TY - JOUR
T1 - Adsorption and activation of CO over flat and stepped Co surfaces
T2 - A first principles analysis
AU - Ge, Qingfeng
AU - Neurock, Matthew
PY - 2006/8/10
Y1 - 2006/8/10
N2 - The adsorption and activation of CO over flat Co{0001}, corrugated Co{112̄0}, and stepped Co{101̄2} and Co{112̄4} surfaces have been analyzed using periodic density functional theory calculations. CO strongly chemisorbs on all these surfaces but does not show a strong dependence on the surface structure. The calculated structure of adsorbed CO on Co{0001} at 1/3 monolayer (ML) of coverage was found to be in good agreement with the experiment. The barrier for CO dissociation over Co{0001} was found to decrease with decreasing CO coverage, taking on a value of 232 kJ/mol at 1/4 ML and 218 kJ/mol at 1/9 ML. The presence of the "zigzag" channel on Co{112̄0} enhances the reactivity slightly by reducing the barrier for CO dissociation to 195 kJ/mol. In contrast, the stepped Co{101̄2} and Co{112̄4} surfaces are much more active than the flat and corrugated surfaces. Both stepped surfaces provide direct channels for CO dissociation that do not have barriers with respect to gas-phase CO. In general the activation barriers lower as the reaction energies become more exothermic. Reconstruction of the step edges that occur in the product state, however, prevents a linear correlation between the reaction energy and the activation energy.
AB - The adsorption and activation of CO over flat Co{0001}, corrugated Co{112̄0}, and stepped Co{101̄2} and Co{112̄4} surfaces have been analyzed using periodic density functional theory calculations. CO strongly chemisorbs on all these surfaces but does not show a strong dependence on the surface structure. The calculated structure of adsorbed CO on Co{0001} at 1/3 monolayer (ML) of coverage was found to be in good agreement with the experiment. The barrier for CO dissociation over Co{0001} was found to decrease with decreasing CO coverage, taking on a value of 232 kJ/mol at 1/4 ML and 218 kJ/mol at 1/9 ML. The presence of the "zigzag" channel on Co{112̄0} enhances the reactivity slightly by reducing the barrier for CO dissociation to 195 kJ/mol. In contrast, the stepped Co{101̄2} and Co{112̄4} surfaces are much more active than the flat and corrugated surfaces. Both stepped surfaces provide direct channels for CO dissociation that do not have barriers with respect to gas-phase CO. In general the activation barriers lower as the reaction energies become more exothermic. Reconstruction of the step edges that occur in the product state, however, prevents a linear correlation between the reaction energy and the activation energy.
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U2 - 10.1021/jp060477i
DO - 10.1021/jp060477i
M3 - Article
C2 - 16884257
AN - SCOPUS:33748370782
SN - 1520-6106
VL - 110
SP - 15368
EP - 15380
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 31
ER -