Recently, Professor Xu Xiaofeng’s research group from the School of Materials Science and Engineering published a research article entitled “Fully-Printed TPMS-Architected Hygroscopic Lattices for High-Yield Solar-Powered Atmospheric Water Harvesting” in Advanced Functional Materials, a leading international journal in materials science. The study presents a high-performance photothermal hygroscopic lattice based on Triply Periodic Minimal Surface (TPMS) architectures fabricated via Digital Light Processing (DLP) 3D printing. The printed structure enables highly efficient solar-powered atmospheric water harvesting and clean water production, offering a promising solution to the global freshwater shortage.
With freshwater scarcity becoming an increasingly critical global challenge, adsorption-based atmospheric water harvesting has emerged as an attractive decentralized water supply technology because of its ability to operate independently of geographical conditions while utilizing low-grade renewable energy. However, conventional hygroscopic salt–polymer composite materials typically possess random porous structures, making it difficult to precisely regulate water vapor adsorption and diffusion. This limitation significantly restricts moisture adsorption kinetics and long-term cycling stability.
To address these challenges, the research team integrated ink chemistry, photopolymerization processing, and mathematical topology design to develop a hygroscopic ink formulation suitable for high-resolution DLP printing. Using this approach, they successfully fabricated three-dimensional hygroscopic lattice matrices based on four TPMS unit structures: Gyroid, Diamond, Split P, and Lidinoid. Within the printable ink, the cationic monomer DMAEA-Q and the anionic monomer AMPS generated a salt-in effect through electrostatic interactions, enabling high loading of lithium chloride (LiCl) while effectively suppressing salt migration and leakage.
TPMS-based hygroscopic matrix and ink, lattice structure, batch preparation, and schematic diagram of outdoor water production device and physical object
The application of DLP printing enabled, for the first time, the precise fabrication of TPMS architectures with continuous curved surfaces and complex curvature gradients for hygroscopic materials. The resulting TPMS lattices exhibited a hierarchical porous structure spanning multiple length scales—from millimeter-scale periodic lattices and micrometer-scale pore walls to nanoscale polymer networks. This multiscale architecture significantly increased the specific surface area, facilitated water vapor transport, and enhanced both capillary absorption of the salt solution and swelling-assisted retention within the polymer network.
The researchers further integrated the TPMS hygroscopic lattices into a multi-cycle atmospheric water harvesting system by designing a three-layer alternating solar water harvesting device. Operating in a dynamic mode consisting of one desorption layer and two adsorption layers, the system effectively alleviated the kinetic mismatch between adsorption and desorption processes. During a continuous 30-day outdoor field test in Qingdao during the summer, the device achieved a daytime water production rate of up to 2.70 L m⁻², with an average daily water yield of 98.9 mL.
This work demonstrates the successful application of DLP-printed TPMS photothermal hygroscopic materials for efficient solar-driven atmospheric water harvesting. The study introduces innovations spanning printable ink formulation, topological structure design, multi-cycle device construction, and techno-economic evaluation, providing new materials and manufacturing strategies for the next generation of customizable, scalable, and cost-effective adsorption-based atmospheric water harvesting technologies.
The paper's first author is Wu Xiaochun, a 2022 Ph.D. candidate in the School of Materials Science and Engineering. The research was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Shandong Province, and the Qingdao Natural Science Foundation, with collaborative contributions from researchers at Ocean University of China, Uppsala University (Sweden), Aalto University (Finland), and the University of Derby (United Kingdom).
Original Article: https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.77027
Text/Images: Wu Xiaochun
