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IPFS News Link • Inventions

UCL research flips the script on self-cleaning materials

• http://www.gizmag.com, By James Holloway
 Mixed-phase titania (another name for titanium dioxide) combines both rutile and anatase titania, the two most abundant forms of the material, both of which can break down water in the presence of UV light. Though anatase titania is more effective than rutile, the combination of the two is more effective still.

In an attempt to explain this property, a 1996 study concluded that electron energy levels in rutile are 0.2 eV lower than in anatase. The precise band gap has significant implications for the properties of the material, and it was this difference that was thought to account for the superior properties when mixing the two. However, a problem with this idea is that electrons have since been observed flowing from rutile to anatase titania when combined, which should not be the case given the lower energy levels in rutile.

"Despite the mountains of research into this material, the explanation for the observed performance increase when mixed-phase samples were employed instead of single phase materials had remained a mystery for decades," says UCL chemist Dr. David Scanlon.