Density functional theory study of methanol adsorption on Au(111) surface

The first-principles density functional theory (DFT) and self-consistent periodic calculation were used to investigate the methanol adsorption on An(111) surface. The adsorption energy, equilibrium geometry, and vibrational frequency of CH3OH on four possible sites (top, hcp, fcc, and bridge) on Au(111) surface were predicted and compared with the experimental data. In the equilibrium adsorption models, the O-H and O-C, bonds are elongated, and the stretch vibrational frequency is red shifted. Meanwhile the O-H bond is activated greatly. On all the four sites, the electron transfers from methanol to the metal surface, and the favorite adsorption occurs at the top site. The possible decomposition pathway was investigated with transition state searching by using complete LST/QST methods. The calculation results prove that decomposition of methanol to methoxy and hydrogen occurs on the Au (111) surface I which is in agreement with the available experimental results. The favorite adsorption sites for methoxy and hydrogen are bridge and fcc sites, respectively.