Preparation of highly porous TiO2 nanotubes and their catalytic applications

A simple procedure for preparing highly porous TiO2 nanotubes is reported. The nanotubes were prepared in the form of a nonwoven mat by emulsion electrospinning a solution containing poly(vinyl pyrrolidone), titanium tetraisopropoxide and oil, followed by calcination in air at 500 °C. The mixed crystalline material comprised anatase and rutile TiO2 particles, whose diameters were about 11 nm and 21 nm, respectively. The highly porous TiO2 nanotube membranes, which had large specific surface areas and excellent ratios of anatase phase to rutile phase, were shown to have excellent catalytic activities. Also the mixture of crystal forms improved the efficiency of photocatalysis because at the mixed interface electrons and holes are separated effectively. The new method for producing highly porous TiO2 nanotubes is versatile and could be extended to the fabrication of various types of highly porous nanotubes.