Recent progress of colloidal chemistry in the synthesis of multimaterial nanostructures incorporating transition‐metal oxides is reviewed. Attention is focused on the emerging class of hybrid nanocrystals (HNCs), in which domains of different materials are interconnected through inorganic junctions in defined spatial arrangements. The level of expertise so far achieved in the preparation of single‐material NCs with finely tuned geometric parameters has been further extended into elegant “seeded growth” approaches for accessing elaborate HNCs by control of interfacial lattice strain and surface energy in liquid media. Various topological configurations are analyzed, including concentric core/shell architectures, hetero‐oligomers grouping spherical material domains and more asymmetric hybrid nanostructures based on rod‐shaped sections. The chemical‐physical properties and technological advantages offered by such multifunctional HNCs are also summarized.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The presence of micro- and nanoplastics in the marine environment is raising strong concerns since they can possibly have a negative impact on human health. In particular, the lack of appropriate methodologies to collect the nanoplastics from water systems imposes the use of engineered model nanoparticles to explore their interactions with biological systems, with results not easily correlated with the real case conditions. In this work, we propose a reliable top-down approach based on laser ablation of polymers to form polyethylene terephthalate (PET) nanoplastics, which mimic real environmental nanopollutants, unlike synthetic samples obtained by colloidal chemistry. PET nanoparticles were carefully characterized in terms of chemical/physical properties and stability in different media. The nanoplastics have a ca. 100 nm average dimension, with significant size and shape heterogeneity, and they present weak acid groups on their surface, similarly to photodegraded PET plastics. Despite no toxic effects emerging by in vitro studies on human Caco-2 intestinal epithelial cells, the formed nanoplastics were largely internalized in endolysosomes, showing intracellular biopersistence and long-term stability in a simulated lysosomal environment. Interestingly, when tested on a model of intestinal epithelium, nano-PET showed high propensity to cross the gut barrier, with unpredictable long-term effects on health and potential transport of dispersed chemicals mediated by the nanopollutants.

We demonstrate the light-induced, reversible wettability of homogeneous nanocrystal-based, thin-film coatings composed of closely packed arrays of surfactant-capped anatase TiO 2 nanorods laterally oriented on various substrates. Under selective pulsed UV laser excitation, the oxide films exhibit a surface transition from a highly hydrophobic and superoleophilic state (water and oil contact angles of ∼110°and less than ∼8°, respectively) to a highly amphiphilic condition (water and oil contact angles of ∼20°and ∼3°, respectively). A mechanism is identified according to which the UV-induced hydrophilicity correlates with a progressive increase in the degree of surface hydroxylation of TiO 2 . The observed wettability changes are not accompanied by any noticeable photocatalytic degradation of the surfactants on the nanorods, which has been explained by the combined effects of the intense and pulsed irradiation regime and of the rodlike nanocrystal morphology. The organic ligands on the oxide are instead assumed to rearrange conformationally in response to the lightdriven surface reconstruction. The amphiphilic state of the UV-irradiated TiO 2 films is then considered as the macroscopic wetting result of alternating hydrophilic and oleophilic surface domains of nanoscale extension. Upon prolonged storage in the dark, ambient oxygen removes the newly implanted hydroxyl groups from the TiO 2 surfaces and consequently affects again the conformations of ligands such that the films are allowed to recover their native hydrophobic/superoleophilic properties.

Here, an approach to realize “smart” solid substrates that can convert their wetting behavior between extreme states under selective light irradiation conditions is described. Hybrid organic/inorganic surfaces are engineered by exploiting photolithographically tailored SU‐8 polymer patterns as templates for accommodating closely packed arrays of colloidal anatase TiO2 nanorods, which are able to respond to UV light by reversibly changing their surface chemistry. The TiO2‐covered SU‐8 substrates are characterized by a dual micro‐/nanoscale roughness, arising from the overlapping of surfactant‐capped inorganic nanorods onto micrometer‐sized polymer pillars. Such combined architectural and chemical surface design enables the achievement of UV‐driven reversible transitions from a highly hydrophobic to a highly hydrophilic condition, with excursions in water contact angle values larger than 100°. The influence of the geometric and compositional parameters of the hybrid surfaces on their wettability behavior is examined and discussed within the frame of the available theoretical models.

White light-emitting diodes (WLEDs) are candidates to revolutionize the lighting industry towards energy efficient and environmental friendly lighting and displays. The current challenges in WLEDs encompass high luminous efficiency, chromatic stability, high colourrending index and price competitiveness. Recently, the development of efficient and low-cost downconverting photoluminescent phosphors for ultraviolet/blue to white light conversion was highly investigated. Here we report a simple route to design high-efficient WLEDs by combining a commercial ultraviolet LED chip (InGaAsN, 390 nm) and boehmite (g-AlOOH) hybrid nanoplates. Unusually high quantum yields (Z yield ¼ 38-58%) result from a synergic energy transfer between the boehmite-related states and the triplet states of the benzoate ligands bound to the surface of the nanoplates. The nanoplates with Z yield ¼ 38% are able to emit white light with Commission International de l'Eclairage coordinates, colour-rendering index and correlated colour temperature values of (0.32, 0.33), 85.5 and 6,111 K, respectively; overwhelming state-of-the-art single-phase ultraviolet-pumped WLEDs phosphors.

Superhydrophobic materials hold an enormous potential in sectors as important as aerospace, food industries, or biomedicine. Despite this great promise, the lack of environmentally friendly production methods and limited robustness remain the two most pertinent barriers to the scalability, large-area production, and widespread use of superhydrophobic materials. In this work, highly robust superhydrophobic silicone monoliths are produced through a scalable and environmentally friendly emulsion technique. It is first found that stable and surfactantless water-in-polydimethylsiloxane (PDMS) emulsions can be formed through mechanical mixing. Increasing the internal phase fraction of the precursor emulsion is found to increase porosity and microtexture of the final monoliths, rendering them superhydrophobic. Silica nanoparticles can also be dispersed in the aqueous internal phase to create micro/nanotextured monoliths, giving further improvements in superhydrophobicity. Due to the elastomeric nature of PDMS, superhydrophobicity can be maintained even while the material is mechanically strained or compressed. In addition, because of their self-similarity, the monoliths show outstanding robustness to knife-scratch, tape-peel, and finger-wipe tests, as well as rigorous sandpaper abrasion. Superhydrophobicity was also unchanged when exposed to adverse environmental conditions including corrosive solutions, UV light, extreme temperatures, and high-energy droplet impact. Finally, important properties for eventual adoption in real-world applications including self-cleaning, stain-repellence, and blood-repellence are demonstrated.

The challenge of making strongly emissive CsPbBr₃ perovskite nanocrystals with a robust surface passivation is solved via Cs₄PbBr₆ → CsPbBr₃ transformation triggered by a reaction of oleylamine ligand with poly(maleic anhydride-1-alt-octadecene).

High-resolution imaging of low-atomic-number chemical elements using electron microscopy is challenging and may require the use of high doses of electrons. Electron diffractive imaging, which creates real-space images using diffraction intensities and phase retrieval methods, could overcome such issues, although it is also subject to limitations. Here, we show that a combination of electron diffractive imaging and high-resolution transmission electron microscopy can image individual TiO(2) nanocrystals with a resolution of 70 pm while exposing the specimen to a low dose of electrons. Our approach, which does not require spherical and chromatic aberration correction, can reveal the location of light atoms (oxygen) in the crystal lattice. We find that the unit cell in nanoscale TiO(2) is subtly different to that in the corresponding bulk.