Imagine a future in which every household has an appliance that pulls water out of the air, even in dry or desert climates, using only the power of the sun.

That could be the result of a prototype developed by researchers from the Massachusetts Institute of Technology (MIT) and the University of California, Berkeley, that sucks water out of the air and stores it using nothing but sunlight and MOFs.

MOFs are metal-organic frameworks that are made from metal ions and organic compounds that form a sponge-like configuration.

What are MOFs? Metal-organic frameworks are crystalline compounds composed of metal ions

Metal-organic frameworks are crystalline compounds composed of metal ions MOFs have a high porosity and are thermally and mechanically stable.

MOFs have a high porosity and are thermally and mechanically stable. The high specific surface area exhibits selective adsorption

The high specific surface area exhibits selective adsorption MOFs are formed by reticular synthesis and there are several hundred different types

MOFs are formed by reticular synthesis and there are several hundred different types Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability

Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability The interior of MOFs can be chemically altered to separate and store gas Source: Department of Chemical and Biomolecular Engineering, University of California, Berkeley.

Researchers tuned the chemical composition of a MOF to be hydrophilic, which in a powder form can not only suck up liquid water but also absorb water vapour. Their findings are reported in the journal Science.

Researchers created a device where a thin layer of MOF powder is placed between two surfaces. The top surface is black and absorbs solar heat, and the lower surface is kept at the same temperature as the outside air.

The powder absorbs the water vapour, then the heat from the top layer releases the water which is collected on the cooler lower surface.

The researchers' tests showed one kilogram of the MOF could collect close to three litres of water per day.

Berkeley chemistry professor Omar Yaghi invented MOFs two decades ago and co-authored the research.

"One vision for the future is to have water off-grid, where you have a device at home running on ambient solar for delivering water that satisfies the needs of a household," he told MIT News.

"To me, that will be made possible because of this experiment. I call it personalised water."

The study was partly funded by ARPA-E, a US Government agency that claims to advance high-potential, high-impact energy technologies in their early stages of development.

With so much water in the atmosphere — enough for the whole world to use without disrupting the environment — tapping into it as a water source has huge potential.

With further development, this prototype could lead to technology that harvests significant amounts of water at any level of humidity, anywhere in the world.

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