The CH3SH molecule deposited on Cu(111) and deprotonation

TL;DR

This study uses computational methods to show that methanethiol prefers dissociative adsorption on Cu(111) surfaces, with temperature and defects influencing the stability and site preference of the adsorbed molecules.

Contribution

First computational demonstration of thermodynamic stability of dissociative methanethiol on Cu(111), highlighting temperature and defect effects on adsorption behavior.

Findings

Dissociative structure is more stable than intact on Cu(111).

Temperature influences adsorption site preference.

Hydrogen bonds with copper surface rather than desorbing.

Abstract

We demonstrate for the first time that when a methanethiol adsorbed on the regular Cu(111) surface, the dissociative structure is thermodynamically more stable than the intact one. The computational results show that at low temperature the methanethiol adsorbate prefers the atop site of the regular Cu(111) surface. As the temperature is increased, the S-H bond is broken and the methylthiolate favors the hollow sites. On the defected Cu(111) surface, the dissociative configuration is still thermodynamically more stable than the nondissociative one. The calculation indicates that the hydrogen initially attached to the sulfur would like to form a bond with the copper surface rather than desorb from it. Even though both copper and gold are the noble metal, the stability of the methanethiol adsorption on the Cu(111) substrate is almost the reverse of that on the Au(111).