In-situ lignin regeneration facilitated corn straw-based photothermal evaporator with high cost-effectiveness

Solar evaporators are one of the most efficient and sustainable water purification strategies, but it requires the use of expensive photothermal materials. Herein, the surface of waste corn straw was modified with condensed lignin by means of in-situ lignin regeneration. The resulting material was composited with hydrophilic chitosan and then applied as a sustainable and cost-effective photothermal material to construct a solar evaporator. The non-radiative transport was conferred by π-π stacking between conjugated aromatic rings of lignin, allowing the composites to demonstrate promising photothermal conversion ability. The composites presented a max evaporation rate of ∼1.44 kg m−2 h−1 under 1 sun, plus they consistently produced clean water in aqueous organic dye solutions (100 ppm RhB dye and 100 ppm MB dye) and seawater. Due to the ultra-low cost of raw materials and uncomplicated manufacturing procedure, these composites displayed a cost-effectiveness of ∼475 g h−1 $−1. Thus, this work provides a green and sustainable method for converting agricultural waste into functional photothermal evaporators, which is meaningful for both materials and environmental science.