查看更多>>摘要：To investigate the relationship between cluster correlation index and nanoclusters during rapid solidification, a molecular dynamics (MD) simulation study has been performed for FexNi(100?x)(40 ≤ x ≤ 80) amorphous alloys. Six kinds of common amorphous clusters with great similarity are explored by the newly developed Largest Standard Cluster Analysis (LSCA). The spatial distribution of clusters is analyzed by the correlation index, which is divided into strongly correlated clusters and weakly correlated clusters, and the effects of two different correlation clusters on the formation of nanoclusters are quantitatively researched. The results reveal that the Z14 correlation index of own connection is the strongest and increases with the increase of Fe content, while the correlation index between A13 and D-A13 is the weakest and it is not obvious with the increase of Fe content. In addition, Fe-rich alloys are more likely to congregate to form large-sized nanoclusters with high packing density due to the strong correlation index.
查看更多>>摘要：The effect of adding both Al2O3 and ZrO2 to limestone (CaCO3) to enhance the cyclic stability and reaction kinetics of endothermic CO2 desorption and exothermic CO2 absorption is investigated. The formation of CaZrO3 and Ca-Al-O compounds, e.g. CA5Al6O14, is evident, which enables a substantial >80% capacity retention over 50 calcination/carbonation cycles. The additives enable fast reaction kinetics where an 80% energy storage capacity is reached within 20–30 min, which is attributed to the synergetic effect of having both Ca-Zr-O and Ca-Al-O ternary additives present. The inert nature of the formed compounds prevents sintering of the particles, whilst allowing ion migration throughout the crystal structures, catalysing the carbonation reaction.
查看更多>>摘要：It is of great significance to develop low cost, high-efficiency and environment-friendly electrocatalysts for hydrogen evolution reaction (HER) from water splitting. Herein, nickel telluride nanosheets grown on Ni Foam (NF) with three different crystal phases (NiTe, Ni2.6Te2 and Ni2.86Te2) are fabricated by one-step hydrothermal tellurization followed annealing process. The non-stoichiometric Ni2.86Te2/NF exhibits superior electrocatalytic HER performance compared to the NiTe/NF and Ni2.6Te2/NF, which is comparable to the state-of-the-art 20 wt% Pt/C catalyst at high current density. The Ni2.86Te2/NF only requires an overpotential of 348 mV to drive the current density of 200 mA cm?2 in a 1.0 M KOH electrolyte. Similarly, The Ni2.86Te2/NF delivered current densities of 200 mA cm?2 at the overpotential of 279 mV in 0.5 M H2SO4. Such excellent performance could be ascribed to the fast electron transfer and positive shift of Dd-band center from its rich defective effect of crystal phase transition, as well as to the exposure of active sites provided by the two-dimensional nanosheets with large specific surface area. This work provides valuable insights for the rational modulation of the crystal phase on the nickel telluride for catalyzing HER.
查看更多>>摘要：Improving the high-frequency properties of the relatively high saturation induction alloys is significance for widening the frequency range of the noise suppression of common mode chokes. Herein, transverse magnetic field annealing after having been nano-crystallized (TA) was performed to the as-quenched Fe76Si13B8Nb1.5Cu1Mo0.5 alloy, and the dynamic properties, microstructure, and dynamic domains were in detail studied comparing with those annealed without magnetic field (NA). It was found that TA at 400 °C caused an increase in permeability at 50 kHz by 41% and a decrease in core loss at 0.2 T and 50 kHz by 30%, in comparison with those of NA. TA at 400 °C induced the ratio of field induced anisotropy constant Ku to average random anisotropy constant<K1> to be ~ 1.3 and inhomogeneous rotation, leading to the promoted domain refinement with increasing frequency and improved high-frequency properties, compared with that of NA bears only<K1> ~5.4 J/m3. Moreover, the role of dual anisotropies on the magnetic domain structures, dynamic magnetization process and magnetic performances were obtained and its correlation model based on the experimental results was established. These results could provide a good guide for performance optimization to meet higher frequency requirements of common mode chokes application.
查看更多>>摘要：The Ti–Fe–Mn alloys have attracted extensive interests due to the excellent hydrogen storage properties of the TiFe and TiMn2 (i.e. the C14 Laves phase) intermetallic compounds. The phase equilibria involving these two phases are essential for the design of hydrogen storage materials. In order to accelerate the design process, a thermodynamic description of the ternary Ti–Fe–Mn system was developed by experimental phase diagram study, ab initio calculations and CALPHAD-type thermodynamic modeling in the present work. The phase equilibria involving TiFe and C14 Laves phases were investigated by using electron probe microanalysis (EPMA). The partial isothermal sections at 1273 and 1373 K were established. Ab initio calculations were carried out to assist the determination of the thermodynamic parameters for the C14 Laves phase. The Ti-Mn system was re-assessed to reproduce the phase diagram data over the entire composition range. The Ti-Fe-Mn system was modeled and optimized based on reliable binary descriptions and experimental data. The TiFe and C14 Laves phases were well described to reproduce the phase equilibria with other phases in the ternary system. Moreover, the developed thermodynamic description of the Ti-Fe-Mn system was successfully applied for the prediction of phase constitutions of hydrogen storage alloys, demonstrating evidently the reliability of the practical use of present model parameters.
