Adsorption of CO2on Model Surfaces of Cesium Oxides Determined from First Principles

Gradient-corrected periodic density functional theory was used to examine the bulk and low index surfaces of several cesium oxides (Cs 2 O, Cs 2 O 2, and CsO 2 ). The adsorption of CO 2 on those surfaces was explored. The cesium-terminated {001} surface of Cs 2 O had a weak affinity for CO 2 with an adsorption strength of only −4.1 kJ mol -1 . In contrast, the Cs 2 O {010} surface exposing both Cs and O atoms adsorbed CO 2 with a strength of −284 kJ mol -1 . The adsorption of CO 2 in the bridged configuration on the {001} and the {100} surfaces of Cs 2 O 2 exhibited adsorption strengths of −101 and −186 kJ mol -1, respectively. The oxygen-rich CsO 2 surface failed to adsorb CO 2 . Results from a Mulliken charge analysis are consistent with the traditional ranking of basicity: Cs 2 O > Cs 2 O 2 > CsO 2 .