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
KAUST DepartmentKAUST Catalysis Center (KCC)
Physical Sciences and Engineering (PSE) Division
Chemical Science Program
Catalysis for Energy Conversion (CatEC)
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AbstractTiN, 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.
SponsorsThis work is partly supported by Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST) of Cabinet Office of Japan, the international exchange program of the A3 Foresight Program of the Japan Society for the Promotion of Science (JSPS), and "Elements Strategy Initiative to Form Core Rersearch Center" (since 2012), Ministry of Education Culture, Sports, Science and Technology (MEXT), Japan.
PublisherAmerican Chemical Society
JournalJournal of Physical Chemistry C