Adsorption and disproportionation reaction of OH on Ag surfaces: dipped adcluster model study

SURFACE SCIENCE

卷:425

Article

Hu, ZM ; Nakatsuji, H

关键词: ab initio quantum chemical methods and calculations;    catalysis;    chemisorption;    hydroxyl;    metallic surface;    models of surface chemical reactions;    silver;    surface chemical reaction;   

DOI  :  10.1016/S0039-6028(99)00215-0

来源: Elsevier

【 摘 要 】

The adsorption and surface disproportionation reactions of OH on various silver surfaces were studied by the dipped adcluster model (DAM) combined with ab initio HF and MP2 methods. Our studies show that OI-I binds strongly to Ag surfaces; the adsorption energies were calculated to be 118.3 kcal mol(-1) at the short bridge site on Ag(110), 108.6 kcal mol(-1) at the fourfold hollow site on Ag(100), and 97.3 kcal mol(-1) at the threefold hollow site on Ag(111). The H-O axis is preferentially perpendicular to the surface for OH on Ag(100) and Ag(111), but tilts about 50 degrees along the [001] azimuthal orientation on Ag(110). The Ag 4d orbital plays an important role in adsorbing OH, whose molecular orbital analysis is described. Coadsorption of OH at the nearest fourfold sites on Ag(100) is stable with the H-O axis perpendicular to the surface; an inclined OH structure is proposed for the coadsorption of OH at the bridge sites and it is shown to be very reactive regarding the surface disproportionation reaction of OH. The structures and energy surfaces for the disproportionation reaction of OH to form H2O on Ag(100) are presented. The present study provides clear information regarding the adsorption, coadsorption and disproportionation of OH on Ag surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.

【 授权许可】

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