Synthesis of TiO2 nanostructures by an electrochemical approach and their applications

Abstract

Synthesis of One-Dimensional (1-D) nanostructures transition metal-oxide materials gained a lot of attention of the scientific community in the last few decades due to their unique properties and potential application in various fields. Particularly $TiO_2$ (titanium-di-oxide or titania) nanostructures (nanoparticles, nanotubes and nanoporous arrays) have been extensively investigated because of their semiconducting nature and versatile applications. Among all the existence synthesis routes of $TiO_2$ nanostructure, electrochemical approach (anodization) is very simple and straight forward process which offers many advantages such as low cost, control over morphology, highly-ordered, vertically oriented, and self-organized oxide nanostructures growth with high-aspect ratio. Anodization of Ti sheet in fluoride containing organic viscous electrolytes under optimized conditions always produced self-organized, highly-ordered and vertically oriented high aspect ratio $TiO_2$ nanotubes with extremely smooth walls morphology. Anodization generally produced nanotubular and nanoporous structure on various valuable metals and alloys. In this study, we report the mass production synthesis of $TiO_2$ nanoparticles for the first time using anodization process. The size of $TiO_2$ nanoparticles was tailored by changing the concentration of the electrolyte in the anodizing process. $TiO_2$ nanoparticles showed higher photocatalytic activity compared to Degussa (P25) under the same conditions. Metal-oxide nanoparticles of various materials such as In, Sn, Ni, Fe, Zn and Cu can also be mass-produced using the same technique. An innovative technique of N_2 gas blowing in conjunction with methanol wetting onto fabricated $TiO_2$ nanotubes after anodization lead to the readily separation of nanotubes from underlying Ti sheet, generating large-scale and robust free-standing TiO2 nanotubes arrays membranes. The approach also provides very clean and shiny, homogeneous and honeycomb-...