Monte Carlo simulations were carried out to systematically investigate the effects of composition, size, and temperature on the surface segregation and structural features of Au−Pt nanoparticles in the present paper. A strong surface Au enrichment was observed in all of the nanoparticles, and the surface segregation of Au was promoted by increasing the particle sizes. It is found that the core−shell structure was preferred in the equilibrium Au−Pt nanoparticles with low Au composition, and three-shell onion-like structure was formed at high Au composition. The competitive multisite segregation was predicted in the core−shell nanoparticles in which Au atoms favor sites at the vertices, edges, and facets. The reverse temperature dependency of segregation for different surface sites has also been discussed.

Monte Carlo simulations were performed to study systematically the surface segregation behaviors and atomic-scale structural features of AuÀAg nanoparticles for a range of alloy compositions, particle sizes, and temperatures. Segregation of Ag to the surface was observed in all the particles considered. The surface segregation was promoted by increasing the particle sizes or Ag compositions and decreasing nanoparticles' temperatures. It was found that the most stable mixing patterns are the onionlike structure with Ag-rich shell for small particles, and the alloyed-core/layered-shell structure for large particles. Accordingly, the calculated alloying extents based on Monte Carlo simulations are consistent with experimental EXAFS analysis, which indicates more obvious alloying features in nanoparticles with larger sizes or at higher temperatures, and more obvious segregated features in nanoparticles under the opposite conditions. The size distribution of Au ensembles on different coordinated sites was analyzed quantitatively, which presented varied composition-and temperature-dependent effects. The possible effects of size and shape distribution of surface ensembles on tuning the catalytic activity and selectivity of bimetallic nanoparticles were also discussed.

Composite membranes have been fabricated made of ultrafine PVDF fibers via a tip-induced electrospinning (TIE) process and Al2O3 nanoparticles via a dip-coating process.

Lithium–sulfur batteries are promising energy‐storage devices because of their high theoretical energy densities. For practical Li–S batteries, reducing the amount of electrolyte used is essential for achieving the high energy densities. However, reducing the electrolyte amount leads to severe performance degradation, mainly because of sluggish deposition of discharge products (Li2S) and the accompanying passivation issue that arise from the insulating nature of Li2S. In this study, a lightweight, robust interlayer, with a 3D open structure and a low surface area is designed and fabricated. The structure facilitates electrolyte infiltration without trapping too much electrolyte. Moreover, the electrocatalytic Co nanoparticles embedded in the skeleton surface within the interlayer effectively promote Li ion diffusion, polysulfides conversion, and Li2S deposition, and therefore enhance the electrochemical kinetics under lean electrolyte conditions. The mechanisms involved in the interlayer effects are investigated by microstructural characterizations, electrochemical performance tests, density functional theory calculations, and in situ X‐ray diffraction characterization. These results show the feasibility of using an interlayer strategy to improve the electrochemical performances of Li–S batteries under lean electrolyte conditions to potentially increase the practical energy densities of Li–S batteries.

The present article is on Metropolis Monte Carlo simulations coupled with semiempirical potentials to obtain the thermodynamically preferred configurations of Ag-Pt nanoalloys. The effects of particle size, morphology or alloy composition on the surface segregation and the chemical ordering patterns were investigated. Surface segregation of Ag is observed in all Ag-Pt nanoalloys. Such segregation develops quickly as the increase of particle sizes or global Ag composition. Generally, Ag surface enrichment is more apparent for more open particles except for large sized icosahedron (ICO) nanoalloys. The most energetically favorable chemical ordering patterns gradually evolve from Pt-core/Ag-shell to onion-like structures when the global Ag composition increases. Due to the site preference of Ag segregation, the presence of partly alloyed facets and Ag blocked vertices or edges at low global Ag compositions can modify the electronic and geometric structures on the nanoalloys' surface. The coupling between Pt and Ag sites is a topic of particular interest for catalysis. The detailed atomistic understanding of atomic arrangements in Ag-Pt nanoalloys is essential to intelligently design robust and active nanocatalysts with a low cost.

Monitoring and early warning of spores germination is of great significance in avoiding their potential pathogenicity. Thus, effective monitoring of markers during spore germination is of great value. A ratio-dependent fluorescent probe based on in situ incorporation of fluorophores in a metal–organic framework (MOF) was designed to monitor a main component of bacterial spores, 2,6-pyridinedicarboxylic acid (DPA), with high sensitivity and specificity. The fluorescence of CdS quantum dots loaded on zeolitic imidazolate framework-8 (ZIF-8) nanocrystals is initially quenched by europium ions. The europium ions, however, can be seized by DPA, leading to restoring the fluorescence of quantum dots. Simultaneously, the fluorescence of another dye molecule, rhodamine 6G, loaded on the ZIF-8 is not affected by DPA and can serve as a stable internal fluorescence reference signal. On this basis, a ratio-dependent fluorescence method for rapid detection of DPA was established. The linear calibration ranged from 0.1 to 150 μM with a detection limit of 67 nM, which is much lower than the amount of DPA (60 μM) released by the contagious number of spores needed to cause anthrax. This analysis platform exhibits good anti-interference ability for monitoring spore germination. The practicable application of the method was verified by monitoring and imaging the release of DPA in the course of spore germination.

We performed Monte Carlo simulations to determine the roles of energetic factors and nanoscale effects in the surface segregation and chemical ordering patterns of Ag-Pd nanoalloy particles.Ag atoms significantly segregate onto the surface and preferentially occupy the low-coordinated sites, which significantly reduce the surface and strain energies of the nanoalloys. The segregation isotherms reveal that surface Ag composition is enhanced with increasing particle size or Ag concentration to circumvent the finite matter effects. Chemical ordering favored by attractive hetero-bonds can coexist and compete with surface segregation. Accordingly, small and Pd-rich nanoalloys display a continuous transition from Pd-core/ mixing-shell to mixingcore/ Ag-shell, where an ordered core is absent as a result of surface segregation and limited Ag supply. By contrast, large nanoalloys with equimolar or Ag-rich concentration exhibit the strong core ordering characteristics of bulk alloys. Particularly, surface patterns with partially alloyed facets and Ag-blocked vertices and edges are formed. This study also discussed the effects of isolating and blocking surface Pd active sites by Ag on the hydrogen evolution reaction and selective hydrogenation of acetylene.

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