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

Abstract

AbstractOrganic 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.