查看更多>>摘要：? 2022 Elsevier B.V.High entropy oxides have gained significant interest over the years due to their unique structural characteristics and correlated possibilities for control of functional properties. However, it is hard to forecast their properties and crystal structures due to the enormous inherent complexity and large number of potential combinations that characterize such systems. In this work, the reported high-entropy rutile-type Al-Cr-Nb-Ta-Ti-O system is first analyzed, and then a series of single-phase rutile-type Ti-Sn-Nb-Ta-Me-O (Me = Ga, Fe, Cr) compositionally complex oxides are designed via the cluster-plus-glue-atom model, and finally synthesized successfully by solid-state reaction method. The crystal structure of samples is determined by XRD, and the composition distribution is determined by EDS mapping. Results show that the cluster-plus-glue atom model can effectively guide the synthesis of rutile-structured high/medium entropy oxides with the assistance of geometric calculation, offering the corresponding solutions for the phase instability caused by the different crystal structures of raw materials and adjusting the lattice parameters of rutile structure by selecting various cations.
查看更多>>摘要：? 2022 Elsevier B.V.Vanadium oxides are promising cathode materials with great potential. Here, we present a simple, safe, and environmentally friendly aging treatment to change the content of V5+ in vanadium oxides. The influence of different V5+ contents in vanadium oxides cathodes on the properties of Zn-ion batteries (ZIBs) is studied. V6O13 and V3O7/V6O13 nanosheets are synthesized by aging VO2 precursors for different periods of time. V6O13 is found to exhibit higher specific capacity and excellent cycling performance compared to VO2 and V3O7/V6O13. It is also characterized by an extremely high capacity of 300 mA h g?1 at a high current density of 5 A g?1. At 0.3 A g?1, it maintains a capacity of 421 mA h g?1 during 100 cycles with a high capacity retention rate of 95%. Changes in the vanadium valence state, structure, and morphology of electrodes during charging and discharging are also investigated for a better understanding of the underlying electrochemical processes.
查看更多>>摘要：? 2022 Elsevier B.V.A magnetic field induced hydrothermal method is applied to synthesize precursors, followed by annealing to prepare mesoporous MnO microchains. Different morphologies of the ultimate products can be dominated by changing the magnetic field strength to acquire good electrochemical performances. The initial high reversible capacity of MnO microchains is 948 mA h g?1. After 250 cycles, the reversible capacity retains about 769 mA h g?1 at 2 C, even after 2000 cycles, the reversible capacity maintains around 198 mA h g?1 at 8 C. The superb electrochemical properties could originate from the mesoporosity of aggregated nanoparticles of the MnO 1D-microchain structure induced by applied magnetic field of 8 T, which is beneficial for the fast transport of Li+ and electron, and can adapt to the dramatic volume change during the Li+ deintercalation.
查看更多>>摘要：? 2022 Elsevier B.V.Manganic manganous oxide (Mn3O4) microspheres were prepared at 550 V discharge voltage in 2 g L?1 NaNO3 solution by one-step method via cathode glow discharge electrolysis (CGDE) plasma technique for high-capacitance supercapacitor electrode materials, in which Mn foil and Pt needle point were served as anode and cathode, respectively. The structure, phase composition and morphology of as-prepared products were characterized by FT-IR, XRD, XPS, SEM, TEM and BET analysis. A mechanism for the fabrication of Mn3O4 microspheres was proposed. The electrochemical behaviors of the Mn3O4 microspheres were examined in 1.0 mol L?1 Na2SO4 electrolyte. The results showed that Mn3O4 microspheres are composed of small nanospheres with sizes of about 20 nm and large nanospheres with sizes of about 177 nm. Specific surface area of microspheres is 48.03 m2 g?1. The Mn3O4 microsphere as an electrode has an outstanding specific capacitance of 360 F g?1 at 0.5 A g?1 and a superior cycling property of 83.6 % capacity retention after 1000 cycles at 1 A g?1, evidencing the potential as an electrode material for supercapacitor.
查看更多>>摘要：? 2022 Elsevier B.V.Oxygen reduction electrocatalysts with multiple heteroatomic doping, abundant defects and porous and layered structures are beneficial for enhancing oxygen reduction reaction (ORR) activity. However, the design and facile preparation of such materials often present great challenges. Herein, Fe, S, N multiple-doped three-dimensional (3D) porous carbon (Fe/S-CN) has been prepared by in-site NaCl template-assisted ball milling and subsequent high-temperature pyrolysis strategy. Due to the multiple doping, abundant defects and porous carbon framework provide rich active sites and rapid mass/electron transport channels, the Fe/S-CN catalyst with low metal content (0.589 wt%) metal species still achieve a high half-wave potential of 0.880 V, exceeding the commercial Pt/C (0.844 V). The Zn-air battery composed of Fe/S-CN catalysts as air cathodes also exhibited excellent performance. This work exhibition a convenient strategy for the fabrication of low-metal ORR catalysts with reciprocity and layered multi-hole and proves its magnificent potential for ORR catalysis and Zn-air batteries.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, AlCrFeNiMnx high-entropy alloy coatings (x = 0, 0.5, and 1) were successfully prepared on a copper substrate by laser cladding. The influence of Mn addition was investigated on the phase constituent, microstructure, and mechanical properties of the HEA coatings. Due to the high-entropy effect, the AlCrFeNiMnx HEA coatings comprised only simple BCC and FCC structure phases. Moreover, the addition of Mn elements inhibited the formation of FCC phases due to the variation of ΔGmix, ΔHmix, δ, ?x and VEC value. The addition of Mn leads to solute effect, so the grains were significantly refined with an increase in Mn content. When the Mn content was 0.5, good comprehensive mechanical properties were obtained with an average Vickers hardness of 625 HV, average friction coefficient value of 0.42, and a mass loss of 1.02 mg.
