An average-sized living room of 90 m3 in a temperate climate—25 °C and 60% relative humidity—contains about a kilogram of water vapor dispersed in the air. Even in the desert, where liquid water is scarce, relative humidity typically hovers around 20%, so there’s still plenty of water in the air. Because it’s constantly refreshed by evaporation from the ocean and atmospheric circulation, the water in the atmosphere can be considered a limitless renewable resource.
Now Omar Yaghi of the University of California, Berkeley, Evelyn Wang of MIT, and their colleagues have taken a step toward tapping that resource by creating a water-collecting device that works at relative humidity as low as 20% and requires no external energy source.1
Their concept is based on a metal–organic framework (MOF), a highly porous material whose properties can be tuned by varying the metal and organic components and how they’re put together....
