Lignin‐Metal Coordination Enables Rapid and Scalable Assembly of Efficient Solar Evaporators

ABSTRACT Solar‐driven evaporation using low‐cost and eco‐friendly biomass‐based materials offers a promising strategy for sustainable freshwater production, yet its practical application remains constrained by complex fabrication processes and insufficient evaporation rates. Herein, this study presents a simple assembly strategy for the rapid fabrication of efficient solar evaporators (<6 min) with a lignin‐Fe 3+ coordination photothermal material immobilized on commercial melamine foam. The boosted photothermal properties of lignin‐Fe 3+ material is achieved through the strengthened π‐π conjugation via lignin fractionation and the coordination‐driven formation of donor‐acceptor structure. Meanwhile, benefited from the rapid water transport of the hydrophilic foam, the evaporator exhibits an evaporation rate of 4.75 kg m −2 h −1 under one simulated solar irradiation (1.0 kW m −2 ) with stability in extreme pH and high‐salinity environments, and can achieve daily freshwater production of 18.64 L m −2 . With cost‐effective accessibility of renewable lignin and melamine foam, and the facile fabrication process, this work presents a promising route toward sustainable and scalable solar‐driven water purification technologies.