查看更多>>摘要：? 2022 Elsevier B.V.Ultrasensitive detection of highly toxic Cr(VI) is of paramount importance as trace amount of Cr(VI) will result in inevitable deterioration to human health and the environment. In this work, a novel methimazole-functionalized SERS optical fiber probe was used for the first time for Cr(VI) determination with ultrahigh sensitivity. A special functionalization process of methimazole was designed after successful fabrication of silver coated fiber probe via a SnCl2-sensitized solvothermal method. Dual functional methimazole guaranteed ultrahigh sensitivity and good stability of the SERS fiber probe for Cr(VI) detection. On one hand, methimazole functions as a Raman reporter which exhibits SERS peak intensity decline in the presence of Cr(VI). On the other hand, methimazole acts as an oxidation inhibitor via coordinating with silver atoms through the lone pair of nitrogen and sulfur atoms. The optimized SERS fiber probe not only presents good stability and excellent reproducibility, but also exhibits ultrahigh sensitivity (10?11 M) which exceeds SERS or other techniques for Cr(VI) determination reported so far.
查看更多>>摘要：? 2022 Elsevier B.V.Compared to other batteries, a next-generation lithium-sulfur (Li-S) battery's specific capacity and energy density are relatively high. However, the actual electrochemical performance (particularly for the cell with a high cathode sulfur content and a lean electrolyte/sulfur ratio) falls well short of practical usage requirements. The ultrathin Ni3B@rGO-PP is designed in this study as a unique modified separator for Li-S cells. Because of its distinct electronic structure, the modified separator shows outstanding adsorption ability toward polysulfide through the boron element's active sites. Additionally, it has excellent electrocatalytic activity, significantly enhancing the performance of Li-S batteries. After the 100th cycle, the cell with 80 wt% sulfur content can retain 819 mA h g?1 under 0.2 C. Also, when the electrolyte/sulfur ratio is reduced to 15 μL mg?1 and 5 μL mg?1, respectively, considerable capacity retention of 736.3 mA h g?1 and 615 mA h g?1 is achieved after the 100th cycle at 0.2 C. What's more, for the high sulfur loading (single-side up to 4.5 mg cm?2) cathode, the cell obtains a retention capacity of 578 mA h g?1 after the 200th cycle under 0.2 C. The surface engineering strategy with the Ni3B@rGO modified coating adopted in this work would open an efficient route to acquire the Li-S battery's outstanding electrochemical capability in the practical application situation.
查看更多>>摘要：? 2022With negligible quantities of nitrogen, wrought and welded solid solution strengthened nickel superalloys usually contain carbides and topologically close-packed phases, such as Laves phase. However, appreciable nitrogen levels on the order of 0.1 % mass fraction drove the precipitation of a range of unanticipated nitride phases in additively manufactured Inconel 625 in the as-deposited and post process hot isostatically pressed conditions. Different nitride phases were observed with small changes in alloy chemistry. Cubic metal nitrides (MN), tetragonal Z-phase (CrNbN), and diamond-cubic metal η-nitrides (M6N) were found within the γ matrix of Inconel 625 containing relatively low Fe (1 %), low Ti (0.02 %), and high Si (0.39 %) mass fractions. Conversely, these phases were replaced by only MN nitrides in a similar Inconel 625 alloy with elevated mass fractions of Ti (0.21 %) and Fe (4 %). These various phases, however, were not fully predicted using state-of-the-art computational thermodynamic tools and databases, indicating a sparsity of data for nickel superalloys. Even after hot isostatic pressing, many nitrides persisted and only experienced slight changes in composition and lattice parameters in both materials. The stability of these nitride phases presents a potential pathway for achieving enhanced high temperature and creep properties within this and similar alloy systems.
