Electrochemical promotion of a platinum catalyst supported on the high-temperature proton conductor La0.99Sr0.01NbO4-δ

D. Poulidi*, G. C. Mather, C. N. Tabacaru, A. Thursfield, I. S. Metcalfe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The recently discovered, high-temperature proton conductor, La0.99Sr0.01NbO4-δ, was used as a support for the electrochemical promotion of a platinum catalyst. Ethylene oxidation was used as a probe reaction in the temperature range 350-450 °C. Moderate non-Faradaic rate modification, attributable to a protonic promoting species, occurred under negative polarisation; some permanent promotion was also observed. In oxidative atmospheres, both the pO2 of the reaction mixture and the temperature influenced the type and magnitude of the observed rate modification. Rate-enhancement values of up to ρ = 1.4 and Faradaic-efficiency values approaching Λ = -100 were obtained. Promotion was observed under positive polarisation and relatively dry, oxygen-rich atmospheres suggesting that some oxygen ion conductivity may occur under these conditions. Impedance spectroscopy performed in atmospheres of 4 kPa O2/N2 and of 5 kPa H2/N2 under dry and slightly humidified (0.3 kPa H2O) conditions indicated that the electrical resistivity is heavily dominated by the grain-boundary response in the temperature range of the EPOC studies; much lower grain-boundary impedances in the wetter conditions are likely to be attributable to proton transport.

Original languageEnglish
Pages (from-to)279-284
Number of pages6
JournalCatalysis Today
Volume146
Issue number3-4
DOIs
Publication statusPublished - 31 Aug 2009

Keywords

  • Ceramic proton conductor
  • Electrochemical promotion
  • Impedance spectroscopy
  • Lanthanum niobate
  • Permanent promotion

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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