Study and achievement of organic-inorganic innovative materials through electrochemical techniques

Abstract

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 sensors, biosensors, clinical diagnostics, biological sensing and energy storage and conversion. In this context, to obtain a stable, durable bond with the surface and controllable process, the electroreduction of aryldiazonium salts is a promising alternative to conventional techniques (as Self Assembled Monolayer), also to ensure conductivity and homogeneity of the organic coating. This work, focused on the achievement of innovative materials developed for a wide range of applications that include biosensors, energy storage and metal-free sensors, is divided in four main topics: 1. Polyaniline electropolimerization on gold surface 2. Polyaniline electropolimerization on nanoporous silicon surface 3. DNA immobilization on gold 4. Polyaniline electropolimerization on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate The common theme about the achievement of these devices is the functionalization of the metal or polymeric electrode base by means diazonium salt (4-nitrobenzenediazonium) electrochemical reduction, prior to further modification with polyaniline or DNA. All these functionalization are realized using electrochemical techniques: organic molecules are grafted on the electrode surface using cyclic voltammetry, as well as aniline electropolimerization. Furthermore, all electrode functionalization step are characterized by Electrochemical Impedance Spectroscopy (EIS), which can give fast and useful information about the surface state. In this thesis results of sensor functionalization and performance varying electrochemical parameter and preparation conditions are presented and discussed, giving a well-developed starting point for following applications