Coherent-Interface-Assembled Ag<sub>2</sub>O‑Anchored Nanofibrillated Cellulose Porous Aerogels for Radioactive Iodine Capture

Nanofibrillated cellulose (NFC) has received increasing attention in science and technology because of not only the availability of large amounts of cellulose in nature but also its unique structural and physical features. These high-aspect-ratio nanofibers have potential applications in water remediation and as a reinforcing scaffold in composites, coatings, and porous materials because of their fascinating properties. In this work, highly porous NFC aerogels were prepared based on <i>tert</i>-butanol freeze-drying of ultrasonically isolated bamboo NFC with 20–80 nm diameters. Then nonagglomerated 2–20-nm-diameter silver oxide (Ag<sub>2</sub>O) nanoparticles (NPs) were grown firmly onto the NFC scaffold with a high loading content of ∼500 wt % to fabricate Ag<sub>2</sub>O@NFC organic–inorganic composite aerogels (Ag<sub>2</sub>O@NFC). For the first time, the coherent interface and interaction mechanism between the cellulose I<sub>β</sub> nanofiber and Ag<sub>2</sub>O NPs are explored by high-resolution transmission electron microscopy and 3D electron tomography. Specifically, a strong hydrogen between Ag<sub>2</sub>O and NFC makes them grow together firmly along a coherent interface, where good lattice matching between specific crystal planes of Ag<sub>2</sub>O and NFC results in very small interfacial straining. The resulting Ag<sub>2</sub>O@NFC aerogels take full advantage of the properties of the 3D organic aerogel framework and inorganic NPs, such as large surface area, interconnected porous structures, and supreme mechanical properties. They open up a wide horizon for functional practical usage, for example, as a flexible superefficient adsorbent to capture I<sup>–</sup> ions from contaminated water and trap I<sub>2</sub> vapor for safe disposal, as presented in this work. The viable binding mode between many types of inorganic NPs and organic NFC established here highlights new ways to investigate cellulose-based functional nanocomposites.