Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (09): 1907-1915.doi: 10.3866/PKU.WHXB201307022

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

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).

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