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

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.