Abstract
The present study reports advanced nitrogen-enriched carbon aerogels (N-CAs) that have been derived from the pyrolysis of polybenzoxazine cross-linked graphene oxide-chitosan aerogels. The role of the BZ chemical structure and the impact of KOH chemical activation of the obtained N-CAs on the BET specific surface area, porosity characteristics, and CO2 adsorption capacity have been studied. The impact of the molecular structure of benzoxazine precursors on the CO2 adsorption behavior has been investigated using two benzoxazines with different chemical forms, namely, main-chain type benzoxazine polymer MCBP(BA-tepa) and star-like telechelic benzoxazine SLTB(4HBA-t403). The N-CA derived from the pyrolysis of GO-CTS- SLTB(4HBA-t403) exhibited a maximum 1218 ± 14 m2 g–1 of BET surface area as well as a considerable total pore volume, micropore volume, and average pore diameter of 0.75 cm3 g–1, 0.65 cm3 g–1, and 0.87 nm, respectively. The investigations indicated that MCBP(BA-tepa) was more favorable for CO2 adsorption than SLTB(4HBA-t403). The N-CAs exhibited excellent adsorption selectivity of CO2 from the CO2/N2 mixture. The resultant N-CA from the pyrolysis of GO-CTS-MCBP(BA-tepa) aerogel at 800 °C showed a high CO2/N2 selectivity of 17.7 ± 0.1 with an excellent reversible adsorption capacity of ∼6.1 mmol CO2 g–1 at 25 °C and 100 kPa. Upon KOH activation of the N-CA, the CO2/N2 selectivity increased to 21.3 ± 0.3, and a maximum adsorption capacity of ∼ 7.34 mmol CO2 g–1 was obtained; thus, these types of N-CAs become one of the promising sorbents that have been recorded for significant CO2 adsorption capacities in the literature.