The temperature programmed decomposition results of methanol, formaldehyde, and formic acid on an O-polar (0001) surface of ZnO are presented. From these results, and similar ones for the Zn-polar (0001) and the nonpolar (1010) and (5051) surfaces, a comparison of the properties of the different ZnO surfaces are made. Oxygen-containing molecules that possess strong dipole moments, such as alcohols, formaldehyde, acetone, and formic acid, interact most strongly with the Zn-polar face, less strongly with the nonpolar face, and least strongly with the O-polar face. This leads to the observed differences in the desorption temperature of molecular desorption, temperature of evolution of the decomposition products, and the fraction of methanol decomposed. These differences are explained by the different magnitudes and orientations of surface dipole moments, a different degree of ionicity of the surface Zn ions, and a different degree of steric hindrance of surface Zn ions for the different surfaces. Desorption of other molecules, such as propene and CO, whose adsorption is dominated by different types of interaction than the alcohols and aldehydes, shows different dependence on the surface structure.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Physical Chemistry|
|State||Published - Dec 1 1985|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry