Revealing the different performance of Li 4 SiO 4 and Ca 2 SiO 4 for CO 2 adsorption by density functional theory.

To reveal the difference between Li 4 SiO 4 and Ca 2 SiO 4 in CO 2 adsorption performance, the CO 2 adsorption on Li 4 SiO 4 (010) and Ca 2 SiO 4 (100) surfaces was investigated using density functional theory (DFT) calculations. The results indicate that the bent configuration of the adsorbed CO 2 molecule parallel to the surface is the most thermodynamically favorable for both Li 4 SiO 4 and Ca 2 SiO 4 surfaces. The Li 4 SiO 4 (010) surface has greater CO 2 adsorption energy ( E ads = -2.97 eV) than the Ca 2 SiO 4 (100) surface ( E ads = -0.31 eV). A stronger covalent bond between the C atom of adsorbed CO 2 and an O S atom on the Li 4 SiO 4 (010) surface is formed, accompanied by more charge transfer from the surface to CO 2 . Moreover, the Mulliken charge of O S atoms on the Li 4 SiO 4 (010) surface is more negative, and its p-band center is closer to the E f , indicating O S atoms on Li 4 SiO 4 (010) are more active and prone to suffering electrophilic attack compared with the Ca 2 SiO 4 (100) surface.