The molecular view could help guide porous materials designed to collect atmospheric moisture with relatively little heat.
Researchers studied two porous metal-organic frameworks, materials with molecule-sized spaces that can hold water. The nickel version remained stable in water and showed a sequence of water adsorption: a first molecule formed several hydrogen bonds, helping anchor later layers.
The nickel material began taking up water below 20% relative humidity, loaded quickly, showed little difference between loading and unloading, and could be regenerated at 60 °C or below. In simulated temperature-swing conditions, its projected water productivity was 0.3044 wt% per minute, or 4.38 kg kg−1 d−1, and it remained stable for more than 100 cycles.
How the material takes up water
The study examined two related metal-organic frameworks: bnn-1-Co, containing cobalt, and bnn-1-Ni, containing nickel. Both were built from the same type of rod-shaped structural unit and contained fluoride, carboxylate and tetrazolate groups.
For bnn-1-Ni, single-crystal X-ray diffraction and density functional theory calculations showed that the first water molecule occupies a binding site where it forms multiple hydrogen bonds. Its calculated adsorption energy was −75 kJ mol−1. That molecule helped anchor the formation of subsequent water layers, whose average adsorption energy was −59 kJ mol−1.
The nickel framework began taking up water below 20% relative humidity, had little hysteresis between water uptake and release, loaded quickly, and required a regeneration temperature of no more than 60 °C. It remained stable for more than 100 cycles. Under simulated temperature-swing conditions, the researchers projected a gravimetric water productivity of 0.3044 wt% min−1, reported as 4.38 kg kg−1 d−1.
The cobalt framework was less stable in water. The researchers attributed the difference to stronger nickel–nitrogen, oxygen and fluorine coordination bonds than the corresponding cobalt bonds.
Evidence and caveats
The researchers combined single-crystal X-ray diffraction, which can show where molecules sit in a crystal, with density functional theory calculations to examine water binding in the nickel material. They also tested water uptake, loading speed, regeneration temperature, cycling stability and hydrolytic stability, and projected performance under simulated temperature-swing conditions. The reported water productivity is a projection from material-level and simulated tests, not a demonstration of a complete atmospheric water-harvesting device. The abstract does not report performance in a field system or compare the material with all existing harvesters.
// Source
Nature Communications · 2026 · DOI: 10.1038/s41467-026-76301-0
Authors: Mei‐Yan Gao, Andrey A. Bezrukov, Alan C. Eaby, Chenghua Deng, Lunjie Liu, Bai-Qiao Song, Sousa Javan Nikkhah, Matthias Vandichel, Michael J. Zaworotko
Institutions: National University of Ireland, Maynooth, Southern University of Science and Technology, Chengdu University of Technology, University of Limerick
