查看更多>>摘要：? 2022 Elsevier B.V.Engineering the van-der-Waals gap by interlayer water confinement and hydration enable superfast ions transfer and intercalation that boosts the charge storage performance. Herein, we report the van-der-Waals gap modification into the layered WO3 nanostructures using cost-effective wet chemical method. The larger water molecules insertion into the hydrated WO3 crystal structure facilitates the expansion of van-der-Waals gap, which results the improvement of nanoplates thickness. The electrochemical performance in the thicker hydrated WO3 nanoplates is enhanced owing to the better crystalline nature and electrical conductivity along with van-der-Waals gap modification. Hence, the significant boost of single electrode specific capacitance from 160 F g?1 to 250 F g?1 at 2 mV s?1 is observed in 1 M H2SO4 aqueous electrolyte. Further an asymmetric supercapacitor of 1.6 V exhibits the capacitance value 27 F g?1 at 1 A g?1 with 8000 Wh kg?1 power density and 87% capacitance retention after 2500 cycles. The van-der-Waal gaps engineering of layered materials is a potential strategy to amplify supercapacitor performance.
查看更多>>摘要：? 2022 Elsevier B.V.Here, a natural and non-toxic inositol additive with six hydroxyl groups is added into the 2 M ZnSO4 aqueous baseline electrolyte to enhance the electrochemical performances of the zinc ion batteries. 2H chemical shift in the Nuclear magnetic resonance demonstrates that the inositol molecule exhibits strongly coordinate with Zn2+ to change its solvation structure, which would significantly decrease the released water molecules number during the reduced deposition on Zn anode surface, hence effectively suppressing the hydrogen evolution reaction, corrosion and by-product formation. Furthermore, the inositol molecules are more wettability to the zinc anode according to the density functional theory calculations and the contact angle experimental results, which could restrict the two-dimensional diffusion of Zn2+, avoiding the agglomeration and zinc dendrite growth. As a result, the Zn||V2O5 employing the 2 M ZnSO4 aqueous electrolyte with 200 mM inositol additive presents a highest discharge specific capacity of 213 mA h g?1, and it still maintains a high reversible specific capacity of 99 mA h g?1 after 1800 cycles under the 1.0 A g?1 current density. The corresponding fundamental mechanism is deeply disclosed, which might devote guidance for solving the issues of ZIBs through electrolyte chemistries.
查看更多>>摘要：? 2022 Elsevier B.V.Prior β grain evolution and phase transformation of selective laser melted (SLM) Ti6Al4V alloy after subtransus and supertransus solution heat treatments are investigated. A method based on the special angle grain boundaries (in the range of 15–55° and 70–85°) is proposed for a clear and straightforward description of the prior β mesostructure. Post solution treatments below β transus retain the prior β grains and alter the fully martensitic microstructure into a mixture of α and α’/β phases. A non-traditional “bimodal structure” consisting of αP and αS’ phases is produced by subtransus treatments at a relatively high temperature. While treatments above β transus lead to the growth of prior β grains and transform the martensitic α’ phases into β phases first, and then back into α’ martensites again during quenching, leading to a new martensitic microstructure. The microhardness is determined by the α lath thickness and the amount of α’ martensite, and the latter is more predominant.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of adding Ag and Cu on the strength and electrical conductivity of Al-Mg-Si conductor alloys was investigated using conventional and modified thermomechanical treatments. In the conventional thermomechanical treatment, the addition of Ag and Cu moderately increased the strength from 296 MPa to 305–316 MPa above the minimum required electrical conductivity (52.5% IACS) compared to that of the base alloy. However, the modification of the thermomechanical treatment could maximize the efficiency of Ag and Cu addition at strengths above 52.5% IACS, exhibiting that the strength was increased from 317 MPa to 341–348 MPa with the Ag and Cu additions. All alloys under the modified thermomechanical treatment (MTMT) showed a superior strength and electrical conductivity compared to their counterparts under the conventional thermomechanical treatment (CTMT), resulting in a wider window in the high end of strength and electrical conductivity. In addition, MTMT led to a shorter post-aging time to reach the minimum required EC, compared to CTMT. The precipitate characteristics under both thermomechanical treatment conditions were analyzed and quantified using differential scanning calorimetry and transmission electron microscopy (TEM). The TEM results revealed that the alloys under MTMT had a higher precipitate number density by more than three times compared to their counterparts under CTMT, leading to the higher strength levels in the MTMT alloys. Strength and electrical resistivity models were then applied to understand the multiple contributions of the main strengthening mechanisms and microstructure features to the mechanical strength and electrical conductivity.
