Influence of surface oxygen groups on V(II) oxidation reaction kinetics

• The V(II) oxidation reaction is sensitive to the amount of surface oxygen groups on a glassy carbon electrode.
• Improvements in V(II) oxidation reaction kinetics correspond to an increase in surface oxygen content (O/C ratio).
• An oxygen-functionalised glassy carbon surface is not stable in the potential range of the V(II)/V(III) redox reaction.

The role of surface oxygen groups on the kinetics of the V(II) oxidation reaction was studied on modified glassy carbon (GC) electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The reaction was found to be sensitive to the presence of oxygen groups on the electrode surface. Higher O/C ratios determined by X-ray photoelectron spectroscopy (XPS) corresponded to higher reactivities and lower charge transfer resistances measured in a 1 M V(II) electrolyte. The stability of an oxidised GC surface was also investigated in a 1 M V(II) electrolyte by potential holding and cycling experiments. It was found that after holding and cycling to successively more negative potentials up to − 0.8 V/RHE, the electrode surface lost its initial reactivity.