During my research internship at EPFL’s Energy Transport Advances Laboratory, I investigated a materials-based approach to atmospheric water harvesting (AWH), with the broader motivation of developing alternatives for regions where conventional freshwater sources are limited.

The idea was to combine the strengths of two materials: MIL-101(Cr), a highly porous metal-organic framework with a strong affinity for water, and PNIPAM, a thermoresponsive polymer hydrogel. The goal was to create a composite that could adsorb water from humid air and then help release it when heated through a relatively mild temperature change.
I first synthesised MIL-101(Cr) under hydrothermal conditions and then incorporated it into the polymer network through in situ free-radical polymerisation. I characterised the resulting material using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and water-uptake measurements.
The results were encouraging. SEM showed well-defined, approximately 230 nm octahedral MIL-101(Cr) particles and a porous, interconnected hydrogel structure with the MOF particles distributed throughout the polymer network. DSC showed a lower critical solution temperature (LCST) of around 32.2 °C, indicating that the thermoresponsive behaviour of the PNIPAM was retained after incorporating the MOF.
At 70% relative humidity, the composite showed rapid initial water uptake and reached a relatively stable level of around 0.4 g of water per gram of MOF-hydrogel. This suggests potential for atmospheric moisture capture under the tested conditions, while also highlighting the need for further experiments across different humidity and temperature conditions.

However, this project was an initial material-level investigation rather than a demonstration of a complete water-harvesting device. The next steps would be to test repeated adsorption-desorption cycles, long-term stability, a wider range of environmental conditions, and ultimately the scalability of the material for practical AWH systems