Relaxation in ZnO (1010), (0001), and (0001) surfaces and the adsorption of CO
An atom superposition and electron delocalization molecular orbital study using cluster models shows surface zinc and oxygen ions relax into the (0001), (0001), and (1010) surfaces. The unsaturated zinc ions present surface states consisting of empty 4s, 4p hybridized orbitals with energy levels beneath the empty 4s, 4p band. The filled bands are O 2p nonbonding, Zn 4s + O 2p bonding, and Zn 3d, in order of increasing ionization potential. A study of CO adsorption to an unsaturated zinc ion on the (1010) surface produces an adsorption energy of 12 kcal/mol, a CO bond length decrease of 0.02 A, and an increase in the CO stretching force constant. The zinc ion unrelaxes to a position above the bulk-like position when CO is coordinated to it. The bonding of CO to zinc consists in closed shell sigma donation interactions of the CO 5sigma orbital with the filled Zn 3d and Zn 4s + O 2p bands with the antibonding counterpart stabilized by the Zn 4s, 4p surface state orbital. This 5sigma donation strengthens the CO bond and transfers charge to the surface. These results support a number of experimental structural, vibrational, and electronic studies in the literature.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH
- OSTI ID:
- 5403699
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 108:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
10 SYNTHETIC FUELS
CARBON MONOXIDE
ADSORPTION
ZINC OXIDES
ELECTRONIC STRUCTURE
SORPTIVE PROPERTIES
ADSORPTION HEAT
MATHEMATICAL MODELS
POTENTIALS
SURFACE IONIZATION
THEORETICAL DATA
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DATA
ENTHALPY
INFORMATION
IONIZATION
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SORPTION
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
ZINC COMPOUNDS
400201* - Chemical & Physicochemical Properties
090100 - Hydrocarbon Fuels- (-1989)