Researchers have unveiled a new way to use sunlight to produce steam and other vapors without heating an entire container of fluid to the boiling point. The research could lead to inexpensive, compact devices for purification of drinking water, sterilization of medical instruments and sanitizing sewage.
Metallic nanoparticles - so small that 1,000 would fit across the width of a human hair - absorb large amounts of light, resulting in a dramatic rise in their temperature. That ability to generate heat has fostered interest among scientists in using nanoparticles in a range of applications. These include photothermal treatment of certain forms of cancer, laser-induced drug release and nanoparticle-enhanced bioimaging.
In the past, researchers also explored the use of nanoparticles in solar energy applications. However, that research focused mainly on using nanoparticles to improve the ability of fluids to conduct heat. Until now, scientists had not reported on the use of nanoparticles, mixed into fluids, to capture sunlight, heat up and change the fluid into steam or other vapor.