查看更多>>摘要：The present work examined the influence of anion type on incorporating WO3 into the MgO layer produced via plasma electrolytic oxidation of AZ31 Mg alloy. Here, three different anions, such as aluminate (AlO2-), silicate (SiO32-), and phosphate (PO43-) were added separately into an alkaline electrolyte containing WO3 nanoparticles. The microstructural observations revealed that the incorporation of the WO3 nanoparticles is affected by the diameter of discharge channels associated with the type of anion added into the electrolyte. The sample produced from phosphate electrolytes had higher thickness but was more porous than those obtained in aluminate or silicate electrolytes. Regardless of anion type, the amounts of WO3 nanoparticles incorporated into the inner layer of PEO coating were more significant than those incorporated into the outer layer, where a WO3-rich inner layer was obtained in the case sample coated in electrolyte with silicate anions. The electrochemical measurements in a 3.5 wt% NaCl solution indicated that the corrosion resistance of the sample coated in silicate electrolyte was superior to other samples in which the sample coated in phosphate electrolyte exhibited the lowest corrosion resistance. This behavior is explained by a mechanism in which every anion produces its microstructural defects under the influence of discharge types, such as type-A, B, C, D, and E, thus, affecting the physical incorporation of WO3 into the MgO layer under plasma conditions. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Zinc-ion batteries (ZIBs) have become potential energy storage devices due to its low cost, environmentally friendly and high safety. The development of ZIBs is facing huge challenges especially in cathode materials. Here, we report a strategy of doping Co into MoS2 to get CoxMo1-xS2 nanosheets with rich dislocation-defects and expanded layer spacing. MoS2 itself has poor Zn2+ diffusivity and low specific capacity due to small layer spacing. The diffusion of Zn2+ is greatly improved by doping of Co. When CoxMo1-xS2 nanosheets are used as positive electrode in ZIBs, the capacity increased from 31.3 mA h g(-1) to 164.1 mA h g(-1), which is increased by more than five times. What's more, even if the current is increased ten times, it still has high capacity (about 40% capacity retention). In addition, the peaks of the Zn2+ intercalation/deintercalation in the CoxMo1-xS2 electrode have been effectively improved, which indicates a much more efficiency Zn2+ intercalation kinetic. Therefore, its capacity has been greatly improved. This research provides a general and effective strategy to reduce the embedding energy barrier of Zn2+ to increase the diffusion rate of Zn2+ and the capacity of ZIBs. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：TiB2 nanoparticles were fabricated by the melt reaction between Al-10Ti and Al-3B master alloys. The reaction mechanism is ascribed to the decomposition of Al3Ti to release free Ti atoms, which diffuse across the AlB2/Al interface and substitute the Al atoms to form TiB2. This substitution produces a layer of pseudoTiB2 on the prism planes {10-10}AlB2 firstly, which has the same lattice structure and the similar values of the lattice parameter as AlB2. It follows the fact that the nucleation occurs at the prism planes {10-10}. Subsequently, the epitaxial transformation of TiB2 particles is initiated inward the pseudo-TiB2, which becomes detached from the substrate owing to the crystallographic mismatch between the two, thus forming the TiB2 nanoparticles. The exposed AlB2 prism surfaces continue to react with Ti atoms until they are totally consumed. Increasing the reaction temperature, prolonging the holding time could improve the extent of reaction, thus increasing the electrical conductivity and reducing the elastic modulus. Especially, the effects of ultrasonic vibration treatment (UVT) on the reaction process were explored. Cavitation and acoustic flow generated by UVT showed a magnificent potential for promoting the reaction in melts. Thanks to the interface reaction, nano-TiB2 particles can be generated. The nano-TiB2p/6201 composites produced by this method recorded significant improvement in the tensile properties.(c) 2022 Elsevier B.V.All rights reserved.
