Photocatalysis of Ag-Loaded TiO2 Nanotube Arrays Formed by Atomic Layer Deposition

Anodic aluminum oxide (AAO) film was used as a template to fabricate TiO2 nanotubes. TiO2 was deposited into the AAO pores by atomic layer deposition (ALD) at 100 degrees C. After the top layer of TiO2 and the AAO template were removed, an ordered array of TiO2 nanotubes remained on the substrate. The tube thickness increased with the cycle number of ALD. The UV-vis absorption spectra of the samples exhibited a red shift as the thickness increased or after annealing. The photocatalytic activity increased with the increase in the wall thickness of TiO2 nanotubes. With deposition of Ag nanoparticles on the tubes, the nanoparticles could act as an electron trapper to slow the electron-hole recombination rate, and thus enhance the efficiency of photodecomposition of methyl orange.