Digital simulations were conducted using DigiElch, Ver. 4.5 software package (Gamry instruments Co., Ltd., Warminster, United States of America) for the simulation of common electrochemical experiments. Redox reactions were treated by Butler-Volmer kinetics with the standard rate constant and transfer coefficient as kinetic parameters. The 5.3 Hz filter at scan rates less than 0.10 V s -1 , and the 590 Hz filter between 0.1 and 3.0 V s -1 , were used. The uncompensated solution resistance, Ru, for 0.1 mol dm -3 TPAP was determined from fits of simulations to voltammograms of Fc + /Fc. Prior to the simulations, CVs of O2/O2 •- with various scan rates at 0.1-3.0 V s -1 (Supporting Information, Figure ) were measured to obtain basic parameters of the CV (Supporting Information, Table ). Then, voltammograms with TPAP in DMF without O2 were recorded and subtracted from the voltammograms of tested solutions to obtain backgroundcorrected curves used for the simulations. Here, the ET coefficients were assumed to be 0.5 for all electrode processes. Semi-infinite diffusion was assumed for the simulation to mimic edge diffusion to the disk. Then, simulations were conducted, and diffusion coefficients used in the simulations were obtained for O2 and O2 •-(4.76 × 10 -9 and 2.15 × 10 -9 m 2 s -1 ), adjusted to match the cathodic peak heights. The electrode area (7.854 × 10 -7 m 2 ) was determined.