The role of iron nitrides in the Fe–N–C catalysis system towards the oxygen reduction reaction

Abstract

Fe-N-C series catalysts are always attractive for their high catalytic activity towards the oxygen reduction reaction (ORR). However, they usually consist of various components such as iron nitrides, metallic iron, iron carbides, N-doped carbon and Fe-N moieties, leading to controversial contributions of these components to the catalysis of the ORR, especially iron nitrides. In this work, to investigate the function of iron nitrides, FeN nanoparticles (NPs) embedded in mesoporous N-doped carbon without Fe-N moieties are designed and constructed by a simple histidine-assisted method. Herein, the use of histidine can increase the N and Fe contents in the product. The obtained catalyst exhibits excellent ORR catalytic activity which is very close to that of the commercial Pt/C catalyst in alkaline electrolytes. Combining the catalytic activity, structural characterization (especially from Mössbauer spectroscopy), and the results of DFT calculations for adsorption energies of oxygen on the main surfaces of FeN including ε-FeN and ζ-FeN, it can be deduced that FeN NPs as active species make a contribution to the ORR catalysis, of which ε-FeN (x ≤ 2.1) is more active than ζ-FeN. In addition, we find that there exists an obvious synergistic effect between FeN NPs and N-doped carbon, leading to the greatly enhanced ORR catalytic activity.

Monodisperse Co9S8 nanoparticles in situ embedded within N, S-codoped honeycomb-structured porous carbon for bifunctional oxygen electrocatalyst in a rechargeable Zn–air battery

“…Recently, noticeable progress has been made in the development of low-cost, resource-rich, and highly efficient oxygen catalysts for the ORR and OER to replace traditional precious metals [14][15][16][17][18][19][20] . Notably, both theoretical calculations and experimental results indicate that monodisperse Co 9 S 8 nanocatalysts can serve as highly efficient bifunctional oxygen electrocatalysts for both the ORR and OER [21][22][23] .…”

N‐Doped Graphene Decorated with Fe/Fe3N/Fe4N Nanoparticles as a Highly Efficient Cathode Catalyst for Rechargeable Li−O2 Batteries

“…Concerning nitrogen, the N 1s spectrum can be deconvoluted into four peaks at 398.5, 399.0, 399.7 and 401.1 eV, which are assigned to pyridinic N, Fe−N compounds, pyrrolic N and graphitic N, respectively . Generally, it is proposed that the sp 2 hybridized pyridinic N and graphitic N could enhance the ORR catalytic activity ,. In addition, the Fe−N centers are also considered to be catalytically active because of their lone‐pair electrons .…”

N,P Co‐Coordinated Manganese Atoms in Mesoporous Carbon for Electrochemical Oxygen Reduction

“…Therefore, numerous carbon‐based nanomaterials have been developed to replace the Pt based composites . Among them, the nitrogen species coordinated first‐row transition metal (e.g., Co, Ni, and Fe) atoms in carbons (M–N–C) are widely considered as promising electrocatalysts for ORR . The M–N–C materials are usually recognized as single‐atom catalysts (SACs), since isolated N‐bonded metals atoms are embedded in carbons.…”