Ab initio calculations of CO2 adsorption on β-C2S(100) and M3-C3S(001) surfaces: An exploration of early CO2 sequestration pathways

• Published in: Environmental research 2022-12, Vol.215, p.114412-114412, Article 114412
• Main Authors: Qi, Chongchong, Xu, Xinhang, Chen, Jie, Guo, Li, Chen, Qiusong
• Format: Article
• Language: English
• Subjects: Calcium silicates; CO2 adsorption; CO2 sequestration and uptake; First-principles calculations; Portland cement
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2022.114412

Investigating CO2 sequestration in cement-based materials is significant for achieving carbon neutrality in the cement and concrete industries. The early CO2 sequestration pathways on cement-based materials are fundamental for CO2 sequestration, which is not clear. Towards this, the adsorption behavior of CO2 on β-C2S(100) and M3-C3S(001) was investigated at the atomic level using density functional theory calculations, which were then compared with water adsorption results. The molecular adsorption configurations of CO2 on both β-C2S(100) and M3-C3S(001) were tilted from their initial configurations due to the influence of surface Ca and O atoms. The CO2 adsorption energy on M3-C3S(001) and β-C2S(100) were −0.458 eV and −0.426 eV, respectively, indicating adsorption on M3-C3S(001) was more energetically favorable. After CO2 adsorption, electrons were transferred from the surface to the CO2 molecule. Furthermore, the Ca–O bond orders of β-C2S(100) and M3-C3S(001) after CO2 adsorption were maximally decreased by 2.79% and 6.99%, respectively. A more significant adsorption influence on surfaces was found for H2O, with more negative adsorption energy, more evident electron transfer, and a greater decrease in bond order. The CO2 adsorption on β-C2S(100) and M3-C3S(001) were still spontaneous at 298 K and 1 atm. This study provides important theoretical insights into early CO2 sequestration at the atomic level, which has practical implications for the design of efficient CO2 sequestration technologies. [Display omitted] •CO2 adsorption on M3-C3S(001) was more energetically favorable than β-C2S(100).•H2O adsorption had a more significant influence on cement surfaces than CO2.•The reaction of hydrate with CO2 is a favored pathway for early CO2 sequestration.•CO2 adsorption on β-C2S(100) and M3-C3S(001) were spontaneous at 298 K and 1 atm.