Graphene membranes with pyridinic nitrogen at pore edges for high-performance CO₂ capture

Membranes based on a porous two-dimensional selective layer offer the potential to achieve exceptional performance to improve energy efficiency and reduce the cost for carbon capture. So far, separation from two-dimensional pores has exploited differences in molecular mass or size. However, competitive sorption of CO₂ with the potential to yield high permeance and selectivity has remained elusive. Here we show that a simple exposure of ammonia to oxidized single-layer graphene at room temperature incorporates pyridinic nitrogen at the pore edges. This leads to a highly competitive but quantitatively reversible binding of CO₂ with the pore. An attractive combination of CO₂/N₂ separation factor (average of 53) and CO₂ permeance (average of 10,420) from a stream containing 20 vol% CO₂ is obtained. Separation factors above 1,000 are achieved for dilute (~1 vol%) CO₂ stream, making the membrane promising for carbon capture from diverse point emission sources. Thanks to the uniform and scalable chemistry, high-performance centimetre-scale membranes are demonstrated. The scalable preparation of high-performance two-dimensional membranes opens new directions in membrane science.