Synthesis of natural heteroatom co-doped porous carbon by co-pyrolysis of kapok tree and peanut bran coupled with microwave activation.

The application of biomass-derived porous carbon in supercapacitors should focus on heteroatom doping and modulation of pore structure. This work presented a technique for synthesizing natural heteroatom co-doped porous carbon by co-pyrolysis coupled with microwave activation of the kapok tree (KT) and peanut bran (PB). PB is a natural heteroatom donor and a precursor of porous carbon. Some S-containing radicals and N-containing functional groups in PB are successfully retained in the biochar, facilitating heteroatom doping in NHDPC. When the mixing ratio of KT and PB is 1:1, the mesoporous volume of NHDPC-5PB can reach 1.81 cm3/g. Relative to the porous carbon NHDPC-0PB synthesized solely through KT pyrolysis, the mesoporous volume of NHDPC-5PB increases by 74.04 %. Moreover, the specific capacitance of NHDPC-5PB at 0.2 A/g attains 346.8 F/g, which is a 36.6 % increase compared to NHDPC-0PB. This study presents a new strategy to prepare natural heteroatom co-doped porous carbon by co-pyrolysis of heteroatom-rich biomass as a heteroatom donor with lignocellulosic biomass. [Display omitted] • Pyrolysis vapors widen pore tunnels and promote metal K etching. • Peanut bran is both a natural heteroatom donor and a porous carbon precursor. • NHDPC-5PB possesses 346.8 F/g at 0.2 A/g and 2807.32 m2/g specific surface area. • NHDPC-5PB shows a specific energy of 8.29 Wh/kg at a specific power of 124.95 W/kg. • Co-pyrolysis improves the retention of O, N, P, and S heteroatoms. [ABSTRACT FROM AUTHOR]