Ag nanoparticle sheet as a marker of lateral remote photocatalytic reactions

Abstract

The lateral remote photocatalytic activity of TiO2 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 max = 470 nm. A quartz substrate was coated with TiO2 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 TiO2 nanotubes.