查看更多>>摘要：Due to the moderate degradation rates and acceptable biocompatibility, Zn-based alloys have attracted more and more attention as biodegradable materials. However, the inferior strength and ductility significantly limit their further applications. In this work, biodegradable Zn-2Cu-0.2Mn-xLi (x = 0, 0.1 and 0.38) alloys were developed with enhanced comprehensive mechanical properties. Also, these novel alloys were found to possess extraordinary antibacterial activity and good biocompatibility. Annealing and hot extrusion were performed on the as-cast alloys. The microstructures, mechanical properties, corrosion behavior, antibacterial ability, hemocompatibility and cytocompatibility of the alloys were systematically studied. Microstructure analysis indicates that primary e-CuZn4 particles are distributed in the Zn grains in all ascast alloys. Addition of Li leads to formation of beta-LiZn4 phase in eutectics and beta-LiZn4 precipitates within the Zn grains. In the as-annealed alloy, secondary epsilon-CuZn4 precipitates and fine beta-LiZn4 precipitates appear in the Zn matrix of the Li-containing alloys. All the as-extruded alloys reveal fibrous morphology and develop (0001) basal texture. Mechanical property test shows that all as-extruded alloys exhibit excellent strength and ductility which can fully meet the benchmark requirement for biodegradable materials. It is worth to notice that, Zn-2Cu-0.2Mn-0.38Li alloy has a tensile yield strength, ultimate tensile strength and elongation as high as 424 +/- 28.3 MPa, 445 +/- 11.1 MPa and 76 +/- 3.35%, respectively. The 24-day in vitro immersion test in the SBF solution shows that the corrosion rates were 0.212 +/- 0.007 mm/year for Zn-2Cu-0.2Mn, 0.197 +/- 0.005 mm/year for Zn-2Cu-0.2Mn-0.1Li and 0.184 +/- 0.008 mm/year for Zn-2Cu-0.2Mn-0.38Li, respectively. It indicates that addition of Li improves the corrosion resistance of the alloys. All as-extruded alloys have antibacterial rates of >= 99% and hemolysis rates of < 5%, exhibiting strong antibacterial activity and good hemocompatibility. The MC3T3-E1 cells show more than 95% viability in 25% extracts of all asextruded alloys in all culturing days. In addition, in this low concentration of extracts, the cells in the alloy groups exhibit good spreading morphology and high ALP expression, suggesting good cytocompatibility. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Dynamic mechanical relaxation processes (i.e., beta relaxation and alpha relaxation) are closely connected with the mechanical and physical properties of metallic glasses. In the current work, the beta relaxation of La60Ni15Al25 metallic glass was studied in sequential heating and cooling experiments by dynamic mechanical analysis. The values of the loss modulus peak were found to reach a relatively stable state during the progress of the heating-cooling cycles. The evolution of the flow unit distribution during thermal cycling was revealed by stress relaxation tests. The experimental results of stress relaxation were well described by a generalized Maxwell model, allowing the analysis of the underlying relaxation time and activation energy distributions. We also show here a suppressed relaxation behavior observed under repeated loading cycles, which is attributed to the annihilation of flow units and the modification of the relaxation time spectrum obtained in the framework of the generalized Maxwell model. (C) 2022 Elsevier B.V. All rights reserved.
V. Butova, VeraAboraia, Abdelaziz M.V. Shapovalov, VictorDzhangiryan, Narek A....
9页
查看更多>>摘要：We report an eco-friendly, simple, and scalable method of FeF2 cathode production. MIL-88A was synthesized in a water medium without any additives. It was used as a source of iron (3 +) ions during pyrolysis. The porous structure of such a sacrificial agent allowed us to incorporate poly-vinylidene fluoride molecules as a guest component into a host MIL-88A framework. Pyrolysis in Ar-flow results in two simultaneous processes: reducing Fe3+ into Fe2+ and forming porous carbon shells for FeF2 nanoparticles. Applying complex analysis of high-resolution TEM images, porosity measurements, and XANES spectroscopy, we have revealed that obtained iron fluoride is composed of nanoparticles with elongated and hexagonal shapes. Both iron fluorides were attributed to tetragonal FeF2 structure type, contained only Fe2+ ions, and were covered with porous carbon shells. The obtained material was used as a cathode for a lithium-ion battery and showed good stability and a high capacity of 425-330 mA h/g. The proposed water-based synthesis of MIL-88A as a precursor in combination with mild pyrolysis conditions and good electrochemical performance make this material promising for cathode application. (c) 2022 Published by Elsevier B.V.
