Biomass-derived graphitic-like hierarchical porous carbon for electrochemical supercapacitor application

Abstract

High conductivity and applicable pore size are typically anticipated as key features for high-performance capacitive carbon electrodes in supercapacitor applications. However, these desired characteristics often conflict with each other, making incorporating both into a single carbon material challenging. Herein, graphitic-like hierarchical porous carbon (GHPC) was synthesized through a straightforward two-step pyrolysis process, utilizing pumpkin skin as the precursor without activating agents. We found that in contrast, to single pyrolysis under N₂ atmosphere, further annealing under H₂ gas effectively improves specific surface area and creates a graphitic-like hierarchical porous structure with mesopores, achieving an effective electrode potential for supercapacitors. GHPC's unique graphitic-like hierarchical porous structure contributes to excellent electrochemical performance achieving a specific capacitance of 274 Fg⁻¹ and exceptional rate capability of 67 % at 1 Ag⁻¹. Furthermore, GHPC showcased an outstanding cyclic stability of 95.7 % at current density of 2 Ag⁻¹ after 5000 cycles in 1 M KOH analyte, comparable to the state-of-the-art chemically activated biomass-derived carbon. These results emphasize the potential of biomass-derived graphitic-like hierarchical porous carbon as a promising electrode material for high-performance supercapacitors.