This is a project
that we just started working on. Jennifer Intrieri has been using
anodic etching at 20 V or so in a sulfuric acid solution to prepare
porous alumina. The aluminum substrate is anodically etched and
simultaneously the interface with the solutions oxidizes. A delicate
balance between dissolution and oxidation leads to the formation of
pores. The pore walls do not dissolve once they have formed because
alumina is an insulator and does not easily pass charge either in the
form of electrons or ions. Therefore, charge can only be forced through
alumina (Al2O3) if the alumina is thin and a high
electric field is present. This condition is fulfilled at the bottom of
the pore; therefore, the pore bottom continues to etch and the pore
propagates. The pores, however, a much present a much longer path to
the conducting alumium substrate and not charge flows through them.
Labs working in Surface Science, Nanotechnology and Catalysis
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