Digital simulation of irreversible one-electron CV )). Thus, the digital simulation analysis of CVs was conducted according to the parameters obtained from the scheme (Figure ), heterogeneous electrode reactions (Equations ( ) and ( )), and complexation reactions as homogeneous solution reactions (Equations ( )-( )). Equal diffusion coefficients for the HB complexes were applied regardless of the charge of O2, assuming that the molecular radii of complexes (O2-H2Q/O2 •--H2Q) are almost the same. Then, parameters for the subsequent 2PCET, which correspond to step (ii) in the three elementary steps (Equation ( )), were obtained along with the fit to the irreversibility of the CVs. Here, the two OH groups of H2Q form HBs, which also serve as PCET reaction sites. Since the stoichiometry of 2PCET is 1:1 producing Q •-and H2O2, the formation of PRC is also considered 1:1. The subsequent reaction must be irreversible to reproduce the irreversibility of the CV and obtain the best fit between the digital simulation and the measured CVs. Based on the above assumptions, the parameters obtained from the digital simulation are summarized in Table .  ks (cm s -1 ) O2 + e -↔ O2 •- -1.284 0.5 0.0092