The (001) surface of tetragonal zirconia, both bare, and fully hydrated or hydroxylated has been theoretically studied. A periodic Hartree-Fock method has been used, by simulating the adsorbent with a thin slab. Pseudopotentials have been employed for core electrons, and a “split-valence” set for valence electrons. Several geometries have been considered for surface water or OH groups. In the two cases, one preferential structure has been individuated, corresponding to a similar adsorption energy (∼ 15 kcal/mol with respect to isolated water molecules); the corresponding electronic structure has been analyzed. The vibrational frequencies of adsorbed OH groups have been calculated; they differ by more than 350 cm−1. Similar differences in OH vibrational frequencies have not been observed in infrared studies of zirconia, which, however, concern the monoclinic phase.
Ab initio study of the bare and hydrated (001) surface of tetragonal zirconia
ORLANDO, Roberto;
1992-01-01
Abstract
The (001) surface of tetragonal zirconia, both bare, and fully hydrated or hydroxylated has been theoretically studied. A periodic Hartree-Fock method has been used, by simulating the adsorbent with a thin slab. Pseudopotentials have been employed for core electrons, and a “split-valence” set for valence electrons. Several geometries have been considered for surface water or OH groups. In the two cases, one preferential structure has been individuated, corresponding to a similar adsorption energy (∼ 15 kcal/mol with respect to isolated water molecules); the corresponding electronic structure has been analyzed. The vibrational frequencies of adsorbed OH groups have been calculated; they differ by more than 350 cm−1. Similar differences in OH vibrational frequencies have not been observed in infrared studies of zirconia, which, however, concern the monoclinic phase.
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