Porous carbons

Abstract

Porous carbon is provided which is a carbonization and optionally an activation product of a precursor resin, which has a pore structure that, as estimated by nitrogen adsorption porosimetry, comprises micropores and mesopores/macropores, said micropores and mesopores/macropores being in a bimodal distribution with few pores of size 2-10 nm, and the mesopores/macropores providing escape routes for volatile products during carbonization of the precursor resin. The porous carbon can be made by a method which comprises (a) forming a precursor resin by reacting a nucleophilic component which comprises a phenolic compound or a phenol condensation prepolymer optionally with one or more modifying reagents with an electrophilic cross-linking agent selected from formaldehyde, paraformaldehyde, furfural and hexamethylene tetramine in solution in a pore former e.g. ethylene glycol so that a phase separation occurs between high molecular weight domains and voids of lower molecular weight material and the pore former increases the material in the voids and gives rise to the mesopores in the precursor resin; (b) removing the pore former from the precursor resin; and (c) carbonizing the precursor resin in an inert atmosphere at a temperature from 600° C. upwards, micropores developing during said carbonization so that the carbonized material comprises (a) micropores of diameter of up to 2 nm and (b) mesopores of diameter of 2-50 nm and optionally macropores of diameter >50 nm.