Molecular dynamics study of the growth of a metal nanoparticle array by solid dewetting

We investigated the effect of the substrate and the ambient temperature on the growth of a metal nanoparticle array (nanoarray) on a solid-patterned substrate by dewetting a Au liquid film using an atomic simulation technique. The patterned substrate was constructed by introducing different interaction potentials for two atom groups (C₁ and C₂) in the graphene-like substrate. The C₁ group had a stronger interaction between the Au film and the substrate and was composed of regularly distributed circular disks with radius R and distance D between the centers of neighboring disks. Our simulation results demonstrate that R and D have a strikingly different influence on the growth of the nanoparticle arrays. The degree of order of the nanoarray increases first before it reaches a peak and then decreases for increasing R at fixed D. However, the degree of order increases monotonously when D is increased and reaches a saturated value beyond a critical value of D for a fixed R. Interestingly, a labyrinth-like structure appeared during the dewetting process of the metal film. The simulation results also indicated that the temperature was an important factor in controlling the properties of the nanoarray. An appropriate temperature leads to an optimized nanoarray with a uniform grain size and well-ordered particle distribution. These results are important for understanding the dewetting behaviors of metal films on solid substrates and understanding the growth of highly ordered metal nanoarrays using a solid-patterned substrate method.     

磷掺杂缺陷WS2纳米片诱导的高效析氢性能

通过超声剥离法制备二硫化钨(WS₂)纳米片,将纳米片和红磷(P)混合,用氩气(Ar)等离子体对混合物进行处理,制备了P掺杂缺陷WS₂纳米片。对制备的材料进行电催化析氢反应(hydrogen evolution reaction,HER)测试,结果表明P掺杂的缺陷WS₂纳米片相对于缺陷WS₂纳米片和WS₂纳米片表现出优越的HER催化活性(较小的过电位和Tafel斜率、优异的稳定性)。密度泛函理论计算结果表明,在WS₂结构中P原子和缺陷结构改善了其电子结构,使其具有更加合适的H⁺吸附能垒和H₂生成动力学性能,从而提高催化活性。     

Interfacial Sites in Ag Supported Layered Double Oxide for Dehydrogenation Coupling of Ethanol to n-Butanol

Upgrading of ethanol to n-butanol through dehydrogenation coupling has received increasing attention due to the wide application of n-butanol. But the enhancement of ethanol dehydrogenation and followed coupling to produce high selectivity to n-butanol is still highly desired. Our previous work has reported an acid-base-Ag synergistic catalysis, with Ag particles supported on Mg and Al-containing layered double oxides (Ag/MgAl-LDO). Here, Ag-LDO interfaces have been manipulated for dehydrogenation coupling of ethanol to n-butanol by tailoring the size of Ag particles and the interactions between Ag and LDO. It has been revealed that increasing the population of surface Ag sites at Ag-LDO interfaces promotes not only the dehydrogenation of ethanol to acetaldehyde but also the subsequent aldol condensation of generated acetaldehyde. A selectivity of up to 76 % to n-butanol with an ethanol conversion of 44 % has been achieved on Ag/LDO with abundant interfacial Ag sites, much superior to the state-of-the-art catalysts.     

Scalable Synthesis of One-Dimensional Mesoporous ZnMnO3 Nanorods with Ultra-Stable and High Rate Capability for Efficient Lithium Storage

The cost-efficient ZnMnO₃ has attracted increasing attention as a prospective anode candidate for advanced lithium-ion batteries (LIBs) owing to its resourceful abundance, large lithium storage capacity and low operating voltage. However, its practical application is still seriously limited by the modest cycling and rate performances. Herein, a facile design to scalable synthesize unique one-dimensional (1D) mesoporous ZnMnO₃ nanorods (ZMO-NRs) composed of nanoscale particles (≈11 nm) is reported. The 1D mesoporous structure and nanoscale building blocks of the ZMO-NRs effectively promote the transport of ions/electrons, accommodate severe volume changes, and expose more active sites for lithium storage. Benefiting from these appealing structural merits, the obtained ZMO-NRs anode exhibits excellent rate behavior (≈454 mAh g⁻¹ at 2 A g⁻¹) and ultra-long term cyclic performance (≈949.7 mAh g⁻¹ even over 500 cycles at 0.5 A g⁻¹) for efficient lithium storage. Additionally, the LiNi_0.8Co_0.1Mn_0.1O₂//ZMO-NRs full cell presents a practical energy density (≈192.2 Wh kg⁻¹) and impressive cyclability with approximately 91 % capacity retention over 110 cycles. This highlights that the ZMO-NRs product is a highly promising high-rate and stable electrode candidate towards advanced LIBs in electronic devices and sustainable energy storage applications.     

