Ag nanoparticle sheet as a marker of lateral remote photocatalytic reactions.

The lateral remote photocatalytic activity of TiO(2) nanotubes fabricated by anodic oxidation, was characterized by use of a 'silver nanosheet' as a marker. The silver nanosheet is a two-dimensional crystalline film composed of myristate-capped silver nanoparticles (d = 5 nm), which has a sharp localized plasmon absorption band at lambda(max) = 470 nm. A quartz substrate was coated with TiO(2) nanotubes to a coverage of 10% and then covered with a silver nanosheet. Upon UV irradiation a rapid decrease in the intensity of the 470 nm plasmon band and an increase in the long-wavelength absorption (550-1000 nm) band were clearly confirmed, indicating fusion of the nanoparticles due to decomposition of the myristate capping agent. Surface morphology measured by high-resolution scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed the decomposition and fusion of silver nanoparticles even in regions of the surface a micron away from the TiO(2) nanotubes.