Substrate-dependent performance of supercapacitors based on an organic redox couple impregnated on carbon

Two different carbon electrodes have been modified with 1,4,9,10-anthracenetetraone (AT) in order to produce composite electrodes combining the double layer capacitance of carbons and the redox capacity of the organic redox couple. Electrodes were prepared by impregnation of AT on both commercial high surface area functionalized carbon and on carbon black. Optimum loading amount, redox activity, and electrochemical potentials of AT were determined to be dependent on the substrate used, and the respective performances were characterized by cyclic voltammetry at different scan rates, and galvanostatic charge discharge experiments. Immobilized AT improves more than 50% of the total capacitances of both bare carbons, even after 1000 cycles at 200 mA g(-1). This increase is attributable to the use of AT, which can exchange up to four electrons, but is also surprisingly effective taking into account that no efforts were undergone to achieve covalent bonding. Although substantial loss of capacitance is observed for both modified carbons at higher rates, the results here discussed are a step forward to determine the contribution of covalent bond to carbon electrode performances and its benefits compared to loosely bound molecules, with the aim of optimizing supercapacitor electrodes based on this combination of materials. (C) 2012 Elsevier B.V. All rights reserved.