查看更多>>摘要：? 2022 Elsevier B.V.Electronic structure regulation is one of the essential strategies for developing advanced electrocatalysts. Herein, FeOOH was electrodeposited on the surface of NiSe2/Ni2O3, resulting in a layered NiSe2/Ni2O3/FeOOH interfacial composite with a unique hierarchical structure and strong electronic interactions. This sheet-like nanostructure provides sufficient space for mass transfer, fully exposes the active sites, and accelerates the reaction kinetics. The optimal sample exhibits excellent oxygen evolution reaction (OER) activity with a low overpotential of 270 mV at a current density of 100 mA cm?2 and a Tafel slope of only 54.7 mV dec?1. It also has excellent durability. This study provides a new perspective for developing efficient electrocatalysts by constructing interfacial composites.
查看更多>>摘要：? 2022 Elsevier B.V.Here, we report a general strategy to obtain low-temperature processed high-quality and large-area metal chalcogenide (CdSe) semiconductors from precursor based benign solution process. Using hydrogen-driven post thermal annealing, the deposited thin films enable expeditious formation at relatively low process temperature (<350°C), which are easily transformed into the corresponding high-quality and large-area films with less defect states and more crystalline structures, indicating enhanced electro-optical properties. The improved metal chalcogenide alloy thin-films are successfully synthesized and the versatility of this facile route is demonstrated by fabricating large-area thin-film-transistors and optoelectronic devices on 4-inch silicon and 2.5-inch borosilicate glass substrates in air ambient. The polycrystalline hydrogenated CdSe-based thin-film-transistor (TFT) exhibited relatively good electro-optical properties such as a maximum field-effect mobility larger than 150 cm2 V?1s?1 with on/off current ratio of> 107 and subthreshold slope of< 1 V decade?1 as well as improved responsivity (9.64 ×10?3 AW?1) and switching speed. To validate our findings, we discussed the detailed mechanism of the reduction of defect states and precisely designed thin film synthesis with process temperature, time, the correlation with molecular composition, physical structure of the films, and the optoelectronic performance of CdSe TFTs.
查看更多>>摘要：? 2022 Elsevier B.V.This work explores effects of Ge and Sb on the formation of secondary phases, with an emphasis laid on the thermo-kinetics of phase transformations and the mechanisms determining the micro-alloying effects. The results reveal that the dominating microstructures in an Al-Mg-Si-Cu alloy, including Mg2Si, Al4Cu2Mg8Si7 (Q), Si and Al2Cu (θ) phases, are thermal activated. Compared to elemental Si, intermetallic compounds like Mg2Si and Q phases have larger critical nucleation radius and phase-transformation energy barrier, and the larger thermodynamic driving force and kinetic migration energy barrier generally result in the finer microstructures. Micro-alloying affects the phase transformations in two ways: the element Sb not only promotes forming Mg3Sb2 phases but also facilitates the formation of elemental Si, Q needles and θ dispersoids through the mismatch effect; whereas the element Ge facilitates the formation of (Ge, Si) structures with different shapes and crystal structures by a substitution behavior following the formation energy criterion.
查看更多>>摘要：? 2022 Elsevier B.V.Al-Mg alloys (AA5083-type) are widely used for superplastic forming. Limited grain boundary sliding as compared to other superplastic alloys limits the formability of Al-Mg based alloys. Grain boundary sliding intensity depends on the grain size, grain boundaries structure, and chemical composition of alloys. To improve superplastic properties of Al-Mg based alloys, we investigated the influence of a minor addition of Zn on the grain boundary relaxation effect and grain boundary sliding ability. The temperature dependence internal friction, superplastic deformation behavior, and microstructural changes during superplastic deformation for the AA5083 alloy and Zn modified alloy were compared. A minor Zn addition of 0.7 wt% does not influence the mean grain size but decreases the relaxation strength and the activation energy of grain boundary relaxation. The mechanisms of superplastic deformation and their contributions to the total strain were analyzed using FIB-milled grids evolution on the samples’ surface. Grain boundary sliding, grain rotations, and intragranular strain included both dislocation slip/creep and diffusional creep were involved in the deformation process. The contribution of grain boundary sliding increased from 10% to 25% for the Zn-free AA5083 alloy to 30–50% for the Zn-modified alloy. In result, a minor Zn addition proved to stimulate grain boundary sliding that decreases stress and increases strain rate sensitivity and elongation-to-failure of the studied alloy.
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