Synthesis of N-doped carbon nanosheets with controllable porosity derived from bio-oil for high-performance supercapacitors

Abstract

Bio-oil, an oxygen-enriched precursor, is the liquid product from the fast pyrolysis of abundant and renewable biomass. Herein, nitrogen-doped porous carbon nanosheets (NPCS) with a unique interlinked architecture were synthesized successfully from bio-oil. The optimized sample shows a high specific surface area of 2566 m² g⁻¹, large pore volume (2.108 cm³ g⁻¹), tunable hierarchical micro-/mesoporous structure and considerable content of heteroatoms (∼5.83 at% N and ∼9.78 at% O). Benefitting from the favorable characteristics mentioned above, it exhibits a prominent specific capacitance of 289 F g⁻¹ at 0.5 A g⁻¹ and excellent rate capability (84.1% capacitance retention at 10 A g⁻¹) in 6 M KOH. In addition, the electrode demonstrates superb cycling stability with only 3% capacitance loss after 10 000 cycles. The assembled symmetric supercapacitor can deliver a superior energy density of 21.0 W h kg⁻¹ at a high power density of 463.0 W kg⁻¹. These results highlight that the as-prepared samples have considerable potential for low-cost and renewable energy storage devices.