To test the hypothesis, experiments were performed using chemically synthesized DHA instead of analyzing the DHA that gradually accumulates through cycling of DHAQ. The latter process is very slow, especially in 2.0 M OH -where the fade rate is only ∼0.4%/day (Figure ). The same amount of DHAQ was generated by electrochemical oxidation of a freshly made DHA electrolyte and of an otherwise-identical electrolyte that sat for more than four weeks under an inert nitrogen atmosphere. This observation indicates that DHA itself is chemically stable and does not undergo any chemical decomposition. Therefore, the red arrow labeled as (1) represents a reaction that either does not occur or occurs at a negligible rate.