Construction of Oxygen-Rich Carbon Foams for Rapid Carbon Dioxide Capture

As carbon dioxide (CO₂) adsorbents, porous materials with high specific surface areas and abundant CO₂-philic groups always exhibit high CO₂ capacities. Based on this consensus, a category of oxygen-rich macroporous carbon foams was fabricated from macroporous resorcinol-formaldehyde resins (PRFs), which were obtained via an oil-in-water concentrated emulsion. By the active effect of potassium hydroxide (KOH) at high temperatures, the resultant carbon foams (ACRFs) possessed abundant micropores with rich oxygen content simultaneously. At the same time, most of the ACRFs could retain the marcoporous structure of their precursor. It is found that porosity of ACRFs was mainly determined by carbonization temperature, and the highest specific surface areas and total pore volume of ACRFs could reach 2046 m²/g and 0.900 cm³/g, respectively. At 273 k, ACRFs showed highest CO₂ capacity as 271 mg/g at 1 bar and 91.5 mg at 15 kPa. Furthermore, it is shown that the ultra-micropore volume was mainly responsible for the CO₂ capacities of ACRFs at 1 bar, and CO₂ capacities at 15 kPa were mainly affected by the oxygen content. It is also found that the presence of macropores would accelerate ACRFs adsorbing CO₂. This study provides ideas for designing a porous CO₂ adsorbent.