Biomass Nanofiber‐Assembled Superhydrophobic Aerogels with Simultaneously Enhanced Mechanical Strength and Shape Recovery

Oil spills and water pollution present significant environmental challenges, calling for the development of sustainable and efficient material solutions. In this study, aerogels are prepared from chitosan and sodium alginate, two renewable natural polysaccharides, through ultrasonication‐assisted nanofiber assembly combined with freeze casting. This approach leverages the inherent electrostatic interactions between two polysaccharides to assemble nanofibers, which are then aggregated into an anisotropic honeycomb‐like cellular microstructure during freeze casting. The addition of methyltrimethoxysilane further consolidates the nanofiber network, resulting in CSNF‐Si aerogels with a superlow density of 0.0198 g cm −3 , yet high mechanical strength (105.7 kPa at 80% strain) and shape recovery (95% after 80% deformation). In addition, the aerogels exhibit superhydrophobicity with a water contact angle of 151° and a rolling angle of 4.3°, enabling effective oil absorption with capacities reaching up to 90 times their own weight. They also demonstrate excellent reusability over multiple oil absorption‐release cycles, thanks to their enhanced shape recovery ability. Furthermore, this study presents a hierarchical fabrication strategy that synergistically integrates molecular, nano‐, and microscale designs to reinforce and functionalize aerogels for sustainable engineering solutions.