Conditions for a large cathodic sequestration of carbon dioxide into glassy carbon. Generation of a carbon poly-carboxylate versatile material
Résumé
Carbon dioxide (being one of the most important pollutants of modern civilisations) is known to be poorly reactive under electron transfer. At a glassy carbon electrode, a saturated solution of CO2 in N,N,- dimethylformamide (DMF) containing tetramethylammonium salts exhibits a large reduction step (threshold a about −1.7 V vs. Ag/AgCl). This step progressively vanishes upon recurrent scans. This behavior suggests that themain electrode reaction is the cathodic charge of GC (allowing the formation of a poly-nucleophilic species) followed by its reaction with electrophilic CO2 species. A dense poly-carboxylation of the material is confirmed by its derivatization with organic electrophiles (formation of redox-marked esters). Moreover, the destruction of the carboxylate layer could be simply achieved by anodic oxidation of this material (analogous to a non-Kolbe reaction with evolution of CO2). This supports a very large multi-layer character of carboxylation deeply affecting the carbon bulk.