Development of high-performance cathode catalyst of polypyrrole modified carbon supported CoOOH for direct borohydride fuel cell
Abstract
Polypyrrole modified carbon supported CoOOH electrocatalyst (CoOOH-PPy-C) is prepared by impregnation-chemical method, and the catalytic properties for the oxygen reduction reaction (ORR) in alkaline media are investigated. The X-ray diffraction and transmission electron microscopy results confirm the presence of the expected CoOOH. The electrochemical tests show that the CoOOH-PPy-C catalyst exhibits good electrocatalytic activity towards ORR. The direct borohydride fuel cell using CoOOH-PPy-C as the cathode catalyst demonstrates a good stability performance. There is only 4% decrease of the cell voltage after 80-h operation. The ORR occurs an average 4-electron transfer pathway on the CoOOH-PPy-C catalyst. The good catalytic activity towards ORR benefits from the Cosbnd N bond, which is identified by X-ray photoelectron spectroscopy test. X-ray absorption fine structure experiments further show that two nearest O atoms are substituted by two N atoms bonding to Co ion at a distance of 1.64 Å. The CoOOH-PPy-C exhibits better electrochemical properties than the Co(OH)2 counterpart even though the valence state of Co ion is +3 in CoOOH-PPy-C. Those results indicate that the bonding of Co ion with N atoms should be a key issue regardless the valence of Co ion.
- Publication:
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Journal of Power Sources
- Pub Date:
- January 2017
- DOI:
- 10.1016/j.jpowsour.2016.11.021
- Bibcode:
- 2017JPS...339...13H
- Keywords:
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- Polypyrrole modified carbon supported cobalt catalyst;
- X-ray photoelectron spectroscopy;
- X-ray absorption fine structure;
- Oxygen reduction reaction;
- Direct borohydride fuel cell