Photocatalytic Effect of Ag/TiO2 Nanotubes Fabricated Using 40 nm-Scale BCP Lithography

Abstract

Uniform TiO2 nanotubes were fabricated using a self- aligned, hole patterned BCP template lithography, atomic layer deposition of TiO2, and reactive ion etching. Also, Ag nanoparticles were deposited onto TiO2 nanotubes using a photochemical deposition method. Using the TiO2 nanotubes deposited with and without Ag nanoparticles, the effect of TiO2 nanotubes and Ag nanoparticles on the photocatalytic degradation was investigated by measuring the concentration change of the methylene blue solution under a UV light irradiation. Anatase phase TiO2 nanotubes with 50 similar to 60 nm height and 40 similar to 50 nm diameter could be successfully fabricated and Ag nanoparticles with 7 similar to 9 nm size could be also formed on the TiO2 nanotubes. The use of TiO2 nanotubes instead of flat TiO2 film improved the photocatalytic effect due to the increased TiO2 surface area and also the use of Ag nanoparticles on TiO2 nanotubes further improved the photocatalytic effect up to 8% by slowing down the rate of electrons and holes recombination on the surface of TiO2. However, when the coverage of Ag nanoparticles on TiO2 nanotubes are too high, possibly due to the decreased UV penetration to TiO2 by the increased surface area covered with Ag nanoparticles, the photocatalytic effect was decreased.