This work underscores the effectiveness of introducing functional heteroatoms at the edges of pores of 2D oxidized graphene for improving CO₂/N₂ separation. The strong affinity between pyridinic N and CO₂, coupled with the 2D nature of pores, enables high selectivity even in dilute CO₂ mixtures with a little sacrifice of permeance as compared to graphene membranes without NH₃ treatment. These results emphasized the challenges in simultaneously optimizing the gas permeance and selectivity for CO₂/N₂ separation in future study. The scalability and feasibility of this approach, utilizing gaseous reactants (O₃ for oxidation and NH₃ for pyridinic-N incorporation), make it an attractive candidate for large-scale carbon capture applications. The impressive CO₂/N₂ separation performance of pyridinic-N-substituted graphene membrane can be adaptive to multiple carbon sources, including concentrated emissions (from steel and cement plants, coal-fired power stations) and low CO₂ concentration (from aluminum production and natural gas processing). The techno-economic analysis of carbon capture indicated the cost of US$ 20 per ton_CO2 for concentrated CO₂ feed and US$ 76 per ton_CO2 for dilute CO₂ feed capture. The selective carbon capture technology in this work realized the separation of diluted CO₂ to improve the recycling of CO₂ so that the emission to atmosphere could be alleviated. This research on screening competitive sorption regimes can be applied to develop high-performance and cost effective CO₂ separation membranes, addressing critical global environ mental challenges.