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

Article abstract of DOI:10.1039/c9ta12207a

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.

Full text of DOI:10.1039/c9ta12207a

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Materials for energy and sustainability
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Q. Cheng, X. Liu, L. Ma, C. Chen, L. Yang, Z. Zou, D. Xie and H. Yang, J. Mater. Chem. A, 2020, DOI:
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Number 12
March 2018
Pages 4883-5230
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ISSN 2050-7488
COMMUNICATION
Zhenhai Wen et al.
An electrochemically neutralized energy-assisted low-cost
acid-alkaline electrolyzer for energy-saving electrolysis
hydrogen generation
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Page 5 of 7
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/C9TA12207A
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'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*
Journal of Materials Chemistry A
Page 6 of 7
View Article Online
DOI: 10.1039/C9TA12207A
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Page 7 of 7
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/C9TA12207A
A table of contents entry
Co/Zn atomic dual-sites anchored on N doped carbon nanofibers for efficient and durable
-2
H -O fuel cells. (~0.65V@400mA cm , 150 hours)
2
2
(
a)Pyrolyse
N /NH
1
8kV
Pre oxidation
2
3
(b)Acid leaching
PAN、Co(NO ) 、ZnO
3
Co/ZnN-C-1st
2
Pristine fiber
1.2
1.0
0.8
0.6
0.4
0.2
1.0
0.8
Co/Zn-NCNF
Pt/C
H
-
O
2
2
Co/Zn-NCNF
2 2
H -O
0.6
0.4
0.2
0.5
0.0
0
1
2
0
40
80
120
160
-
2
)
Co/ZnN-C fiber
Current density (A cm
Time (h)