▎ 摘　　要

Identifying stable systems with high CO2 adsorption capacity is an essential goal in CO2 capture and storage technologies. We have carried out a comprehensive first-principles study to explore the CO2 capture capacity of 16 representative metal-doped graphene systems where the metal dopants can be stabilized by single- and double-vacancies. The maximum number of adsorbed CO2 molecules was determined by a combination of adsorption energy and bond distance criteria. Generally, while the double-vacancy can bind metal dopants more strongly than the single-vacancy, single-vacancy graphene with metal dopants are better sorbents, with each Ca, Sc and Y dopant binding up to 5 CO2 molecules. CO2 capture involves significant charge transfer between the CO2 molecule and the dopant-vacancy complexes, where defective graphene acts as a charge reservoir for binding CO2 molecules. Some systems are predicted to involve the formation of a bent CO2 anion. Ca-doped single-and double-vacancy graphene systems, however, readily form oxides upon reaction with CO2, thus they are less reusable for CO2 capture.