Conductivity of TiO2 nanotubes: Influence of annealing time and temperature

One-Dimensional Titanium Dioxide Nanomaterials: Nanotubes

“…As formed (amorphous) TiO 2 nanotubes show a significantly lower photocatalytic activity than tubes annealed to anatase or rutile 29,358,359,626,673 . Figure 29.a shows comparison of the photocatalytic activity of TiO 2 nanotubes annealed at different temperatures and environments.…”

“…Several authors investigated the solid state electrical conductivity of anodic TiO 2 nanotube layers, [29][30][31][32][33] mainly as a function of annealing conditions or effects of dopants. The majority of the work is carried out with two-point measurements, such as in Figure 19.a, where a top contact metal (mainly Au, Pt, Al) is evaporated and the resistivity to the Ti-back contact is measured.…”

“…TiO 2 behaves in electrochemical I-V curves mostly as a typical n-type semiconductor with a current blocking characteristic in the anodic direction and a current passing behavior in the cathodic direction 29 . A general feature of highly-doped n-type semiconductors is that when a sufficiently high anodic bias is applied, valence band ionization and tunneling breakdown may occur 400 .…”

“…These nanotube geometries may be considered (in a physical sense) as "true" nanotubes, as quantum size and dimensionality may fully be effective on physical and chemical properties, such as electron mobility, optical band-gap, and surface reactivity [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] .…”

Titania Nanotubes by Electrochemical Anodization for Solar Energy Conversion

“…• C; rutile begins to form above 500 • C. 48,49 This latter transformation is accelerated by the oxidation at the TiO 2 /substrate interface of the Ti substrate to rutile TiO 2 upon heating, leading to the growth of the rutile phase from the bottom of the nanotubes; in fact, TiO 2 nanotubes removed from the substrate or grown with a protective NbTiO 2 underlayer remain purely anatase up to 600…”