Insight into molecular grafting of carbon aerogels for electrochemical capacitors applications

Molecular grafting of carbon aerogels, made from the polycondensation of resorcinol and formaldehyde, was studied in order to enhance their specific capacitance in electrochemical capacitors. Grafting of redox entities, anthraquinone, was performed via aryl diazonium reduction. While aryl diazonium salt to carbon aerogel molar ratio does not seem to have an impact on the number of chemisorbed or physisorbed anthraquinone, increasing reaction time, even up to 24 hours, leads to an increase of chemisorbed anthraquinone moieties. Physisorption of anthraquinone occurs at the initial stage of the modification and does not evolve with time or molar ratio. Interestingly, physisorbed and chemisorbed anthraquinone moieties are all electroactive and despite an inevitable decrease of the specific surface area, an important increase of the specific capacity of anthraquinone functionalized carbon aerogel up to 84 mAh.g -1 is observed.