These unintentionally produced carbon-rich microscopic stalks absorb and release water differently to every other material we know about. They can absorb more water at low humidities, then expel it as the humidity increases to 50-80 percent – other materials simply carry on taking in the extra liquid in the air.
http://www.sciencealert.com/scientists-accidentally-create-nanorods-that-harvest-water-from-the-air