The dynamics of the flexible pore functional group leading to dynamic PLD must be associated with a competitive uptake of CO2; otherwise, the selective gating of CO2 discussed above would not be feasible. To understand this, the density distributions of CO2 and O2 on the porous graphene lattice (pore-13) were analyzed (Figure ). It shows that CO2 adsorbs much more strongly than O2 in the entire temperature range (298-423 K). At 298 K, the CO2 population is 8-fold higher than that of O2 in the feed side of the pore, and a weak density peak on the permeate side is observed only for CO2. This competitive uptake is due to strong charge polarity in the C=O group, which attracts CO2 to electronegative O. As expected, the interaction weakens at higher temperatures, reducing the CO2/O2 occupancy ratio to 2.5 at 423 K. Similar trends are observed for pore-10 and pore-16 (Supplementary Figures and).