Synthesis of Copper‐Substituted CoS2@CuxS Double‐Shelled Nanoboxes by Sequential Ion Exchange for Efficient Sodium Storage

The construction of hybrid architectures for electrode materials has been demonstrated as an efficient strategy to boost sodium‐storage properties because of the synergetic effect of each component. However, the fabrication of hybrid nanostructures with a rational structure and desired composition for effective sodium storage is still challenging. In this study, an integrated nanostructure composed of copper‐substituted CoS₂@Cu_xS double‐shelled nanoboxes (denoted as Cu‐CoS₂@Cu_xS DSNBs) was synthesized through a rational metal–organic framework (MOF)‐based templating strategy. The unique shell configuration and complex composition endow the Cu‐CoS₂@Cu_xS DSNBs with enhanced electrochemical performance in terms of superior rate capability and stable cyclability.     

A computer simulation of nucleation and growth of thin films

~~A computer simulation of nucleation and growth of thin films~~     

关于对偶Steiner多项式的根的注记

受凸体的Steiner多项式的启发,定义了星体的对偶Steiner多项式,并利用对偶Aleksandrov-Fenchel不等式讨论了对偶Steiner多项式的根.进而,得到了关于对偶Steiner多项式的根的一些不等式,这些不等式恰好是关于Steiner多项式的根的不等式的对偶形式.     

Melting and glass transition for Ni clusters

The melting of NiN clusters (N = 29, 50-150) has been investigated by using molecular dynamics (MD) simulations with a quantum corrected Sutton-Chen (Q-SC) many-body potential. Surface melting for Ni147, direct melting for Ni79, and the glass transition for Ni29 have been found, and those melting points are equal to 540, 680, and 940 K, respectively. It shows that the melting temperatures are not only size-dependent but also a symmetrical structure effect; in the neighborhood of the clusters, the cluster with higher symmetry has a higher melting point. From the reciprocal slopes of the caloric curves, the specific heats are obtained as 4.1 kB per atom for the liquid and 3.1 kB per atom for the solid; these values are not influenced by the cluster size apart in the transition region. The calculated results also show that latent heat of fusion is the dominant effect on the melting temperatures (Tm), and the relationship between S and L is given.     

Synthesis and field-emission properties of the tungsten oxide nanowire arrays

High-density, uniformly distributed and quasi-aligned tungsten oxide nanowire arrays have been synthesized by a conventional thermal evaporation approach on indium tin oxide (ITO) coated glass substrates without any catalysts. The temperature of the substrate was . The tungsten oxide nanowires are single crystalline with growth direction of [0 1 0]. For commercial applications, field emission properties of tungsten oxide nanowires were studied under a poor vacuum at room temperature. The electron field-emission turn-on field (E_to), defined as the macroscopic field required to produce a current density of , is about . The performance reveals that the tungsten oxide nanowire arrays can be served as a good candidate for commercial application in field-emission displays.     

Interface interaction within nanopores in thin films of an amphiphilic block copolymer and CTAB

Anion exchange membranes with semi-interpenetrating polymer network (semi-IPN) were prepared based on quaternized chitosan (QCS) and polystyrene (PS). The PS was synthesized by polymerization of styrene monomers in the emulsion of the QCS in an acetic acid aqueous solution under nitrogen atmosphere at elevated temperatures. The semi-IPN system was formed by post-cross-linking of the QCS. A hydroxyl ionic conductivity of 2.80×10(-2) S cm(-1) at 80°C and a tensile stress at break of 20.0 MPa at room temperature were reached, respectively, by the semi-IPN membrane containing 21 wt.% of the PS. The durability of the semi-IPN membrane in alkaline solutions was tested by monitoring the variation of the conductivity and the mechanical strength. The degradation of the conductivity at 80°C was about 5% by immersing the membrane in a 1 mol L(-1) KOH solution at room temperature for 72 h and at 60°C for 50 h, respectively. The tensile stress at break at room temperature could maintain about 20.0 MPa for the membrane soaking in a 10 mol L(-1) KOH solution at ambient temperature for more than 70 h. The water swelling of the semi-IPN membranes was discussed based on the stress relaxation model of polymer chains, and it obeyed the Schott's second-order swelling kinetics.     

Synthesis of highly functionalized chiral 3,3'-disubstituted oxindoles via an organocatalytic enantioselective Michael addition of nitroalkanes to indolylidenecyanoacetates

An efficient bifunctional cinchona alkaloid derived thiourea-promoted enantioselective conjugate addition of nitroalkanes to indolylidenecyanoacetates has been developed under neat conditions. The process leads to synthetically interesting densely functionalized 3,3'-disubstituted oxindoles with creation of up to three stereogenic centers.     

Field emission and room temperature ferromagnetism properties of triangle-like ZnO nanosheets

Triangle-like ZnO nanosheets have been synthesized via conventional thermal evaporation method at a low temperature of 550 °C using CuO as catalyst. The obtained samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX) and photoluminescence (PL) spectra. The great influences of Cu catalyst on the morphology of the obtained ZnO nanostructures were investigated. The field emission measurements confirmed that the ZnO nanosheets possessed good performance with a turn-on field of 3.1 V μm⁻¹ and a field enhancement factor of 3250, which have promising application as a competitive cathode material in FE microelectronic devices. Room temperatures ferromagnetism has been observed in the triangle-like ZnO nanosheets, although the products consist of only nonmagnetic elements.     

脉冲溅射V2O5薄膜结构和性能研究

V2O5薄膜具有很好的离子注入/退出可逆性,是最有潜力的锂离子储存层的候选材料之一,它的电学特性与制备方法、化学计量比、结构和取向等有直接关系,仔细控制工艺参量是制备出在锂电池上应用的V2O5薄膜关键。研究中采用脉冲磁控反应溅射方法,通过精确地控制氧分压、基底温度等关键工艺参量,在石英玻璃和硅片上制备V2O5薄膜。利用X射线衍射和X射线光电子谱,分析了薄膜的成分、相结构、结晶和价态情况,用原子力显微镜表征了薄膜的微观结构,用分光光度计测量从200—2500nm波段V2O5薄膜纯度高、相结构单一、结晶度好。高低温电阻变化2个量级,薄膜的光学能隙为2.46eV。     

First-principles study on the phase transitions,crystal stabilities and thermodynamic properties of TiN under high pressure

The structural and thermodynamic properties of titanium nitride (TiN) have been investigated by merging first-principles calculations and particle-swarm algorithm. The three phases are identified for TiN, including the B1, the $P{6}_3/mmc$, and the B2 phases. A new phase of anti-TiP structure with the space group $P{6}_3/mmc$ has been predicted. The calculated phase transition from the B1 to the $P{6}_3/mmc$ occurs at 270 GPa. The vibrational, elastic, and thermodynamic properties for the three phases have been calculated and discussed.