Low-temperature decomposition of methanol on Au nanoclusters supported on a thin film of Al2O3/NiAl100.
Phys Chem Chem Phys
; 13(8): 3281-90, 2011 Feb 28.
Article
em En
| MEDLINE
| ID: mdl-21264394
ABSTRACT
With a variety of surface probe techniques, we investigated low-temperature decomposition of methanol on Au nanoclusters formed by vapor deposition onto an ordered Al(2)O(3)/NiAl(100) thin film. Upon adsorption of methanol on the Au clusters (with mean diameter 1.5-3.8 nm and height 0.45-0.85 nm) at 110 K, some of the adsorbed methanol dehydrogenates directly into carbon monoxide (CO); the produced hydrogen atoms (H) begin to desorb near 125 K whereas most of the CO desorbs above 240 K. The reaction exhibits a significant dependence on the Au coverage the produced CO increases in quantity with the Au coverage, reaches a maximum at about 1.0-1.5 ML Au, whereas decreases with further increase of the Au coverage. The coverage-dependence is rationalized partly by an altered number of reactive sites associated with low-coordinated Au in the clusters. At least two kinds of reactive sites for the low-temperature decomposition are distinguished through distinct C-O stretching frequencies (2050 cm(-1) and 2092 cm(-1)) while the produced CO co-adsorbs with H and methanol.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2011
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Article