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 tert-butanol freeze-drying of ultrasonically isolated bamboo NFC with 20–80 nm diameters. Then nonagglomerated 2–20-nm-diameter silver oxide (Ag2O) nanoparticles (NPs) were grown firmly onto the NFC scaffold with a high loading content of ∼500 wt % to fabricate Ag2O@NFC organic–inorganic composite aerogels (Ag2O@NFC). For the first time, the coherent interface and interaction mechanism between the cellulose Iβ nanofiber and Ag2O NPs are explored by high-resolution transmission electron microscopy and 3D electron tomography. Specifically, a strong hydrogen between Ag2O and NFC makes them grow together firmly along a coherent interface, where good lattice matching between specific crystal planes of Ag2O and NFC results in very small interfacial straining. The resulting Ag2O@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– ions from contaminated water and trap I2 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.Keywords: aerogel; Ag2O nanocrystals; coherent interface; iodine capture; nanofibrillated cellulose

•Cellulose nanofibers from natural pine needle were successfully fabricated.•Pine needle nanofibers were characterized.•Ultralight and highly flexible and hydrophobic nanofiber aerogels were made.To obtain the nanofibriled cellulose from natural pine needles, a combination of chemical pretreatments and subsequently ultrasonic treatments was employed for removing the hemicelluloses and lignins and splitting the bundled cellulose into pine needle nanofibers. Using SEM and diameter distribution method, it was confirmed that the obtained pine needle nanofibers had a narrow diameter from 30 to 70 nm. The crystalline type of the pine needle nanofibers was the cellulose I type. The crystallinity reached 66.19%, which was increased by 7.61% as compared with the raw material pine needles. The TGA and DTG results showed that the degradation temperature of the nanofibers was increased to approximately 267 and 352 °C compared with 221 and 343 °C of the raw material fibers, respectively. Furthermore, the highly flexible and ultralight pine needle nanofibers aerogels were prepared from the aqueous pine needle nanofibers solution using the freezing-drying technique. Aerogels were studied by SEM observation and nitrogen gas adsorption. The mechanical properties were measured in compression for aerogels. This study provides a new opportunity to fabricate novel nanomaterials from waste biomass materials, which is crucial for the fully utilizing of abundant biomass resources.

Magnetic wood would have potential uses in electromagnetic shielding, indoor electromagnetic wave absorption and heavy metal adsorption. In this study, magnetic wood composites with improved thermal stability and mechanical properties as well as UV resistance were prepared by modification with magnetic CoFe2O4 and hydroxyapatite (HAP) via a hydrothermal process. The functional groups and morphology of the modified wood were examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDXA). The results indicated that the magnetic CoFe2O4 nanoparticles precipitated on the wood substrate during the alkali treatment, and then the hydroxyapatite was grown on the wood surface via the electrostatic interactions between the calcium cations and the negatively charged OH− anions. Moreover, the magnetic, thermal and mechanical performances and the UV-resistance of the CoFe2O4/HAP-modified wood composites were also evaluated.

To determine the hydrothermal growth conditions for ZnO nanocrystals on the surface of bamboo and to further develop new ZnO/bamboo hybrid materials, ZnO nanostructured materials with six morphologies, namely, spheroidal nanoparticles, nanoparticles, nanoneedles, nanograsses, nanowall networks, and nanoorchids, were successfully grown on the surface of bamboo via a low-temperature hydrothermal method based on sol–gel-prepared ZnO seed layers. The effects of temperature, time, molar ratio (zinc acetate/sodium hydroxide), and zinc salt precursor (zinc nitrate, zinc sulfate, zinc chloride, and zinc acetylacetonate) on the ZnO morphologies were comprehensively studied. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive spectrometry (EDS) were employed to characterize the morphology, chemical structure, and crystalline structure of the ZnO nanomaterials deposited on the bamboo surface. The ZnO nanostructure morphology was most sensitive to temperature and could be controlled by the reaction temperature. All of the as-prepared ZnO nanostructured materials were wurtzite. ZnO nanomaterials were bonded through the interaction between the hydroxyl moiety of the bamboo surface and the corresponding ZnO. A possible hydrothermal fabrication mechanism was also proposed. Further research is required to assess the improvements in the properties of bamboo from the hydrothermal deposition of nanomaterials at the bamboo surface.

