[en] The fiber reinforced metal tubes have been proved to exhibit an excellent crashworthy performance and a high ratio of strength to weight in many experiments. Some theoretical models are promoted to predict the mean crushing force, which benefits the design of these structures. Based on the solution of Wang and Lu, the theoretical analysis is presented in this paper to consider the eccentricity factor, which represents the ratio of the outward part to the total folding length. The agreement between the calculated and experimental data reveals that the analytical model is reasonable. (paper)

[en] An unprecedented trinuclear Ni(II) complex assembled from an asymmetric Salamo-type ligand 6-ethoxy- 4′,6′-dichloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol (H₂L) is synthesized. The Ni(II) complex with the general formula [Ni₃(L)₂(μ₃-OAc)₂]·3CH₃CN is characterized by IR, UV-vis, and fluorescence spectra and the single crystal X-ray analysis. All the Ni(II) atoms are hexacoordinated with slightly distorted octahedral symmetries. Interestingly, each Ni(II) atom is not located on the N₂O₂ cavity of the asymmetric Salamo-type (L)^2– unit, and two μ₃-OAc ions adopt an uncommon μ₃-η²:η¹ binding mode connecting the Ni1, Ni2, and Ni3 atoms. Furthermore, the crystallizing acetonitrile molecules successfully assemble into an infinite 2D network by hydrogen bonding and C–H···π interactions.

[en] The spin electronic states coupling associated with enhanced photocatalytic activity of TiO₂ microstructures annealed in Ar and O₂ are designed to explore its ferromagnetism. The samples annealed in Ar show 0.023 emu g⁻¹ magnetic moments related to adsorbed S atom concentration, which is seven times larger than that of samples annealed in O₂. Finally, their saturated magnetization decreases sharply as increasing annealing temperature. Spectral analysis and density function theory calculation disclose that the ferromagnetism originates from spin electronic state coupling between adsorbed S atoms and oxygen vacancies as well as magnetic moments disappearing arises from the changes of adsorbed S atom and O vacancy distribution as annealing temperature. (paper)

[en] The formation of Schottky barriers between 2D semiconductors and traditional metallic electrodes has greatly limited the application of 2D semiconductors in nanoelectronic and optoelectronic devices. In this study, metallic borophene was used as a substitute for the traditional noble metal electrode to contact with the 2D semiconductor. Theoretical calculations demonstrated that no Schottky barrier exists in the borophene/2D semiconductor heterostructure. The contact remains ohmic even with a strong electric field applied. This finding provides a way to construct 2D electronic devices and sensors with greatly enhanced performance.

[en] The electronic states associated with enhanced photocatalytic activity of anodic anatase TiO₂ nanotubes (NTs) annealed in N₂ and O₂ are investigated by photoluminescence (PL). The NTs annealed in N₂ show a green peak related to oxygen vacancies and its position blueshifts with deceasing temperature, whereas those annealed in O₂ show a double peak at 475-600 nm and the energy separation increases with decreasing temperature. Spectral analysis and density function theory calculation disclose that the double peak results from residual oxygen vacancies and oxygen atoms on the NT wall and the increased energy separation arises from the larger difference between the inner and outer NT stress at low temperature.

[en] In tin dioxide nanostructures, oxygen vacancies (OVs) play an important role in their optical properties and thus regulation of both OV concentration and type via external strain is crucial to exploration of more applications. First-principle calculations of SnO_2 (110) surface disclose that asymmetric deformations induced by external strain not only lead to its intrinsic surface elastic changes, but also result in different OV formation energy. In the absence of external strain, the energetically favorable oxygen vacancies(EFOV) appear in the bridging site of second layer. When -3.5% external strain is applied along y direction, the EFOV moves into plane site. This can be ascribed that the compressed deformation gives rise to redistribution of electronic wave function near OVs, therefore, formation of newly bond structures. Our results suggest that different type OVs in SnO_2 surface can be controlled by strain engineering.

[en] p-type ultrathin 3C-SiC nanocrystals are coated on heat-treated n-type TiO₂ nanotube arrays formed by electrochemical etching of Ti sheets to produce heterostructured photocatalysts. Depending on the amounts of 3C-SiC nanocrystals on the TiO₂ nanotubes, photocatalytic degradation of organic species can be enhanced. The intrinsic electric field induced by the heterojunction promotes separation of the photoexcited electrons-holes in both the TiO₂ nanotubes and 3C-SiC nanocrystals. Hence, holes can more effectively travel to the surface of 3C-SiC nanocrystals and there are more electrons on the surface of TiO₂ nanotubes consequently forming more ^•O₂⁻ and ^•OH species to degrade organic molecules.

[en] The low quantum yield (∼10⁻⁵) has restricted practical use of photoluminescence (PL) from MoS₂ composed of a few layers, but the quantum confinement effects across two-dimensional planes are believed to be able to boost the PL intensity. In this work, PL from 2 to 9 nm MoS₂ quantum dots (QDs) is excluded from the solvent and the absorption and PL spectra are shown to be consistent with the size distribution. PL from MoS₂ QDs is also found to be sensitive to aggregation due to the size effect

[en] Regulation of magnetism and half-metallicity has attracted much attention because of its potential in spintronics. The magnetic properties and electronic structure of graphitic carbon nitride (g-C₄N₃) with external strain are determined theoretically based on the density function theory and many-body perturbation theory (G₀W₀). Asymmetric deformation induced by uniaxial strain not only regulates the magnetic characteristics but also leads to a transformation from half-metallicity to metallicity. However, this transition cannot occur in the structure with symmetric deformation induced by biaxial strain. Our results suggest the use of strain engineering in metal-free spintronics applications

[en] 3C-SiC/n-type ZnS heterostructured nanospheres synthesized hydrothermally deliver enhanced photocatalytic performance under visible light excitation. The heterostructured catalysts consisting of 3C-SiC and ZnS nanocrystals with a mean size being less than 5 nm exhibit extended light absorption to the visible range. The proper band structure of the 3C-SiC and ZnS nanocrystals and intrinsic electric field induced by the heterojunction promote separation of photoexcited electrons and holes in the ZnS and 3C-SiC nanocrystals resulting in the increased photocatalytic efficiency. The associated mechanism is studied and proposed