Oxidation of Silanes to Silanols on Pd Nanoparticles: H2 Desorption Accelerated by Surface Oxygen Atom

摘要

The oxidation of silane to silanol on the clean and oxygen-covered Pd(111) surface is investigated with periodic density functional theory calculations to gain a better understanding of the effect of surface oxygen atom on Pd nanoparticle catalysts. The calculations confirmed that this catalytic reaction is initiated by the dissociative adsorption of silane on the Pd surface. The resultant silyl group is attacked by a water molecule to form silanol and an H atom on the Pd surface with inversion of configuration at the Si center. An activation energy of 11.3 kcal/ mol is required for the water addition, and the transition state for this step is energetically highest in the entire reaction profile. These computational results are in good agreement with our stereochemical and kinetic studies. The H atoms on the Pd surface inhibit further reaction, and therefore, they should be removed to achieve the catalytic activity experimentally. We found that the role of the surface oxygen atom is to facilitate the desorption of H2 from the Pd surface without the formation of OH and H2O. The introduction of surface oxygen atoms can enhance the catalytic ability of metal nanoparticles for green organic reactions.