Doping of cathodically polarized glassy carbon by natural graphite. A simple procedure for overlaying different carbons with electrochemically modifiable graphene layers

The reduction of graphite (at ca. −2 V vs. Ag/AgCl, in DMF containing tetraalkylammonium salts) deposited onto smooth glassy carbon leads to intense graphite exfoliation that can be monitored through voltammetric scans or by fixed-potential electrolyses (E < −1.8 V). These simple and extremely efficient processes result in very stable modified carbon surfaces exhibiting simple and astonishingly reproducible voltammetric responses (both in nature and intensity). The reduction peaks assigned to the cathodic doping of deposited graphene layers are found to be proportional to the scan rate. The modification of these graphene-like surface structures in two types or reactions: with a series of organic electrophiles (in the reaction with doped graphene that acts as a poly-nucleophile) or with in situ generated benzyl-type radicals was successfully achieved and compared with the results obtained on smooth carbon surfaces. Striking examples with additions of hexylferrocene, benzylic derivatives of anthraquinone, anthracene and perylene, and of para-substituted benzyls (R = NO2, I, Br, F) certainly underline the interest for these new materials.