Current Transients in Blocking Electrochemistry Experiments Modeled by Analog Simulation of Diffusion

In blocking particle-impact electrochemistry, the single collision events often show current transients that do not immediately lead to the expected steady-state current but rather appear distorted or bouncy, with a short delay before reaching again a stable current. This artifact-looking increase of current up to a steady state, observed in both soft and hard insulating particle impacts, seems to be a physicochemical effect rather than a mechanical one. The reorganization of the diffusion layer around the disruptive insulating entity on the electrode surface is expected to induce a change in the shape of the measured current and could be the cause of this effect. To investigate this, we present here an original analog simulation of the transient current flowing through the working ultramicroelectrode during a blocking impact. By modeling single electrochemical impacts using only diffusion, we obtained a similarly shaped signal thanks to an analog simulator based on an electric network composed of resistors and capacitors. We suggest that the relaxation of the diffusion layer after a blocking impact is the main cause of such distortion in the current transients.