•The TiO2 films with desirable wettability were achieved on the wood surface.•The wettability of the TiO2-treated wood surface could be tuned by adjusting the precursor solution pH.•This research may provide a simple method to fabricate a desirable TiO2/wood surface suitable for various environments with different humidity.TiO2 thin films with different wettability were fabricated on the wood surfaces by a simple low-temperature hydrothermal method with the precursor solution pH adjusted by hydrochloric acid/sodium hydroxide. The morphologies of TiO2 films have been changed from sphere species to filmy ones by adjusting pH of precursor solution. The TiO2 films synthesized at the precursor solution pH of 1~10 were mainly primary existed in anatase phase without other structure, and the TiO2-treated wood surfaces presented different wettability with the water contact angles ranged from 9.6° to 132.7°, when the precursor solution pH were controlled to the range of 1~14. Such a wood surface with the desirable wettability shows great potential, as it may be selectively used in the various environments with different humidity.The wood surfaces with different wettability between hydrophilicity and hydrophobicity were fabricated by adjusting the precursor solution by HCl/NaOH.

•A robust superhydrophobic wood surface was achieved by a two-step method.•The prepared wood maintained superhydrophobicity under various conditions.•This research may provide a functional coating on wood surface.A two-step method containing low-temperature hydrothermal synthesis with TiO2 precursor solution and subsequent modification with fluoroalkyl silane on wooden substrates was investigated. Scanning electron microscopy (Scanning electron microscope) images showed that the TiO2-treated wood substrate was covered with uniform TiO2 particles, which generated a roughness on the wood surface favoring the formation of the superhydrophobic surface, and the decoration of (heptadecafluoro-1,1,2,2-tetradecyl)trimethoxysilane on TiO2-based wood surface acted as a crucial role in improving the repellency toward water. The superhydrophobic wood surface with the water contact angle (WCA) of 152.9°, maintained superhydrophobic property with the WCA larger than 150° after immerse in 0.1 M hydrochloric acid solution for one week, irradiating under UV light for 24 h, or boiling at 150 °C for 10 h. The prepared wood surface showed multi-functions including super repellency toward water, anti-acid, and high-temperature–humidity-resistant. On the basis of the results, the functional coating on the wood surface provided an enlarged field of the wood works, such as historic structure protection.

•α-Chitin nanofibers (∼20 nm) from prawn shell were fabricated via pulsed ultrasonic treatment (60 KHz, 300 W, pH = 7).•We made highly transparent film (transmittance achieved 90.2% at 600 nm) and flexible ultralight foam using α-chitin nanofibers.•This paper provides ultrasonication as a new way to fabricate ultralong nanofibers from natural polysaccharide materials.α-Chitin nanofibers were fabricated with dried shrimp shells via a simple high-intensity ultrasonic treatment under neutral conditions (60 KHz, 300 W, pH = 7). The diameter of the obtained chitin nanofibers could be controlled within 20–200 nm by simply adjusting the ultrasonication time. The pulsed ultrasound disassembled natural chitin into high-aspect-ratio nanofibers with a uniform width (19.4 nm after 30 min sonication). The EDS, FTIR, and XRD characterisation results verified that α-chitin crystalline structure and molecular structure were maintained after the chemical purification and ultrasonic treatments. Interestingly, ultrasonication can slightly increase the degree of crystallinity of chitin (from 60.1 to 65.8). Furthermore, highly transparent chitin films (the transmittance was 90.2% at a 600 nm) and flexible ultralight chitin foams were prepared from chitin nanofiber hydrogels.

•Millimeter-long nanostructured TiO2 was fabricated using cellulose as a template.•The as-prepared TiO2 showed a superior photocatalytic ability to decompose phenol.•A feasible method for fabricating TiO2 photocatalyst was introduced.We report a millimeter-long TiO2 fiber with nanostructures fabricated using bamboo cellulose fiber as a template. The method includes the in situ synthesis of titanium oxide nanoparticles in the cellulose fiber template and subsequent removal of the cellulose matrix by calcination. The prepared samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and transmission electron microscope (TEM) techniques. XRD pattern confirmed the crystalline phase of the prepared TiO2 is anatase phase. From the observation of SEM image, the cellulose-templated TiO2 inherited the initial millimetric length of the bamboo cellulose. TEM image revealed the millimeter-long TiO2 was comprised of the spherical nanoparticles with the diameter of about 30 nm. Meanwhile, the as-fabricated TiO2 presented a superior photocatalytic ability to decompose phenol under ultraviolet irradiation. This approach is facile, and would provide ready access to metallic oxide nanostructures of desired morphology and size with the appropriate templates.Graphical abstract