Effect of annealing temperature on the phase transition, structural stability and photo-electrochemical performance of TiO<inf>2</inf> multi-leg nanotubes

In this report we study the effect of annealing temperature on the structural stability, phase transformation and photo-electrochemical performance of TiO2 multi-leg nanotubes. Multi-leg nanotubes were synthesized using electrochemical anodization method, and as synthesized nanotubes were annealed in air at the temperatures ranging from 500 to 900 °C.We observed that multi-leg morphology is preserved upto 900 °C and a dominant rutile phase is observed at this temperature. X-ray diffraction and Raman spectra measurements were carried out to study the crystallite size, phase transformation and phonon confinement effects. The multi-leg nanotubes annealed at 900 °C shows enhanced photo-electrochemical performance; this is attributed to mixed phase, increase in crystallite size and decrease in defects.