Abstract
To explore high-performing alternatives to platinum-based catalysts is highly desirable for lowering costs and thus promoting fuel cell commercialization. Herein, self-supported Fe-N-C materials were prepared by the pyrolysis of dual precursors including EDTA ferric sodium (EDTAFeNa) and melamine (MA), followed by acid-leaching and final annealing. Towards an oxygen reduction reaction (ORR) in 0.1 M KOH, the as-prepared MA/EDTAFeNa-HT2 delivered onset (Eonset) and half-wave (E1/2) potentials of 0.97 and 0.84 V vs. RHE, respectively, identical with that of a state-of-the-art Pt/C catalyst, accompanied with predominantly a four-electron pathway. The introduction of MA and extension of acid-leaching promoted a positive shift of 50 mV for E1/2 relative to that of only the EDTAFeNa-derived counterpart. It was revealed that the enhancement of ORR activity is attributed to a decrease in magnetic Fe species and increase in pyridinic/quanternary nitrogen content whilst nearly excluding effects of the graphitization degree, variety of crystalline iron species, and mesoscopic structure. The usage of dual precursors exhibited great potential for the large-scale production of inexpensive and efficient Fe-N-C materials.
Highlights
self-supported Fe-N-C catalysts (SSFNCCs) generated from the leaching for oxygen reduction reaction (ORR) in 0.1 M KOH
SSFNCCs generated from the pyrolysis of sole
EDTAFeNa and MA co-derived MA/EDTAFeNa-HT2 prepared under different pyrolysis temperature (HT2) catalysts were synthesized by EDTAFeNa and MA co-derived MA/EDTAFeNa-HT2 catalysts were synthesized by a modified method reported in the previous literature [13]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. By pyrolyzing a ferrous EDTA chelate, syntheses of SSFNCCs have been reported [12,13,14]; their electrocatalytic performance is still inferior to that of the Pt/C catalyst These results imply that it is inadequate and even difficult for a single nitrogen-containing precursor to concurrently control the porous structure, nitrogen content, and coordination of Fe atoms with N and C, which are key factors affecting ORR performance [15,16,17,18,19]. Lou et al [20] reported porous N-doped carbon matrix-supported N-doped carbon nanotube assemblies with embedded iron carbide nanoparticles (Fe3C@N-CNT assemblies), which were fabricated via a dual-MOFs pyrolysis route where Fe-based MILwere fabricatedwere via afirstly dual-MOFs pyrolysis route where.
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