A Nanostructured Moisture‐Absorbing Gel for Fast and Large‐Scale Passive Dehumidification

Abstract Dehumidification is significant for environmental sustainability and human health. Traditional dehumidification methods involve significant energy consumption and have negative impact on the environment. The core challenge is to expose hygroscopic surfaces to the air, and appropriately store the captured water and avoid surface inactivation. Here, a nanostructured moisture‐absorbing gel (N‐MAG) for passive dehumidification, which consists of a hydrophilic nanocellulose network functionalized by hygroscopic lithium chloride, is reported. The interconnected nanocellulose can transfer the captured water to the internal space of the bulky N‐MAG, eliminating water accumulation near the surfaces and hence enabling high‐rate moisture absorption. The N‐MAG can reduce the relative humidity from 96.7% to 28.7% in 6 h, even if the space is over 2 × 10⁴ times of its own volume. The condensed water can be completely confined in the N‐MAG, overcoming the problem of environmental pollution. This research brings a new perspective for sustainable humidity management without energy consumption and with positive environmental footprint.