Oxygen reduction at the basal plane of stress-annealed pyrolytic graphite in acetonitrile solutions

The oxygen reduction process occurring at the basal plane of stress-annealed pyrolytic graphite (SAPG) in acetonitrile containing 0.2 M tetrapropylammonium tetrafluoroborate has been studied by cyclic voltammetry. The first step is reported to be outer-sphere electron transfer to form the superoxide radical anion. The second step is reported to be the reduction of products formed by a following chemical reaction involving the superoxide radical anion and the SAPG surface. Support for this mechanism is based on a comparative study using mercury electrodes.