查看更多>>摘要：? 2022 Elsevier B.V.Rechargeable aqueous zinc ion batteries (ZIBs) are one of the most promising candidates for large-scale energy storage, due to their high capacity, high hydrogen evolution potential, safe and cost-effective components while benefiting from the abundance of active materials. However, ZIBs still suffer from suitable cathode materials with high capacity and superior cycling stability. Herein, we study a new strategy for the synthesis of tunable crystallite sizes ZnMn2O4/Mn2O3 nanocomposite using the pulsed potential method. The effect of synthesis potential on structural, morphological, and electrochemical properties of nanocomposite was investigated via different characterization techniques. According to our results, the functional and electrochemical properties of ZnMn2O4/Mn2O3 nanocomposite are profoundly affected by the synthesis potential. The crystallite sizes of synthesized nanocomposites can be tuned from 20.2 nm to 29.3 nm, depending on the applied potential. However, the exposed surface area of nanomaterials is ranged between 50.3 m2 g?1 and 132.0 m2 g?1. The developed nanocomposite was investigated as the cathode material for aqueous zinc ion batteries. The ZnMn2O4/Mn2O3 nanocomposite exhibited an excellent discharge capacity of 216.8 mAh g?1 at 0.2 A g?1 after 200 cycles. In addition, the developed cathode showed to preserve 97.8% of its initial capacity for 2000 cycles at 2 A g?1. Apart from the high specific capacity and long cycle stability, the facile synthesis method can offer the ZnMn2O4/Mn2O3 nanocomposite as a high-performance cathode material for durable zinc ion batteries.
查看更多>>摘要：? 2022Controlling the shape, morphology, and porosity of hollow nanostructures is a pivotal issue for adjusting the characteristics of tailor-made nanomaterials to expand their application to more fields. Although many hollow metal oxides have been developed, studies on the construction of hollow bimetal oxide heterostructures with controllable nanocavities in different morphologies and high crystallinity through Kirkendall effect is still ascendant. Using this strategy, nickel nanotubes with smooth walls was acquired through continuous oxidation treatments on CuNi nanowires at 200 °C. Oxidation treatment at high temperature (300 °C) on CuNi nanowires produced nickel oxide nanotubes containing periodic copper nanoparticles, nickel oxide nanotubes with a bamboo-like structure and nanoforests. In addition, thin CuO nanowires with diameters of 5–10 nm grew on nanowires at 400 °C. Finally, the mechanisms of sculpting nanocavities at high and low temperatures were elucidated. An in-depth understanding of the thermally stimulated Kirkendall effect in bimetals has a significant influence on the design and fabrication of new hollow multifunctional hetero-nanostructures with potential applications in energy storage, catalysis, and gas sensing.
查看更多>>摘要：? 2022 Elsevier B.V.Chitosan (CTS) is a well-known adsorbent capable of absorbing copper ions. It's also a high-quality biomass carbon source. The carbon skeleton formed by the pyrolysis of CTS has outstanding electrical conductivity, which can help copper azide (CA), a new type of primary explosive that's particularly sensitive to electrostatic stimuli, be more electrostatically safe. The CTS-Cu complex is precipitated by using CTS to adsorb and flocculate copper ions in wastewater. To construct the Cu@carbonized chitosan (CCTS) precursor material, the organic ligands in the CTS-Cu complex are calcined into a porous three-dimensional carbon matrix, and the copper ions are transformed into copper nanoparticles embedded in CCTS. The azide reaction converts copper nanoparticles (CuNPs) into high-energy CA. With its good electrical conductivity, CCTS maintains its framework structure and effectively improves the electrostatic safety of composite energetic materials. CA@CCTS has a CA content of 69.7%, an electrostatic ignition energy (E50) of about 1.19 mJ, and a heat release of 1803.22 J/g. This work takes advantage of CA and CTS's environmental friendliness. CA@CCTS, as a novel lead-free primary explosive, has good electrostatic safety while containing a high proportion of CA.
