Metal nanoparticles and conducting polymer nanostructured systems by electrochemical synthesis: from modeling to applications

In the framework of Materials Science, electrochemical deposition is an area of considerable interest, both from theoretical principles and applied standpoint. On the one hand, the theoretical investigations aim at advance the knowledge of the mechanism of deposition that occurs by nucleation and growth. On the other hand, the research on the experimental conditions to produce forefront materials with designed functionalities by electrochemical methods is nowadays a constantly evolving challenge. In this context, the present thesis concerns both theoretical and experimental approaches. The theoretical investigations are performed to gain insight into the early stage of the electrodeposition process on a generic substrate in the case of instantaneous and progressive nucleation. In particular, it is relevant to obtain an exhaustive description of the kinetics in terms of nucleus growth law, electrode surface coverage and mean film thickness from the current-time curves. Furthermore, it is also important to investigate the effect of spatial arrangement of nuclei on current density. The experimental investigation is aimed at designing and producing conducting polymer based system by electrochemical deposition for bio-energy related applications. The thesis is organized as follows. The Chapter 1 is devoted to an overview of the principles of electrodeposition, of the theoretical background to the study of nucleation via potentiostatic current transient modeling and to illustrate the main features of conducting polymer systems. Chapter 2 deals with the theoretical outcomes obtained in the case of progressive and instantaneous nucleation in diffusion-controlled growth. In Chapter 3 we present the experimental results on the electrodeposition of platinum at ITO substrate with particular attention to the early stage of growth. Nucleation density and nearest neighbor distribution functions have been measured and theoretical approaches have been employed to describe these quantities. In the same chapter, the morphological, structural and electrochemical characterizations of the deposits are also reported, in an attempt to gain insight into the role of deposition parameters on film morphology. Chapter 4 concerns the electrodeposition of conducting polymer systems where the theoretical models, already developed in the literature, have been used for describing electropolymerization. A study on the morphology, structure, and functionality of the deposit is therefore mandatory for a complete characterization of the produced materials. Finally, these conducting polymers systems have been used as scaffolds for cell-culture and as electrode materials for bio-energy related applications. Preliminary results of this research are also presented and discussed in Chapter 4. In the last chapter, the main thesis outcomes are reviewed. Furthermore, some prospective points for the future work of this research are discussed.