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Title: Cobalt-polypyrrole-carbon black (Co-PPY-CB) Electrocatalysts for the Oxygen Reduction Reaction (ORR) in Fuel Cells: Composition and Kinetic Activity

Abstract

Electrocatalysts consisting of polypyrrole (PPY) and Co deposited on carbon black (CB) at several compositions were prepared and tested for the oxygen reduction reaction (ORR) in a HClO4 buffer (pH = 1) using a rotating ring-disk electrode (RRDE). It was determined that the most favorable catalyst composition (prior to calcination) had a CB:PPY weight ratio of 2 and a pyrrole:Co (i.e., PY:Co) molar ratio of 4. This catalyst had an onset potential of 0.785 V (vs. RHE) and a mass activity of ca. 1 A/g{sub cata} at the fuel cell relevant voltage of 0.65 V. Furthermore, it was found that the number of electrons exchanged during the ORR with the catalyst was ca. 3.5 and resulted in 28% yield of H{sub 2}O{sub 2} at 0.65 V, which hints to an indirect 4e{sup -} reduction of O{sub 2} to H{sub 2}O, with H{sub 2}O{sub 2} as an intermdiate. From energy dispersive spectroscopy (EDS) and extended X-ray absorption fine structure (EXAFS) analysis, it is proposed that a PY:Co ratio of 4 favors the formation, prior to calcination, in the catalyst precursor of Co-N complexes in which Co is coordinated to 3 or 4 N atoms, resulting in strong Co-N interactions that limitmore » the formation upon calcination of low ORR activity Co nanoparticles. These Co-N complexes give rise upon calcination to CoN{sub x-2} sites in which the coordination of Co could favor the adsorption on them of O{sub 2}, which would make those sites particularly active and selective. At the same mass acitivity of 1 A/g{sub cata}, the voltage yielded by the catalyst was 200 mV lower than that for a state-of-the-art Pt (10 wt.%) catalyst, whoch H{sub 2}O{sub 2} output at 0.85 V was 39% and involves the exchange of 3.2 e{sup -}, overall making our material an attractive substitute to noble metal ORR electrocatalysts.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE SC OFFICE OF SCIENCE (SC)
OSTI Identifier:
1041806
Report Number(s):
BNL-97484-2012-JA
Journal ID: ISSN 0926-3373; TRN: US201212%%218
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Applied Catalysis B: Environmental
Additional Journal Information:
Journal Volume: 105; Journal Issue: 1/2; Journal ID: ISSN 0926-3373
Country of Publication:
United States
Language:
English
Subject:
04 OIL SHALES AND TAR SANDS; 30 DIRECT ENERGY CONVERSION; ABSORPTION; ADSORPTION; ATOMS; BUFFERS; CALCINATION; CARBON BLACK; CATALYSTS; COMPLEXES; ELECTRIC POTENTIAL; ELECTROCATALYSTS; ELECTRODES; ELECTRONS; ENERGY; FINE STRUCTURE; FUEL CELLS; INTERACTIONS; KINETICS; MASS; MATERIALS; METALS; OXYGEN; POTENTIALS; PRECURSOR; PRODUCTION; REDUCTION; RISE; SPECTROSCOPY; WEIGHT; YIELDS

Citation Formats

Nguyen-Thanh, D, Frenkel, A, Wang, J, OBrien, S, and Akins, D. Cobalt-polypyrrole-carbon black (Co-PPY-CB) Electrocatalysts for the Oxygen Reduction Reaction (ORR) in Fuel Cells: Composition and Kinetic Activity. United States: N. p., 2011. Web. doi:10.1016/j.apcatb.2011.03.034.
Nguyen-Thanh, D, Frenkel, A, Wang, J, OBrien, S, & Akins, D. Cobalt-polypyrrole-carbon black (Co-PPY-CB) Electrocatalysts for the Oxygen Reduction Reaction (ORR) in Fuel Cells: Composition and Kinetic Activity. United States. doi:10.1016/j.apcatb.2011.03.034.
Nguyen-Thanh, D, Frenkel, A, Wang, J, OBrien, S, and Akins, D. Sat . "Cobalt-polypyrrole-carbon black (Co-PPY-CB) Electrocatalysts for the Oxygen Reduction Reaction (ORR) in Fuel Cells: Composition and Kinetic Activity". United States. doi:10.1016/j.apcatb.2011.03.034.
@article{osti_1041806,
title = {Cobalt-polypyrrole-carbon black (Co-PPY-CB) Electrocatalysts for the Oxygen Reduction Reaction (ORR) in Fuel Cells: Composition and Kinetic Activity},
author = {Nguyen-Thanh, D and Frenkel, A and Wang, J and OBrien, S and Akins, D},
abstractNote = {Electrocatalysts consisting of polypyrrole (PPY) and Co deposited on carbon black (CB) at several compositions were prepared and tested for the oxygen reduction reaction (ORR) in a HClO4 buffer (pH = 1) using a rotating ring-disk electrode (RRDE). It was determined that the most favorable catalyst composition (prior to calcination) had a CB:PPY weight ratio of 2 and a pyrrole:Co (i.e., PY:Co) molar ratio of 4. This catalyst had an onset potential of 0.785 V (vs. RHE) and a mass activity of ca. 1 A/g{sub cata} at the fuel cell relevant voltage of 0.65 V. Furthermore, it was found that the number of electrons exchanged during the ORR with the catalyst was ca. 3.5 and resulted in 28% yield of H{sub 2}O{sub 2} at 0.65 V, which hints to an indirect 4e{sup -} reduction of O{sub 2} to H{sub 2}O, with H{sub 2}O{sub 2} as an intermdiate. From energy dispersive spectroscopy (EDS) and extended X-ray absorption fine structure (EXAFS) analysis, it is proposed that a PY:Co ratio of 4 favors the formation, prior to calcination, in the catalyst precursor of Co-N complexes in which Co is coordinated to 3 or 4 N atoms, resulting in strong Co-N interactions that limit the formation upon calcination of low ORR activity Co nanoparticles. These Co-N complexes give rise upon calcination to CoN{sub x-2} sites in which the coordination of Co could favor the adsorption on them of O{sub 2}, which would make those sites particularly active and selective. At the same mass acitivity of 1 A/g{sub cata}, the voltage yielded by the catalyst was 200 mV lower than that for a state-of-the-art Pt (10 wt.%) catalyst, whoch H{sub 2}O{sub 2} output at 0.85 V was 39% and involves the exchange of 3.2 e{sup -}, overall making our material an attractive substitute to noble metal ORR electrocatalysts.},
doi = {10.1016/j.apcatb.2011.03.034},
journal = {Applied Catalysis B: Environmental},
issn = {0926-3373},
number = 1/2,
volume = 105,
place = {United States},
year = {2011},
month = {12}
}