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Cobalt/zinc dual-sites coordinated with nitrogen in nanofibers enabling efficient and durable oxygen reduction reaction in acidic fuel cells

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Abstract

The key to reducing the cost of proton-exchange-membrane fuel cells (PEMFCs) is to develop highly efficient non-precious metal catalysts for the oxygen reduction reaction (ORR). Herein, we fabricated Co/Zn atomic dual-sites anchored on N doped carbon nanofibers (Co/Zn–NCNF) via electrospinning, carbonization and post-treatment technologies. Aberration-corrected STEM microscopy verifies the existence of uniformly dispersed Co/Zn atomic pairs within the NCNF. X-ray adsorption fine structure spectroscopy combined with the fitting and calculated results further ascertain the coordination structure of Co/Zn dual-sites with a configuration of N2CoN2ZnN2. Such a Co/Zn–NCNF catalyst exhibits greatly enhanced ORR activity with onset and half-wave potentials of 0.997 V and 0.797 V/RHE in an acidic electrolyte, compared to the Co or Zn mono-doped sample. Density functional theory calculations reveal that the novel N2CoN2ZnN2 structure, different from the traditional Co–N4 or Zn–N4, could largely lower the dissociative barrier of the *OOH intermediate during the ORR, thereby boosting the electrocatalytic activity. Finally, the H2–O2 PEMFC assembled using Co/Zn–NCNF as a cathodic catalyst displays a maximum power density of 0.603 W cm−2 together with a remarkable stability of ca. 0.65 V after 150 h discharging at a current density of 400 mA cm−2, paving the way for the future development of non-precious metal PEMFCs.

Graphical abstract: Cobalt/zinc dual-sites coordinated with nitrogen in nanofibers enabling efficient and durable oxygen reduction reaction in acidic fuel cells

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Supplementary files

Article information


Submitted
06 Nov 2019
Accepted
13 Jan 2020
First published
15 Jan 2020

J. Mater. Chem. A, 2020, Advance Article
Article type
Paper

Cobalt/zinc dual-sites coordinated with nitrogen in nanofibers enabling efficient and durable oxygen reduction reaction in acidic fuel cells

J. Zang, F. Wang, Q. Cheng, G. Wang, L. Ma, C. Chen, L. Yang, Z. Zou, D. Xie and H. Yang, J. Mater. Chem. A, 2020, Advance Article , DOI: 10.1039/C9TA12207A

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