查看更多>>摘要：? 2022 Elsevier B.V.A huge acceleration of the yellow band defect luminescence (YB) with increasing Si and Ge doping concentration in GaN layers has been observed and studied. The donor doping concentrations in the n-type GaN varied from 5 × 1016 cm?3 to 1.5 × 1019 cm?3 for undoped, Si-doped, and Ge-doped samples. Consequently, the fastest component of the photoluminescence (PL) decay time curve accelerated from 0.9 ms to 40.3 ns, and the mean decay time from 20 ms to 260 ns with increasing doping concentration. We have proposed an explanation based on a theoretical model of donor-acceptor pair transition (DAP) and electron-acceptor (e-A0) recombination at higher dopant concentrations, which is supported by several measurement techniques as room-temperature radioluminescence (RL), PL measurements or thermally stimulated luminescence (TSL). Last but not least, we have shown a change in the morphology of samples with the increasing dopant concentration, especially 3D columns formation with the high level of Si-doping and its influence on the light extraction from the GaN layer. The paper shows an uncommon way of dealing with slow unwanted YB, which detriment the GaN luminescence properties.
查看更多>>摘要：? 2022 Elsevier B.V.High-performance electrode material Mn-doped Bi2O3 with a nanorod morphology is synthesized by a simple soft chemical method. Such material keeps the high stability and high ion conduction efficiency of Bi2O3, while its specific capacity is also enhanced by Mn ions doping treatment. The doping of Mn ions effectively increases the number of oxygen vacancies, modifying the local electron structure, promoting the charge transfer and ion migration of the electrode, leading to high energy density and power density. The mechanism of the electron structure and transfer property affected by Mn doping are also investigated by experimental and theoretical processes. Based on nickel foam substrate, the specific capacitance of the Mn-doped Bi2O3 electrode can reach 1295.6 F g?1 with a current density of 1 A g?1. It also has a high energy density of 149.25 Wh kg?1 and a high power density of 864 W kg?1. Furthermore, Mn-doped Bi2O3 also shows good cycle stability of metal oxide, which can maintain 100% coulomb efficiency and 98% cycle retention rate after 5000 cycles.
查看更多>>摘要：? 2022 Elsevier B.V.In the present investigation, the implication of grain size on the high-temperature hot corrosion (HTHC) response in Alloy 617 is studied. Towards this, specific thermal and thermo-mechanical processing schedules were employed to attain a wide range of grain sizes (7–70 μm), while maintaining other microstructural features like Σ3n (n ≤ 3) boundary fraction, retained strain, and precipitate fraction nearly at constant. Subsequently, these specimens were exposed to Na2SO4 + NaCl + V2O5 (75 wt% + 20 wt% + 5 wt%) salt mixture at 1273 K for 24 h. Post-corrosion analyses reveal the formation of a highly porous and thick oxide scale on the as-received (AR) specimen (~32 μm), a relatively less porous and non-uniform oxide scale on the very coarse-grained specimen (~70 μm), and a homogeneous and dense Cr-rich scale on the very fine-grained microstructure (~7 μm). Such a protective scale on the very fine-grained specimen, developed due to the enhanced diffusivity of Cr, obstructs the entry of corrodents and thereby minimizes the percolation depth (~60 μm). The percolation depth is relatively higher (~130 μm) in the very coarse-grained specimen due to the development of a porous and non-uniform oxide scale. However, its percolation depth is still lower than the AR specimen (~ 305 μm), because of the reduced grain boundary area available for the diffusion of the corrosive species into the substrate. The AR specimen has exhibited the maximum percolation depth due to the simultaneous presence of fine and coarse grains, leading to the failure of both the aforementioned resistive mechanisms i.e., the accelerated formation of a protective Cr-rich scale and lesser availability of diffusion paths for the ingression of the corrosive species.
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