Facile and fast polyaniline-directed synthesis of monolithic carbon cryogels from glucose

The development of simple, rapid and sustainable synthesis for carbon cryogels with controllable properties is highly desired in various applications fields. Herein, a template-free hydrothermal synthesis of monolithic nitrogen-doped carbon cryogels was developed, where glucose was used as the carbon precursor and polyaniline (PANI) as nitrogen source and a novel crosslinking agent. The monolithic hydrogels can be formed in only 2h at a low hydrothermal temperature (140 degrees C), the shortest time and the lowest temperature for the hydrothermal synthesis of monolithic hydrogels up to now. During the hydrothermal process, the crosslinking effect of PANI resulted in the formation of a 3D hydrogel network composed of interconnected coral-like fibers. The structural properties and surface chemistry can be tuned easily by changing the aniline concentration and carbonization temperature, making carbon cryogels a hierarchically porous structure with nanofiber diameter of 60-200 nm and a high specific surface area of similar to 900 m(2)g(-1). The resulting carbon cryogels exhibited an excellent CO2 uptake capacity of 4.12 mmol g(-1) at 25 degrees C under 1 atm (higher than most of the hydrothermal carbons reported without activation and comparable to those with KOH activation), good recyclability and CO2 /N-2 selectivity of 9.2.