Adsorption of thiophene on RuS2:: An ab initio density-functional study

The adsorption of thiophene on stoichiometric and reduced (100) surfaces of RuS2 has been studied using ab initio density-functional molecular dynamics. On the stoichiometric surface, the thiophene molecule is shown to adsorb in a tilted eta(1) position where the S atom of the molecule forms a bond with the surface Ru atom similar to that in the bulk RuS2, but there is no activation of the molecule. Formation of sulfur vacancies on the surface creates a chemically active surface and possibility of thiophene adsorption in the eta(2) position, where the molecule is activated. These findings are in good agreement with recent experimental evidence of a drastic increase in catalytic activity of the reduced RuS2 surface and should contribute to a better understanding of unique catalytic properties of RuS2 for thiochemistry applications.