Forward and reverse scans in square wave voltammetry applied to the first order CE mechanism: Ti(IV)/Ti(III) system in acidic oxalate media

A dimensionless analysis of the first order CE mechanism, whatever the rate of the charge transfer, in square wave voltammetry and incidentally in normal pulse voltammetry is presented. The quantitative description of the limiting cases of the mechanism and of the kinetic steady-state currents for reversible and irreversible electrochemical reactions, permits diagrams to be drawn, delimiting zones of preponderance for the various types of currents. Reverse scans (from the plateau towards the foot of the corresponding polarographic wave) are also studied and their interest in kinetic studies is discussed. In a subsequent experimental part, the kinetics of the Ti(IV)/Ti(III) system in acidic (HClO4, H2SO4) oxalate media is investigated and the validity of the theoretical predictions is checked.