Sugar beet pulp derived oxygen-rich porous carbons for supercapacitor applications

As a low-cost biomass, sugar beet pulp (SBP) was employed to prepare new activated porous carbons by microwave-assisted hydrothermal method followed by chemical activation with Mg(CH3COO)2⸱4H2O or ZnCl2 as activation agents. Various characterization techniques were employed to reveal the surface chemistry and morphology of the porous carbons. The porous carbons have micro and mesoporous structures according to the N2 adsorption-desorption isotherms and the highest specific surface area (SBET) was reached up to 950 m2/g. The oxygen content of porous carbons was proposed by elemental analysis and FT-IR spectroscopy. The oxygen-rich activated carbons exhibited very high methylene blue (MB) adsorption capacity up to 270.14 mg/g. The as-prepared activated sample exhibits high specific capacitance (263 F/g in 6 M KOH). A symmetric supercapacitor was assembled and researched in different electrolytes. The symmetric cell exhibited a high energy density of 21.8 Wh/kg at a power density of 449 W/kg and good capacitance retention of 77% over 10,000 cycles in 1 M Na2SO4 electrolyte. The high electrochemical performance of the SBP-derived porous carbons shows that they are highly promising for supercapacitor applications.