491604.fig.007a
(a) Square wave voltammetry in 0.1 M NaOH
491604.fig.007b
(b) Square wave voltammetry in 0.1 M HCIO4
Figure 7: SWV profiles of FeTPP/C catalyst as a function of heat treatment temperature in (a) 0.1 M NaOH and (b) 0.1 M HClO4 electrolytes. Insets show the peak potential of the Fe2+/3+ redox couple as a function of the heat treatment temperature. SWV experiment parameters: step potential −5 mV, amplitude −20 mV, and scan frequency −10 Hz.