First-principles modeling of H2CO3 molecular adsorption on CaSiO3(001) surface for application in the sequestration and utilization of CO2

This work employed density functional theory (DFT) to further study the adsorption of H2CO3, HCO3−, and CO32− on the CaSiO3(001) surface, which could provide additional insights into the mechanism of carbonation on the CaSiO3 surface. It was concluded that the carbonation of CO2 promoted carbon sequestration, whereby the aqueous carbonation route increased the reaction rate substantially compared to direct gas–solid carbonation. H2CO3 is more conducive to CO2 sequestration, which can be attributed to the interaction of H atoms with the surface. Further, H2CO3 can be converted into HCO3− or CO32− on the CaO-terminated (001) surface, whereas only HCO3− was formed on the SiO-terminated (001) surface. All the adsorption energies of H2CO3 were negative, suggesting that H2CO3 adsorption was energetically stable and spontaneous. The most likely adsorption model of HCO3−, having negative adsorption energy, was the one adsorbed on the SiO-terminated (001) surface, in which HCO3− is transformed into CO32−. The other adsorption models of HCO3− and all the adsorption models of CO32− have positive adsorption energies. Considering the adsorption process of H2CO3, HCO3− and CO32− adsorption reactions may occur successively to some extent depending on the environment.