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Voltage-step Transient in Redox Systems II. 1D Approximation (revisited)
Wein, Ondřej
Using the well-known Cottrell asymptote, voltage-step transient experiment could provide data on bulk concentration and diffusion coefficient of working depolarizer, essential in the liming-current techniques. However, the Cottrell asymptote is not directly applicable in an early stage of the voltage-step transient process,. There are three additional transport resistances that cannot be neglected at extremely high initial currents: Faradaic resistance at surface of working electrode, Ohmic losses in its intimate neighborhood, and the galvanometric constraint in the outer circuit (galvanometer, current follower, potentiostat). Non-linear effect of these additional transport resistances on the transient current is calculated in a 1D approximation, i.e. assuming uniform accessibility of the working electrode, for finite voltage steps.
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