2 s-1 and 10-6 mmol mL-1, respectively.
