Current-Potential-Time Response of the Second-Order Co-Reactant Mechanism: An Analytical Theoretical Approach

An analytical approach is presented for the voltammetric and chronoamperometric study of a second-order cyclic-type mechanism where two species are ‘activated’ electrochemically and subsequently react in solution, as observed in co-reactant electrochemiluminescence mechanisms. Closed-form expressions are derived for the current-potential-time response and for the surface species concentrations as a function of the chemical rate constant, the concentration ratio of the initial species, and their formal potentials. Their effects on the voltammetric signal are analyzed, pointing out a wave-splitting behaviour for fast kinetics, which is tied to the rates of formation and consumption of the ‘activated’ co-reactant.