Electrochemical Insertion of CO2 into Silver in a Large Extent

Jacques Simonet (1)

1 ISCR - Institut des Sciences Chimiques de Rennes

The reduction of solutions of carbon dioxide (saturated at the room temperature in organic polar solvents such as acetonitrile, AN, or N,N-dimethylfomamide, DMF, containing tetraalkylammonium salts TAAX) was achieved at smooth silver electrodes. Under these conditions, reduction steps were obtained beyond -1.7 V vs Ag / AgCl with exact potentials depending on the size of TAA+ cations. An unexpected behaviour is noticeable with tetramethylammonium salts (TMA+X-) leading to a progressive electrode inhibition upon scans or fixed potential electrolysis at E < -2V. These results are in agreement with the formation of a thick layer of the form \Ag-CO2-,TMA+\ strongly sensitive to di-oxygen, water, organic π-acceptors; this layer is considered as a reducing reagent of low chemical stability and can be oxidized before silver. Placed under pure argon atmosphere, the layer decomposes – presumably by instability of TMA+ in reducing media that permits trapping of large superficial amounts of CO2 in the material supposing the formation of multi-layers of CO2 (up to 5×10- 6 mol cm- 2). These novel \silver-CO2\ materials could be seen as dual catalytic-electrophilic electrodes

Mots clés: Ag-CO2 dual materials; Silver electrodes; modified electrodes; cathodic carboxylation

Domaines: Chimie; Matériaux

Jacques Simonet. Electrochemical Insertion of CO2 into Silver in a Large Extent. Electrochemistry Communications, 2015, 58, pp.11-14. ⟨10.1016/j.elecom.2015.05.011⟩. ⟨hal-01158457⟩