Nano-nitride cathode catalysts of Ti, Ta, and Nb for polymer electrolyte fuel cells: Temperature-programmed desorption investigation of molecularly adsorbed oxygen at low temperature

Ryohji Ohnishi, Kazuhiro Takanabe, Masao Katayama, Jun Kubota, Kazunari Domen

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

TiN, NbN, TaN, and Ta3N5 nanoparticles synthesized using mesoporous graphitic (mpg)-C3N4 templates were investigated for the oxygen reduction reaction (ORR) as cathode catalysts for polymer electrolyte fuel cells. The temperature-programmed desorption (TPD) of molecularly adsorbed O2 at 120-170 K from these nanoparticles was examined, and the resulting amount and temperature of desorption were key factors determining the ORR activity. The size-dependent TiN nanoparticles (5-8 and 100 nm) were then examined. With decreasing particle size, the density of molecularly adsorbed O2 per unit of surface area increased, indicating that a decrease in particle size increases the number of active sites. It is hard to determine the electrochemical active surface area for nonmetal electrocatalysts (such as oxides or nitrides), because of the absence of proton adsorption/desorption peaks in the voltammograms. In this study, O2-TPD for molecularly adsorbed O2 at low temperature demonstrated that the amount and strength of adsorbed O2 were key factors determining the ORR activity. The properties of molecularly adsorbed O2 on cathode catalysts are discussed against the ORR activity. © 2012 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)496-502
Number of pages7
JournalJournal of Physical Chemistry C
Volume117
Issue number1
DOIs
StatePublished - Dec 28 2012

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials

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