CO在Pd低指数晶面吸附的DFT分析

DFT Study of Carbon Monoxide Adsorption on Low Index Surfaces of Pd

采用密度泛函理论(DFT)中B3LYP计算方法对CO在Pd(100)、Pd(110)和Pd(111)3个低指数晶面上的3种不同的吸附模式(顶位吸附、空位吸附和桥位吸附)进行了探讨,从CO在3个晶面吸附的结合能、几何结构、集居数以及净电荷分析得到:CO与Pd面均形成强的σ-π键;CO在3个晶面上均倾向于桥位吸附,在Pd(111)晶面上中毒最深。对CO在3个晶面上吸附的结合能和活化程度进行了比较,发现CO在3个晶面的中毒应按以下顺序减弱:Pd(111)>Pd(100)>Pd(110);空位吸附时的活化程度最高,桥位吸附时的活化程度最低。

CO adsorption on the three low index surfaces of Pd, i. e. , （100）, （110） and （111） was studied by the density-functional theory （DFT） with method of B3LYP. The three adsorption patterns of CO adsorption on Pd, top, hollow and bridge, respectively, were taken into account of calculation. By means of calculation results, that is, binding energy, geometrical structure, Mulliken population and net charge, it has concluded that a strong σ -π bond is formed with CO adsorption on Pd surfaces; CO adsorption on Pd surfaces prefers the bridge pattern to others; and the most se- vere CO poisoning happens on Pd （111 ）. The poisoning to the three Pd surfaces decreases in sequence： Pd （111 ） 〉 Pd （100） 〉 Pd （110）. Meanwhile, the degree of CO molecule activation with adsorption on Pd increases in the order： hollow 〉 top 〉 bridge.