Abstract
Gold (Au) nanocrystals were thermally evaporated and implanted into a TiO 2 film by a two-step vacuum process. In the experiment, two different specimens, as-prepared sample Au/Ti/Si substrate and source material Ti powder were combined. In the first stage, the materials underwent thermal evaporation (at 850°C for the first material and at 1050°C for the second material) under a vacuum pressure of ∼ 10 -3 Torr for 1 h. In the second step, the vacuum system was fed with air and maintained at 760 Torr for 1 h. The air pressure implanted the Au nanoclusters into the TiO 2 film. The process also synthesized TiO 2 nanowires. High-angle annular dark-field imaging by a scanning transmission electron microscope (HAADF/STEM) revealed that the Au nanocrystals (nanoclusters) were highly dispersed in the TiO 2 film and its nanowires. The diameters of the TiO 2 nanowires ranged from 60 to 100 nm, and their lengths were up to 3 μm. High-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy mapping, HAADF/STEM, X-ray photoelectron spectroscopy, and X-ray diffractometry were used to elucidate the formation process of the as-synthesized products. The results indicated that as-synthesized nanowires had been formed by a combination of solid-liquid-solid and vapor-solid mechanisms. © 2009 The Electrochemical Society.