物理化学学报 >> 2013, Vol. 29 >> Issue (09): 1907-1915.doi: 10.3866/PKU.WHXB201307022

理论与计算化学 上一篇    下一篇

密度泛函理论研究十二烷硫醇在Au(111)面上的吸附

范晓丽, 冉润欣, 张超, 杨永良   

  1. 西北工业大学, 凝固技术国家重点实验室, 西安 710072
  • 收稿日期:2013-05-06 修回日期:2013-07-01 发布日期:2013-08-28
  • 通讯作者: 范晓丽 E-mail:xlfan@nwpu.edu.cn
  • 基金资助:

    国家自然科学基金(20903075, 21273172)及高等学校学科创新引智计划(111)(B08040)资助项目

Density Functional Theory Study on the Adsorption of Dodecylthiol on Au(111) Surface

FAN Xiao-Li, RAN Run-Xin, ZHANG Chao, YANG Yong-Liang   

  1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, P. R. China
  • Received:2013-05-06 Revised:2013-07-01 Published:2013-08-28
  • Contact: FAN Xiao-Li E-mail:xlfan@nwpu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20903075, 21273172) and Program of Introducing Talents of Discipline to Universities, China (111 Project) (B08040).

摘要:

采用第一性原理方法研究了十二烷硫醇(C12H25SH)分子在Au(111)面上未解离和解离吸附的结构、能量和吸附性质,在此基础上分析判断长链硫醇分子在Au(111)面吸附时S―H键的解离, 以及分子链长度对吸附结构和能量的影响. 计算了S原子在不同位置以不同方式吸附的系列构型, 结果表明在S―H键解离前和解离后,均存在两种可能的表面结构, 直立吸附构型和平铺吸附构型; 未解离的C12H25SH分子倾向于吸附在top位, 吸附能为0.35-0.38 eV; H原子解离后C12H25S基团倾向于吸附在bri-fcc位, 吸附能量为2.01-2.09 eV. 比较分析未解离吸附和解离吸附, 发现C12H25SH分子未解离吸附相较于解离吸附要稳定, 未解离吸附属于弱化学吸附.局域电子态密度和差分电荷密度分析进一步验证了S―H解离后S原子与表面之间成键的数目增加, 而且键合更强. 同时我们发现长链硫醇的吸附能量较短链硫醇的吸附能量略大, S原子与表面Au原子之间的距离略小.

关键词: 密度泛函理论, 十二烷硫醇, Au(111)面, 吸附结构, 平铺构型, 电子结

Abstract:

By applying the first-principles methods based on density functional theory and the slab model, we have studied the non-dissociative and dissociated adsorptions of a dodecylthiol (C12H25SH) molecule on Au(111) surface. Based on the calculated results, the fate of the H atom has been analyzed, and the longchain adsorption and short-chain adsorption have been compared. We have performed structure optimizations for a series of initial structures with the S atom located on different sites with different tilt angles. This structure optimizations gave two surface structures before and after the dissociation of S―H; the standing-up and lying-down adsorption structures. Our calculations indicate that the C12H25SH molecule prefers to stay on the top site, the corresponding adsorption energies are 0.35-0.38 eV. The dissociated C12H25S group prefers to adsorb on the bri-fcc site, with adsorption energies of 2.01-2.09 eV. We have compared the non-dissociative C12H25SH/Au(111) and dissociated C12H25S/Au(111) with the H atom adsorbing onto Au and desorbing as H2, and found that the non-dissociative adsorption is more stable. The formation energy and the electronic structure showed that the non-dissociative adsorption belongs to the weak chemisorption, whereas the interaction between the S atom and Au surface becomes much stronger following cleavage of the S―H. A comparison of the adsorption of long-chain thiols on Au(111) surface with that of the short-chain thiols, indicates that the adsorption energies of the long-chain thiols are slightly larger, and the distances between the S atomand the surface Au atoms are slightly shorter.

Key words: Density functional theory, Dodecylthiol, Au(111) surface, Adsorption structure, Lying-down configuration, Electronic structure

MSC2000: 

  • O641