A research group led by Prof. CHEN Tao at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), in collaboration with researchers at Max Planck Institute of Microstructure Physics, has developed entangled mesh hydrogels (EMHs) via cryogelation, achiecving rapid atmospheric water harvesting. The study was published in Advanced Materials.

The freshwater scarcity has severely influenced the economic development and human living quality. Sorption-based atmospheric water harvesting is a promising solution to help alleviating freshwater scarcity. Hygroscopic salt-hydrogel composites (HSHCs) are representative and ideal sorbents. However, the sluggish sorption/desorption kinetics has limited the performance enhancement and further applications of sorption-based atmospheric water harvesting.

To address this issue, researchers at NIMTE used a cryogelation method to engineer a stable macroporous topology within EMHs. Compared with conventional hydrogels for HSHCs, the obtained EMHs possess superior mass transport performance.

Researchers embedded hygroscopic LiCl and photothermal graphene oxide flakes into the EMHs, achieving high-performance hygroscopic EMHs with both remarkably enhanced moisture sorption and solar-driven water desorption kinetics.

In addition, a rapid-cycling harvester prototype based on the obtained HEMHs was developed for practical solar-driven sorption-based atmospheric water harvesting. Under natural solar illumination, the harvester records a freshwater yield of 2.85 L_water kg_sorbents^-1 day^-1 through continuous eight sorption/desorption cycles, outperforming the reported hydrogel-based sorbents.

This strategy based on engineering polymer networks also shows excellent generality as it can ben extended to other hydrogels used in HSHCs.

The generic network engineering approach to improve mass transport properties shows great application potential in batteries, catalysis, biomedicine, and other emerging fields.

This work was financially supported by the Natural Science Foundation of China (No. 52373094), Ningbo Science and Technology Bureau (No. 2021Z127), International Cooperation Project of Ningbo City (No. 2023H019), the Sino-German Mobility Program (No. M-0424), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2023313), and Alexander von Humboldt Foundation, etc.

Fig. The network engineering of EMHs enables rapid atmospheric water harvesting (Image by NIMTE)

Contact
XIAO Peng
Ningbo Institute of Materials Technology and Engineering
Email: xiaopeng@nimte.ac.cn