Nanocellulose–MOF‐Derived Carbon Hybrid Aerogels with Hierarchical Micro/Nanostructures for Solar‐Driven Water Evaporation

Abstract Solar‐driven interfacial evaporation is a highly promising method for sustainable water purification. However, simultaneously achieving high photothermal efficiency and strong structural durability remains a considerable challenge. Here, a hierarchically engineered bilayer evaporator is introduced, fabricated entirely through aqueous processing. This device combines a vertically aligned nanocellulose layer for water transport with a plasmonically enhanced, metal–organic framework (MOF)‐derived carbon layer for photothermal conversion. Using a sequential ice‐templating technique, both layers feature anisotropic microchannels that facilitate rapid, capillary‐driven water transport and efficient vapor release, while providing robust interfacial adhesion without requiring additional binders. The photothermal layer, made of ZIF‐8‐derived porous carbon uniformly decorated with gold nanoparticles (AuNPs), achieves broadband solar absorption of 95.9% and efficient localized heating through plasmonic effects. At an optimal AuNP loading of 40 wt%, the evaporator reaches a peak water evaporation rate of 2.36 kg m −2 h −1 and an apparent solar‐to‐vapor efficiency of 119% under 1 sun illumination. The system performs well in highly saline water, offers excellent self‐cleaning, and is both fully biodegradable and scalable. This work introduces an eco‐friendly and scalable platform for efficient solar vapor generation with potential in seawater desalination, off‐grid freshwater supply for remote and disaster‐affected regions, and sustainable wastewater treatment and reuse.