Decisive role of pore-edge termination in determining the CO2 selectivity of Å-scale pores in graphene

Zero-dimensional pores in graphene hold strong promise for carbon capture, yet the role of pore-edge functional groups remains poorly understood. Using molecular dynamics simulations and potential-of-mean-force calculations, we show that pore-edge chemistry determines whether Å-scale pores are selective. Oxygen-functionalized pores (O-pores) exhibit highly selective CO 2 /O 2 transport, whereas similarly sized hydrogen-terminated pores (H-pores) are non-selective. This difference arises from markedly stronger CO 2 -pore interactions in O-pores, where CO 2 adsorbs at the pore mouth for up to a nanosecond, compared to residence times up to two orders of magnitude shorter in H-pores. We further develop a velocity-corrected transition-state-theory model that accurately predicts gas transport through both pore types by accounting for molecule-pore interactions at the transition state. These findings provide a robust framework for rational membrane design and highlight the benefits of oxidative pore-formation protocols for carbon-capture membranes.