The foam consists of two materials: cellulose and graphene oxide, which conducts heat. When the foam is suspended in a container of water and it is exposed to sunlight the graphene oxide converts light into heat, which evaporates the water. Working a little like an absorbent sponge, the cellulose moves the water to the surface, while the contaminants and salt settle in the container.
Researchers at Washington University say the constituents are inexpensive and can be produced in large quantities. So, the next step is to scale up the technology to produce large amounts of clean drinking water for those in need globally.