查看更多>>摘要：? 2022It has been a hot research topic to look for inexpensive alternative oxygen evolution reaction (OER) catalysts to replace noble metal-based materials due to their scarcity. Transition metals are ideal candidates because of their high abundance, impressive activities, and easy accessibility. However, a facile method leading to improved performance and stability is still needed. Herein, a highly efficient carbon-encapsulated bimetal catalyst derived from Ni-based metal-organic-frameworks (MOF) was successfully prepared through the low-temperature (350 ℃) pyrolysis of Prussian blue analogue (PBA) precursors under H2/Ar atmosphere. Cube-structured PBA as template and precursor，parameters during the pyrolysis process including temperature and calcination atmosphere can be tuned to control the structure and properties of the catalysts. Benefiting from the porous three-dimensional (3D) cubic structure and abundant defect-rich amorphous N-doped carbon shell, Ni3Fe@NC-350 exhibits excellent OER activity. The as-prepared catalysts exhibited excellent catalytic performance for OER in 1.0 M KOH with an overpotential of 237 mV to achieve 10 mA cm?2. More importantly, the presented catalyst has an extremely good durability.
查看更多>>摘要：? 2022 Elsevier B.V.Aqueous zinc-ion batteries (AZIBs) are attractive alternatives to conventional battery technologies owing to their low-cost, safety and environmental friendliness. The development of AZIBs has thus far proceeded rapidly; however, finding suitable materials for AZIB cathodes with high capacity, long-cycle stability, fast reaction kinetics has proved challenging. In this study, a manganese vanadate precursor (Mn0.04V2O5·1.17 H2O; MVO) was prepared using a simple hydrothermal method and calcined at a low temperature (250 °C) to generate oxygen vacancies (Mn0.04V2O5?x·0.64 H2O; MVO-250). The presence of oxygen vacancies effectively provide active sites, increase surface reactivity to improve zinc-ion storage, and inhibit the dissolution of electrode materials in the electrolyte. Consequently, MVO-250 exhibits a superior specific capacity and long-cycle performance to MVO. Moreover, after 4000 cycles at 5 A g?1, the discharge specific capacity of the MVO-250 electrode remain at 150 mA h g?1, while that of MVO is only (76 mA h g?1). Owing to its high pseudocapacitance (90.5%) at 1.0 mV s?1, MVO-250 has a higher zinc ion diffusion coefficient than MVO (77.2%). This research demonstrates the diverse potential applications prospect of the modification of AZIBs cathode materials with oxygen vacancies.
查看更多>>摘要：? 2022 Elsevier B.V.Provide more active sites and concise preparation is an effective technology in renewable energy storage sets. A soluble graphitic carbon nitride (SCN) nanosheets promoted two-dimensional nano electrochemical activity flake NiFe-LDH is successfully fabricated through electrostatic self-assembly, as a layer by layer high performance electrode (NiFe-LDH@SCN) for supercapacitor. The g-C3N4 guarantees the effectiveness of the combination through the ζ-potential of g-C3N4 flake (?19.5 mV) and NiFe-LDH flake (+15.6 mV), moreover, ensures the exposure of more active sites of NiFe-LDH. The optimized electrode shows an impressive specific capacitance of 1060.4 F g-1 at 1 A g-1 and remains 770.8 F g-1 at 10 A g-1. The fabricated hybrid supercapacitor (HSC) exhibits a magnificent energy density (up to 68.7 Wh kg-1) along with the power density of 827.5 W kg-1 in the wide voltage window of 1.7 V and a prominent long-term stability (83.3 % of capacitance retention even after 8000 cycles). Finally, two HSCs in series can light 40 LEDs. Hence, this work demonstrates the great potential of g-C3N4 in developing high-performance LDH-based energy storage devices.
