Effect of viscosity and applied potential on oscillations at a Pt–Pt dual-electrode in a ferricyanide system

This paper outlines the effect of viscosity and applied potential on oscillations occurring at two platinum electrodes placed proximal to each other. Potential oscillations taking place on the primary electrode (WE1) under galvanostatic control in the ferricyanide system are affected by the solution viscosity as it modifies the convective feedback mechanism necessary for oscillations. Measured transition times correlate with those calculated using Sand equation thus allowing the estimation of current density windows for periodic oscillation for different solution viscosities for pre-determined transition times. Current oscillations on the secondary working electrode (WE2) – under potentiostatic control and induced by the potential oscillations on WE1 – can be tuned through the applied potential. At higher potentials the reaction is oxidation of [Fe(CN)6]4− and the coupling is primarily through the transfer of [Fe(CN)6]4− from WE1 to WE2 via H2 evolution whilst at more cathodic potentials the reduction of [Fe(CN)6]3− takes place at both WE1 and WE2 and the convective feedback from WE1 refreshes the surface of both electrodes simultaneously.