Porous polymer solar evaporator resists salt buildup

Researchers at Donghua University have developed a lotus-root-inspired solar evaporator that moves water quickly, resists salt buildup and generates electricity from waste heat. The composite material could improve desalination in coastal, off-grid and water-stressed areas.

Why it matters: - Freshwater scarcity is increasing demand for desalination systems that are efficient, low-cost and durable outside the lab. - Salt buildup, weak mechanical strength and wasted heat remain major barriers for solar desalination devices. - The new material combines water production and low-grade heat recovery in one platform, which could improve overall system efficiency.

What happened: - Researchers from Donghua University reported a biomimetic solar evaporator in Chinese Journal of Polymer Science. - The paper was published online April 9, 2026. - The design is called SH@FPCP. - The source article carries DOI 10.1007/s10118-026-3586-9.

The details: - SH@FPCP combines a polymerized high internal phase emulsion (PolyHIPE) scaffold with a sulfonic hydrogel network. - The structure is inspired by lotus roots, which use hollow channels for gas exchange and fibrous tissues for water movement. - The PolyHIPE framework provides open macropores that help vapor escape quickly. - Hydrogel filaments running through the pores supply water and help redistribute dissolved salt. - A fluorinated polypyrrole-modified framework boosts the photothermal response under sunlight. - Under one-sun irradiation, the evaporator reached 3.19 kg m−2 h−1 evaporation. - The material maintained stable salt-resistant operation for more than one week. - The evaporator worked in NaCl solutions from 3.5 wt% to 20.0 wt%. - Mechanical testing showed a compressive strength of 1298 kPa at 5% strain. - The rigid porous scaffold reinforces the softer hydrogel network.

Between the lines: - The main advance is integration, not a single feature. - Open pores, water pathways, salt management and photothermal conversion are built into one architecture. - That matters because real desalination systems often fail from a mix of salt crusting, structural collapse and lost heat. - The authors also frame the design as a model for using biology to guide practical materials engineering.

What’s next: - The team says the platform still needs scale-up, device optimization and field validation. - SH@FPCP could be adapted for decentralized water-treatment systems in coastal, off-grid and water-stressed regions. - The material may also support wastewater cleanup. - The study reports removal of organic dyes including methylene blue and methyl orange. - When paired with a thermoelectric module, the device generated 720 mW m−2 of power density, 110 mV of open-circuit voltage and 10.4 mA of short-circuit current under one-sun irradiation in a wet state. - Even while generating power, the evaporator kept a 3.05 kg m−2 h−1 evaporation rate. - Outdoor testing showed the condensed water met World Health Organization drinking-water standards.

The bottom line: - SH@FPCP points to a multifunctional solar desalination approach that makes freshwater, resists salt and captures some of the heat that would otherwise be wasted.