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Electrochemical synthesis of materials

Andre Avelino Pasa - UFSC, Laboratório de Filmes Finos e Superfícies

Electrochemical synthesis of materials (electrodeposition) is a process that allows the preparation of solid deposits on the surface of conductive materials. It is a commercially highly relevant process, providing the basis for many industrial applications, such as metal plating on surfaces as protective coatings, and copper interconnections in microprocessor chips. Nowadays, electrodeposition is an important technique for the preparation of nanostructures such as nanowires, nanofibers, nanopilars, etc.

Electrodeposits are formed by the action of an electric current passing in an electrochemical cell, a device that consists of two conductive or semi-conducting electrodes immersed in an electrolyte. Electrolytes for electrodeposition are usually aqueous solutions containing positive and negative ions, prepared by dissolving metal salts. The electric current that flows between the two electrodes in the presence of an external voltage is because of the motion of charged species, via migration and diffusion, towards the surfaces of the polarized electrodes. At the surface of the electrodes, the conduction mechanism must change from ionic to electronic, an interface process mediated by the occurrence of electrochemical reactions that promote the reduction or the oxidation (redox reactions) of the ionic species.

In this tutorial, the electrodeposition will be described in detail with emphasis on the synthesis of materials on metallic and semiconducting substrates. The growth process of metals and semiconductors on these substrates will be characterized by different techniques such as atomic force microscopy, scanning and transmission electron microscopy, and X-ray diffractometry. Additional techniques as vibrating sample magnetometry, optical reflectivity and electrical conductivity as a function of temperature will be also employed for the determination of the physical properties of the electrodeposits.

The students will also have the opportunity to visit the laboratory and participating of a sequence of experiments for the preparation and characterization of a material formed by electrochemical synthesis.