Development and characterization of nanoporous and hybrid materials through electrochemical techniques for energetic applications

This PhD project, focused on the achievement of nanoporous and hybrid materials, is divided in two main topics: the first one is the synthesis of nanoporous nickel electrodes through electrochemical dealloying; the second one is the preparation of polyaniline/porous silicon hybrid materials by aniline electropolymerization on n-type porous silicon surface. Both materials have been synthetized and characterized by electrochemical methods in order to study the effect of the parameters of preparation on their properties. A particular attention was pointed out on the photoactivity and catalytic behavior. The main results show that porous nickel can be obtained by selective etching of copper from Ni-Cu deposits, under pulsed voltage conditions. The highest values of surfaces have been obtained adopting a low ratio between the corrosion and relaxation time. These surfaces result fully exploitable for the hydrogen and oxygen evolution reactions, as well as for photoelectrochemical applications. Concerning the porous silicon, the results show that an improved photoactivity can be achieved by electropolymerization of polyaniline, using the electroreduction of diazonium salt as underlayer. The hybrid samples present a higher photocurrent with respect to unmodified porous silicon, from the visible to the near-infrared region. Depending on the electrochemical conditions adopted for the synthesis, an increase in photocurrent more than one order of magnitude has been founded.