Fig. 6. (a–c) CV current–potential responses of P-400 at different scan rates. Inset in (c): i vs. ν^1/2. (d) CVs of P-400 in different pH KOH solutions. (e) The enlarged part showing the CVs in (d). (f) The dependence of the precatalytic redox peak potentials E₁ and E₂ on pH.