Investigation of oxygen electroreduction on polyvinylferrocene coated glassy carbon electrodes

The electroreduction of O2 has been investigated at a bare glassy carbon (GC) electrode and a polyvinylferrocene (PVF) coated glassy carbon electrode (PVF-GC) in both 0.1 M NaClO4 solution and phosphate buffer solutions of various pH values by using cyclic voltammetry and chronoamperometry. Two well-defined reduction peaks were observed at about −0.55 and −0.80 V versus SCE at PVF-GC electrode while one reduction peak was observed at about −0.85 V versus SCE at GC electrode in 0.1 M NaClO4 solution and phosphate buffer solutions of pH >6. Two peaks at PVF-GC electrode indicated a two-step four-electron pathway of O2 in these mediums. The first peak was ascribable to the two-electron reduction of O2 to H2O2, while the second peak was assigned to the reduction of H2O2 to H2O. The electrocatalytic effects of PVF matrix for the reduction O2 and the reduction of H2O2 were observed. The effects of the film thickness, O2 concentration, pH and potential scan rates were investigated.