Effect of electrochemical treatment of glassy carbon electrodes on electrode surface and vanadium^lv-vanadium^v kinetics

The V^IV-V^V electrode kinetics of polished and non-polished glassy carbon electrodes were monitored during repeated cathodic and anodic treated. Although anodic treatment initially enhances the electrode kinetics, repeated treatment leads to the reverse: i.e. the kinetics is inhibited by anodic treatment and enhanced by cathodic treatment. The kinetics of the system was investigated using cyclic voltammetry (CV) and impedance spectroscopy (EIS) and the two techniques show strong agreement. The enhancement factor between the activated (i.e. cathodically treated) and deactivated (i.e. anodically treated) electrodes was as high as 11.5. Scanning electron microscopy (SEM) shows that the electrode surface is stable with only limited cracking. CV analysis in sulfuric acid shows very stable values for current density on anodically treated electrodes but a proportional relationship between current density and treatment number on cathodically treated electrodes suggesting functionalization of the system through repeated reduction and oxidation of the electrodes. These functionalized sites may be easily reduced or oxidized allowing toggling between the activated and deactivated states of V^IV-V^V electrode kinetics.