Design of B/N Co-doped micro/meso porous carbon electrodes from CNF/BNNS/ZIF-8 nanocomposites for advanced supercapacitors

Boron (B) and nitrogen (N) co-doped 3D hierarchical micro/meso porous carbon (BNPC) were successfully fabricated from cellulose nanofiber (CNF)/ boron nitride nanosheets (BNNS)/ zinc-methylimidazolate framework-8 (ZIF-8) nanocomposites prepared by 2D BNNS, ZIF-8 nanoparticles, and wheat straw based CNFs. Herein, CNF/ZIF-8 acts as versatile skeleton and imparts partial N dopant into porous carbon structure, while the introduced BNNS can help strengthen the hierarchical porous superstructure and endow abundant B/N co-dopants within BNPC matrix. The obtained BNPC electrode possesses a high specific surface area of 505.4 m²/g, high B/N co-doping content, and desirable hydrophilicity. Supercapacitors assembled with BNPC-2 (B/N co-doped porous carbon with a CNF/BNNS mass ratio of 1꞉2) electrodes exhibited exceptional electrochemical performance, demonstrating high capacitance stability even after 5 000 charge-discharge cycles. The devices exhibited outstanding energy density and power density, as well as the highest specific capacitance of 433.4 F/g at 1.0 A/g, when compared with other similar reports. This study proposes a facile and sustainable strategy for efficiently fabrication of rich B/N co-doped hierarchical micro/meso porous carbon electrodes from agricultural waste biomass for advanced supercapacitor performance.