Revealing the different performance of Li4SiO4 and Ca2SiO4 for CO2 adsorption by density functional theory

To reveal the difference between Li4SiO4 and Ca2SiO4 in CO2 adsorption performance, the CO2 adsorption on Li4SiO4 (010) and Ca2SiO4 (100) surfaces was investigated using density functional theory (DFT) calculations. The results indicate that the bent configuration of the adsorbed CO2 molecule parallel to the surface is the most thermodynamically favorable for both Li4SiO4 and Ca2SiO4 surfaces. The Li4SiO4 (010) surface has greater CO2 adsorption energy (E-ads = -2.97 eV) than the Ca2SiO4 (100) surface (E-ads = -0.31 eV). A stronger covalent bond between the C atom of adsorbed CO2 and an O-S atom on the Li4SiO4 (010) surface is formed, accompanied by more charge transfer from the surface to CO2. Moreover, the Mulliken charge of O-S atoms on the Li4SiO4 (010) surface is more negative, and its p-band center is closer to the E-f, indicating O-S atoms on Li4SiO4 (010) are more active and prone to suffering electrophilic attack compared with the Ca2SiO4 (100) surface.

Automated summary

The difference in CO2 adsorption performance between Li4SiO4 and Ca2SiO4 was revealed through density functional theory calculations. The results showed that the bent configuration of the adsorbed CO2 molecule parallel to the surface was the most thermodynamically favorable, and that Li4SiO4 had higher CO2 adsorption energy, stronger covalent bond, and more charge transfer compared to Ca2SiO4.