J. B. Day, P. Vuissoz, E. Oldfield
Dec 25, 1996
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0
Influential Citations
38
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Journal
Journal of the American Chemical Society
Abstract
The adsorbate resulting from the potentiostatic, catalytic decomposition of methanol (0.1 M CH3OH in 0.5 M H2SO4) on a platinum black electrode has been studied via 13C nuclear magnetic resonance spectroscopy, at open cell potential. Cyclic voltammetry results indicate that coverage is a function of electrodecomposition time and potential. The spin−spin relaxation time T2 is dependent on surface coverage and ranges from ∼3 to ∼1.8 ms at coverages ranging from 0.3 to 0.75 ML, due to the increased effectiveness of 13C−13C dipolar interactions at high coverage. At 0.5 ML, the temperature dependence of the 13CO T2 (in a 2H2O-exchanged electrolyte system) has been determined from 80 to 250 K. There is a well-defined peak in relaxation rate at ∼170 K which can be modeled using a simple diffusional model having an activation energy of 7.9 ± 2.0 kcal/mol. Spin−lattice relaxation results from 10 to 250 K reveal Korringa behavior, with a T1T product (and Knight shift) that is independent of surface coverage, and ha...