Low-cost production of mesoporous carbon/carbon composite cryogels

A carbon/carbon (C/C) composite cryogel was prepared by dispersing cotton fibers (CF) in a resorcinol and formaldehyde (RF) sol, followed by solvent exchange with t-butanol, freeze drying and pyrolysis under inert atmosphere. The mass ratio of CF to RF was increased from 0% up to 25% to observe the mesopore structure change of C/C composites under a selected RF synthesis condition. The porous structures were characterized by nitrogen adsorption and mercury porosimetry, and their structure was observed by a scanning electron microscope (SEM). The mesopore diameter of the C/C composites increases slightly with the increase of CF content. The preparation can increase the mesopore volume and also reduce the production cost compared with carbon cryogels prepared without CF. The SEM images show that nanoporous gel spheres appeared after the freeze drying step. These spheres are converted to be nanoporous carbon spheres with surrounding nanocages, and CF are converted into carbon fibers at the same time by pyrolysis.