Controlled synthesis of anatase TiO2nanotube and nanowire arrays via AAO template-based hydrolysis

Abstract

A novel and facile method was successfully developed to fabricate nanotube (NT) and nanowire (NW) arrays through an anodic aluminum oxide (AAO) template-based Ti(OC₄H₉)₄ hydrolysis process. The wall thickness of the TiO₂ NTs can be controlled by adjusting the concentration of Ti(OC₄H₉)₄ solutions. A continuous series from thin-walled NTs to completely filled NWs were synthesized using Ti(OC₄H₉)₄ solutions of different concentrations from 0.1 to 2.0 M. The TiO₂ NTs and NWs in the AAO membrane transformed from amorphous to nanocrystalline anatase completely after annealing at 650 °C, which is higher than the phase transformation temperature of TiO₂ powder. Optical spectra of the synthesized TiO₂ NT and NW arrays/AAO composite nanostructures were characterized and showed a blue shift of the optical absorption edge with the decrease of NT wall thickness, due to the nanoscale effect and shape dependent transformation.