Researchers at Henan Normal University have developed a new metal-organic framework (MOF) capable of harvesting water directly from the air in extremely dry environments, offering a potential solution for regions facing severe water scarcity.
The study, published in Green Chemical Engineering , focuses on gallate-based MOFs made from low-cost materials including magnesium, cobalt, and nickel. Among them, the magnesium-based material, Mg-gallate, showed the strongest performance, capturing 170 mg of water per gram at just 0.2% relative humidity (RH), one of the highest water uptake capacities reported for porous materials under such ultra-low humidity conditions.
Atmospheric water harvesting is being explored as a sustainable solution to the growing global water crisis, particularly in arid regions where traditional adsorbent materials struggle to function efficiently. Current technologies often lose effectiveness in environments with very low moisture levels, such as deserts.
The researchers found that Mg-gallate combines strong water adsorption capacity with excellent stability. The material remained structurally stable after 28 days in water and maintained strong performance after 20 adsorption-desorption cycles. It also demonstrated high selectivity for water molecules over nitrogen, making it suitable for extracting water directly from air.
In particular, the material's performance is driven by hydrogen-bonding interactions between water molecules and oxygen-containing groups inside the MOF structure, alongside ultramicroporous channel filling effects. The MOF was successfully produced on a gram scale using inexpensive raw materials and standard laboratory methods, highlighting its potential for future large-scale production.
The researchers believe the technology could support atmospheric water harvesting in deserts and other ultra-dry environments, while also offering potential applications in semiconductor dehumidification, electronics protection, natural gas dehydration, and even space-based water recovery systems.
"Water scarcity is one of the most pressing survival challenges facing humanity in the coming decades. What makes Mg-gallate particularly exciting is that it works precisely where other materials give up: at the edge of detectability for humidity," says corresponding author Jianji Wang. "We are not just improving on existing benchmarks by a small margin; at 0.2% relative humidity, this material is operating in territory that was essentially inaccessible before. And because we can synthesise it in gram quantities from inexpensive, commercially available starting materials, there is a genuine path from the laboratory to real-world deployment."
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Contact the author: Jianji Wang, Henan Normal University, jwang@htu.edu.cn
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Green Chemical Engineering
Experimental study
Not applicable
Gallate-based metal-organic frameworks for atmospheric water harvesting under ultra-low humidity
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.