UV-activated material captures water from air by reconfiguring crystals into traps
A New Approach to Atmospheric Water Harvesting
A team of chemists at the University of Iowa has developed a groundbreaking light-activated crystal structure that can extract water from the air and store it within nanoscale cavities. This innovation presents a novel method for atmospheric water harvesting, offering potential solutions for regions facing water scarcity.
The material is constructed using metal-organic frameworks (MOFs), which are porous structures created by connecting metal atoms with organic molecules. Initially, the designed lattice lacked usable cavities for water storage. However, the breakthrough occurred when the structure was exposed to ultraviolet light. This exposure triggered a chemical rearrangement within the crystal, reshaping its internal architecture and forming tiny cavities capable of capturing water molecules from the air.
Researchers describe this process as transforming the material into a solid-state water harvester that operates solely on sunlight, eliminating the need for external power sources or complex machinery. The effect was observed at the microscopic level using X-ray diffraction, which revealed the presence of water molecules inside the newly formed cavities after light exposure.
Light Opens Water Traps
Leonard MacGillivray, an adjunct professor in the Department of Chemistry and former department chair, highlights the significance of this discovery. “We have found and validated a way to capture and store water that would require only sunlight,” he says. “You can transport the crystal lattice and eventually release the water on demand. That’s why it’s such an advance.”
The material's behavior is based on a structural shift initiated by UV light. The organic linkers within the MOF rearrange into a new configuration, creating spaces that act as storage sites for water molecules. Under laboratory conditions, the system can store about 5 percent of its weight in water. While this amount is modest at the single-crystal level, researchers believe scaling up the architecture could significantly enhance overall water capture potential.
Sun-Powered Water Capture
The team envisions this concept as a foundation for developing new water-harvesting technologies, particularly for regions experiencing severe water shortages. Nevindee Samararathne Muhandiramge, a graduate researcher, emphasizes the importance of the "intelligent" aspect of the material. “UV light is freely available from the sun. So, the next step would be to determine the limits of the water uptake in terms of mass percent and push that limit as far as we can.”
Another advantage of the material is its self-assembly property, which allows for potentially large-scale production in the future. However, the current version remains a proof of concept. The material uses cadmium as a test element, which would need to be replaced with safer alternatives before real-world deployment.
Future Research and Development
Researchers plan to focus on improving water uptake efficiency and testing whether the system can operate reliably outside controlled laboratory conditions. Their work suggests a new direction for water-harvesting materials that integrate structural chemistry with environmental responsiveness, relying solely on sunlight as the energy input.
The study, titled “Photo capture of water by single crystals of a nonporous metal−organic material,” was published in the Journal of the American Chemical Society. This research opens exciting possibilities for sustainable water solutions and highlights the potential of light-activated materials in addressing global water challenges.
