Investigation of thermal and electrochemical degradation of fuel cell catalysts

Mei Cai, Martin S. Ruthkosky, Belabbes Merzougui, Swathy Swathirajan, Michael P. Balogh, Se H. Oh

Research output: Contribution to journalArticle

152 Citations (Scopus)

Abstract

A significant problem hindering large-scale implementation of proton exchange membrane (PEM) fuel cell technology is the loss of performance during extended operation and automotive cycling. Recent investigations of the deterioration of cell performance have revealed that a considerable part of the performance loss is due to the degradation of the electrocatalyst. In this study, an attempt is made to experimentally simulate the degradation processes such as carbon corrosion and platinum (Pt) surface area loss using an accelerated thermal sintering protocol. Two types of Tanaka fuel cell catalyst samples were heat-treated at 250 °C in humidified helium (He) gas streams and several oxygen (O2) concentrations. The catalysts were then cycled electrochemically in pellet electrodes to determine the hydrogen adsorption (HAD) area and its evolution in subsequent electrochemical cycling. Samples that had undergone different degrees of carbon corrosion and Pt sintering were characterized for changes in carbon mass, active Pt surface area, BET (Brunauer, Emmett and Teller) surface area, and Pt crystallite size. Studies of the effect of oxygen and water concentration on two Tanaka catalysts, dispersed on carbon supports with varying BET areas, revealed that carbon oxidation in the presence of Pt follows two pathways: an oxygen pathway that leads to mass loss due to formation of gaseous products, and a water pathway that results in mass gains, especially for high BET area supports. These processes may be assisted by the formation of highly reactive OH and OOH type radicals. Platinum surface area loss, measured at varying oxygen concentrations and as a function of sintering time using X-ray diffraction (XRD), CO chemisorption, and electrochemical hydrogen adsorption, reveal an important role for carbon corrosion rather than an increase in Pt particle size for the surface area loss. Platinum surface area loss during 10 h of thermal degradation was equivalent to electrochemical degradation observed over 500 cycles for a Tanaka Pt/Vulcan electrode cycled between 0 and 1.2 V (normal hydrogen electrode-NHE). Carbon mass loss observed for 5 h of thermal degradation was comparable to that obtained during a potential hold for 86 h at 1.2 V (NHE) and 95 °C for the same catalysts.

Original languageEnglish
Pages (from-to)977-986
Number of pages10
JournalJournal of Power Sources
Volume160
Issue number2 SPEC. ISS.
DOIs
Publication statusPublished - 6 Oct 2006
Externally publishedYes

Fingerprint

electrocatalysts
thermal degradation
Platinum
Fuel cells
platinum
degradation
Degradation
Carbon
Catalysts
carbon
Oxygen
Hydrogen
corrosion
sintering
Sintering
oxygen
Corrosion
catalysts
cycles
Electrodes

Keywords

  • Carbon corrosion
  • Degradation mechanism
  • Electrocatalyst
  • PEM fuel cell
  • Thermal oxidation

ASJC Scopus subject areas

  • Electrochemistry
  • Fuel Technology
  • Materials Chemistry
  • Energy (miscellaneous)

Cite this

Cai, M., Ruthkosky, M. S., Merzougui, B., Swathirajan, S., Balogh, M. P., & Oh, S. H. (2006). Investigation of thermal and electrochemical degradation of fuel cell catalysts. Journal of Power Sources, 160(2 SPEC. ISS.), 977-986. https://doi.org/10.1016/j.jpowsour.2006.03.033

Investigation of thermal and electrochemical degradation of fuel cell catalysts. / Cai, Mei; Ruthkosky, Martin S.; Merzougui, Belabbes; Swathirajan, Swathy; Balogh, Michael P.; Oh, Se H.

In: Journal of Power Sources, Vol. 160, No. 2 SPEC. ISS., 06.10.2006, p. 977-986.

Research output: Contribution to journalArticle

Cai, M, Ruthkosky, MS, Merzougui, B, Swathirajan, S, Balogh, MP & Oh, SH 2006, 'Investigation of thermal and electrochemical degradation of fuel cell catalysts', Journal of Power Sources, vol. 160, no. 2 SPEC. ISS., pp. 977-986. https://doi.org/10.1016/j.jpowsour.2006.03.033
Cai, Mei ; Ruthkosky, Martin S. ; Merzougui, Belabbes ; Swathirajan, Swathy ; Balogh, Michael P. ; Oh, Se H. / Investigation of thermal and electrochemical degradation of fuel cell catalysts. In: Journal of Power Sources. 2006 ; Vol. 160, No. 2 SPEC. ISS. pp. 977-986.
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