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Polyvinyl alcohol (PVA)/laponite (LP) nanocomposite coatings were fabricated via a facile one-step coassembly process. The formed nanocoatings contain a high concentration of LP nanosheets, which can be well aligned along the substrate surface during the coassembly process. Due to the highly orientated structure, the flexible nanocoatings exhibit ultra-high transparency and superior mechanical properties, and can also act as excellent gas barriers. Such nanocoatings can be exceptional candidates for a variety of applications, such as food packaging.

A self-assembled two-dimensional montmorillonite nanocoating enables significantly enhanced corona resistance in the Kapton film.

A one-pot self-assembled nanocoating with a well-defined nanostructure was created consisting of polyvinyl alcohol (PVA) and montmorillonite (MMT) and applied to double-walled corrugated cardboard (CB) via spray coating. X-ray diffraction (XRD) analysis revealed the intercalation of PVA into the interstitial spaces of the MMT nanosheets and the alignment of the nanosheets. Vertical burning test, surface burning test, and horizontal burning test showed marked reductions in afterflame time, afterglow time, and flame spread, displaying quick self-extinguishing behaviors. Scanning electron microscopy (SEM) images revealed a uniform coating of the surface of CB before burning tests. After burning, the coated CB samples formed a dense char layer that protected the underlying fibers. A PVA/MMT nanocoating applied via spray coating greatly inhibited flame spread and improved flame retardancy. A one-pot coassembled nanocoating consisting of polyvinyl alcohol and montmorillonite was developed to significantly improve the flame retardancy of cardboard.

Significance Smart devices characterized by micro-/nanotopographies, such as cracks, wrinkles, folds, etc., have been fabricated for widespread application. Here, with the combination of multiscale hierarchical architecture, ultrathin metal nanocoatings with high optical/photothermal tunability and morphological versatility, and surface/interface engineering, a set of multifunctional devices with multistimuli responsiveness was fabricated. These devices can adapt to external stimuli with reversible and instantaneous responses in optical signals, which include strain-regulated light-scattering properties, photothermal-responsive wrinkled surface coupled with moisture-responsive structural color, and mechanically controllable light-shielding properties. The structural designs that rationally overlay micro-/nanostructured ultrathin nanocoatings with other elements are the key to realize this advanced system, which provides avenues for designing versatile, tunable, and adaptable multifunctional devices., Inspired by the intriguing adaptivity of natural life, such as squids and flowers, we propose a series of dynamic and responsive multifunctional devices based on multiscale structural design, which contain metal nanocoating layers overlaid with other micro-/nanoscale soft or rigid layers. Since the optical/photothermal properties of a metal nanocoating are thickness dependent, metal nanocoatings with different thicknesses were chosen to integrate with other structural design elements to achieve dynamic multistimuli responses. The resultant devices demonstrate 1) strain-regulated cracked and/or wrinkled topography with tunable light-scattering properties, 2) moisture/photothermal-responsive structural color coupled with wrinkled surface, and 3) mechanically controllable light-shielding properties attributed to the strain-dependent crack width of the nanocoating. These devices can adapt external stimuli, such as mechanical strain, moisture, light, and/or heat, into corresponding changes of optical signals, such as transparency, reflectance, and/or coloration. Therefore, these devices can be applied as multistimuli-responsive encryption devices, smart windows, moisture/photothermal-responsive dynamic optics, and smartphone app–assisted pressure-mapping sensors. All the devices exhibit high reversibility and rapid responsiveness. Thus, this hybrid system containing ultrathin metal nanocoatings holds a unique design flexibility and adaptivity and is promising for developing next-generation multifunctional devices with widespread application.

CsxWO3 nanorods can be used to sensitize the single layer g-C3N4, where full spectrum light harvesting excited electrons to drive the photocatalytic reduction of N2 into NH3. Under UV light, both water splitting and solar ammonia synthesis reaction exhibit high activity. However, selectivity towards ammonia over hydrogen is realized under NIR irradiation. With the control of methanol, O2 can directly decide the NH3 or H2 evolution on photocatalyst. The origin is the strong capture of O2 with the electrons from the photocatalyst under light irradiation to yield the oxygen active species, which transfer electrons subsequently with help of methanol to generate NH3. However, H2 production will be suppressed by O2. And with its sacrifice, methanol preserves the produced NH3 from oxidation. The O2-sacrificial agent mediated NH3 evolution reaction found here provides insights in the promotion role of them in other catalysis.