CO2 adsorption on mineral sorbents has a potential to sequester CO2. This study used a density functional theory (DFT) study of CO2 adsorption on barium oxide (BaO) in the presence of H 2O to determine the role of H2O on the CO2 adsorption properties on the (2 × 2; 11.05 Å × 11.05 Å) 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 CO2 molecule, a single H 2O 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 2 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).
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