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Cobalt/Zinc Dual-sites Coordinated with Nitrogen in Nanofibers Enabling Efficient and Durable Oxygen Reduction Reaction in Acidic Fuel Cells

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 cathodic oxygen reduction reaction (ORR). Herein, we fabricated Co/Zn atomic dual-sites anchored on N doped carbon nanofibers (Co/Zn-NCNF) catalyst via electrospinning, carbonization and post-treatments technologies. Aberration-corrected scanning transmission electron microscope (AC-STEM) verifies the existence of uniformly dispersed Co/Zn atomic pair within the NCNF. Meanwhile, the X-ray adsorption fine structure spectroscopy (XAFS) combined with fitting and calculated results further ascertain the coordination structure of Co/Zn dual-sites with the configuration of N2CoN2ZnN2. Such a Co/Zn-NCNF catalyst exhibits greatly enhanced ORR activity with the onset (Eonset) and half-wave (E1/2) potentials of 0.997 and 0.797V/RHE in acidic electrolyte, compared to the Co or Zn mono-doped sample. Density functional theoretical (DFT) calculation reveals that the novel N2CoN2ZnN2 structure, different from the traditional Co-N4 or Zn-N4, could largely lower the dissociative barrier of *OOH intermediate during the ORR, thereupon boosting the electrocatalytic performance. Finally, the assembled H2-O2 PEMFC using Co/Zn-NCNF as cathodic catalyst displays a maximum power density of 0.603 W cm-2 together with a remarkable stability after 150 h discharging at current density of 400 mA cm-2, paving the way for the future development of non-precious metal PEMFCs.

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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, Accepted Manuscript
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, X. Liu, L. Ma, C. Chen, L. Yang, Z. Zou, D. Xie and H. Yang, J. Mater. Chem. A, 2020, Accepted Manuscript , DOI: 10.1039/C9TA12207A

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