Generalized Randles–Ševčík Equation for Voltammetry Initiated at the Equilibrium Potential

Electrochemically reversible cyclic voltammetry of a simple A/B redox couple at a macroelectrode under conditions of semi‐infinite linear diffusion from a bulk solution containing variable amounts of A and B is investigated. In particular, nonstandard conditions where the start potential corresponds to the equilibrium potential of the A/B couple, as governed by the Nernst equation and controlled by the relative concentrations of A and B, are considered. This contrasts with the conventional choice of an extreme potential corresponding to negligible current flow in a solution containing exclusively either A or B. Simulations using physics‐informed neural networks (PINNs) are employed to generate Randles–Ševčik‐type equations for the peak currents corresponding to different equilibrium potentials as controlled by the concentration ratios of A to B with the expected proportionality to the square root of scan rate in all cases. The peak currents are larger than those seen for the conventional start condition for the same concentration of oxidized or reduced species and, experimentally, permit an independent check on the correctness of the formal potential of the A/B couple.