Theoretical study of possible active site structures in Cobalt- Polypyrrole catalysts for oxygen reduction reaction

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DOIResolve DOI: http://doi.org/10.1021/jp2027719
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TypeArticle
Journal titleThe Journal of Physical Chemistry C
Volume115
Issue33
Pages1667216680; # of pages: 9
Subjectnonprecious group metal; density functional theory (DFT); oxygen reduction reaction (ORR); Fuel Cells
AbstractThe active site structure of nonprecious group metal catalyst is a puzzle which inhibits innovative synthetic route design and impedes breakthroughs. In an effort to understand the origin of the catalytic activity of Co-PPy composites, we employed density functional theory (DFT) and experimental measurements to investigate the structure and energy of possible catalytic sites and the corresponding reaction pathways for the oxygen reduction reaction (ORR). Four different structures of the active site are examined, including two previously postulated in the literature. In order to determine the probability of their existence, the stability of each structure is evaluated. The corresponding Co(III)/Co(II) redox potentials are calculated and, based on the obtained data, the involvement of either Co(III) or Co(II) in the ORR under fuel cell-relevant conditions postulated. Possible configurations of oxygen adsorption on the active centers are also examined, including the end-on and side-on cases. The possible reaction pathways and reaction products generated at the various active centers are evaluated based on Yeager0s concept correlating ORR products with the configuration of oxygen adsorption. The catalytic activity is found to be significantly different for the various sites and depends strongly on the electrode potential. The computational data are critically compared with experimental spectroscopic (EXAFS and FTIR) and electrochemical data (CV, RDE, and RRDE). The insights into the active structures and their associated catalytic activity as well as selectivity for four-electron oxygen reduction are expected to provide guidance for further catalyst optimization.
Publication date
LanguageEnglish
AffiliationNRC Institute for Fuel Cell Innovation; National Research Council Canada
Peer reviewedYes
NPARC number19518274
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Record identifier350482b7-28fd-47d5-a988-483a3f743915
Record created2012-02-21
Record modified2017-03-23
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