화학공학소재연구정보센터
Applied Surface Science, Vol.320, 681-688, 2014
Insights into the effect of coverage on CO adsorption and dissociation over Rh(100) surface: A theoretical study
The adsorption, dissociation and desorption of CO at different coverage over Rh(1 0 0) surface have been systematically investigated using density functional theory method together with the periodic slab model. Our results show that at the coverage less than or equal to 4112 ML, CO favored the most stable bridge site adsorption, and the adsorption energies of CO have little difference; while at the coverage greater than or equal to 5112 ML, the lateral repulsive interaction begins to affect the adsorption structures and the corresponding adsorption energies of adsorbed CO molecules, and the interaction will be stronger with the increasing of CO coverage, which leads to CO migration over Rh(1 0 0) surface when CO coverage is greater than or equal to 10112 ML The adsorption energies of these CO molecules will decrease successively until the saturated adsorption with the CO coverage of 12112 ML. Further calculations on CO dissociation indicate that when CO coverage is greater than or equal to 3112 ML, the dissociation of adsorbed CO molecules will be unfavorable both kinetically and thermodynamically, suggesting that only molecule CO adsorption are favored. Considering the catalytic activity of Rh(1 0 0) surface toward CO dissociation and the higher CO coverage under the continuous supply of CO in syngas conversion, it is to be expected that only molecule CO adsorption exist on Rh catalyst. (C) 2014 Elsevier B.V. All rights reserved.