The effects of iodine and oxygen modification on the adsorption of methanol on the Ag(110) surface were studied by density-functional theory (DFT) method using cluster model approximation. It is found that methanol was weakly adsorbed in the form of physisorption on a clean silver surface. However, after the surface was modified by oxygen or iodine, methanol can undergo a stable form of molecular chemisorption because the pre-adsorption of iodine and oxygen increases the adsorption energy of methanol. And image charge model was used to verify our deduction that charge modification is the essence of modification of iodine and oxygen on the surface of silver catalyst in partial oxidation reaction of methanol to formaldehyde. This may help with the selection of promoter for this kind of reaction.

Key words: IODINE, OXYGEN, SILVER, METHANOL, ADSORPTION