We demonstrate a Fe- or Co-catalyzed synthesis of graphitic carbon aerogels from polyacrylonitrile that bypasses the use of supercritical fluid drying and takes place at lower temperatures (up to 1500 oC) compared to conventional graphitization (&gt;2400 oC). The process starts with the preparation of polyacrylonitrile-crosslinked iron and cobalt oxide xerogel powders via free-radical surface-initiated polymerization of acrylonitrile monomer on the network of the sol-gel derived metal oxide suspension. These wet-gel powders were dried under vacuum at 50 °C to yield xerogel powders, which were compressed into pellets. These pellets were then aromatized (300 °C, O2), and subsequently pyrolyzed at temperatures varying from 800 °C to 1500 °C under Ar to give eventually Fe- or Co-doped graphitized carbons. Treatment with aqua regia removed the metal nanoparticles completely leaving behind pure graphite aerogels. High porosities, in the range of 60% to 70% v/v, were created during (a) the pyrolytic carbonization/graphitization of polyacrylonitrile, and (b) the removal of the metal. Characterization of all intermediates and final aerogels was carried out with solid-state 13C NMR, powder-XRD, Raman, TEM, SEM, and N2-sorption. Pure graphitic carbon aerogels had crystallite size in the range of 30-170 Å along the (111) plane, as calculated from powder-XRD data using the Scherrer equation. The crystallite width along the a-axis was in the range of 20-70 nm (from Raman data using Knight’s formula). These graphitic carbon aerogels showed stacking of up to 300 graphene layers with interlayer spacing of 3.36 Å (by TEM), and different nanomorphologies ranging from nanorods, nano-worms, nanofibers, and platelets (by SEM).

Monolithic graphitic-carbon aerogels from compressed powders of polyacrylonitrile-crosslinked iron oxide or cobalt oxide xerogels

ACS Spring Meeting 2021

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