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Bimetallic MOF–hydrogel composites offer a promising strategy for efficient atmospheric water harvesting (AWH) through synergistic moisture sorption and solar-driven water release. Herein, a multifunctional composite (VHN_ (Cr d Al) M /CaCl 2) is developed by integrating a Cr/Al bimetallic metal–organic framework (BMOF) into a thermoresponsive Valine-HEMA-NIPAM (VHN) hydrogel matrix and further loaded with CaCl 2. This hybrid material leverages the high surface area and hydrophilicity of the MOF, the porous nature and swelling–deswelling responsiveness of the hydrogel, and the hygroscopic properties of CaCl 2. The composite demonstrates superior atmospheric water uptake capability under highly humid conditions (90% RH), reaching up to 4. 9 g·g –1. Under 1 kW m –2 solar irradiation, the composite rapidly heats to ∼46 °C within 2 min, enabling efficient water release with a desorption rate of 0. 8 g·g –1 ·h –1. The composite maintains stable performance across multiple sorption–desorption cycles, indicating excellent durability and reusability. Under low-to-moderate humidity conditions, the CaCl 2 nanocrystals efficiently incorporated within the porous network demonstrate effective atmospheric water sorption, achieving uptake capacities of 0. 85 g·g –1, 1. 01 g·g –1, 1. 53 g·g –1, and 3. 04 g·g –1 at 20%, 40%, 60%, and 80% RH, respectively. These findings establish the developed hybrid as a scalable and energy-efficient material for atmospheric water harvesting in arid environments, offering strong potential for real-world deployment in sustainable water technologies.
Sahoo et al. (Sat,) studied this question.