Sol−Gel Template Synthesis of Semiconductor Nanostructures

TLDR

The template method prepares nanostructures by depositing material within pores of nanoporous membranes, yielding nanofibrils or tubules, and has previously employed electrochemical, electroless, and polymerization techniques. This study introduces the first use of sol‑gel chemistry to fabricate semiconductor nanofibrils and tubules inside alumina template pores. Sol‑gel derived TiO₂ fibrils of 200 nm diameter were synthesized and employed as photocatalysts for salicylic acid decomposition. TiO₂, WO₃, and ZnO nanostructures were produced; the 22 nm TiO₂ nanofibrils were single‑crystal anatase with c‑axis alignment, and their bundles were also single crystalline, indicating a highly organized fibril arrangement.

Abstract

The template method for preparing nanostructures entails synthesis of the desired material within the pores of a nanoporous membrane or other solid. A nanofibril or tubule of the desired material is obtained within each pore. Methods used previously to deposit materials within the pores of such membranes include electrochemical and electroless deposition and in situ polymerization. This paper describes the first use of sol−gel chemistry to prepare semiconductor nanofibrils and tubules within the pores of an alumina template membrane. TiO2, WO3, and ZnO nanostructures have been prepared. TiO2 nanofibrils with diameters of 22 nm were found to be single crystals of anatase with the c-axis oriented along the fibril axis. Bundles of these fibrils were also found to be single crystalline, suggesting that the indiviual fibrils are arranged in a highly organized fashion within the bundle. Finally, 200 nm diameter TiO2 fibrils were used as photocatalysts for the decomposition of salicylic acid.