N-doped Carbon Synthesized from N-containing Polymers as Metal-free Catalysts for the Oxygen Reduction under Alkaline Conditions
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Date
2013
Authors
Zhao, Anqi
Masa, Justus
Muhler, Martin
Schuhmann, Wolfgang
Xia, Wei
Journal Title
Journal ISSN
Volume Title
Publisher
Electrochimica Acta
Abstract
Nitrogen-doped carbon materials were synthesized and used as metal-free electrocatalysts for the oxygen reduction reaction (ORR) under alkaline conditions. The synthesis was achieved by thermal treatment of nitrogen-containing polymers diluted in different carbon materials. Polypyrrole, polyaniline and polyacrylonitrile were used as N precursors. Carbon black and two types of commercial carbon nanotubes were used as carbon matrices. The obtained N contents were in the range of 1–1.8 wt.%. Different N species including pyridinic, pyrrolic and quaternary N were quantitatively determined by X-ray photoelectron spectroscopy. The ORR activities were evaluated in 0.1 M KOH. Rotating disc electrode studies revealed the presence of multiple active centers in all the samples. The sample obtained using polypyrrole and small diameter nanotubes (ca. 15 nm) had the highest onset potential at −0.07 V vs. Ag/AgCl/3 M KCl, which also showed a significantly higher electrochemical stability than the sample from carbon black and polypyrrole. The ORR activity was not correlated to the total nitrogen amount, but to the amount of pyridinic and quaternary N species. For the onset potential and the (Npyridinic + Nquaternary)/Ntotal ratio a quasi-linear relation was found, which points to the substantial role of pyridinic- and quaternary-N species in ORR catalysis.
Description
Keywords
Nitrogen-doped carbon; Pyrolysis; Electrocatalysis; Oxygen reduction reaction
Citation
Zhao, A., Masa, J., Muhler, M., Schuhmann, W., & Xia, W. (2013). N-doped carbon synthesized from N-containing polymers as metal-free catalysts for the oxygen reduction under alkaline conditions. Electrochimica Acta, 98, 139-145.https://doi.org/10.1016/j.electacta.2013.03.043