In situ ESR spectro-electrochemical investigation of the superoxide anion radical during the electrochemical O2 reduction reaction in aprotic electrolyte Original Research Article

For the first time, electrochemically generated superoxide ions on a porous carbon electrode are investigated by means of in situ electrochemical ESR technique at ambient conditions. Superoxide ions image are detected as the product of the electrochemical O2 reduction reaction. The redox couple (O2/image) is reversible in DMSO electrolyte. The superoxide ions are believed to be absorbed and de-mobilized on the carbon surface. Overlapping a symmetric carbon ESR signal, the anisotropic signal of the superoxide is observed. The g-factor of the carbon ESR spectra is found to be 2.0025, which is almost identical to that of a free electron; Anisotropic g-factors for the image are g⊥ = 2.0031, g// = 2.0750.