Figure 4: Interaction of nitrite on Fe–N/C and N/C catalysts.
From: In situ electrochemical quantification of active sites in Fe–N/C non-precious metal catalysts
(a) Comparison between homogeneous reduction of aqueous nitrite (3 mM NaNO2 in acetate buffer), and excess current associated with reductive stripping of intermediate on Fe–N/C or N/C catalyst. The reductive stripping curve is produced by subtracting the unpoisoned from poisoned curve in Fig. 3g. Inset is the complete nitrite reduction curve for homogeneous nitrite in solution. (b) Chronoamperometric transients for determination of the reductive stripping charge for the Fe–N/C catalyst; (c) kinetic current density of Fe–N/C catalyst before and after the poisoning step. O2-saturated electrolyte, 5 mV s−1 background and iR-corrected rotating disk electrode experiments at 1,600 r.p.m., electrolyte: 0.5 M acetate buffer, loading: 0.27 mg cm−2.
