Adsorption and Dissociation of Methanol on Pd(111),Pd/Au(111)and Pd/Rh(111)Surfaces

摘要

cqvip:The adsorption and dissociation behaviors of methanol on Pd(111), Pd/Au(111) and Pd/Rh(111) surfaces were studied using a periodical slab model and the PW91 generalized gradient approximation(GGA) within the framework of first-principles calculations based on density functional theory(DFT). The adsorption energy and geometric parameters for the three surfaces showed that methanol is preferentially adsorbed onto the top-Pd sites and that the adsorption energy of methanol on these surfaces decreases in the order Pd/Au(111) > Pd/Rh(111) > Pd(111). After adsorption, the C–O, C–H and O–H bonds in methanol adsorbed onto these surfaces are elongated and the vibrational stretching frequency of the O–H bond is obviously redshifted. Furthermore, the first step for the possible dissociation pathway for methanol on these surfaces was calculated. Our results indicate that the O–H bond in methanol decomposes producing methoxy and a hydrogen atom, with the Pd/Au(111) surface exhibiting the smallest dissociation barrier.