Amorphous nanomaterials have aroused extensive interest due to their unique properties derived from the distinct atomic structure of long-range disorder while short- to medium-range order. Herein, an overview of state-of-art...
Functional fabrics with various unique properties are necessary for making fantastic superior costumes just like a superhero suit in Marvel Comics, which are not only dreams of boys but also emerging textiles to facilitate human life. On the basis of the inspiration of a phenomenon in an extracurricular experiment for kids, we develop a biofabrication strategy to endow silk textiles with various unique physical and chemical properties of functional nanomaterials, where the functional textiles are weaved using silk spun by silkworms that are fed with functional nanomaterials. To confirm the feasibility of this strategy, a photoluminescent plain weave was prepared successfully via feeding biocompatible luminescent nanoparticles to Bombyx mori silkworms. As the functional nanomaterials are enclosed in the silkfibers, the given special properties will be permanent for further application. Considering the wondrous diversity of properties that a variety of nanomaterials possesses may be given to silk fabric, it is promising to see various miraculous costumes in the coming future.
The catalytic properties of supported metal heterostructures critically depend on the design of metal sites. Although it is well-known that the supports can influence the catalytic activities of metals, precisely regulating the metal-support interactions to achieve highly active and durable catalysts still remain challenging. Here, the authors develop a support effect in the oxide-supported metal monomers (involving Pt, Cu, and Ni) catalysts by means of engineering nitrogen-assisted nanopocket sites. It is found that the nitrogen-permeating process can induce the reconstitution of vacancy interface, resulting in an unsymmetrical atomic arrangement around the vacancy center. The resultant vacancy framework is more beneficial to stabilize Pt monomers and prevent diffusion, which can be further verified by the density functional theory calculations. The final Pt-N/SnO 2 catalysts exhibit superior activity and stability for HCHO response (26.5 to 15 ppm). This higher activity allows the reaction to proceed at a lower operating temperature (100 °C). Incorporated with wireless intelligent-sensing system, the Pt-N/SnO 2 catalysts can further achieve continuous monitoring of HCHO levels and cloudbased terminal data storage.
Engineering the local three-dimensional structure of metal sites has important effect to maximize the activity and selectivity of single-atom site catalysts. Here, we engineer a strain-assisted single Pt sites structure on highly curved MoS 2 surface to enhance the H 2 S sensor property. Through introducing N-methyl-2-pyrrolidone (NMP) as guiding molecules, a multilayer MoS 2 structure with bending base planes is achieved. This bending behavior can not only inject uniform in-plane strain into the original inert MoS 2 basal plane but also introduce sufficient accessible sites to anchor Pt monomers. Further experimental and theoretical results show that the high-curvature MoS 2 surface endows 0.8% stretch strain onto the low-coordinated single Pt sites with a unique "tip" effect, which will lead to more accumulation of electrons around the Pt species, thus accelerating the electric transfer process between H 2 S and supports. The final catalyst delivers the pronouncedly enhanced H 2 S
“Unprotected” Pt nanocrystals were modified with triphenylphosphine (PPh3), octadecylamine (ODA), poly(vinylpyrrolidone) (PVP), poly(vinyl alcohol) (PVA), and dodecanethiol (DT) to investigate the effect of protective agents on the intrinsic catalytic property of Pt nanocrystals. By evaluating the catalytic performance of these model catalysts for the hydrogenation of para‐chloronitrobenzene (p‐CNB), it was found that direct or indirect interaction between nanocrystals and protective agents imposed a great impact on the catalytic performance of the nanocrystals. Protective agents with different electron‐donating ability (PPh3, ODA, PVP, and PVA) directly altered surface electronic state of Pt nanocrystals to bring the surface Pt atoms into an electron‐rich state, which would exert influence on the hydrogenation course by changing the adsorption and the reactivity of reactant, intermediates, and products. In contrast, DT exerted an indirect influence on the Pt nanocrystals. The coordinated Pt atoms were oxidized by DT to generate cationic Pt species on the surface of nanocrystals, and the cationic species would simultaneously improve the hydrogenation rate and selectivity to para‐chloroaniline by polarizing the N=O bond in the −NO2 group of p‐CNB and altering the electronic state of Pt nanocrystals, respectively. This work provided further insights into nanocatalysis, which is helpful for further design and application of highly efficient nanocrystal catalysts.
The nucleation pathway determines the structures and thus properties of formed nanomaterials, which is governed by the free energy of the intermediate phase during nucleation. The amorphous structure, as one of the intermediate phases during nucleation, plays an important role in modulating the nucleation pathway. However, the process and mechanism of crystal nucleation from amorphous structures still need to be fully investigated. Here, in situ aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) is employed to conduct real‐time imaging of the nucleation of ultrathin amorphous nanosheets (NSs). The results indicate that their nucleation contains three distinct stages, i.e., aggregation of atoms, crystallization to form lattice‐expanded nanocrystals, and relaxation of the lattice‐expanded nanocrystals to form final nanocrystals. In particular, the crystallization processes of various amorphous materials are investigated systematically to form corresponding nanocrystals with unconventional crystalline phases, including face‐centered‐cubic (fcc) Ru, hexagonal‐close‐packed (hcp) Rh, and a new intermetallic IrCo alloy. In situ electron energy‐loss spectroscopy (EELS) analysis unveils that the doped carbon in the original amorphous NSs can migrate to the surface during the nucleation process, stabilizing the obtained unconventional crystal phases transformed from the amorphous structures, which is also proven by density functional theory (DFT) calculations.
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