Fe3O4/polyvinyl alcohol decorated delignified wood evaporator for continuous solar steam generation

Wood-based solar desalination is emerged as one of the promising methods to address the water shortage problem. Herein, a wood evaporator was designed by a two-layer structure: a hydrophobic top layer (Fe3O4) and a superhydrophilic delignified wood bottom layer. The Fe3O4 coated delignified wood (Fe-D-Wood) demonstrates an evaporation rate of 1.3 kg m−2 h−1 and a conversion efficiency of 73%. Fe3O4 with a narrow bandgap (0.8 eV) affords a broad light absorption and polyvinyl alcohol (PVA) enhances the affinity between Fe3O4 and wood substrate, and the wood evaporator presents a good anti-fouling property. Two reasons contribute to such self-regenerating ability: i) salts are difficult to deposit on the hydrophobic layer, and ii) the rapid water uptake promotes the re-dissolution of salts into bulk water. Such wood-based evaporator holds great potential for practical desalination applications.