Formation of a Bifunctional Redox System Using Electrochemical Reduction of Platinum in Ferrocene Based Ionic Liquid and Its Reactivity with Aryldiazonium

Abstract

The electrochemical reduction of platinum in ferrocene based ionic liquid, 1-ferrocenylethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([FcEMIM][TFSI]), has been investigated on both macro and micro platinum electrodes. The electrochemical and X-ray photoelectron spectroscopy (XPS) analyses of the reduced platinum evidence the presence and the intercalation of the ferrocene imidazolium into the platinum surface. The resulting metal-organic phase was anticipated to be of the general formula [Ptn(δ-), FcEMIM(δ+)]. Next, the spontaneous reaction of the electrogenerated Pt phases as reducing agent with phenyl diazonium salts was performed. The "reduced platinum phase" reacts with nitrophenyl diazonium salts, without applying any external potential, and conduces to the attachment of nitrophenyl groups onto the surface. Detailed experiments based on cyclic voltammetry and XPS were carried out to follow the occurrence of the grafting. Indeed, both experiments evidence the presence of ferrocene and nitrophenyl groups on the Pt surface. As a result, a bifunctional active surface containing two redox systems has been obtained.