乙烷在Ni(111)表面的吸附和分解  

Ethane Adsorption and Decomposition on Ni(111) Surface

作　　者：张福兰[1,2] 李来才[1] 田安民[3] 

机构地区：[1]四川师范大学化学与材料学院,成都610066 [2]长江师范学院化学系,重庆涪陵408003 [3]四川大学化学学院,成都610064

出　　处：《物理化学学报》2009年第9期1883-1889,共7页Acta Physico-Chimica Sinica

基　　金：四川省青年基金和四川省教育厅重点项目资助~~

摘　　要：研究了乙烷在Ni(111)表面解离的可能反应机理,使用完全线性同步和二次同步变换(complete LST/QST)方法确定解离反应的过渡态.采用基于第一性原理的密度泛函理论与周期平板模型相结合的方法,优化了C2H6裂解反应过程中各物种在Ni(111)表面的top,fcc,hcp和bridge位的吸附模型,计算了能量,并对布居电荷进行分析,得到了各物种的有利吸附位.结果表明,乙烷在Ni(111)表面C—C解离的速控步骤活化能为257.9kJ·mol-1,而C—H解离速控步骤活化能为159.8kJ·mol-1,故C—H键解离过程占优势,主要产物是C2H4和H2.A possible decomposition mechanism for ethane on Ni（111） surface was investigated using first-principles density functional theory （DFT） and a self-consistent periodic calculation. The transition states were determined using complete linear synchronous transit and quadratic synchronous transit （LST/QST） methods. All the species involved in this process had four possible adsorption sites （top, fcc, hcp, and bridge） on the Ni（111） surface and all these were fully optimized to obtain their equilibrium geometries and electronic structures. The corresponding adsorption energies and Mulliken charge analyses of these species were predicted and compared. Favorable adsorption sites on the Ni（111） surface for these species were found. In the C--C bond activation pathway, the energy barrier of the rate-limiting step was 257.9 kJ·mol^-1. However, the energy barrier of the rate-limiting step was only 159.8 kJ·mol^-1 for the C--H bond activation pathway, which suggested that the C--H bond activation pathway would be preferred. As a result, the main products are C2H4 and H2.

关 键 词：乙烷 Ni(111)表面 吸附 密度泛函理论 过渡态 

分 类 号：O647.31[理学—物理化学]