Sol−Gel Template Synthesis of Semiconductor Oxide Micro- and Nanostructures

The template method for synthesizing nanostructures involves the synthesis of the desired material within the pores of a nanoporous membrane or other solid. Our work has involved using porous alumina and polymeric filter membranes as the templates. Fibrils or tubules of the desired material are formed within each pore of the template membrane. A number of synthetic methods have been used to synthesize these nanostructures. This paper reviews sol−gel template synthesis: the use of sol−gel chemistry to synthesize semiconductor oxide micro- and nanostructures within the pores of micro- and nanoporous membranes. For example, TiO 2 nanotubules and nanofibers of the anatase form have been synthesized. The high surface area offered by these TiO 2 nanostructures has been used for photodecomposition of salicylic acid in sunlight. Enzyme immobilization by stannous bridges inside the TiO 2 tubes has also been studied. In addition, V 2 O 5 fibrous electrode materials have been prepared by this method and Li intercalation electrochemistry is reported here. Other semiconductor oxides such as MnO 2, Co 3 O 4, ZnO, WO 3, and SiO 2 have also been prepared.