A DFT Study on the Adsorption of CO2 Molecules on CaO(001) Surface at Different Coverages

The CO2adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structures at different coverages, the mechanism of CaO(001)surface carbonating into CaCO3has been explored. At low coverages(≤1/3 ML), CO2molecule prefers sitting in parallel pattern on the CaO(001) surface, while the structure of the CaO(001)surface remains unchanged. At medium coverage(4/9 ～ 2/3 ML), the repulsive interactions between oxygen atoms of CO2become stronger, and the calcium carbonation structure appears on the CaO(001) surface. At high coverage( ≥ 7/9 ML), the structure of the CaO(001) surface is deeply damaged, and a few CO2molecules have penetrated into the surface and bound to the O atom of the second layer(sub-surface), eventually forming the layered structure of CaCO3.Additionally, herein has discussed the simulation of HREELS and thermodynamical stability of these structures at different coverages.