查看更多>>摘要：The ZrxTi1?xO2 (x = 0.0–0.5) nanofibers were synthesized by an electrospinning process. The influences of zirconium incorporation on the structure, phase composition, lattice parameters, morphology, specific surface area, and surface states were investigated in terms of XRD, SEM, BET, and XPS tests. The humidity sensing performances were also carried out in detail. It can be concluded that the replacement of Zr at Ti-site had significant impacts with regard to the phase structure: the anatase-rutile phase transformation was inhibited by Zr4+ ion doping; Zr4+ ion was successfully incorporated into the TiO2 lattice through a substitutional mode resulting in the formation of solid solution ZrxTi1?xO2 (x = 0.1–0.2) with anatase structure; when the Zr4+ ion was saturated, excessive Zr4+ ion formed new phase of Ti2ZrO6 and ZrTiO4 (nominal x ≥ 0.3); the lattice parameters and the cell volume increased as Zr4+ ion incorporation. The solid solution Zr0.2Ti0.8O2 nanofibers had the highest Ti3+ abundance among the samples with x ≤ 0.2, accompanied by the highest oxygen vacancies. Moreover, the solid solution Zr0.2Ti0.8O2 nanofibers exhibited the best humidity sensing properties: excellent sensitivity as proven by four orders of magnitude change to impedance at 11–95% relative humidity (RH), negligible hysteresis, rapid response and recovery speed as well as superior stability, which were induced by high concentration of oxygen vacancies combined with reactive Ti3+ ions. A detailed study of the sensing mechanism was also performed in terms of complex impedance spectra.
查看更多>>摘要：The enhancement of both transparency and piezoelectric properties in transparent ferroelectric ceramics is a challenge. In this work, we prepared transparent 0.75Pb(Mg1/3Nb2/3)O3-0.25PbTiO3:xPr3+ ceramics by oxygen atmosphere sintering together with hot pressing sintering. When x = 1.5 mol%, a transparency of 68% @ 900 nm (close to the theoretical value ~71%) was achieved, and the piezoelectric properties increased to twice as much as those in undoped ceramics (x = 0). The small average domain size (below 200 nm) that far below the visible light wavelength was believed to benefit light transmittance. Meanwhile, the minute amount of tetragonal component induced by Pr3+ irons, was supposed to be responsible for the improved piezoelectric properties. These merits make Pr3+-doped 0.75PMN-0.25PT transparent ceramics promising functional materials for transparent piezoelectric devices.
查看更多>>摘要：The ternary Ag/La-TiO2?x heterojunctions were prepared successfully and was used for the photocatalytic degradation of tetracycline (TC) under visible light irradiation. Using numerous techniques, the factors affecting the structure, morphology and optoelectronic properties of Ag/La-TiO2?x composites were systematically discussed. Due to the higher photoinduced charge separation efficiency, the as-prepared composites possessed the excellent visible-light photocatalytic degradation activity of TC. The ·O2- was the primary active species as well as the h+ and ?OH were the essential active species during the process of photocatalytic degradation. Moreover, the mechanism of photocatalytic degradation of TC by Ag/La-TiO2?x composites was given, and the degradation pathways of TC during the process of photocatalytic were also considered. Based on the synergism of the introduction of Ti3+ and Ov, the inhibition charges recombination caused of La and the SPR effect of Ag nanoparticles, the photocatalytic performance of the Ag/La-TiO2?x composite observably improved. Due to the excellent photocatalytic properties and stability, the Ag/La-TiO2?x hybrid composites are expected to have significant potential applications in energy conversion and environmental remediation.
查看更多>>摘要：One of the key challenges has been taken to design high performance hybrid energy storage devices using electrodes based on capacitive graphene nanoplatelets (GNPs) and pseudocapacitive metal organic frameworks (MOFs) with high energy storage, power density and long-life cycles. Herein, we are introducing novel hybrid capacitors based on highly porous composite electrodes of ZIF-67/GNPs and ZIF-8/GNPs and redox additive electrolyte (RAE) that is, 0.2 M [K3(Fe (CN)6)] in 1 M Na2SO4. The ZIF-67/GNPs and ZIF-8/GNPs composite electrodes were used to fabricate the asymmetric supercapacitor devices using MOFs/GNPs as a positive electrode and GNPs as the negative electrode in the presence of RAE exhibited high energy and power densities of 85.8 W h kg?1 and 60.7 W h kg?1 and 7500 W kg?1 and 7370 W kg?1, respectively at current density of 1 Ag?1. The asymmetric devices retain excellent capacitances of up to 97.7% (ZIF-67/GNPs) and 97.1% (ZIF-8/GNPs) along with remarkable columbic efficiencies near 100% after 10,000 charge discharge cycles at 2 Ag?1 in a wide voltage range of (0.0–1.5 V).
查看更多>>摘要：MoS2/CoS2 heterostructures on nitrogen-doped carbon nanosheets as an efficient electrocatalyst for hydrogen evolution reaction (HER) are prepared using zeolitic imidazolate frameworks-67 as precursors. Two dimensional (2D)/2D MoS2/CoS2 heterostructures consist of layered CoS2 and MoS2. The (210) facet of CoS2 and the (002) facet of MoS2 contacted vertically resulted in improved electrons and holes transfer in the interface. The ratios of CoS2/MoS2 plays an important role to get high performance (CoS2/MoS2/NC-n%, e.g. n = 20, 25, 30, 35 wt%). Meanwhile, sample CoS2/MoS2/NC-25% revealed the best HER activity, suggesting the sample has the largest number of active sites and the fastest electron transfer rate. In addition, sample CoS2/MoS2/NC-25% exhibited the lowest onset potential of 51 mV, the lowest potential of 215 mV at 10 mA cm?2, and the smallest Tafel slope of 80.0 mV dec?1. The result is utilizable for the construction of heterostructures with excellent HER performance.
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Elsevier