Figure shows the linear voltammograms of O2 (4.8 × 10 -3 mol dm -3 ) in the presence of H2Q (0, 1.0, 3.0, 5.0 × 10 -3 mol dm -3 ). In the voltammograms, the potential was swept in the range from -1.0 to -1.6 V vs. Fc + , Fc, focusing on the redox of O2/O2 •-and the initial reactivity between O2/O2 •-and H2Q. The voltammograms maintain a one-electron cathodic current up to 5.0 mol dm -3 of added H2Q. Additionally, notable CV behaviors are that the cathodic current of O2/O2 •-slightly decreased at the top of pc1, and instead, a prepeak appears. To simulate the CVs, we established the equilibrium scheme shown in Figure and used the Nernst equation for thermodynamic analysis with a redox potential (EOx,Red) of O2/O2 •-;