Fig. 2

Cyclic voltammetry of cobalt phthalocyanine catalytic films. Top a–c CoPc1@MWCNTs, bottom d–f CoPc2@MWCNTs. a, d CV of a cobalt phthalocyanine catalytic film deposited onto a glassy carbon electrode (d = 3 mm) in 0.5 M NaHCO₃ at v = 0.1 V s⁻¹ under argon (red, pH 8.5) and CO₂ (blue, pH 7.3). b, e CV at various scan rates of the Co^II/Co^I wave under argon atmosphere. c, f Variation of the peak current vs. scan rate for the Co^II/Co^I redox wave. A redox active catalyst concentration of Γ = 1.45 ± 0.12 nmol cm⁻² was obtained from i_p = n²F²vSΓ/4RT for both catalysts