Interaction of CO, CO2 and O2 with nonpolar, stepped and polar Zn surfaces of ZnO

W. H. Cheng, Harold H Kung

Research output: Contribution to journalArticle

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Abstract

The nonpolar (1010), stepped (4041) and (5051), and the polar (0001) surfaces of ZnO were prepared. Stable unreconstructed nonpolar and stepped surfaces were obtained. LEED analyses showed that the step height and the step width of the stepped surfaces were similar to the theoretical values. The polar surface showed a 1 × 1 LEED pattern of six-fold symmetry after annealing at 500°C, and evidence of a more complicated pattern at 300-400°C. Temperature programmed desorption of CO resulted in the desorption of CO from the stepped and the polar surfaces. However, desorption of CO2 was observed from the stoichiometric nonpolar surface, and no desorption from the reduced nonpolar surface. CO2 was also observed by interacting CO with all surfaces at elevated temperatures. A total of four temperature programmed desorption peaks of CO2, α, β, γ, and δ were observed. The α and β peaks were observed on the nonpolar and the stepped surfaces, and the γ peak was observed on the polar surface. The α peak was assigned to adsorption on a surface ZnO pair, and the β peak was assigned to adsorption on an anion vacancy or a step. While adsorbed water enhanced the β, preadsorbed methanol reduced it. O2 adsorption was similar on the nonpolar and the stepped surfaces, but was weak on the polar surface.

Original languageEnglish
Pages (from-to)21-39
Number of pages19
JournalSurface Science
Volume122
Issue number1
DOIs
Publication statusPublished - Oct 2 1982

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Carbon Monoxide
interactions
desorption
Desorption
Temperature programmed desorption
Adsorption
adsorption
Vacancies
Anions
temperature
Methanol
Negative ions
methyl alcohol
Annealing

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Interaction of CO, CO2 and O2 with nonpolar, stepped and polar Zn surfaces of ZnO. / Cheng, W. H.; Kung, Harold H.

In: Surface Science, Vol. 122, No. 1, 02.10.1982, p. 21-39.

Research output: Contribution to journalArticle

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AB - The nonpolar (1010), stepped (4041) and (5051), and the polar (0001) surfaces of ZnO were prepared. Stable unreconstructed nonpolar and stepped surfaces were obtained. LEED analyses showed that the step height and the step width of the stepped surfaces were similar to the theoretical values. The polar surface showed a 1 × 1 LEED pattern of six-fold symmetry after annealing at 500°C, and evidence of a more complicated pattern at 300-400°C. Temperature programmed desorption of CO resulted in the desorption of CO from the stepped and the polar surfaces. However, desorption of CO2 was observed from the stoichiometric nonpolar surface, and no desorption from the reduced nonpolar surface. CO2 was also observed by interacting CO with all surfaces at elevated temperatures. A total of four temperature programmed desorption peaks of CO2, α, β, γ, and δ were observed. The α and β peaks were observed on the nonpolar and the stepped surfaces, and the γ peak was observed on the polar surface. The α peak was assigned to adsorption on a surface ZnO pair, and the β peak was assigned to adsorption on an anion vacancy or a step. While adsorbed water enhanced the β, preadsorbed methanol reduced it. O2 adsorption was similar on the nonpolar and the stepped surfaces, but was weak on the polar surface.

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