Phase-response characteristics of the transfer function of a spatially limited electrochemical cell

Investigation of the dynamic characteristics of diffusion transducers is of great practical importance because of the wide utility of these devices in instruments for measuring the movement parameters and wave fields. Previously, cathode currents were the object of investigation because their difference was used as an output signal in several useful devices. In this work we investigated the amplitude and phase relationships between currents measured on both cathodes and anodes over a wide range of frequencies in a four-electrode electrochemical cell. It was shown in experiment that the sum of the currents recorded on the four electrodes of a molecular electronic cell (MEC) is zero, as follows from the condition of conservation of an electric charge. At frequencies as low as ∼0.1 Hz the frequencies of the signal currents of the anode and the nearest cathode coincided. As the frequency grew to f ∼80 Hz, the phase difference monotonously increased to values close to π. Previous theoretical models suggested, explicitly or implicitly, that the phases of the signal currents coincided over the whole range of frequencies in each anode-cathode pair. The results of the experiment were explained within the framework of the theoretical model of a four-electrode electrochemical cell, which is based on the one-dimensional equation of convective diffusion and takes into account the limited space of the cell.