The silver-graphene electrode. Building, stability, and catalytic efficiency

The cathodic polarization of smooth silver surfaces covered with natural graphite in dimethylformamide or acetonitrile containing tetraalkylammonium salts induces a spectacular exfoliation process followed by the release of almost all deposited graphite particles; the ablation goes practically to the last (few) layer(s) of graphene in immediate contact with Ag. Another efficient method to form such interesting interfaces consists in the deposit of graphite micro-flakes (pre-exfoliated at a mercury pool at - 2 V) by rubbing them onto small size Ag electrodes. The as-prepared silver/graphite surfaces are stable and exhibit reproducible voltammetric responses related to the reduction (doping) of remaining graphene layers. Their nature and intensities (not related to diffusion and quasi perfectly proportional to the scan rate) essentially depend on the size of the concerned TAA(+) cations. Total amounts of electricity involved in reduction/oxidation are quite stable and can be assigned to the doping of remaining graphene layers attached to Ag. The average coverage based on TAA(+) mono-layer formation was estimated to be <10(-9) Mol cm(-2). Chemical modifications of these carbon layers and first experiments concerning catalytic properties assigned both to graphene and Ag are presented. (C) 2014 Elsevier B.V. All rights reserved.