HCOO在Cu(110)、Ag(110)和Au(110)表面的吸附(英文)

Formate Adsorption on Cu(110), Ag(110) and Au(110) Surfaces

采用密度泛函理论(DFT)以及广义梯度近似方法(GGA)计算了甲酸根(HCOO)在Cu(110)、Ag(110)和Au(110)表面的吸附.计算结果表明,短桥位是最稳定的吸附位置,计算的几何参数与以前的实验和计算结果吻合.吸附热顺序为Cu(110)(-116kJ·mol-1)>Ag(110)(-57kJ·mol-1)>Au(110)(-27kJ·mol-1),与实验上甲酸根的分解温度相一致.电子态密度分析表明,吸附热顺序可以用吸附分子与金属d-带之间的Pauli排斥来关联,即排斥作用越大,吸附越弱.另外还从计算的吸附热数据以及实验上HCOO的分解温度估算了反应CO2+1/2H2→HCOO的活化能,其大小顺序为Au(110)>Ag(110)>Cu(110).

The adsorption of formate （HCOO） on Cu（110）, Ag（110）, and Au（110） surfaces has been studied by the density functional theory （DFF） and generalized gradient approximation （GGA） with slab model. To find the most stable adsorption site of HCOO on M（110） （M-Cu, Ag, Au）, we investigated several adsorption forms like bidentate and monodentate adsorption sites. The calculated results show that the most stable adsorption site is short-bridge bidentate form for all the three metals, which is independence of the metallic lattice constants. The calculated atomic geometries agree well with the experimental results and the previous calculaition results. Adsorption energy of formate follows the order of Cu（110） （-116 kJ· mol-1）〉Ag（110）（-57 kJ·mol-1）〉Au（110）（-27 kJ·mol-1）, in agreement with decomposition temperature of formate measured by experiments. The order of the adsorption energy can be explained by Pauli repulsion between molecular orbitals of formate with d-band of metal, i.e., the more occupied population of formate, the larger Pauli repulsion, which results in the weaker adsorption of formate. In addition, the activation energy of formate synthesis from CO2 and H2 was predicated using the adsorption energy of formate and the decomposition temperature of formate, which follows the order of Au（110）〉Ag（110）〉Cu（110）.