Density Functional Theory (DFT) Studies of CO Oxidation over Nanoporous Gold: Effects of Residual Ag

• 作 者: PuWang;XiangqiongTang;JianTang;YongPei;
• 机 构: Department of Chemistry,Key Laboratory of Environmentally Friendly Chemistry and Applications of Min
• 出 处: 2014第二届中国网络安全大会
• 发表日期: 2014年期

　　We report a systematically study of reaction mechanism of CO oxidation over nanoporous gold (NPG)based on the recent progress of structural characterization of NPG.The Agx@Au(111)and Agx@Au(100)slabs(x = 1 – 3)are built to mimic the local structure of NPG.The CO oxidation pathways over two model catalysts are investigated via the density functional theory(DFT) calculations.Totally 50 reaction pathways are examined at different active site of two model catalysts.A simplified microkinetics model termed the Sabatier analysis which is built on the adsorption energies and activation barriers is used to evaluate the reaction rate of different reaction pathways.The presence of residual Ag content in NPG may promote the adsorption of O2 species.However,the barrier height of OCOO* intermediate dissociation is affected strongly by the local surface structure and the presence of nearby co-adsorbed CO molecule.The co-adsorbed CO molecule nearby the reaction active site can promote the dissociation of OCOO* reaction intermediate via an electrophilic attack process,which is denoted as a tri-molecular CO self-promoting oxidation mechanism.The presence of residual Ag atom can facilitate the attack of co-adsorbed CO to OCOO* intermediate and lead to increased reaction rate.