Ni2P Interlayer and Mn Doping Synergistically Expedite the Hydrogen Evolution Reaction Kinetics of Co2P

Transition metal phosphide is regarded as one of the most promising candidates to replace noble-metal hydrogen evolution reaction (HER) electrocatalysts. Nevertheless, the controllable design and synthesis of transition metal phosphide electrocatalysts with efficient and stable electrochemical performance are still very challenging. Herein, a novel hierarchical HER electrocatalyst consisting of three-dimensional (3D) coral-like Mn-doped Co₂P@an intermediate layer of Ni₂P generated in situ by phosphorization on Ni foam (MnCoP/NiP/NF) is reported. Notably, both the incorporation of Mn and introduction of the Ni₂P interlayer promote Co atoms to carry more electrons, which is beneficial to reduce the force of the Co−H bond and optimize the adsorption energy of hydrogen intermediate (|ΔG_H*|), thereby making MnCoP/NiP/NF exhibit outstanding HER performance with onset overpotential and Tafel slope as low as 31.2 mV and 61 mV dec⁻¹, respectively, in 1 m KOH electrolyte.     

Structure Engineering of BiSbSx Nanocrystals Embedded within Sulfurized Polyacrylonitrile Fibers for High Performance of Potassium-Ion Batteries

Potassium-ion batteries (PIBs) are regarded as promising candidates in next-generation energy storage technology; however, the electrode materials in PIBs are usually restricted by the shortcomings of large volume expansion and poor cycling stability stemming from a high resistance towards diffusion and insertion of large-sized K ions. In this study, BiSbS_x nanocrystals are rationally integrated with sulfurized polyacrylonitrile (SPAN) fibres through electrospinning technology with an annealing process. Such a unique structure, in which BiSbS_x nanocrystals are embedded inside the SPAN fibre, affords multiple binding sites and a short diffusion length for K⁺ to realize fast kinetics. In addition, the molecular structure of SPAN features robust chemical interactions for stationary diffluent discharge products. Thus, the electrode demonstrates a superior potassium storage performance with an excellent reversible capacity of 790 mAh g⁻¹ (at 0.1 A g⁻¹ after 50 cycles) and 472 mAh g⁻¹ (at 1 A g⁻¹ after 2000 cycles). It's one of the best performances for metal dichalcogenides anodes for PIBs to date. The unusual performance of the BiSbS_x@SPAN composite is attributed to the synergistic effects of the judicious nanostructure engineering of BiSbS_x nanocrystals as well as the chemical interaction and confinement of SPAN fibers.     

Fabrication and characterization of TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> composite nanoparticles and polyurethane/(TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript>) nanocomposite films

TiO₂–SiO₂ composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO₂–SiO₂ composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO₂–SiO₂) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO₂–SiO₂ composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO₂–SiO₂ composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO₂–SiO₂ core surface via surface functionalized reaction. The particle size of TiO₂–SiO₂ composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid films. The average particle size of the TiO₂–SiO₂ composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO₂–SiO₂ composite nanoparticles are well dispersed in the PU matrix.     

Representation type of endomorphism algebras of exceptional sequences of typeA n

LetF be an algebraically closed field, be a quiver of typeA _n . In this paper we prove that the endomorphism algebras of exceptional sequences over are sums of finitely many tilted algebras of typeA _m wherem≤n by using perpendicular categories, and thus the endomorphism algebras of exceptional sequences of typeA _n are representation-finite. Supported by Chinese Postdoctorate Fund and Beijing Youth Fund     

基于2D Chebyshev-Sine映射的图像加密算法

混沌系统因对初始条件和参数具有极度的敏感性、遍历性和不可预测性,被广泛应用于图像加密领域。提出了一种二维映射——二维Chebyshev-Sine映射。通过分析轨迹图得到映射,与其他混沌映射相比,此映射拥有更宽广的混沌范围和良好的遍历性,对初始条件和系统参数具有高度敏感性,实现成本相对较低。基于此,提出了一种线性混合层图像加密算法:通过行移位和列混合有效改变图像像素空间位置和像素频域中的值,同时使用了中国剩余定理的扩散原则。实验仿真结果证明,此加密算法具有抵抗差分攻击和选择明文攻击的性能,且运行速度快,安全性较高。     

精准微创个体化医疗、3D打印及计算机导航技术在骨科临床的研究进展

随着近年来3D打印、有限元分析及计算机导航技术迅速发展, 为智能精准微创个体化医疗尤其是骨科临床应用提供了路径和方法. 本文首先对当前精准微创的个性化医疗发展趋势, 以及3D打印和有限元分析在骨科的临床应用进行介绍, 并详细探讨了计算机导航技术在骨科中的临床应用价值和存在的不足, 最后对未来3D打印和骨科计算机导航技术的发展趋势进行了展望.