Pore-structure regulation of biomass-derived carbon materials for an enhanced supercapacitor performance

Herein, we report a dual-porogen synthesis strategy to fabricate a micro-/meso-/macroporous carbon material for supercapacitors from biomass. The hierarchically porous carbon material was produced in a facile way by pyrolyzing C₁₀H₁₄N₂Na₂O₈/KOH (dual-porogen) and walnut peel (biomass carbon source) along with HCl solution etching. Such an admirable dual-porogen strategy opened up the closed pores and broadened the range of pore distribution for the carbon material from 0.55-1.76 nm to 0.59-2.53 nm as the mass ratio of walnut peel and C₁₀H₁₄N₂Na₂O₈ increased from 1 : 0 to 1 : 2, making up for the shortcomings of the narrow microporous distribution caused by the use of potassium hydroxide exclusively. As expected, the hierarchically porous carbon materials with a regulated structure with an appropriate pore volume, broadened pore-size distribution, ultrahigh specific surface area, as well as the effective hetratom dopping manifested its remarkable capacitor performances. The highest specific capacitance for a porous carbon material achieved was 557.9 F g^-1 (at 1 A g^-1) and 291.0 F g^-1 (at 30 A g^-1). The highest power density could reach up to 5679.62 W kg^-1, and energy density achieved was 12.44 W h kg^-1, thus greatly promoting its use in the design and synthesis of high-performance electrode materials for supercapacitors.