Using magnetron sputtering and heat treatment, Ag@TiO2 nanotubes are prepared. The effects of heat-treatment temperature and heating time on the evolution of Ag nanofilms on the surface of TiO2 nanotubes and microstructure of Ag nanofilms are investigated by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Ag atoms migrate mainly on the outmost surface of the TiO2 nanotubes, and fast diffusion of Ag atoms is observed. The diffusivity for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes at 400 °C is 6.87 × 10−18 m2/s, which is three orders of magnitude larger than the diffusivities for the diffusion of Ag through amorphous TiO2 films. The activation energy for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes in the temperature range of 300 to 500 °C is 157 kJ/mol, which is less than that for the lattice diffusion of Ag and larger than that for the grain boundary diffusion. The diffusion of Ag atoms leads to the formation of Ag nanocrystals on the outmost surface of TiO2 nanotubes. Probably there are hardly any Ag nanocrystals formed inside the TiO2 nanotubes through the migration of Ag.
Digital Object Identifier (DOI)
LW is grateful for the financial support from the National Natural Science Foundation of China (51301118, 51274149) and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi province (2013108). WGZ is grateful for the support from China Scholarship Council and the Fundamental Research Funds for the Central Universities. FY is grateful for the support from the “Hundred-People-Plan” Program of Shanxi (2014). LYM is grateful for the support from Natural Science Foundation of Shanxi province (2015021066).
Zhang, Wanggang; Liu, Yiming; Zhou, Diaoyu; Wang, Hui; Liang, Wei; and Yang, Fuqian, "Fast Diffusion of Silver in TiO2 Nanotube Arrays" (2016). Chemical and Materials Engineering Faculty Publications. 16.