Facile fabrication of a dual hierarchical TiO2 nanostructure

A dual hierarchical TiO2 nanostructure is directly fabricated by electrochemically anodizing of an electropolished Ti substrate in an ethylene glycol electrolyte containing small amounts of fluoride with a two-step process, which is carried out at room temperature in a two-electrode electrochemical cell under 30 V for 3 h plus 10 min. The formed nanostructure consists of a nanoporous top layer (similar to 60 nm thickness) and a nanotubular underneath layer (similar to 600 nm thickness). The highly regular nanopores (similar to 100 nm diameter) in hexagonal shape distribute over the top layer and the underneath layer is arranged with the well-aligned nanotubes (similar to 50 nm diameter). The dual parts of the hierarchical nanostructure are both composed of TiO2, which exhibits anatase phase after being annealed at 450 degrees C under ambient air for 3 h. The facile fabrication of this dual hierarchical TiO2 nanostructure inspires to prepare other nanoscale materials with alike complex geometries by the similar approach. (C) 2011 Elsevier B.V. All rights reserved.