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Improved energy technologies might be possible thanks to research into making and modifying nanorods and nanotubes of titania. The development could also lead to novel medical applications, improved catalysts for hydrogen production, more efficient solar cells, and even better sunscreens. Wei-Qiang Han of the Brookhaven National Laboratory in Upton, New York, and colleagues have made two important discoveries in this area. First they found they could enhance the absorption of light by titania. Secondly, they extended this work to allow them to make even better iron-doped titanate nanotubes. "Titanium dioxide's ability to absorb light is one the main reasons it is so useful in industrial and medical applications," explains Han. Doping this compound has been the standard approach to improving its photochemical properties. However, Han and colleagues have taken a new approach. They hollowed out nanorods of titanate salt by simply heating them in air. This process evaporates water, transforming titanate to titania, leaving very densely spaced, regular, polyhedral nanoholes within. The modified material is 25% more efficient at absorbing ultraviolet (UVA and UVB) radiation. Their second study, with colleagues at Carnegie Institution of Washington, led to a new synthesis for iron-doped titanate nanotubes, hollow tubes measuring approximately 10 nanometres in diameter and up to one micrometre in length. These experiments were also aimed at improving the material's photoreactivity. The scientists demonstrated that the resulting nanotubes exhibited noticeable reactivity in the water-gas-shift reaction for hydrogen production. The various materials developed were all analysed using transmission electron microscopy, energy-dispersive X-ray spectrometry, in-situ X-ray diffraction, UV-vis spectroscopy, synchrotron IR spectroscopy, and temperature-dependent magnetometry at the National Synchrotron Light Source at Brookhaven. The EDS study revealed that the iron-doping ratio in the second study is about 0.5%, while IR and UV-vis spectra reveal the effects of doping. The in situ XRD experiments demonstrated how the trititanate structure changes to form the titania phase under a reductive atmosphere. Related links:
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