Structure and
semiconductor properties of titanium suboxide-based
composite electrocatalysts
Chem.
Met. Alloys 14 (2021)
58-63
https://doi.org/10.30970/cma14.0418
Alexander VELICHENKO, Vasyl KORDAN, Olesia SHMYCHKOVA,
Valentina KNYSH, Pavlo DEMCHENKO
Naked Ti/TiO2
nanotubes contain a significant amount of X-ray amorphous compounds on the
surface, which are most likely hydrated titanium oxides. The main crystalline
phase is titanium dioxide in the allotropic form anatase. Metallic titanium is
present on the surface in trace amounts. Thermal treatment of this material at
a temperature of 500°C for 3 hours in an air atmosphere led to an increase in
the proportion of the crystalline phase. The content of metallic titanium
increased significantly, reaching about a third. A partial electrochemical
reduction of the nanotubes allowed obtaining more electrically conductive
titanium suboxides. After a cathodic reduction of the nanotubes for one hour, a
galvanic coating with metallic platinum was uniformly deposited on the surface
of the material. Thermally treated Ti/TiO2 nanotubes are an n-type
semiconductor with a flat-band potential equal to –0.589 V and a carrier
concentration of 6×1020 cm-3. Such a high
concentration of carriers is obviously due to the small thickness of the oxide
film and its non-stoichiometry, as a result of which
the surface is not very depleted in electrons, since titanium metal acts as a
donor.
SEM-images of the following surfaces: reduced
Ti/TiO2-Pt nanotubes (left); thermally treated reduced Ti/TiO2-Pt
nanotubes (right).
Keywords
Platinized Ti/TiO2
/ Nanotubes / Thermal treatment / Charge carriers / Phase composition