Modification of carbon electrode in ionic liquid through the reduction of phenyl diazonium salt. Electrochemical evidence in ionic liquid

Abstract

Electrochemical reduction of the 4-nitrophenyl diazonium salt in ionic liquid media has been investigated at carbon electrode. The ionic liquid chosen for this study was 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI]. The cyclic voltammetry study demonstrated the possibility of the electrochemical grafting of the nitrophenyl groups onto carbon electrode after the reduction of its corresponding diazonium in ionic liquid. The electrochemical characterization of the modified electrode achieved on ionic liquid displays the presence of the nitrophenyl group at the carbon surface. Moreover, the surface concentration of the attached group obtained in this media was found to be around 1.7 × 10 −10 mol cm −2, this value may suggest the possibility of the formation of monolayer. Furthermore, the characterization of the modified electrode in [EMIM][TFSI] showed the conversion of some NO 2-phenyl groups to NHOH-phenyl. This observation could indicate the presence of surface interaction between the reduced NO 2-phenyl and the ionic liquid cation, thanks to the presence of acidic proton in the ionic liquid cation.