Thermoresponsive Aerogel Enabling Ultrafast Adsorption-Release Cycles for Atmospheric Harvesting

Abstract

The key bottleneck in the atmospheric water harvesting field lies in developing high-performance adsorbent materials capable of effectively adsorbing and releasing water under low humidity conditions. In this study, we successfully developed a novel hygroscopic moisture-absorbing gel (HMA), a composite material combining biomass-derived nanofibrillated cellulose with a thermoresponsive hydroxypropyl cellulose (HPC) network, designed for encapsulation of hygroscopic lithium chloride. The HMA leverages its hydrophilic gel network to rapidly adsorb and retain water at room temperature, while the thermoresponsive properties of HPC enable efficient water release through a hydrophobic mechanism under mild heating conditions. The results demonstrated that HMA exhibited saturated water absorption capacities of 0.62 and 1.08 g g^–1 at RH 30 and 50%, respectively. Furthermore, it released 80% of its adsorbed water within just 30 min. In addition, the HMA demonstrated excellent stability and mechanical strength under all-climate conditions, with an average of 7.01 L kg^–1 water being produced in a day through 12 cycles. In summary, HMA presents a sustainable and efficient strategy for atmospheric water harvesting in arid regions.