CO2 Adsorption on H2O ‐Saturated BaO (1 0 0) and Induced Barium Surface Dissociation

CO2 adsorption on a barium oxide (BaO) surface saturated with a monolayer of H2O molecules was studied; a monolayer of H2O molecules on the BaO surface exhibits nondissociative or dissociative adsorption. During the nondissociative reaction, a hydroxyl ion‐terminated surface is produced, resulting in the formation of barium hydroxide (Ba(OH)2) on the surface. The Ba(OH)2 from the substrate associates with the tightly bound CO2 molecule, resulting in the formation of barium carbonate (BaCO3). In contrast, during the dissociative H2O adsorption, a hydrogen‐terminated surface is produced, which strongly adsorbs CO2 molecules. The H2O molecules on a fully saturated BaO surface (containing multiple layers of H2O molecules) readily aggregate, and Ba dissociation takes place on the hydrated surface, possibly resulting in a surface containing Ba defects.