A theoretical simulation of carbon dioxide adsorption capture on amine-functionalized graphene oxides

Abstract

Amine-functionalized graphene oxides (AFGOs) are potential candidates for CO₂ capture applications, as the amine functional groups could act as effective sites, promoting CO₂ adsorption strength and selectivity. However, the CO₂ adsorption mechanism on AFGO appears to be ambiguous, particularly with no explicit identification of the chemically bonded species. In this work, density functional theory and microkinetic simulations were carried out to investigate the physical and chemical adsorption mechanisms and behavior between AFGO and CO₂. Our findings indicate that the van der Waals and hydrogen bonding (HB) interactions constitute physical binding modes between the aminated GO and CO₂. The chemical adsorption pathways on AFGO materials have been revealed by the transition state search method, in which the relevant CO₂ adsorption species, including carbamic acid and carbamate, and their formation conditions were theoretically identified on AFGOs. The chemisorption mechanisms have been recognized to be the nucleophilic interaction between GO-supported amines and CO₂, simultaneously assisted by the cooperative effect of multiple HB interactions. More specifically, the surface hydroxyl groups and water molecules can serve as proton transfer media and offer HB interactions, thus regulating the reaction activity and chemical adsorption species. This theoretical work presents a new insight into CO₂-AFGO interaction mechanisms, which is valuable for designing aminated GO adsorbents.