Aug 5, 2008
Alkaline mix cuts the cost of titanate nanotubes
Researchers in the UK have made titanate nanotubes at low temperature (100 °C) and under atmospheric conditions by carrying out the reflux synthesis in a mixture of aqueous NaOH and KOH. According to the University of Southampton team, developers have been on the look out for a simple way of preparing nanostructured titanates and the group thinks that its low-cost, high-yielding process could be ideal.
Nanostructured titanates have a wide range of potential applications thanks to the material's open mesoporous morphology, high aspect ratio and good ion-exchange properties.
"Prominent areas like photocatalysis, solar cells and lithium batteries could potentially take nanostructured titanates onboard very quickly," Dmitry Bavykin of the University of Southampton's Energy Technology Research Group told nanotechweb.org. "Titanate nanotubes can also make a contribution to the area of drug delivery, which is experiencing rapid growth. One of the most exciting uses of titanate nanotubes is for hydrogen storage. However, research in this area is in its early stage."
Making the material
A favoured route to the synthesis of titanate nanotubes is hydrothermal treatment of titanium dioxide at 120–150 °C (typically in 10 mol dm–3 sodium hydroxide solution), which gives a substantial conversion to titanate nanotubes in less than 24 hours. Unfortunately, the need to use pressurized reactors for the preparation of material greatly increases the manufacturing cost.
Attempts to avoid autoclave operations by keeping the synthesis temperature below the boiling point of the alkaline solution usually result in the production of a much less desirable multilayered, sheet-like structure with a relatively low specific surface area.
To overcome this, Bavykin and his colleagues carry out the reflux synthesis in a mixture of aqueous NaOH and KOH. The composition of the mixture can be tuned to favour the formation of nanotubes rather than nanofibres of nanosheets.
After 48 hours of refluxing at 100 °C, the group reports that almost complete conversion was achieved.
The researchers presented their results in Nanotechnology.
About the author
James Tyrrell is editor of nanotechweb.org.