查看更多>>摘要：? 2022 The Author(s)Among the different families of shape memory alloys (SMA), the Fe-Mn-Si-Cr-Ni alloys have attracted a renewed interest because of its low cost, high corrosion resistance and high recovery strength during the shape memory effect, and the new technologies of additive manufacturing offer unforeseen possibilities for this family of SMA. In the present work, the reversible γ ? ε martensitic transformation (MT), responsible for the shape memory effect, is studied in two Fe-Mn-Si-Cr-Ni alloys with high (20.2 wt%) and low (15.8 wt%) Mn content, produced by the conventional route of casting and rolling, in comparison with the MT in another similar alloy, with intermediate Mn content (19.4 wt%), which was produced by gas atomization and additive manufacturing through laser metal deposition. The forward and reverse γ ? ε MT is studied by mechanical spectroscopy through the internal friction spectra and the dynamic modulus variation, together with a parallel microstructural characterization including in-situ observation of the γ ? ε MT during cooling and heating at the scanning electron microscope. The evolution of the transformed fraction of ε martensite, evaluated through the integral area of the internal friction peak, was followed along thermal cycling in all three alloys. Both, the internal friction and the electron microscopy studies show that the ε martensite amount increases very fast during the first few cycles, and then decreases with a tendency towards its stabilization for many tens of cycles. The results show that the γ ? ε MT is more stable on cycling in the additive manufactured sample than in the conventionally processed samples, opening new avenues for designing shape memory steels to be specifically processed through additive manufacturing.
查看更多>>摘要：? 2022 Elsevier B.V.Nickel-molybdenum-tungsten (Ni-Mo-W) alloys have been suggested for applications of advanced micro-electro-mechanical systems (MEMS) in extreme environments due to their high strength, good electrical conductivity, and excellent thermal stability. In this work, we have carried out combinatorial experiments to reveal composition-dependent phase formation, physical properties, and thermal stability of Ni-Mo-W alloy films. Combinatorial synthesis through a magnetron sputtering process fabricated thin films with a composition range of Ni56–92Mo6–38W0.5–7.5. Structural analysis for the as-deposited combinatorial film revealed that a nanotwinned and strongly textured nano-columnar fcc structure was formed in the Ni-rich compositions, while solute content greater than 30% resulted in the formation of metallic glasses. The specimen exhibited very high hardness (8.8–12.5 GPa) and moderate electrical resistivity (85–135 μΩ ? cm), and both the properties were found to increase with solute concentration. Annealing of the combinatorial film at 600 ℃ for 1 h revealed that nanotwinned structure is thermally stable for high Ni concentrations. Metallic glasses with high solute concentration also exhibited high thermal stability and were not crystallized after annealing. Alloys with intermediate solute content experienced the transformation from the amorphous to fcc nanocrystalline phase with nanotwins. The annealed combinatorial film maintained high hardness and moderate electrical resistivity after annealing.
查看更多>>摘要：? 2022 Elsevier B.V.Aiming at the deficiencies of the three typical “external gettering” systems: metal-oxide equilibrium deoxidation (MED), halide flux deoxidation (HFD) and electrochemical deoxidation (ECD), a novel deoxidation method based on the combination of oxytropic rare earth metal Y and Ca for in-depth deoxidation of Zr-O solid solution was proposed. The thermodynamic properties of the deoxidation method were analyzed, and it was found that the addition of metallic Y could significantly improve the deoxidation ability of the Ca-CaCl2 system, because Y could form Y-Y2O3 equilibrium to “anchor” the activity of CaO (aCaO) at a very low level. When the activity of Y2O3 (aY2O3) and aCaO in the flux conforms to aY2O3< 18.9a3CaO at 1173 K, the deoxidation mode is thermodynamically feasible. Experiments were conducted to verify the method. The results showed that even if CaO was saturated in CaCl2 flux, the oxygen content of Zr-O solid solution could still be controlled at the level of less than 100 ppm, thus the “anchoring effect” of Y on aCaO was verified. The oxygen content, phase and microstructure of the reacted Y specimens were analyzed, which suggested that when the ratio of CaO was less than 40 % of its solubility in CaCl2 flux, the oxygen potential of the system was controlled by Y-O solid solution, and when it was greater than 40 %, the oxygen potential of the system was controlled by Y-Y2O3 equilibrium.
