Facile preparation of hierarchical porous carbons with tailored pore size obtained using a cationic polyelectrolyte as a soft template

Hierarchical porous carbons (HPCs) were obtained by carbonization of resorcinol-formaldehyde (RF) gels prepared in the presence of a cationic polyelectrolyte as a soft template. The porosity of the gels is maintained during air drying due to the stabilizing effect of a cationic polyelectrolyte on the sol–gel nanostructure. The proposed method greatly simplifies the production of porous carbon by making it unnecessary to use complex drying procedures, cumbersome solvent exchanges, and long curing times. Additionally, pore size of the HPCs can be tailored (from mesoporous to macroporous range) by controlling the amount of polyelectrolyte in the initial stage of RF polymerization. The HPCs have a high specific surface area (up to 675 m2/g), large specific capacitance (up to 140 F/g) and areal capacitance (up to 0.1 F/cm2), in acidic media. Significantly retention of the specific and areal capacitances of 72% are observed at high scan rates of 200 mV/s, making it suitable as an active material for fast supercapacitor applications.

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► Hierarchical porous carbons (HPCs) are obtained.
► Cationic polyelectrolyte as a soft template is used in the synthesis of porous gel.
► The presence of the polyelectrolyte avoids the collapse of the wet gel during drying.
► HPC has a specific capacitance of 140 F/g and high areal capacitance of 0.1 F/cm2.
► HPC surface remains accessible at 200 mV/s with retention of the capacitance of 72%.