Adsorption of CH3I on Ag(1 1 1) and Ag2O(1 1 1) surface: A density functional theory study

First-principles density functional study has been performed to systematically investigate the adsorption of CH3I on Ag(1 1 1) and Ag2O(1 1 1) surfaces at different coverages. It is found that the adsorption energy of CH3I on two surfaces at all sites is coverage-dependent, and the adsorption is thermodynamic favorable. The interaction between CH3I and two surfaces can be mainly attributed to the hybridization of I(p) state and Ag(d) state. For the adsorption of CH3I on Ag(1 1 1) surface, fcc site is the most stable site whether at lower or higher coverage. For Ag2O(1 1 1) surface, AgCUS site and AgCUS(AgCSA) site is more favorable at lower and higher coverage, respectively. The large adsorption energy occurred on the adsorption of CH3I on AgCUS(AgCSA) site is due to the strong interaction between I atom and AgCUS atom and the formation of HO bond according to the LDOS and CDD calculations.