Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (02): 263-270.doi: 10.3866/PKU.WHXB201211231

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Dissociative Adsorption of Methanethiol on Cu(111) Surface: a Density Functional Theory Study

FAN Xiao-Li, LIU Yan, DU Xiu-Juan, LIU Chong, ZHANG Chao   

  1. State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, P. R. China
  • Received:2012-08-13 Revised:2012-11-19 Published:2013-01-14
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20903075, 21273172), Programof Introducing Talents of Discipline to Universities, China (111 Project) (B08040), and Northwestern Polytechnical University Foundation for Fundamental Research, China (JC20100226).

Abstract:

The interaction of methanethiol (CH3SH) molecules with the Cu(111) surface was investigated using a first-principles method based on density functional theory, and a slab model. A series of possible adsorption configurations constructed using S atoms on different sites with different tilt angles were studied. It was found for the first time that the non-dissociative molecular adsorption of CH3SH on the Cu(111) surface with the S atom sitting on the top site belongs to the weak chemisorption, and the adsorption energy is 0.39 eV. After the dissociation of the S―H bond, the S atom is located at the bridge site, with a small shift toward the hollow site. The dissociative adsorption structure is thermodynamically more stable than the intact one, and the adsorption energy is 0.75-0.77 eV. Two reaction pathways have been studied for the transition from non-dissociative adsorption to dissociative adsorption, and the activation energy barrier along the minimum energy path is 0.57 eV. The results of the calculations indicated that the released H atom prefers to form a bond with the copper surface, rather than desorbing in the H2 molecular form. Comparing the local density of states of S atoms in the single CH3SH, CH3SH/Cu(111), and CH3S/Cu(111) structures, we found that the bonding between the S atoms and the substrate is much stronger in the dissociated adsorption states.

Key words: Methanethiol molecule, Cu(111) surface, Density functional theory, Adsorption geometry, Dissociation, Local density of states

MSC2000: 

  • O641