Transition metal doped TiO2 (Ni, Fe, Cu) and nanocomposite TiO2 powders with rutile
phase were synthesized by mechanical alloying and heat treatment, and were characterized by
XRD, TEM, UV-DRS, and PL (Photoluminescence). Photocatalytic activity was also investigated
with the degradation rate of 4-chlorophenol and measured by total organic carbon analyzer. TEMEDP
and XRD patterns showed that the transition metal doped powders (only alloyed powder) were
in the form of rutile phase with the particle size of 20-30 nm. The average grain size of transition
metal doped powders was in the range of less than 10 nm. However, after heat treatment, the
alloyed powder formed composite of the titanate and rutile phase. The UV-DRS and PL
investigation showed that Ni doped 8 wt% nanocomposite TiO2 had the higher wavelength range
(600-660 nm) (2.0-1.9 eV) than that of the commercial P-25 powder(380-400 nm) by Degussa Co.
indicating that the Ni 8 wt% doped nanocomposite TiO2 shifted the absorption into the visible light
region and thus, enhanced the photocatalytic activity. Further, these results agreed well with TOC
investigation. Formation of titanate in transition metal doped TiO2 due to heat treatment was found
to control the grain growth of nano-sized TiO2 and to enhance its thermal stability at high
temperature.
