Transient chronoamperometric current at rotating disc electrode for second-order ECE reactions

Dimensionless current versus potential for various values of parameters. [Display omitted] •Approximate analytical expression of the concentration profile.•Explicit closed formulation of the limiting current for a uniformly accessible rotating disc electrode (RDE).•Sensitivity analysis of parameters.•Comparison of numerical and analytical solutions of nonlinear equations. The approximate transient chronoamperometric limiting current generated from the electrochemical reaction in a rotating disc electrode for second-order ECE reactions is derived when the chemical step is irreversible. This model is based on nonlinear reaction–diffusion equations containing a nonlinear term related to homogeneous reaction. By solving the nonlinear equations applying a new approach of homotopy perturbation methods, simple and closed-form expressions for the reactant concentration and the current response as a function of the rotation rate and diffusion coefficients are obtained. The impact of various physical parameters on concentration and current has been analyzed and graphically displayed. Sensitivity analysis of parameters such as rate constant, the ratio of bulk concentration, the thickness of diffusion layer on current is discussed. In addition, the concentration/current expressions match well with the numerical and limiting case results.