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

Resorcinol-formaldehyde (RF) cryogels were synthesized by sol-gel polycondensation of resorcinol with formaldehyde and freeze-drying 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 < 700 m(2)/g). Cyclic voltammetry experiments at various scan rates (2 to 200 mV s(-1)) were carried out to study the electrical double-layer charging of carbon cryogel electrodes in 0.5 mol dm(-3) HClO4 solution. It has been demonstrated that the total specific capacitance can further be divided 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 (nu(-1/2)), as well as linear dependence of the reciprocal specific charge (1/C) on the square root of the potential scan rate (nu(1/2)).