Effect of halogen atoms (Cl, Br, I) on the structure and catalytic behavior of Ag(111) surface: a density functional theory study

A comparative study on the effects of different halogen atoms (Cl, Br, I) o n the structure and catalytic behavior of Ag(111) has been performed with a series of cluster calculations using the density functional theory method. The results of calculations show that the atomic adsorption energies of ha logen and oxygen atoms on the Ag(111) surface are in the order O>CI>Br>I re gardless of the relaxation of the surface. However, iodine atoms show the g reatest effect on the structure of Ag(111) surface compared with the other halogen atoms (Cl, Br). Based on the results of calculations, the promoting effects of the halogen atoms on the two oxidation reactions catalyzed by s ilver, i.e. the epoxidation of ethylene and the partial oxidation of methan ol, have been discussed. (C) 2000 Elsevier Science B.V. All rights reserved .