Iron Carbide Nanoparticles Encapsulated in Mesoporous Fe‐N‐Doped Carbon Nanofibers for Efficient Electrocatalysis

Abstract

Exploring low‐cost and high‐performance nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in fuel cells and metal–air batteries is crucial for the commercialization of these energy conversion and storage devices. Here we report a novel NPMC consisting of Fe3C nanoparticles encapsulated in mesoporous Fe‐N‐doped carbon nanofibers, which is synthesized by a cost‐effective method using carbonaceous nanofibers, pyrrole, and FeCl3 as precursors. The electrocatalyst exhibits outstanding ORR activity (onset potential of −0.02 V and half‐wave potential of −0.140 V) closely comparable to the state‐of‐the‐art Pt/C catalyst in alkaline media, and good ORR activity in acidic media, which is among the highest reported activities of NPMCs.

A Bonded Double-Doped Graphene Nanoribbon Framework for Advanced Electrocatalysis

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 10 noted that except for the individual nanoparticle section, atomic Fe signals were also dispersed along the carbon/nitrogen matrix, probably revealing that some of the Fe species are fixed by coordination with N atoms. 24 These Fe species are believed to form highly active Fe-N sites, which have been shown to exist in previous reports. [24][25][26]…”

“…24 These Fe species are believed to form highly active Fe-N sites, which have been shown to exist in previous reports. [24][25][26][27] HRTEM images of the Fe-N-GNFs catalyst show that the Fe 3 C nanoparticles are encapsulated in a highly graphitic carbon shell to form a core-shell structure (Figure 1d, e and Figure S1). An interplanar spacing of 0.35 nm can be easily observed in the graphitic layers, which corresponds to the (002) plane of graphitic carbon, and the thickness of the graphitic shell is approximately 10 nm.…”

“…[24][25][26][27][28] Among those alternatives, M-N/C catalysts outperform many of their counterparts because of the fact that the active sites located in this type of catalyst are believed to involve M-N coordination bond at defects in graphitic carbon, which have been confirmed to be the most active ORR catalytic sites. 10 Despite the above mentioned tremendous progress, the performance of alternative catalysts is still not satisfactory.…”

Electrospun core–shell nanofibers derived Fe–S/N doped carbon material for oxygen reduction reaction

“…In order to replace precious metal catalysts, developing of earth abundant materials with high efficiency electrocatalysis activity for ORR catalysts has been attracting substantial research interest [15] . Recently, the nonprecious doped metal carbon composites with transition metal (such as Fe, Co and Ni) [16,17,18] and heteroatoms (such as N or S) [19] has been demonstrated as the most potential ORR catalyst under the basic conditions, for its easy availability, excellent activity and good durability. Ye et al, utilizes hierarchical as noble-metal free electrocatalyst for ORR and the current density of Fe 3 O 4 -Co 3 O 4 yolk-shell nanostructures is also much higher than that of Co 3 O 4 and Fe 3 O 4 nanoparticles [20] .…”

“…To overcome this obstacle, nanostructured catalyst supports have been developed to compensate the conductivity and dispersibility of catalysts, maximize the electroactive surface area of catalysts, and improve their catalytic activity and durability [22] . Among these materials, doped carbon nanofibers have proven to be an effective way to elevate the catalytic activity of metal compounds for ORR, which not only provides sufficient pathway for mass transfer, but facilitates charge transfer [17] .…”