Nanoporous Oxide Structures

Nanoporus Oxide Structures

SEM micrographs of porous alumina membranes prepared at different accelerated voltages.
SEM micrographs of porous alumina membranes prepared at different accelerated voltages.

Today nanoporous oxides can be found in every field of common life. They are used as catalyst carrier, adsorbers, ion changers, etc. For the synthesis of inorganic functional materials they espacially can be used in high temperature synthesis as templating materials. The absence of organic compounds make inorganic oxidic structures resistant against temperatures up to more than 1000 °C. For the synthesis of nanostructured and mesostructured materials porous oxide structures therefore are commonly used as templating, means structure directing agents. As a result of such a synthetic approach the templated material shows an inverse structure of the template itself. Thus the morphology of the material to be synthesised can be controlled by the structure of the template itself.

Cross section of PAOX membrane with parallel pore alignment. The pore channels are oriented orthogonal to the surface.
Cross section of PAOX membrane with parallel pore alignment. The pore channels are oriented orthogonal to the surface.

In the last decade porous anodic aluminum oxide (PAOX) has attracted much scientific interest because of its uniform structure. PAOX can be synthesised by an anodic oxidation of aluminum in an electrolytic process. The resulting oxide consists of a homogenious, coherent, nano- or mesoporous oxide structure. The pore diameters of pores are uniform depending on the accelerating voltage in the elctrolytic process and they are totally parallel arranged, perpendicular to the surface of the membrane. Herein the pore diameter can be varried between 6 – 300 nm, depending on the cell voltage within the electrolytic process.The main interest in the field of PAOX is the synthesis of coherent structures over seeral square centemeters and subsequently a use of these structures as templating materials for carbon nanotubes as well as ordered 1D nanostructures.

Publications

  • Eur. J. Inorg. Chem. (2005), 2352.
  • Eur. J. Inorg. Chem. (2006),s 1723-1736.