Ab initio study on the adsorption and oxidation of HCHO with Ag-2 cluster

We present an ab initio study on the adsorption and oxidation of HCHO on th e Ag-2 dimer. HCHO is found to weakly adsorb on the neutral Ag-2 cluster an d the adsorption energy increases when the Ag-2 cluster is positively charg ed. The adsorption of HCHO on Ag-2 is promoted by pre-adsorbed OH species w hile coadsorbed H has no effect. The formation of eta(2)-methylendioxy is i nhibited if the Ag-2 cluster is positively and properly charged, which enha nce the selectivity of the partial oxidation of methanol. These results pro vide insight into the reaction mechanism of HCHO on silver surfaces and may guide the design of novel catalysts. (C) 1999 Elsevier Science B.V. All ri ghts reserved.