Photocatalytic effect of Ag/TiO₂ nanotubes fabricated using 40 nm-scale BCP lithography

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 5060 nm height and 4050 nm diameter could be successfully fabricated and Ag nanoparticles with 7 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.