A flake-like N, O co-doped hierarchical porous carbon derived from chitin with enhanced supercapacitance

Abstract

Biomass-derived porous carbon materials are considered as suitable candidate for supercapacitors (SCs). However, it is desirable but relatively challenging to find a suitable biomass to prepare porous carbon material for SCs with ultrahigh specific surface area, optimal hierarchical porous structure and abundant heteroatom content. Herein, we provide a facile and low-cost strategy using chitin as carbon precursor and KOH as activator to prepare N, O co-doped hierarchical porous carbon (HPC). The obtained HPC shows the original stacked 2D flakes structure of chitin with an ultrahigh specific surface area of 3362 m2 g−1 and a large pore volume of 2.090 cm3 g−1. KOH plays an important role in regulating the pore structure. N,O heteroatoms in chitin form a uniform self-doping. Benefiting from the influence of these physicochemical properties, the obtained electrode exhibits sufficient active sites and continuous conducting pathway, and provides a high specific capacitance of 395.9 F g−1 at a current density of 0.5 A g−1 in a three-electrode system using 6 M KOH aqueous electrolyte, which is quite superior and comparable to other biomass-based SCs. The assembled symmetrical SC has a considerable energy density of 25.58 Wh Kg−1 at a power density of 180 W Kg−1 and an excellent cycle stability (91.67% after 5000 cycles at 5 A g−1). Therefore, this strategy provided a green and sustainable chitin resource for large-scale synthesis of HPC to construct high performance SCs and other high value-added energy storage devices.