The effect of faradaic processes on the resonance of electrochemical cells

Abstract

Electrolytic cells consisting of mercury electrodes immersed into pure aqueous sulphuric acid solution (ideally polarizable electrodes) and in the one containing Ti3+/Ti4+ redox couple (presence of a faradaic process) were shown to resonate with an induction coil connected in series when a.c. of appropriate frequency is applied across the circuit. The parameters of this faradaic resonance, ωr (resonance frequency) and Ar (amplification factor at resonance) depend on the properties of the system such as the concentration of the redox couple and the electrode potential, as well as on the amplitude of the applied a.c. Higher harmonics have been detected even with the lowest applied amplitude (1 mV). A detailed theoretical consideration has been given to the expected resonance properties of an electrode based on purely activation controlled electrode process as well as of the one in which some diffusional effects become significant, for overpotential changes in the linear domain. This was done in an attempt to assess the value of faradaic resonance measurements for studying kinetic properties of electrochemical cells.