查看更多>>摘要：Laves type AB(2) intermetallics belong to the most abundant group of intermetallic compounds containing over 1000 compounds. A large variety of the chemical nature of A (Mg, Ca, Ti, Zr, Rare Earth Metals) and B (V, Cr, Mn, Fe, Co, Ni, Al) metals together with the existence of the extended solid solutions formed by mixing various selected components on both A and B sites dramatically extends the list the known binary and ternary individual compounds. A vast majority of the Laves type intermetallics crystallises with C15 / FCC MgCu2 and C14 / hexagonal MgZn2 types of structures, both formed for a large range of ratios between the atomic radii of the A and B components outside the ideal ratio r(A)/r(B)= 1.225. Their hydrogenation per-formance is defined by the chemical composition and structure of the alloys and proceeds according to the following alternative / parallel mechanisms: (a) Formation of the insertion type interstitial hydrides con-taining up to 6-7 at. H/f.u.AB(2); (b) Amorphisation of the alloys on hydrogenation; (c) Disproportionation with the formation of a binary hydride of the A metal and depleted by A metal B-components based alloys/ hydrides. Equilibrium pressures of hydrogen desorption from the AB(2)-type hydrides span a huge range of ten orders of magnitude and thus Laves type-based intermetallics satisfy the requirements for various applications including getters of hydrogen gas, volume-and mass-efficient hydrogen storage materials operating at ambient conditions, materials for the efficient thermally driven compression of hydrogen gas with an output pressure of several hundred bar and high capacity and high rate anode materials for the metal hydride batteries operating in a challenging temperature range -at subzero temperatures and also above 60 degrees C. The paper contains references to 245 publications and will guide the future work in the areas of fundamental research and also in advancing the applications of the hydrides of the Laves type inter-metallics. (C) 2022 The Author(s). Published by Elsevier B.V.
查看更多>>摘要：With the progress of society, people have higher and higher requirements for energy battery anode materials. Commercial graphite electrode is limited by its specific capacity and can no longer meet people's needs. As a result, it is urgent to study high-performance anode materials for lithium-ion batteries. In this work, the sea urchin-like Co-Co Prussian blue analogue@Ni-1,3,5-Benzenetricarboxylate (Co-Co PBA@Ni-BTC) assembled from one-dimensional nanorods is prepared by a flexible one-step hydrothermal method using Co-Co PBA and Ni-BTC metal-organic frameworks as templates. Hierarchical microspheres constructed by nitrogen-doped carbon layer coated NiCo2O4/NiO composite nanorods (NiCo2O4/NiO@C) are further prepared by two-step calcination. After 200 cycles at a current density of 1 A g(-1), the capacity can be maintained at 1432.8 mAh g(-1) and the coulombic efficiency is up to 98.1%. When the current density reaches 5 A g(-1), its capacity can still be maintained at 894.3 mA h g(-1). The excellent electrochemical performance comes from the one-dimensional nanostructure and highly uniform nitrogen-doped carbon coating. This work provides new ideas for the application of metal-organic framework materials in lithium-ion battery anode materials. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：A novel high entropy silicide (NbMoTaWV)Si-2 coating was prepared on a NbMoTaWV high entropy alloy by silicon pack cementation. The single-phase structure of (NbMoTaWV)Si-2 was obtained due to the high entropy effect and sluggish effect of NbMoTaWV refractory high entropy alloy. The processing parameters could affect the coating structure and thickness. Low temperature favored the formation of single-layer (NbMoTaWV)Si-2 layer while high temperatures (1200 ? and 1300 ?) produced two layers coating, (NbMoTaWV)Si-2 layer and (NbMoTaWV)Si-2/(NbMoTaWV)(5)Si-3 mixed interdiffusion layer. Coating with reasonable thickness and minimized cracks could be obtained under proper processing parameters. The oxidation test of coating specimens was conducted at 1200 ? for up to 96 h. The high entropy of (NbMoTaWV) Si-2 suppressed the generation of metallic oxides and promoted the formation of dense and intact SiO2 layer, which largely improved the oxidation resistance of NbMoTaWV. Failure in corners was observed in most coating specimens after exposed for 48 h, and the failure mechanism was also discussed. (C) 2022 Published by Elsevier B.V.
Thi, Lan NguyenPhan, Thi Thuy TrangNgoc, Tri NguyenViswanath, N. S. M....
15页
查看更多>>摘要：To overcome the limitations in the reversibility of Fe2+/Fe3+ in the Fenton reaction, a reasonable concept of the addition of photoinduced electron donors has been developed. In this study, a facile solid-state reaction has been used to synthesize composites of Prussian Blue and g-C3N4 as an effective catalyst in the photo Fenton reaction for organic pollutants decomposition. As a result, the degradation efficiencies of Rhodamine B and Tetracycline under the photo-Fenton catalytic process are 94.1% and 84.3%, respectively, after 60 min of treatment. Therein, a step-scheme model of electron-hole transport accelerated by a built-in electric field was ascribed as the origin of the significant improvement in the catalytic performance of the composites. A reasonable pathway for charge carrier transfer was proposed and demonstrated by both experimental and calculation proofs. Furthermore, the theoretical calculation result indicates that the decomposition of H2O2 to hydroxyl radicals is preferable on Prussian Blue, while the g-C3N4 is considered an electron-generator. Additionally, the decomposition mechanism of organic pollutants under the photo-Fenton reaction of the composites was also investigated. (C) 2022 Elsevier B.V. All rights reserved.
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