Templating techniques to contro the nanostructure and to incporporate metal nanoparticles in porous titanium dioxide structures

Abstract

The nanostructural properties of a material play an important role in the performance of the material. One method that allows the manipulation of the architecture of materials over a range of length scales is the use of templates or structure directing agents.

Titanium dioxide has been studied extensively due to the many potential and realized applications of this non-toxic, stable semiconductor. Applications relying on the photoactive properties of the titanium dioxide could be enhanced by a decrease in electron/hole recombination reactions. The addition of a noble metal to the titanium dioxide has been reported to lead to such an improvement, and an increased efficiency of the material in photocatalysis.

In this presentation a novel, template-based synthesis of porous titanium dioxide materials containing metal nanoparticles will be demonstrated. The template, an agarose gel, is formed in aqueous solution, allowing the incorporation of the metal salt or preformed metal nanoparticles during or after the template formation. The metal containing porous gel is then coated with amorphous titanium dioxide by performing sol-gel chemistry within the pores. On removal of the template, a porous metal/titanium dioxide nanocomposite is formed, and then characterized to determine pore size and structure, metal nanoparticle distribution, specific surface area and the crystal phase of the titanium dioxide.

The photodecomposition of organic pollutants in the presence of the nanocomposites has also been studied to ascertain the benefit of the metal incorporation and the synthesis route that leads to materials with highest efficiency in this application.