image: The bio-inspired solar evaporator, with an external photothermal layer and an internal water supply channel, enhances brine transport to form a porous salt shell that facilitates vapor release and brine transport. This design breaks the trade-off between stable evaporation and salt accumulation.
Credit: ©Science China Press
The global shortage of freshwater has become one of the world's most critical challenges. While traditional seawater desalination provides a feasible solution, the discharge of concentrated brine wastewater has severely impacted marine ecosystems. In recent years, solar-driven interfacial evaporation technology has been widely recognized as one of the most promising approaches for freshwater production, thanks to its environmental sustainability and high efficiency.
However, conventional solar evaporators suffer from salt crystallization, which poses a major challenge in the solar desalination process. Deposited salt crystals on the evaporator’s surface not only drastically reduces sunlight absorption but also obstruct brine supply, ultimately causing a sharp decline in evaporation performance and significantly shortening the evaporator’s lifespan. As a result, conventional solar evaporators must balance stable evaporation with salt accumulation. Overcoming this limitation and achieving long-term, efficient, and stable evaporation in the continuous desalination of high-salinity brine is the key objective for next-generation evaporator design.
Inspired by the salt secretion and brine transport mechanisms of mangroves, the research team from Shandong First Medical University developed a bioinspired solar evaporator with an external photothermal layer and internal water supply channels. The external photothermal layer enables efficient sunlight absorption, rapid vapor diffusion, and uniform surface salt crystallization. Meanwhile, the internal water supply channels facilitate continuous brine transport, ensuring timely replenishment at the crystallization surface to sustain evaporation. This design not only minimizes photothermal material consumption, but also enhances brine transport efficiency, forming porous salt crystals on the evaporator's surface. As a result, it enables continuous, high-efficiency evaporation and automated salt collection from near-saturated brine, ultimately achieving complete separation of water and salt.
The bio-inspired solar evaporator demonstrated outstanding evaporation performance (3.98 kg m⁻² h⁻¹), efficient salt collection capacity (1.27 kg m⁻² h⁻¹), long-term durability (continuous operation for 7 days), and zero liquid discharge desalination under the 25 wt% brine conditions. In outdoor tests, the bio-inspired solar evaporator achieved a record-high water production rate of 3.50 kg m⁻² h⁻¹. Additionally, it can purify various contaminated water sources into fresh water that meets World Health Organization standards.
Compared to conventional solar evaporators, bio-inspired solar evaporators overcome the long-standing trade-off between stable evaporation and salt accumulation, achieving efficient and stable desalination and salt collection under high-salinity brine conditions. Importantly, by extending this design concept to other solar desalination systems, its broad applicability has been demonstrated. This study proposes a universal design strategy for solar evaporators, providing crucial insights for the development of next-generation s highly efficient and stable evaporators capable of continuous desalination of high-salinity brine.