Theory of square-wave voltammetry of two electron reduction with the intermediate that is stabilized by complexation

An influence of complexation of reactant and intermediate on square-wave voltammograms of reversible, two-step electrode reaction is analyzed theoretically. The potentials of the first and the second peak of the split net response depend on stability constants of complexes, the standard potentials of individual electron transfers and on the concentration of ligand: EP,1−E10=(RT/F)(ln FM+−ln FM2+) and EP,2−E10=E20−E10−(RT/F)ln FM+, where FM2+=1+β1,acL−+β2,acL−2+… and FM+=1+β1,bcL−+β2,bcL−2+….

► Two-step electrode reaction is analysed. ► The intermediate is stabilized by complexation. ► The separation of two peaks of the response increases at high ligand concentration.