부산대학교 도서관

The overall performance of proton exchange membrane fuel cells is limited by the sluggish kinetics of the oxygen-reduction reaction (ORR). Among the most active PGM-free ORR electrocatalysts are metal-nitrogen-carbon (M-N-C), such as Fe–N–C. The Fe–N 4 ensembles in these PGM-free catalysts, present in different configurations, are proposed to be the active sites for the ORR in acid. In this work, we have synthesized a Fe/N/C catalyst via thermal treatment of a polymeric C x N y precursor obtained by the wet-polymerization of melamine (a nitrogen rich molecule) and terephthaldehyde. The materials obtained (Im-FeNC-1HT and Im-FeNC-2HT) display high ORR activity in acid electrolyte compared to other Fe–N–C catalysts prepared with precursors different than 2-methylimidazole or ZIF-8. Characterization data indicate the formation of high- and low-spin Fe-N x ensembles, with a site density of 4.4·1019 sites Fe ·g−1 estimated by electrochemical stripping of NO. The ORR activity was evaluated in a RRDE configuration in 0.1 M HClO 4 and in MEA configuration in a single cell. [Display omitted] • A high N/C ratio precursor such as melamine used to synthesize Fe–N–C catalysts. • FeN 4 C 10 and FeN 4 C 12 moieties formed during the synthesis. • Site Density of exposed Fe sites determined by in situ and ex situ analyses. • ORR activity demonstrated in RDE and MEA configurations. [ABSTRACT FROM AUTHOR]