Successful application of a commercial cationic surfactant mixture (benzalkonium chloride) as porosity stabilizer in porous carbons fabrication

Abstract

Porous carbons (BSPCs) were obtained by carbonization of resorcinol-formaldehyde gels in the presence of cationic surfactants mixture (benzalkonium chloride) which act as porosity stabilizer. The application of an inexpensive industrial grade surfactant mixture as porosity stabilizer permits obtaining porous carbons with well-developed micro and mesoporosity at low cost. The stabilizing effect on the sol–gel nanostructure allows maintaining the gels porosity during conventional air drying, simplifying the production of porous carbon by making unnecessary complex drying procedures (e.g. supercritical drying), cumbersome solvent exchanges, and long curing times. The carbonization process of BSPCs studied by TGA shows that the stabilizer and non-carbon elements (hydrogen and oxygen) are only eliminated during pyrolysis at temperature above 600 °C. The BSPCs morphological and textural properties were studied by scanning electron microscopy and nitrogen physisorption isotherms. The BSPCs present large specific surface areas (up to 645 m2/g) containing mesopores and micropores. Furthermore, the pore distribution and morphology depend on the monomer (resorcinol) to stabilizer (benzalkonium chloride) ratio. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to study the electrochemical properties of the carbon materials. The BSPCs exhibit a large specific capacitance (up to 179 F/g at 2.8 mHz in 1 M H2SO4) The results suggest that porosity stabilization of resorcinol/formaldehyde gels could be performed using different cationic surfactants, even commercial mixtures like benzalkonium chloride.