Competitive Adsorption of CO2 and H2O Molecules on the BaO (100) Surface: A First-Principle Study

CO2 adsorption on mineral sorbents has a potential to sequester CO,. This study used a density functional theory (DFT) study of CO2 adsorption on barium oxide (BaO) in the presence of H2O to determine the role of H2O on the CO2 adsorption properties on the (2 x 2; 11.05 angstrom x 11.05 angstrom) BaO (100) surface because BaO shows a high reactivity for CO2 adsorption and the gas mixture of power plants generally contains CO2 and H2O. We investigated the adsorption properties (e.g., adsorption energies and geometries) of a single CO, molecule, a single H2O molecule on the surface to achieve molecular structures and molecular reaction mechanisms. In order to evaluate the coordinative effect of H2O molecules, this study also carried out the adsorption of a pair of H2O molecules, which was strongly bounded to neighboring (-1.91 eV) oxygen sites and distant sites (-1.86 eV), and two molecules (CO2 and H2O), which were also firmly bounded to neighboring sites (-2.32 eV) and distant sites (-2.23 eV). The quantum mechanical calculations show that H2O molecule does not influence on the chemisorption of CO, on the BaO surface, producing a stable carbonate due to the strong interaction between the CO2 molecule and the BaO surface, resulting from the high charge transfer (-0.76 e).