TY - GEN
T1 - Coverage dependence of CO surface diffusion on Pt nanoparticles
T2 - 233rd ACS National Meeting
AU - Babu, P. K.
AU - Kobayashi, T.
AU - Chung, H.
AU - Oldfield, E.
AU - Wieckowski, Andrzej
PY - 2007
Y1 - 2007
N2 - We have studied the effects of CO coverage on surface diffusion rates of CO adsorbed on nanoparticle Pt catalysts in sulfuric acid media by using 13C EC-NMR at 253 - 293 K. For CO coverage from 1.0 to 0.36, the diffusion coefficients follow Arrhenius behavior and both activation energy (Ed) and pre-exponential factor (DCO) show CO coverage dependence. When the coverage is increased from 0.36 to 1.0, Ed increases from 6.0 to 8.4 kcal/mol and DCO from 1.1 × 10-8 to 3.7 × 10-6 cm2/s. At partial CO coverage, our data support the free site hopping model of adsorbed CO as the major surface diffusion mechanism. When the diffusion coefficient was estimated from CO stripping measurements by using an electrochemical modeling protocol, the diffusion coefficients were a few orders of magnitude larger than those obtained from the EC-NMR experiments. Overall these results are important for improving our understanding of electrochemical surface dynamics that play a crucial role in controlling fuel cell reaction rates.
AB - We have studied the effects of CO coverage on surface diffusion rates of CO adsorbed on nanoparticle Pt catalysts in sulfuric acid media by using 13C EC-NMR at 253 - 293 K. For CO coverage from 1.0 to 0.36, the diffusion coefficients follow Arrhenius behavior and both activation energy (Ed) and pre-exponential factor (DCO) show CO coverage dependence. When the coverage is increased from 0.36 to 1.0, Ed increases from 6.0 to 8.4 kcal/mol and DCO from 1.1 × 10-8 to 3.7 × 10-6 cm2/s. At partial CO coverage, our data support the free site hopping model of adsorbed CO as the major surface diffusion mechanism. When the diffusion coefficient was estimated from CO stripping measurements by using an electrochemical modeling protocol, the diffusion coefficients were a few orders of magnitude larger than those obtained from the EC-NMR experiments. Overall these results are important for improving our understanding of electrochemical surface dynamics that play a crucial role in controlling fuel cell reaction rates.
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M3 - Conference contribution
AN - SCOPUS:37349015963
SN - 084127438X
SN - 9780841274389
T3 - ACS National Meeting Book of Abstracts
BT - 233rd ACS National Meeting, Abstracts of Scientific Papers
Y2 - 25 March 2007 through 29 March 2007
ER -