Laser-Engineered Graphene on Wood Enables Efficient Antibacterial, Anti-Salt-Fouling, and Lipophilic-Matter-Rejection Solar Evaporation

Advances in solar steam generation have made a promise in mitigating the water scarcity problem. However, their practical use could be curtailed by the vaporized pollutants and the longevity limited by biofouling and salt-fouling that are often overlooked. Here, a flake of wood is reported to be engineered into a miniaturized solar water treatment device by a laser engraving process and demonstrates advantages over common solar systems. The device is structured to mimic the centralized water treatment plants, which contains a superhydrophilic graphene bottom layer for lipophilic organic matter rejection and antifouling, an intrinsic wood microchannels layer for water transport and thermal management, and a hydrophobic graphene top layer for solar-driven desalination while inhibiting salt deposition. The pore size of wood differentiates the water flux and hence the evaporation performance, and the balsa wood with a larger pore size possesses a higher evaporation rate of 1.6 ± 0.02 kg m-2 h-1 compared with pine wood. The hierarchical design achieves a solar energy conversion efficiency of 110% and a lipophilic organic matter removal efficiency of >90% and significantly improves longevity even at high salinity. This work illuminates a sustainable and cost-effective pathway for water treatment and shows potential for wastewater reuse.