Solar-Driven Bifunctional Adsorption-Storage Films for Ultra-Fast Dehumidification and Freshwater Supply in...

Indoor humidity strongly affects both building energy demand and occupant health in hot and humid climates, but it remains largely controlled by energy-intensive mechanical systems and is seldom exploited as a source of freshwater. Here, we demonstrate a passive humidity regulation and freshwater harvesting strategy enabled by cost-effective adsorption films (18.79$·m^-2) that couple moisture capture, storage, and release within indoor environments. The films rapidly reduce relative humidity from 90.7% to 21.6% within one hour while maintaining long-term operational stability and release the captured moisture to produce freshwater at a rate of approximately 1.1 kg·m^-2·day^-1 under ambient conditions. Leveraging the harvested water, an autonomous plant irrigation system is achieved, enabling sustained regulation of indoor CO₂ concentration (about 920.2 ppm) without manual intervention. Global-scale projections indicate that this passive approach could reduce building energy consumption by up to 29.9 kWh·year^-1·m^-2 and associated carbon emissions by 16.5 kg·year^-1·m^-2, with an exceptionally short payback period of 48 days. This work reframes indoor humidity from a latent load to a recoverable resource, offering an integrated route towards water harvesting, energy reduction and healthier indoor environments in sustainable buildings.