Adsorption of ethanol on Si(1 0 0) from first principles calculations

The chemisorption of ethanol (C2H6O) on Si(1 0 0) is studied from first principles calculations, using a slab approach. Ethanol molecule initially interacts with the Si surface through the barrierless formation of a “dative bond”; from this physisorbed state ethanol can proceed to react with the surface via a number of possible pathways, the most relevant ones being characterized by O–H bond cleavage or O–C bond cleavage. We find that, although the product obtained by the O–C bond cleavage is thermodynamically more stable, the O–H bond cleavage process is kinetically favored. Other possible chemisorbed configurations and reaction paths have been investigated together with the effect of different surface coverages. Our results are in agreement with experimental findings; however they exhibit important differences with respect to those obtained in previous calculations based on a single-dimer cluster model.