A sponge-like device absorbs water and solar energy to generate steam efficiently (pictured).
Gang Chen at the Massachusetts Institute of Technology in Cambridge and his colleagues placed a layer of graphite flakes on top of a piece of carbon foam. The foam floats in water, soaking it up and wicking the liquid to the graphite, which absorbs solar radiation. Thanks to the insulating foam, heat builds up in the porous graphite layer, causing the absorbed water to evaporate.
The apparatus can trap 85% of the incoming solar energy to generate steam when sunlight is focused to ten times its normal intensity. The device could help to purify and desalinate water in remote areas, the authors say.