Solar-driven interfacial evaporation has emerged as a sustainable approach to desalination because it concentrates solar heat at the water–air interface rather than heating the entire water body. However, several barriers still limit practical use. Salt crystals can accumulate on the evaporation surface, blocking vapor pathways and reducing long-term efficiency. Many hydrogel- or aerogel-based evaporators also lack sufficient mechanical strength, making them vulnerable to deformation or collapse. Meanwhile, the low-grade heat generated during evaporation is often wasted. Based on these challenges, there is a need to conduct in-depth research on integrated evaporator designs that combine salt management, structural durability, and energy recovery.
Researchers from Donghua University, reported the new design in Chinese Journal of Polymer Science. The article was published (DOI: 10.1007/s10118-026-3586-9) online on April 9, 2026. The team developed a biomimetic PolyHIPE/hydrogel composite evaporator for salt-resistant solar desalination and simultaneous power generation.
The material, named SH@FPCP, takes functional inspiration from lotus roots, whose hollow channels support gas exchange while fibrous tissues guide water movement. In SH@FPCP, the interconnected macroporous PolyHIPE framework works like vapor channels, helping steam leave quickly during evaporation. Hydrogel filaments threaded through the pores act as water and salt-transport pathways, continuously replenishing water and helping dissolve accumulating salts. A fluorinated polypyrrole (FPPy)-modified framework provides strong photothermal response under sunlight. This combined architecture delivered an evaporation rate of 3.19 kg m−2 h−1 under one-sun irradiation, while maintaining stable salt-resistant operation for more than one week. It also performed steadily in sodium chloride (NaCl) solutions from 3.5 wt% to 20.0 wt%. Mechanical testing showed a compressive strength of 1298 kPa at 5% strain, demonstrating that the rigid porous scaffold effectively reinforces the softer hydrogel network.
The authors said the study shows how a biological structure can guide the design of more practical solar desalination materials. They said the key advance is not a single function, but the way several functions are built into one architecture: open pores speed vapor release, hydrogel pathways sustain water supply, sulfonic groups assist salt management, and the photothermal framework converts sunlight into heat. They also said this integrated strategy helps address problems that often appear together in real desalination settings, including salt buildup, weak mechanical stability, and wasted thermal energy.
The system also makes use of heat that would otherwise be lost during evaporation. When SH@FPCP was coupled with a thermoelectric (TE) module, the temperature difference between the hot photothermal surface and the cooler water-contacting side generated electricity through the Seebeck effect. Under one-sun irradiation in a wet state, the device achieved a power density of 720 mW m−2, an open-circuit voltage (Voc) of 110 mV, and a short-circuit current (Isc) of 10.4 mA. Even during power generation, the evaporator maintained a high evaporation rate of 3.05 kg m−2 h−1. Outdoor testing further showed that the condensed water met World Health Organization (WHO) drinking-water standards.
This biomimetic evaporator points toward durable, multifunctional solar desalination systems for water-stressed, coastal, and off-grid regions. Its value lies in producing freshwater while improving the overall use of solar-derived heat. The platform may also support wastewater purification, as the study showed removal of organic dyes including methylene blue (MB) and methyl orange (MO). With further scale-up, device optimization, and field validation, PolyHIPE/hydrogel evaporators could become part of decentralized water-treatment technologies that are lightweight, salt-resistant, mechanically robust, and capable of generating small but useful amounts of electricity.
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References
DOI
10.1007/s10118-026-3586-9
Original Source URL
https://doi.org/10.1007/s10118-026-3586-9
Funding information
This work was financially supported by the National Natural Science Foundation of China (Nos. 52373172 and 52473055), the National Key Research and Development Program of China (Nos. 2022YFB3807100 and 2022YFB3807102), the Chang Jiang Scholar Program (No. T2023082), the Shanghai Science and Technology Plan Project (No. 25DX1400200), the Natural Science Foundation of Shanghai (No. 23ZR1401100) and the Key Technology Research and Development Program of Shanghai (No. 25CL2900800).
About Chinese Journal of Polymer Science
Chinese Journal of Polymer Science (CJPS) is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry, Chinese Academy of Sciences. CJPS is edited by a distinguished Editorial Board headed by Professor Qi-Feng Zhou and supported by an International Advisory Board in which many famous active polymer scientists all over the world are included. Manuscript types include Editorials, Rapid Communications, Perspectives, Tutorials, Feature Articles, Reviews and Research Articles. According to the Journal Citation Reports, 2024 Impact Factor (IF) of CJPS is 4.0.