Efficient conversion of biomass waste to N/O co-doped hierarchical porous carbon for high performance supercapacitors

Aiming at the double carbon goals, the transfer of biomass waste to high value-added products for energy conversion and storage is strongly required. Herein, a N/O co-doped 3D hierarchical porous carbon is fabricated via an efficient KOH-assisted protocol to convert orange peels into high performance carbon-based electrode for supercapacitor application. KOH not only creates porous structure for high surface area, but also exposes the intrinsic nitrogen source buried in biomass for structural N-doping. Consequently, the resultant carbon possessed a hierarchical architecture with interconnected multiscale vacancies and optimized pore size distribution, together with a beneficial co-doping of N and O heteroatoms, thereby contributing to an intense surface entrapment, short ion transportation distance, fast mass transportation and sturdy skeleton. Gratifyingly, it is demonstrated as a satisfactory electrode for supercapacitor with excellent specific capacitance of 352 F g-1 at 0.5 A g-1, attractive rate capability of 71.6% capacitance retention at a 100-fold higher current density and superior cycling stability of only 0.5% loss in capacitance reservation after 10,000 cycles at an ultrahigh current density of 50 A g-1. By taking advantage of the inherent composition and structure of biomass, the conversion of orange peels to advanced carbon-based electrode materials open up a brand-new bioinspired design of structural doping functional carbon towards the field of energy storage.