CO₂ and SO₂ sorption on the alkali metals doped CaO(100)surface: A DFT-D study

Highlights: • Basic oxygen surface sites are active sites for CO₂ and SO₂ adsorption. • Doping alkali metals on CaO(100) is favorable for CO₂ and SO₂ adsorption. • Cs is a preferable dopant of CaO(100) for CO₂ and SO₂ adsorption. - Abstract: The electronic properties of the pristine and alkali metals doped CaO(100) surfaces, as well as their propensity toward CO₂ and SO₂sorption are studied using the dispersion-corrected density functional theory (DFT-D). Various interaction modes between the acidic gas and surfaces are considered. The results show that the basic oxygen surface sites are active adsorption sites for CO₂ and SO₂, with monodentate-like coordination formed on each surface. Further, charge analysis is conducted, showing a charge transfer fromeach surface to the adsorbate. The comparison of adsorption energies indicates that CO₂ and SO₂ show stronger adsorption on alkali metal-doped CaO than that on pristine CaO. The metal Csis the preferred dopant for high sorption capacity, whichhave agreat strengthening effect onCO₂ and SO₂ binding.