Micronleaf-shape graphene interfaces on wood transverse sections as advanced photothermal evaporators for water purification

Similar to transpiration, the formulation of interfacial solar evaporation has been designed to perform water treatment. The concept involves wood-based support (tree) with a graphene-based layer acting as leaves. To enhance light absorption and solar-thermal conversion capacity, a novel holly-leaf graphene (HLG) layer with an individual hollowed-out structure was engineered. The formation mechanism of this HLG was shown to be linked to the strong capillarity forces in the polyporous wood. By creating biomimetic leaves made of graphene, the light-to-heat conversion performance can be improved, while exhibiting substantially lower thermal conductivity (74 mW/m/K) than natural wood. Under solar irradiation, HLG/wood exhibits an outstanding evaporation rate of 1.96 kg/m2/h, with an impressive efficiency of 94%. A theoretical model of HLG/wood based on the thermal management capability was built to further confirm its structural superiority in facilitating photothermal conversion. Consequently, a bilayer evaporator based on HLG/wood has the potential to revolutionize water purification processes, including desalination of seawater, removal of heavy metal ions, and treatment of organic dye-contaminated wastewater.