EXPLICIT FINITE-DIFFERENCE DIGITAL-SIMULATION OF THE EFFECTS OF RATE-CONTROLLED PRODUCT ADSORPTION OR DEPOSITION IN DOUBLE-POTENTIAL-STEP CHRONOCOULOMETRY

The case is considered where the product of an electrode reaction deposits and/or is adsorbed at the electrode surface but the reactant does not. Rate constants for deposition-dissolution and adsorption-desorption are introduced into an explicit finite-difference simulation program that calculates the combined effects of diffusion, surface accumulation and the electrode reaction on the surface fluxes of reactant and product. The simulations are shown to give accurate results in the limits of no deposition and of rapid reversible deposition where analytic solutions exist. As an example. the program is used to fit data for the surfactant-induced deposition of the methyl viologen cation radical from aqueous solution in the presence of sodium n-decyl sulfate.