查看更多>>摘要：? 2022 Elsevier B.V.Lithium-Sulfur (Li-S) battery is a potential alternative energy storage system owing to its high theoretical capacity, low cost, and eco-friendly features. However, the commercialization of Li-S battery has been hindered by the notorious “shuttle effect”. To overcome the above-mentioned long-standing problem, herein, an advanced separator modified by N and P heteroatoms co-doped carbon frameworks with confined Co2P nanoparticles (named Co2P/Co/C) has been successfully prepared. The introduction of functional coating can obviously enhance the thermal stability of separator. To be specific, it showed higher initial decomposition temperature (475 ℃) and lower maximum mass loss rate (1.755%℃?1) values than the Celgard separator (400 ℃ and 2.915%℃?1, respectively). Notably, when kindled separators directly, the modified separator can quench by itself with many residual remains. In addition, the engineered functional layer possesses the capability of capturing lithium polysulfides (LiPSs), and then confines them within the cathode region so that the “shuttle effect” can be restrained effectively. After assembling the modified separator in the Li-S cell, compared with the cell with Celgard separator of low initial specific discharge capacity (730 mAh g?1), the cell with Co2P/Co/C separator delivered a superior initial discharge capacity of 1310 mAh g?1 at 0.5 C. Also, the modified cell can perform remarkably enhanced rate performances. In addition, As a consequence of these merits, the modified separator with improved thermal stability, preferable fire safety, and satisfied electrochemical performances shows significant guiding value for advancing the practical application of Li-S batteries.
查看更多>>摘要：? 2022 Elsevier B.V.The influence exerted by the specific type of the lanthanide cation and calcination temperature on the crystal and local structures of Ln2(WO4)3 tungstates (Ln = La–Dy) prepared by a coprecipitation is studied using synchrotron X-ray diffraction, X-ray absorption fine structure (XAFS) spectroscopy, Fourier transform infrared (FT-IR) and Raman spectroscopies, photoluminescence, simultaneous thermal analysis, and inductively coupled plasma atomic emission spectroscopy. The combination of these experimental techniques enabled a structural insight into Ln tungstates at multiple characteristic scales, i.e. short-range of metal atom coordination (XAFS), medium-range of the network of chemical bonds (FT-IR and Raman spectroscopies), and long-range or 3D periodicity within crystallites (XRD). It is found that the onset of amorphous precursor crystallization is observed at 575–600 °C/3 h and leads to the formation of Ln2(WO4)3 nanocrystalline powders with a monoclinic (sp. gr. C12/c1 (15)) structure. An increase in the calcination temperature leads to the growth of crystallite size and a decrease in microstrains. In the case of Dy2(WO4)3 an additional orthorhombic phase emerges (sp. gr. Pbcn(60)) at 1000 °C. It is shown that the local structure of all well-crystallized compounds being studied contains lanthanide ions in the form of Ln3+ and tungsten ions in the form of WO42? tetrahedra. The local structure in the monoclinic phase can be represented as a superposition of two non-equivalent tungstate tetrahedra: W(1)O4 (C2 site symmetry) and W(2)O4 (C1 site symmetry). The LnO8 polyhedra are strongly irregular, and the Ln3+ cations occupy low-symmetry sites.
查看更多>>摘要：? 2022 Elsevier B.V.The niobate-based alkali-free ferroelectric glass-ceramics were realized through the synthesis of mother glass by way of melt-annealing technique, followed by temperature-controlled crystallization. As the crystallization temperature raised, the ratio of the ferroelectric crystal phase precipitated in the mother glass enhanced continuously, resulting in the enlargement of the permittivity. Attribute to the rise of grain size, pores and cracks tend to appear in the microstructure of glass-ceramics with high crystallization temperature, leading to lower breakdown strength. The theoretical simulation was applied to reveal the internal mechanism, exploring the outcome of heat treatment temperature on the breakdown electric field. The maximum theoretical energy storage density reaches to 18.44 J/cm3 at the crystallization temperature of 800 °C. The single-layer capacitor made from the G800 sample exhibited extremely high power density (230 MW/cm3) and superior actual discharge energy density (1.5 J/cm3) at 600 kV/cm. These results indicate that alkali-free niobate-based glass-ceramics is a kind of encouraging candidate material for pulse capacitors.