查看更多>>摘要：? 2022 Elsevier B.V.The phase diagram of the Fe-Si binary system was precisely determined using FE-EPMA/WDS and thermal analysis of DSC. It was confirmed that the concentration ranges of the β-Fe2Si and ζα-FeSi2 phases are slightly narrower and shifted toward higher Fe concentrations compared with the literature, and the other iron-silicide phases have low but certain concentration ranges less than 1 at%. The A2/B2/D03 order-disorder transition and Curie temperatures in the BCC phases exhibited concentration dependences consistent with those temperatures reported by Meco and Napolitano, and the Curie temperatures of the α”-Fe3Si (D03) alloys deviated higher from the extrapolated values of the α-Fe (A2) phase with increasing Si content and bent at the stoichiometric composition of 25 at%Si. Invariant reaction temperatures were mostly coincident with those of the phase diagram in the literature, except for the peritectoid temperature of the η-Fe5Si3 phase, whereas a small discrepancy was revealed in the solidus and liquidus lines.
查看更多>>摘要：? 2022 Elsevier B.V.Two-dimensional transition metal dichalcogenide semiconductors owning a large intrinsic spin-orbit coupling (SOC) are considered the best candidates to generate, detect and manipulate the spin currents. The SOC defines the interconversion of spin and charge currents via Rashba Edelstein effect (spin Hall effect) and its reciprocal as inverse Rashba Edelstein effect (inverse spin Hall effect). However, the spin signal originated in low dimensional materials because of Rashba Edelstein effect or spin Hall effect yet needed to be addressed with distinguishable measurement technique. Here, we demonstrate experimentally the room temperature interconversion of spin and charge currents in Graphene/WSe2 van der Waals heterostructure which is induced by proximity effect. Remarkably, the spin currents induced by Rashba Edelstein effect and spin Hall effect are discriminated and extracted individually via external magnetic field, respectively. The magnitude of spin transport and their corresponding spin efficiencies (αREE=1.47±0.03%) and (θSHE==4.5±0.07%) are modulated via applied electric field and temperature. Such electric, and magnetic field tunability of the spin transport through the non-magnetic materials may provide a new approach to fabricate the fast and low-power spintronic devices for quantum scale applications.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of a high magnetic field (HMF) on phase transition and microstructure formation in Fe-Ga alloys with a Ga concentration of about 25 at.% has been investigated using experimental research and ab initio modeling. We found that the HMF of 25 T significantly accelerates the D03 to L12 transformation in the hyperstoichiometric Fe-27 %Ga alloy upon isothermal annealing at 475 °C. At the same time, the field has little effect on the transformation in the hypostoichiometric Fe-24 %Ga alloy. We have found that HMF does affect the kinetics of the transformation rather than the energy of the phases. We have shown that the effect of HMF is mainly associated with the ferromagnetic ordering of magnetic moments, which leads to lattice instability of the D03 phase and enhancement of the D03 → L12 transition due to the initiation of the barrierless mechanism.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, Co9S8 nanoparticles embedded polyaniline-based carbon nanotubes (Co9S8/C nanotubes) have been prepared vis polymerization of aniline, rotary evaporation and further calcination, in which the melamine tubes from protonated melamine under the induction of NO3-, serve as templates for the preparation of PAIN tubes by polymerization. After calcination, PANI-based carbon nanotubes provide a good carrier for Co9S8 nanoparticles. The N doping in the carbon nanotubes and unique structure endow Co9S8/C nanotubes with good electronic and ionic conductivity. As a result, Co9S8/C nanotubes show favorable rate capability (645 mA h g?1 at 0.2 A g?1 and 524 mA h g?1 at 0.5 A g?1) and superior cycling performance at 1.0 A g?1 for 500 cycles, making them promising anode candidate for high-performance lithium-ion batteries.
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