Hierarchical porous nitrogen-doped carbon nanosheets derived from zinc-based bioMOF as flexible supercapacitor electrode

Abstract

We propose an efficient and flexible supercapacitor electrode material based on hierarchically structured nitrogen-doped graphene-like carbon nanosheets (H-NCNs) with accordion-like shape. H-NCNs were obtained by pyrolyzing zinc-based biometal–organic frameworks (Zn-bioMOFs) and using urea as nitrogen source at high temperature (800 °C) under nitrogen atmosphere, and Zn-bioMOFs were synthesized using biomass molecules, i.e., curcumin. Inheriting from the features of Zn-bioMOF, H-NCNs showed hierarchical structures and unique accordion-like morphology. By changing the urea dosage, the nitrogen-doping degree and porosity of H-NCNs were regulated, optimizing the supercapacitive performance. H-NCNs-8 prepared with Zn-bioMOF/urea mass ratio of 1:8 exhibited high specific capacitance and superior rate capability (293 F g−1 at 0.25 A g−1 and 188 F g−1 at 50 A g−1). The H-NCNs-assembled symmetric supercapacitor offered long cycle life of over 40,000 cycles at 2 A/g and high energy density of 17.6 Wh kg−1 at 250 W kg−1, outperforming most carbon nanomaterial-related ones. Accordingly, the proposed flexible interdigital solid microsupercapacitor demonstrated high areal capacitance, high areal energy densities, and long cycle stability. The present work can provide promising application prospects of MOFs in the field of supercapacitors and flexible electronics.