Correlation between structure and oxidation behavior of carbon aerogels

• The carbon aerogels were prepared using the sol-gel polymerization in the solvent saturated vapor atmosphere.
• The oxidation reaction of carbon aerogel was studied by temperature-programmed TGA analysis at different heating rates.
• The variation of activation energy with progress of the oxidation reaction was calculated using isoconversional methods.
• The complex and multi-step nature of the oxidation was revealed by the observed change in activation energy.
• The relative significance of microstructural parameters on the overall rate of oxidation was studied.

In order to investigate the effect of microstructure on oxidation behavior of carbon aerogel, three samples with different pore structure were prepared. These carbon aerogel samples were synthesized via the novel method of sol-gel polymerization in solvent-saturated vapor atmosphere and the following pyrolysis step. The structural characteristics of the unreacted carbon aerogel and the overall rate of oxidation have determined using pore structure analysis methods and thermo-gravimetric analysis (TGA) under non-isothermal condition, respectively. It was found that the initial pore structure and the reaction condition have an important effect on the reaction pathway. The changes in apparent activation energy with the degree of conversion are presumably due to the changes in the oxidation control mechanisms with progress of the reaction and further reveal a multistep kinetic process. So, two different processes were suggested to control the global oxidation kinetics, their relative contribution being temperature and structure-dependent. The reported study may be relevant towards energy storage applications of carbon aerogel at high temperature where the pore structure plays a key role.