Adsorption of CO2 Molecule on the (MgO)9 and (CaO)9 Nanoclusters; A Theoretical Study

Binding configurations of CO2 on (MgO)9 and (CaO)9 cluster models are investigated by means of density functional theory model calculations. The results show that CO2 adsorbs as monodentate on MgO and CaO terrace site leads to formation of surface carbonates CO3 2- . Marginal differences in the binding stabilities between the CO2 molecule and surface O2- site were found to be significantly similar. The estimated adsorption energies are 1.47 eV and 1.52 eV at the (MgO)9 and (CaO)9 clusters, respectively. The similarity in binding energies is discussed in terms of cluster electropositivity. Adsorbed CO2, to (MgO)9 surface vibration frequencies are calculated and compared to the experiment.