Dynamic Tailoring Porosity and Surface Chemistry of Ultramicroporous Carbon Spheres for Highly Selective Post-combustion CO Capture.

Carbon capture has emerged as a pivotal carbon neutrality technology for addressing greenhouse effect challenges. Porous carbons are one of the most promising adsorbents for CO capture and separation from flue gas, yet their traditional synthesis necessitates inert atmospheres to avoid oxidation, which greatly restricts the large-scale production at a low cost and advanced industrial applications. Herein, we propose an innovative pathway for large-scale fabrication of porous carbons via one-step pyrolysis in an air environment. Porosity and surface chemistry can be concurrently tailored by controlling the air-assisted pyrolysis process, and the optimization mechanism is unveiled in detail. The resultant materials feature well-interconnected hierarchical porosity with highly proportioned ultramicroporosity, uniform spherical morphology, and high surface heteroatom doping levels. By leveraging porosity and surface chemistry, the optimal sample exhibits superior CO capture behaviors of satisfactory CO uptake and ultrahigh selectivity. CO/N selectivity reaches up to 160 at 0.15 bar and 25 °C, and it still achieves up to 76 at 1.0 bar and 25 °C, ranking it in the top 5% of the reported porous carbons. We explore the correlations between porosity, surface heteroatoms, and CO capture behaviors. Porosity has a decisive function on CO capture capacity and selectivity, especially ultramicroporosity, and surface heteroatoms doping could have a positive promotion in selectivity caused by extra CO-philic sites. This work pioneers a feasible approach for large-scale directional design of functional porous carbons through air-assisted pyrolysis under mild conditions.