High-performance, salt-resistant, and stable wood-based solar evaporator equipped with sodium alginate-based...

Harnessing renewable solar energy for photothermal evaporation and seawater desalination holds significant potential for alleviating freshwater scarcity. However, evaporators reported recently often suffer from limitations in environmental compatibility, salt resistance, and stability. Herein, we report a green and straightforward approach to fabricate a dual-layer solar evaporator (STF-wood) by equipping wood-based materials with a sodium alginate-based photothermal skin. The functional skin, synthesized through the chelation of tannic acid (TA), sodium alginate (SA), and Fe³⁺, not only exhibits excellent photothermal conversion efficiency but also forms a dense network that restricts the movement of free water, thereby enhancing the localized heat effect. Moreover, the positively charged surface of the skin can prevent the passage of salt ions through the Donnan effect, demonstrating superior salt resistance. STF-wood is capable of operating stably in seawater with an evaporation rate of 1.92 kg m^-2 h^-1 and maintains a similar rate even after undergoing 5-hour ultrasonic treatment. This work presents a sustainable and efficient solution to compensate for the shortcomings of environmental compatibility and operational stability for solar evaporator.