Electrochemical alternatives to adapt the conventional procedures of surface functionalization to the local scale

International audienc

Redox properties and reactivity of a polythiophene-modified electrode in presence of ferrocene in solution or fixed onto the polymer network

A polymer-modified electrode (PME) was tested for the examination of the electrode reactivity in presence of an electroactive specie. Ferrocene (Fc) was chosen as redox probe and cyclic voltammetry (CV) was used to investigate the redox activity of the polymer. The polythiophene matrix used can be easily post-functionalized, allowing to investigate the redox behaviour of a surface-tethered ferrocene conducting polymer compare to the redox properties of the film when the ferrocene is free in solution. Results reported show dramatic changes in voltammetric patterns obtained at \u27organic electrode\u27 compared to Pt electrode. When Fc was in solution, the current peak ascribed to Fc oxidation at PME increases promptly as the conductivity of the film switch \u27ON\u27. When Fc units were grafted onto the polymer network, the quartz crystal microbalance shows that the Fc oxidation was assisted by the conducting polymer chain

Apports et limitations de la stratégie du greffage pour le stockage de l’électricité

For over two decades, the electrochemical storage of electricity has embarked upon its organic revolution. Pseudo-supercapacitors, redox supercapacitors and fully organic hybrid systems have already won the scientific and industrial communities, although further efforts are needed regarding their energy density and stability in order to be integrated into structures having a long service life (aeronautic, automotive, building industry, etc.). A recent strategy consists in grafting fast redox-active small molecules to a porous carbon network. Assembling these generic modular elements to infinity yields a wide range of possible combinations and specific rules must be followed in order to ensure that this grafting is beneficial. This article presents the contributions and limitations of grafting and concludes with a novel alternative to the grafting on carbon

Grafting of Quinones on Carbons as Active Electrode Materials in Electrochemical Capacitors

The electrochemical performance of electrochemical capacitors can be improved with electroactive quinone molecules. Systems based on redox active electrolyte as well as physisorbed and chemically grafted molecules have been investigated. In all these cases, carbon materials were used as substrate and electrode material. This short review will mainly describe work related to these systems and materials from the authors’ laboratories. Nonetheless, some important studies from other research groups will be discussed

Enhancing the performance of a diazonium-modified carbon supercapacitor by controlling the grafting process

The activated Norit carbon was modified by grafting the 4-nitrobenzenediazonium salt in the presence or in the absence of a radical scavenger (DPPH: 2,2-diphenyl-1-picrylhydrazyl) to produce modified carbon powders having different surface organic layers going from monolayer to multilayer. The surface chemistry and pore texture of carbon products were studied by TGA, chemical elemental analysis and nitrogen gas adsorption measurements. The resulting powders were used as active components in supercapacitors working in alkaline media to investigate the impact of the grafting on the electrochemical performances. Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the charge/discharge process in aqueous 1 M KOH. The present work demonstrates that the high double-layer capacitance and the low ionic resistance of the pristine carbon can be preserved by limiting the growth of the grafted layer with DPPH