Functionalisation and chemical characterisation of cellulose-derived carbon aerogels

A series of nitrogen- and oxygen-functionalised carbon aerogels was produced from a carbon aerogel derived from cellulose acetate. Samples were oxidised by H₂O₂ or HNO₃ and/or enriched in nitrogen by reaction with gaseous ammonia or co-heating of the carbon aerogel and melamine. Porosity variations and morphology were monitored using N₂ adsorption and helium pycnometry. The surface chemistry was characterised by elemental analysis, FTIR and XPS spectroscopy, pH of the point of zero charge and acid/base titration. The prepared carbons are mainly mesoporous and show a moderate porosity development (S_BET between 160 and 300 m²/g). The applied chemical methods allow producing a wide range of functionalised carbon aerogels differing in terms of oxygen and nitrogen groups, their distribution and basicity. Both oxidation methods introduce a similar amount of oxygen, while the produced carbons differ in term of their acid/base character. Treatment with ammonia produces the most basic materials, which is partly due to the introduction of basic nitrogen groups, but also to the reduction of the acidic oxygen functionalities.