Janaina S. Santos

COMPARAÇÃO E CONSTRUÇÃO DE REATORES DE "MILD" E "HARD ANODISATION" PARA FABRICAÇÃO DE ALUMINA ANÓDICA POROSA

The mild anodization (MA) reactor is exemplified for its operational simplicity and its excellent control over the experimental parameters that are involved in the anodization process. This method provides porous anodic alumina films with a regular cell-arrangement structure. This offers a better cost-benefit ratio than the other equipment configurations that are used to fabricate nanoporous structures (i.e., ion beam lithography). Conversely, the hard anodization (HA) reactor produces oxides at a rate that is 25 to 35 times faster than the MA reactor. The produced oxides also have greater layer thicknesses and interpore distance, and with a uniform nanopore spatial order (> 1000). In contrast to MA reactors, the construction of an HA reactor requires special components to maintain anodisation at a high potential regime. Herein, we describe and compare both reactors from a technical viewpoint.

Electrochemical Synthesis of Nanostructured Materials

Abstract This chapter addresses the application of electrochemical synthesis techniques, such as electrodeposition and anodic oxidation of metals, from a practical standpoint. Some fundamental aspects of electrochemistry are addressed, and examples of the use of the electrodeposition technique for obtaining metallic structures, such as nanoscale bi- or multilayers, are presented. Techniques for characterization of metallic nanostructure, such as atomic force microscopy and the use of electrochemical quartz crystal microbalance, are also described. The synthesis of nanostructures from anodic oxides is discussed, with application to porous anodic alumina and titanium dioxide nanotubes as examples. The anodic doping technique can be used to modify the properties of these oxides. Thus, through simple explanations, using didactic language, and with the aid of figures taken from the literature, we provide the reader with a basic guide to the synthesis of new nanomaterials using electrochemical methods.

SÍNTESE ELETROQUÍMICA DE MATERIAIS NANOESTRUTURADOS

Este capitulo aborda, de forma pratica, a aplicacao de tecnicas eletroquimicas de sintese como a eletrodeposicao e a oxidacao anodica de metais. Alguns aspectos fundamentais da eletroquimica sao abordados, e sao apresentados exemplos da utilizacao da tecnica de eletrodeposicao para obtencao de estruturas metalicas com bi- ou multicamadas em escala nanometrica. Tambem sao descritas tecnicas de caracterizacao do deposito metalico, como a microscopia de forca atomica e a microbalanca eletroquimica de cristal de quartzo. A sintese de nanoestruturas a partir de oxidos anodicos e abordada, com exemplos de aplicacao da alumina anodica porosa e dos nanotubos de dioxido de titânio. A tecnica de dopagem anodica pode ser utilizada para modificar as propriedades destes oxidos. Dessa forma, atraves de explicacoes simples, em linguagem didatica e com o auxilio de figuras com exemplos da literatura, o leitor encontrara um guia basico para sintese de novos materiais na escala nanometrica utilizando metodos eletroquimicos.