The production of hydrochar-based hierarchical porous carbons for use as electrochemical supercapacitor electrode materials

A comparative study of various hydrochar-based porous carbons was carried out. These porous carbons, synthesized from biomass by H3PO4, NaOH and KOH activation, were examined for use in supercapacitors. The micropores and mesopores had been introduced into the hydrochar simultaneously. Porous carbons exhibited different electrochemical performance due to the difference of their porosity. The prepared carbons showed a hierarchical porous structure, the corresponding BET surface areas and pore volumes were 1355–3322 m2/g and 1.45–2.53 cm3/g. The highest specific capacitance was 179.4 F/g at a current density of 6.25 A/g, and appeared to be a promising electrode material for supercapacitors.