Meso- and micro- porous composite carbons derived from humic acid for supercapacitors

Herein, humic acid (HA), a kind of biomass (natural polymer), is firstly adopted as a raw material for synthesis of activated carbons (ACs) via a high-temperature activation procedure with KOH. Their porous textures as well as surface groups are fully characterized by N-2 sorption isothermal analysis, SEM, TEM, XPS and IR, respectively. The HA-derived ACs show very high specific surface areas (up to 2990.32 m(2)g(-1)). Furthermore, electrochemical studies such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD) are carried out to evaluate their specific capacitance and rate capability. It reveals that HA-derived ACs possess high specific capacitance (350 Fg(-1)) at a scan rate of 5 mVs(-1) in I M H2SO4, Moreover, supercapacitors based on HA-derived ACs demonstrate good cycling stability in which the 92% initial capacitance has been retained even after 9000 cycle numbers at a high current density of 1 A g(-1). (C) 2014 Elsevier Ltd. All rights reserved.