Not so long ago, chemical engineers discovered how to use titanium dioxide to keep buildings free of discoloring pollution. Landmarks such as the virgin-white Dives in Misericordia Church in Rome and the Marunouchi Building in Tokyo were among the first to be coated with the semiconductor, which breaks down organic molecules—including those in grime and pollution—when exposed to light and water and then releases them into the air. Soon after, TiO2-based self-cleaning products, like SunClean windows from PPG Industries, hit the home market.
But to bring the technology inside the home, where it could eliminate the need for hours of tedious housework every week, researchers must overcome a major limitation: The technology currently responds only to ultraviolet light from the sun. Enter materials engineer Michael Cortie and his colleagues at the Institute for Nanoscale Technology in Sydney, Australia, who are working to perfect a coating that can respond to the visible spectrum—that is, the lightbulb hanging from your bathroom ceiling. So long, toilet brush.
Launch the slideshow to see how titanium oxide reacts with light to zap dirt at the molecular level.