Bromate Reaction on a Rotating Disc Electrode: A New Method of Obtaining Approximate Analytical Solutions for Stationary Regime

Abstract

A new method (AA approximation) is proposed for obtaining approximate analytical solutions of a system of equations describing the transport of the basic reagents for the electroreduction process of the BrO$_{3}^{ - }$ anion on a rotating disc electrode in an acid medium in the presence of very small additions of molecular bromine. This process is of significant interest both from the fundamental point of view (as an example of a new electrochemical EC'' mechanism with autocatalytic properties) and from the applied point of view in the context of prospects to create, on its basis, innovation power sources—bromate redox flow batteries. Since the previously proposed method for solving the system of kinetic transport equations for this system turned out to be inapplicable for very large diffusion layer thicknesses and very strong currents, here a new method of obtaining approximate analytical expressions for concentration profiles and maximum current is proposed. It has been shown that its predictions are in good agreement with the results of the numerical solution of the same problem in a wide range of system parameters, including the region of very large diffusion layer thicknesses, which confirms the validity of the used analytical approximations.