Nanoparticles that efficiently absorb light energy and convert it into heat can act as miniature steam generators in a liquid.
Naomi Halas, Peter Nordlander and their colleagues at Rice University in Houston, Texas, used lenses to focus sunlight on carbon or gold–silica nanoparticles suspended in water. Within a few seconds, steam at a temperature well above 100 °C was generated around the particle surfaces and bubbled away, whereas the bulk of the water heated up only gradually.
This method of using sunlight to generate high-temperature steam could be used to sterilize waste or surgical instruments without the need to boil a large volume of fluid, the authors suggest. The same effect may improve distillation: sunlight focused on nanoparticles in an ethanol–water mixture produced vapours richer in ethanol than conventional thermal distillation.
ACS Nano http://dx.doi.org/10.1021/nn304948h (2012)
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Instant steam from sunlight. Nature 491, 641 (2012). https://doi.org/10.1038/491641a