Laser‐Architected Hierarchical Wood Evaporator for Salt‐Resistant Solar Desalination and Dual‐Mode Water–Electricity Cogeneration

Freshwater scarcity and intermittent solar irradiation motivate the development of technologies for freshwater production and electricity generation. However, salt accumulation limits the long‐term operation of solar interfacial evaporators. A laser‐architected delignified balsa wood evaporator (DBW/LCC) with a 3D cylindrical array and laser‐carbonized surfaces is fabricated through delignification, laser engraving, and in situ laser carbonization. The array enhances light trapping and exposes additional sidewall area. Vertically aligned hydrophilic channels sustain capillary water supply and, together with the hydrophobic top surface, establish asymmetric wettability. DBW/LCC achieves an average absorptance of 99.46% over 250–2500 nm. The wetted surface exhibits a valley–plateau temperature difference of ∼1.2°C. Thermo–solutal Marangoni circulation may contribute to brine redistribution. The evaporator maintains stable evaporation for 150 h in 20 wt.% brine without visible salt deposition. Under 1 sun, it achieves a mass‐loss rate of 5.09 kg m −2 h −1 normalized to its horizontal projected area, with an apparent evaporation efficiency of 99.85% calculated using an effective enthalpy. Coupled with a thermoelectric module, it generates voltages of 86.3 mV under 1 sun and 79.8 mV at a wind speed of 9.6 m s −1 without illumination. This platform offers a route to decentralized water–electricity cogeneration.