Efficient cathodic carboxylation of graphene: Building a new versatile material

• Preparation of carboxylated graphene as a new material
• New three-dimensional electrodes
• Easy electrode modification by redox groups
• Hydrophilization of carbonaceous materials
• Possible applications both in organic and aqueous media

Carbon dioxide is known to be poorly reactive under cathodic conditions. When glassy carbon-graphene electrodes are put in contact with a saturated solution of CO2 in N,N-dimethylformamide (DMF) containing tetrabutylammonium salts (TBAX) and polarized at potentials < − 1.7 V vs. Ag/AgCl (i.e. before own reduction of CO2), their reduction steps vanish and a large sudden inhibition takes place during further recurrent scans. This suggests that the principal electrode reaction is the cathodic charge of graphene resulting in poly-nucleophilic species followed by their reaction with electrophilic CO2 in solution. A quite dense poly-carboxylation of the material is chemically confirmed. The grafting of a large panel of reactive electrophiles (eventually carrying a redox group) on these graphene-based carboxylate-covered surfaces was achieved and allowed on the easy building of a wide variety of modified electrodes. The enhanced hydrophilicity of those materials renders possible their use in aqueous media.

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