查看更多>>摘要：? 2022 Elsevier B.V.The promising high-capacity anode material of Zn2SnO4 suffers from large volume expansion and poor conductivity during cycle, and hence its practical application in lithium-ion batteries is blocked seriously. Herein, to achieve high capacity and improved cyclic stability of Zn2SnO4-based anode, we introduce a dual-stable engineering strategy that the Zn2SnO4 is encapsulated within a porous carbon shell and a void structure is constructed between the inner Zn2SnO4 and outer carbon shell simultaneously. The as-fabricated Zn2SnO4-based composite is therefore referred to as Zn2SnO4 @V@PC. It is demonstrated that the combined action of the porous carbon and the void effectively suppresses the volume effect of the Zn2SnO4 and enhances the electrochemical kinetics of the electrodes and hence the structural stability and electrochemical kinetics of the Zn2SnO4 @V@PC are improved significantly. As a result, the Zn2SnO4 @V@PC delivers 961.5 mA h g?1 after 350 cycles at 200 mA g?1 and 438.2 mA h g?1 after 600 cycles at 1000 mA g?1, thereby having potential application in advanced lithium-ion battery anodes.
查看更多>>摘要：? 2022The increasing demand for high energy density battery systems has accelerated the development of lithium metal batteries, and it is imperative to seek strategies for alleviating the large volume change and inhibiting dendrite growth of the Li metal anode. 3D porous anode current collectors cooperated with surface modification have been considered as effective methods. Herein, we develop 3D porous Cu with modest pores by powder metallurgy method, combined with surface modification by lithiophilic Ag nanoparticles. The obtained ingenious porous structure ensures the reduction of local current density when served as the Li anode current collector, while the Ag nanoparticle layer provides numerous lithiophilic nucleation sites. Smooth and uniform Li plating morphologies are confirmed on the PM Cu@AgNP electrode surface, and the PM Cu@AgNP-Li symmetric cell presents a stable cycle of 1600 h, which effectively inhibits the Li dendrite growth. When coupled with the LiFePO4 cathode, the assembled full cell exhibits superb capacity retention and stability for 600 cycles at 0.5 C. This facile and rational strategy with synergistic effect of modest pores and surface lithiophilicity provides a way to achieve highly stable Li metal anodes for next-generation Li batteries.
查看更多>>摘要：? 2022 Elsevier B.V.Yttrium perovskite ferrite has a stable and symmetrical crystal structure and a simple preparation route. However, it exhibits poor absorption performance at 17–18 GHz. Several studies in the past have reported on the formation of mixed-valence states induced by the addition of monovalent K ions. In this study, YFeO3 was synthesized by doping with monovalent K via the sol-gel auto combustion method. This greatly optimized the wave-absorbing properties and effective bandwidth of YFeO3. The influence of different K additions on the absorption properties of the materials was also studied. All the hybrid composites showed excellent absorbing properties, with Y0.8K0.2FeO3 having an effective bandwidth of 4.88 GHz at a simulated thickness of 2.0 mm, Furthermore, the reflection loss (RL) value of Y0.7K0.3FeO3 reached ? 30.56 dB at 15.44 GHz (effective bandwidth up to 4.72 GHz) corresponding to the thickness of only 1.6 mm. This demonstrates that this broadband effect is greater than other similar materials. Moreover, the as-prepared samples completely covered the X and Ku band at only 2.2 mm, and the maximum effective bandwidth reached 5.28 GHz at 2.0 mm. The excellent wave absorption and frequency broadening effects were due to the various loss mechanisms and improved impedance matching characteristics caused by doping.
查看更多>>摘要：? 2022 Elsevier B.V.The multiferroic heterointerfaces, based on perovskite transition metal oxides, have been established as the effective way to build an interface with emergent phenomena owing to the coexistence and competition of complex interaction at the interface. Here, the La0.67Sr0.33MnO3/Pb(Zr0.52Ti0.48)O3 (LSMO/PZT) multiferroic superlattices (SLs) grown on (001)-, (110)-, and (111)-oriented SrTiO3 substrates have been systematically investigated. An inverted hysteresis loop (IHL) with a negative coercivity and remanence was found in the (001)- and (111)-oriented SLs, while was absent in (110)-oriented SLs. Detailed magnetic measurements demonstrate the contribution of both scanning field and temperature to the IHL, and the positive exchange bias in the minor hysteresis loops indicates the antiferromagnetic coupling between the interface and the bulk. The polarity discontinuity at the (001)- and (111)-oriented LSMO/PZT interface leads to the charge redistribution and is responsible for the unexpected IHL phenomenon. Our study highlights the significance of the electronic reconstruction due to the polarity discontinuity at the interface and provides a new approach to deal with complex magnetic interactions at the interface.
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