Electrochemical impedance of mercury electrodes with hematite particles adhered

Abstract The effect of hematite particles adhesion on the electrochemical impedance of mercury electrodes was studied at different electrode potentials. The impedance decreases as the number of attached particles increases; this impedance decrease is related to strong adhesion of particles. The impedance diagrams show, in the low frequency range, the presence of a constant phase element (CPE), with an exponent of ca. 0.5. The experimental results are analyzed in terms of an equivalent circuit including the CPE. The magnitude of this CPE is directly related to the coverage of the electrode. A qualitative interpretation for this behavior, when an AC signal is applied, is proposed in terms of a pore model for the metal/hematite particles interphase. Keywords: PARTICLE ADHESIONELECTROCHEMICAL IMPEDANCEHEMATITEEQUIVALENT CIRCUITPORE MODEL