Directly synthesized nitrogen-and-oxygen–doped microporous carbons derived from a bio-derived polybenzoxazine exhibiting high-performance supercapacitance and CO2 uptake

[Display omitted] •A new bio-based benzoxazine monomer (VFBZ-CN) was successfully prepared.•VFBZ-CN benzoxazine monomer had lower thermal curing temperature (196 °C).•The poly(VFBZ-CN)-800 shows outstanding energy storage performance and CO2 uptake. We have prepared a new bio-derived benzoxazine monomer (VFBZ-CN) through condensation of natural renewably sourced compounds—vanillin, formaldehyde, and furfurylamine—and then investigated its thermal stability and thermal curing polymerization behavior before and after polymerization at various temperatures. Differential scanning calorimetry revealed that VFBZ-CN possessed a thermal curing temperature (196 °C) lower than those of the typical Pa-type (263 °C) and Boz-Va benzoxazine (223.8 °C) monomers, presumably because the presence of its cyano groups facilitated ring opening of the oxazine units. We used various techniques to examine the porosity, morphology, structure, chemical composition, and electrochemical properties of the poly(VFBZ-CN) materials obtained after carbonization at 700 and 800 °C and KOH activation [giving poly(VFBZ-CN)-700 and poly(VFBZ-CN)-800, respectively]. The gravimetric capacitance of poly(VFBZ-CN)-800 (506 F g−1) was higher than that of poly(VFBZ-CN)-700 (171 F g−1) at 0.5 A g−1 in KOH solution; the former also displayed outstanding cycling stability, with retention of 99.43% of its capacitance after 2000 cycles. We attribute the superior performance of poly(VFBZ-CN)-800 as a supercapacitor electrode to its more porous carbon structure and higher N and oxygen atoms contents. In addition to their potential for energy storage, these N- and O-doped microporous carbons displayed high degrees of CO2 capture.