A new route for the fabrication of corn starch-based porous carbon as electrochemical supercapacitor electrode material

A new route has been developed for the fabrication of porous carbon from corn starch by a two-step process: hydrothermal carbonization and chemical activation with H3PO4. The as-prepared porous carbons were characterized by scanning electron microscopy, powder X-ray diffraction, fourier transform infrared spectra, C, H, N, O, S analyzer, N2 adsorption, zeta potential measurements, cyclic voltammetry and galvanostatic charge/discharge techniques. A blocky structure morphology of the porous carbon was achieved. The porous carbons showed a high specific surface area of 1239 m2 g−1 and a large pore volume of 1.40 cm3 g−1. The electrode delivered higher specific capacitance (144 F g−1) and energy density (19.9 Wh kg−1 at a power density of 311 W kg−1) than commercial porous carbon at a current density of 0.625 A g−1 in 6 mol L−1 KOH electrolyte. Also, the supercapacitor device exhibited superior cycling stability. The results demonstrated that corn starch-based porous carbons will be a kind of promising electrochemical supercapacitor electrode materials.