Long-term stability of moisture-capturing hydrogels by preventing metal-mediated degradation

Sorbent-based atmospheric water harvesting promises passive, geography-independent, and economical freshwater production. Achieving low water cost through moisture harvesting demands inexpensive, high-performance, and durable sorbents. Among all sorbents, hydrogel salt-composites have exceptional performance at a low cost. However, hydrogel durability has so far been overlooked, ultimately preventing moisture capture from realizing reliable, inexpensive water production. In this work, we systematically study hydrogel-salt composite degradation under different conditions. We demonstrate that commonly used polyacrylamide-lithium chloride (PAM-LiCl) are intrinsically durable, with a limited decrease (~50%) in their elastic moduli, even at elevated temperatures (75 °C) and for prolonged durations (>8 months). In contrast, degradation quickly occurs (