Janus-structured wood-based evaporator: Electrospun lignin carbon nanofibers (LCNFs) with in situ Fe₃O₄ growth enable solar-driven seawater desalination and purification

In response to water scarcity and energy crises, solar-driven interfacial evaporation technology offers a highly promising industrial solution for seawater desalination due to its “zero energy consumption” and environmentally friendly characteristics. The aromatic ring structure of lignin exhibits excellent light absorption properties, making it a highly suitable material for interfacial evaporation photothermal applications. This study employs electrospun lignin nanofiber membranes that have undergone high-temperature carbonization, with Fe₃O₄ nanoparticles in situ loaded onto their surfaces to form a photothermal layer. Polyvinylidene fluoride (PVDF) serves as both a binder and hydrophobic modifier, bonding at the interface with delignified wood blocks (DW). Based on this design, the fabricated LCNFs/Fe₃O₄@DW evaporator achieves an evaporation rate of 1.76 kg·m −2 ·h −1 under one standard solar irradiance, with an evaporation efficiency of approximately 88.54%, outperforming most conventional wood-based or carbon-based photothermal evaporators. Long-term cycling tests and simulated seawater evaporation experiments demonstrate the material's excellent salt resistance and purification durability. In summary, this study not only validates the application potential of lignin-based nanofiber composites in solar thermal conversion but also achieves functional integration of “solar desalination, salt resistance and scale prevention, and water purification” through precise Janus surface design. It provides a novel strategy that combines environmental sustainability with practical applicability for industrializing solar-driven interfacial evaporation technology.