Simpler and greener grafting method for improving the stability of anthraquinone-modified carbon electrode in alkaline media

Black Pearls, a high surface carbon black, was modified by surface grafting of anthraquinone molecules. Firstly, the modification involved the adsorption of 2-aminoanthraquinone on the porous carbon powder. Secondly, the resulting powder was used to form a composite film electrode by mixing with a carbon additive and a binder. Thirdly, grafting of anthraquinone molecules was either electrochemically induced or left to occur spontaneously in aqueous acidic media. Overall, this procedure requires a much smaller volume of solvents and is simpler than the traditional method, which involves numerous washing steps with several organic solvents to remove unreacted species. The resulting anthraquinone modified electrodes, when tested in aqueous 1 M KOH, delivered a comparable specific capacitance and found to be more stable upon charge/discharge cycling than electrodes prepared by the traditional method. Our new electrochemical method allowed to improve the grafting efficiency and to decrease the amount of non-covalently adsorbed anthraquinone molecules, which are desorbed upon cycling. (C) 2014 Published by Elsevier Ltd.