Adsorption of CS on MgO microcrystals: formation of a S-doped MgO surface

The interaction of carbon disulfide, CS2, with polycrystalline MgO was investigated by means of infrared and UV-visible spectroscopies and ab initio electronic structure calculations. The aim was to understand the modi cations of the surface properties of MgO microcrystals induced by the substitution of O2- with S2- anions. The interaction of CS2 with MgO shows the formation of thiocarbonates followed by O-S exchange reactions and formation of Mg2+-S2- clusters in a MgO matrix. The O-S exchange reaction involves mainly the low-coordinated O2- anions at the steps and corner sites, and only at high temperature are a small number of O2- anions at the (100) terrace sites involved. The replacement of the O with the S atoms at the low-coordinated sites of the MgO surface transforms the reactive polycrystalline material into a chemically inert system.