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Title: Effect of Cerium, Cobalt and Nickel Contaminants on the Oxygen Reduction Reaction at Platinum Electrodes

Abstract

State of the art proton exchange membrane fuel cells contain metallic cations as alloyed Pt catalysts or as additives to improve the chemical stability of membranes. While these novel materials have improved the performance and durability, they can leach out contaminants such as Ce, Ni and Co ions into the ionomer, impact the potency of the additive, decrease the ionomer conductivity and reduce fuel cell performance. We report here that in presence of Ce, Ni and Co, the ionomer conductivity (Nafion 211) decreases by a factor of ~3 with 5.2-19.2 mg metal cm -3 at 80°C, 100% RH. As a result, this performance correlates with a decrease in ORR performance, most notably lower limiting currents 1.1x10 -1 mA cm -2 in proton form vs. 6.2-8.2x10 -2 mA cm 2 with 6-12 mgmetal cm -3 and lower ORR onset potentials at 25°C, 100% RH.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1];  [2];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1415415
Report Number(s):
LA-UR-17-25970
Journal ID: ISSN 1938-6737
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ECS Transactions (Online)
Additional Journal Information:
Journal Name: ECS Transactions (Online); Journal Volume: 80; Journal Issue: 8; Journal ID: ISSN 1938-6737
Publisher:
Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Energy Sciences

Citation Formats

Dumont, Joseph Henry, Baker, Andrew M., Maurya, Sandip, Kim, Yu Seung, Mukundan, Rangachary, Myers, Deborah J., and Borup, Rod L. Effect of Cerium, Cobalt and Nickel Contaminants on the Oxygen Reduction Reaction at Platinum Electrodes. United States: N. p., 2017. Web. doi:10.1149/08008.0861ecst.
Dumont, Joseph Henry, Baker, Andrew M., Maurya, Sandip, Kim, Yu Seung, Mukundan, Rangachary, Myers, Deborah J., & Borup, Rod L. Effect of Cerium, Cobalt and Nickel Contaminants on the Oxygen Reduction Reaction at Platinum Electrodes. United States. doi:10.1149/08008.0861ecst.
Dumont, Joseph Henry, Baker, Andrew M., Maurya, Sandip, Kim, Yu Seung, Mukundan, Rangachary, Myers, Deborah J., and Borup, Rod L. 2017. "Effect of Cerium, Cobalt and Nickel Contaminants on the Oxygen Reduction Reaction at Platinum Electrodes". United States. doi:10.1149/08008.0861ecst.
@article{osti_1415415,
title = {Effect of Cerium, Cobalt and Nickel Contaminants on the Oxygen Reduction Reaction at Platinum Electrodes},
author = {Dumont, Joseph Henry and Baker, Andrew M. and Maurya, Sandip and Kim, Yu Seung and Mukundan, Rangachary and Myers, Deborah J. and Borup, Rod L.},
abstractNote = {State of the art proton exchange membrane fuel cells contain metallic cations as alloyed Pt catalysts or as additives to improve the chemical stability of membranes. While these novel materials have improved the performance and durability, they can leach out contaminants such as Ce, Ni and Co ions into the ionomer, impact the potency of the additive, decrease the ionomer conductivity and reduce fuel cell performance. We report here that in presence of Ce, Ni and Co, the ionomer conductivity (Nafion 211) decreases by a factor of ~3 with 5.2-19.2 mgmetal cm-3 at 80°C, 100% RH. As a result, this performance correlates with a decrease in ORR performance, most notably lower limiting currents 1.1x10-1 mA cm-2 in proton form vs. 6.2-8.2x10-2 mA cm2 with 6-12 mgmetal cm-3 and lower ORR onset potentials at 25°C, 100% RH.},
doi = {10.1149/08008.0861ecst},
journal = {ECS Transactions (Online)},
number = 8,
volume = 80,
place = {United States},
year = 2017,
month = 8
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on August 24, 2018
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  • The effects of phosphorus acid additions on the oxygen reduction reaction at platinum electrodes in concentrated phosphoric acid were studied. The oxygen reduction currents decreased, and the Tafel slopes became more negative upon the addition of small concentrations of phosphorus acid. In addition,the phosphorus acid oxidation current tended to complete with the oxygen reduction current. These effects became more pronounced at higher phosphorus acid concentrations and at higher temperatures. Upon the addition of phosphorus acid the number of electrons involved in the oxygen reduction reaction decreased from a value close to four to a value approaching two, suggesting promotion ofmore » a two-electron reduction to peroxide. Therefore, in studies of the electrochemical reduction of oxygen in hot concentrated phosphoric acid or in fuel cell systems using hot concentrated phosphoric acid as electrolyte, it is recommended that precautions be taken against the inadvertent formation of the phosphorus acid. The removal of phosphorus acid from concentrated phosphoric acid by repeated potential cycling at 100 mV/s between + 0.5 and +1.50 V (vs. dynamic hydrogen electrode) was demonstrated.« less
  • Cobalt nanowires (CoNWs) are coated with platinum (Pt) by partial galvanic displacement, forming core/shell wires 200 300 nm in diameter and 100 200 1m in length. PtCoNWs are characterized for activit y in the oxygen reduction reaction (ORR) with rotating disk electrode half5cells in 0.1 M perchloric acid electrolytes. The resulting catalysts demonstrate ORR specific activi ties in the range 2053 2783 1A cm Pt 2 , comparable to the specific activity of polycrystalline Pt. The specific activi ties of PtCoNWs increase with decreasing Pt content and exhibit a corresponding increase in Pt lattice compression. P tCoNWs have exhibited amore » maximum mass activity of 79 3 mA mg Pt 1 , 2.6 times greater than carbon5supported Pt nanopart icles.« less
  • Platinum electrodes covered with a perfluoro-sulfonated ionomer membrane show unique behaviors in comparison with bare platinum immersed in aqueous solutions. The electrochemical interface between the metal and the polymer can be different from the interface between the metal and the solution phase. In this context, platinum electrodes covered with such a polymer membrane are an interesting system, and deserve detailed study. Here the oxygen reduction reaction at the platinum surface covered with a perfluoro-sulfonated ionomer membrane is investigated kinetically in 0.1 N H{sub 2}SO{sub 4} in the presence of 0.001 N Na{sup +}, K{sup +}, or Ca{sup 2+} ions, usingmore » rotating disk electrodes. It is discovered that the impurity ions, even in a small amount, hinder enormously the rate of the charge transfer step of oxygen reduction at the platinum covered with perfluoro-sulfonated ionomer. Especially the effect of Na{sup +} in the membrane is very serious considering the fact that there exists only 2% NA{sup +} of the exchange site in the membrane phase at this condition. Platinum covered with perfluoro-sulfonated ionomer membrane has historically attracted much research interest, based on the fact that oxygen concentration and H{sup +} ion concentration in the membrane are both larger than those in normal acidic solutions, and could show larger catalytic activity than in bare platinum. However, this expectation encountered disappointing failure. Results here indicate that such a paradox could be accounted for by the effect of the metal-polymer interface that alters the reaction conditions of oxygen reduction.« less