Highly porous N-doped activated carbon monoliths (ACMs) are fabricated by carbonization and physical activation of mesoporous polyacrylonitrile (PAN) monoliths in the presence of CO₂. The monoliths exhibit exceptionally high CO₂ uptake; 5.14 mmol g⁻¹ at ambient pressure and temperature and 11.51 mmol g⁻¹ at ambient pressure and 273 K.

Mesoporous polyacrylonitrile (PAN) monolith has been fabricated by a template-free approach using the unique affinity of PAN towards a water/dimethyl sulfoxide (DMSO) mixture. A newly developed Thermally Induced Phase Separation Technique (TIPS) has been used to obtain the polymer monoliths and their microstructures have been controlled by optimizing the concentration and cooling temperature.