writer：Xuefeng Han, L. Zhong, L. Zhang, L. Zhu, M. Zhou, S. Wang, D. Yu, H. Chen,Y. Hou, Yongmei Zheng*
keywords：Water harvesting
source：期刊
Issue time：2023年

Drought and water scarcity are two of the world’s major problems.

Solar-powered sorption-based atmospheric water harvesting technology is a

promising solution in this category. The main challenge is to design materials

with high water harvesting performance while achieving fast water vapor

adsorption/desorption rates. Here, a superhydrophilic photothermic hollow

nanocapsule (SPHN) is represented that achieves efficient atmospheric water

harvesting in outdoor climates. In SPHN, the hollow mesoporous silica

(HMS) is grafted with polypyrrole (PPy) and also loaded with lithium chloride

(LiCl). The hollow structure is used to store water while preventing leakage.

The hydrophilic spherical nanocapsule and the trapped water produce more

free and weakly adsorbed water. Significantly lower the heat of desorption

compared to pure LiCl solution. Such SPHN significantly improves the

adsorption/desorption kinetics, e.g., absorbs 0.78–2.01 g of water per gram of

SPHN at 25 °C, relative humidity (RH) 30?80% within 3 h. In particular,

SPHN has excellent photothermal properties to achieve rapid water release

under natural sunlight conditions, i.e., 80?90% of water is released in 1 h at

0.7–1.0 kW m?2 solar irradiation, and 50% of water is released even at solar

irradiation as low as 0.4 kW m?2. The water collection capacity can reach

1.2 g g?1 per cycle by using the self-made atmospheric water harvesting

(AWH) device. This finding provides a way to design novel materials for

efficient water harvesting tasks, e.g., water engineering, freshwater generator,

etc.

https://doi.org/10.1002/smll.202303358