Quantum chemical study of CO2 physisorption and chemisorption on EDA-grafted graphene oxide

Organic amine grafting on graphene oxide (GO) is a potentially good CO₂ adsorbent. The mechanism of CO₂ capture by ethylenediamine grafted GO (EDA-GO) is studied in detail by quantum chemical method in this article. A reasonable adsorbent model is constructed, and through electrostatic potential analysis, it is found that the larger negative electrostatic potential (GOEP/GOCA: N(180)/N(30) site) is a better potential adsorption site. The physical adsorption energies are also larger (−44.37 kJ/mol, −49.90 kJ/mol) at the larger negative electrostatic potential sites. The quantum chemical calculation of CO₂ adsorption is carried out at the optimal reaction site. Results show that EDA grafted on epoxy and carboxyl groups of GO have good adsorption performance for CO₂. The catalytic effect of H₂O in the atmosphere can significantly reduce the adsorption reaction energy, which only needs 20–45 kJ/mol. Compared with EDA-GOEP, EDA-GOCA has lower physical adsorption energy and chemical adsorption energy barrier. EDA-GOCA has good adsorption performance. Moreover, the desorption energy barrier (29.0 kJ/mol) is slightly higher than the adsorption energy barrier (23.3 kJ/mol), which is conducive to adsorption and desorption repeatedly. It is helpful in the recycling and reuse of adsorbents. For the adsorption of CO₂ by EDA-GO, the conversion of hydroxyl and epoxy groups to carboxyl groups is very important. This study would contribute to the development and design of solid CO₂ adsorbents based on GO. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.