Characterization of carbon cryogel synthesized by sol–gel polycondensation and freeze-drying

Abstract

Resorcinol-formaldehyde (RF) cryogels were synthesized by sol–gel polycondensation of resorcinol with formaldehyde and freeze-drying was carried out with t-butanol. Carbon cryogels were obtained by pyrolyzing RF cryogels in an inert atmosphere. Characterization by nitrogen adsorption showed that carbon cryogels were micro and mesoporous materials with high surface areas ( 500 m 2/ g<S BET <750 m 2/ g ). Cyclic voltammetry experiments at various scan rates (2–200 mV s −1) have been performed to study the electrical double-layer charging of carbon cryogel electrodes in 0.5 mol dm −3 HClO 4 solution. It has been demonstrated that it is possible to divide further total specific capacitance into mesoporous and microporous specific capacitance by analyzing the linear dependence of the specific capacitance ( C) on the reciprocal of the square root of the potential scan rate ( ν −1/2), and linear dependence of the reciprocal specific charge (1/ C) on the square root of the potential scan rate ( ν 1/2).