ELECTROCHEMICAL PREPARATION OF GOLD/POLYANILINE ELECTRODES THROUGH ELECTROGRAFTING OF DIAZONIUM SALTS

摘要: The functionalization of conductors and semiconductors using organic molecules is a very important issue in the development of novel organic/inorganic heterostructures suitable as materials in biosensors, clinical diagnostics and biological sensing. In this context, to obtain a stable and durable bond with the surface, the electroreduction of aryldiazonium salts is a promise alternative to conventional techniques (as Self Assembled Monolayer), also to ensure conductivity and homogeneity of the organic coating.Gold can be considered as the best substrate, however it is characterized by its high cost. In order to obtain disposable sensors which can be used for low cost determinations, the amount of gold can be minimized using polymeric substrates coated with thin films of gold. The main drawback of these electrodes is the poor repeatability of such characteristics as roughness and homogeneity, which can influence the quality of subsequent deposition of organics. In this work, the results of an experimental study on electrochemical preparation of nanocomposite films of polyaniline (PANI) are reported in which the electrodes are constituted by a thin film of gold obtained by physical vapor deposition on kapton sheets. A two steps approach is adopted in order to obtain a stable and uniform coating: 1) functionalization of gold surface by 4-nitrophenyl group and electrochemical reduction of the nitro group to amine; 2) electropolymerization of aniline onto the surface of the aminophenyl-modified gold electrode. Cyclic voltammetries and electrochemical impedance spectroscopy are used to characterize the electrode surfaces after each step. The resulting …