查看更多>>摘要：In this work, a composite material consisting of ultrafine Fe3O4 with (ca. 15 nm) uniformly anchored in reduced graphene oxides (rGO) is synthesized and reported to be applied in anodes for lithium-ion battery. The obtained hollow Fe3O4 /rGO composites (H-Fe3O4/rGO) (827.3 mA h g(-1)) has much superior specific capacity than that of the solid Fe3O4/rGO composites (S-Fe3O4/rGO) (654.9 mA h g(-1)) after 550 cycles of the coin cell at 0.5 A g(-1). Even if the cells are tested at 1 A g(-1), H-Fe3O4/rGO displays a remarkable specific capacity of 917.4 mA h g(-1) as well as the capacity retention rate of 56.7%, compared with S-Fe3O4/rGO (573.9 mA h g(-1), the capacity retention rate of 37.7%). Such a sufficient cyclic stability and rate capability in the H-Fe3O4/rGO composite is mainly attributed to the ultrafine hollow structure for shortening Li+ diffusion path and conductive rGO beneficial to rapid electron transfer. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Bimetallic compounds can offer higher electrochemical activity and capacity than monometallic ones owing to their rich chemical valences. Herein, the performance enhancement of monometallic compounds by introducing metal ions was demonstrated, and the effects of different metal ions were investigated. Through introduction of metal ions into LDHs under a hydrothermal environment, one kind of 2D/2D hierarchical CoM-LDH(M=Fe or Mn)/MXene composites were successfully synthesized. It was found that the introduced Fe ions extremely improves the specific capacity and the introduced Mn ions extremely enhances the rate capability of monometallic composite. The fabricated CoFe-LDH/MXene (CF-MX10) electrode exhibits a specific capacity of 808 F g(-1) at current density of 0.5 A g(-1), much higher than that of CoMnLDH/MXene (CM-MX10, 562 F g(-1) ) and Co(OH)(2)/MXene (C-MX10, 270 F g(-1)). The high areal capacity or rate capacity are attributed to strong synergistic effect between CoM-LDH and MXene, as well as the introduction of metal ions that change the architecture and the electronic or ionic conductivity, which leads to much improved electrical conductivity and electrochemical stability. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：Spectral coverage and saturability within 700-1100 nm of phosphor-converted near infrared light-emitting-diodes (pc-NIR LEDs) are crucial for the practical applications in bioimaging, food quality analysis and night vision fields, while developing ultra-broadband NIR phosphors are still a challenge. Herein, we reported a broadband NIR phosphor LiInP2O7: Cr3+ in phosphate system. The emission spectrum of this phosphor covers 700-1200 nm with a full width at half maximum (FWHM) of 165 nm and an emission peak centering at 860 nm under 460 nm excitation. This broadband emission is verified to be derived from T-4(2) (g) -> (4)A(2) (g) transition of Cr3+ in a single crystal site. To further expand the emission spectrum, Cr3+ -> Yb3+ energy transfer in LiInP2O7 was designed, and an ultra-broadband emission with a FWHM of 225 nm was obtained through appropriate amount of Yb3+ codoping. The energy transfer efficiency can reach as high as 81% in this material. Furthermore, the energy transfer mechanism, quantum yield, thermal stability and fabrication performance were investigated in detail, demonstrating the ability of achieving ultra-broadband and efficient NIR emission of LiInP2O7: Cr3+, Yb3+ phosphor material. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The isothermal compression of four typical microstructures in the cogging process for Ti-6Al-4V was conducted at strain rates ranging from 0.01 to 1 s(-1) with varying temperatures. The flow behavior of dif-ferent microstructures was compared. The Hansel-Spittel (H-S) and strain compensated Arrhenius (S-C-A) constitutive equations (CEs) were calibrated. To improve prediction ability, a modified H-S CE considering the evolution of microstructure was proposed and embedded in the finite element code. The original, modified H-S, and S-C-A CEs were evaluated based on the average absolute error (W) and relative error ratio (Delta%). Compared with the original H-S and S-C-A CEs, the W (-2.5%similar to 2.5%) of the modified CE was found to be smaller and the Delta% was more concentrated. Furthermore, hot forging experiment and finite element si-mulation (FES) at different speeds were performed. The average relative error (AARE) of load-stroke for the H-S and modified H-S CEs is 13.51% and 3.67%, respectively. The comparisons between the FES and hot forging experiment indicate that the modified CE is more accurate for the simulation of the cogging process. (C) 2021 Elsevier B.V. All rights reserved.
Sheikh, Arif D.Vhanalakar, V. K.Katware, A. S.Pawar, K. K....
11页
查看更多>>摘要：Recently organic-inorganic halide perovskites like MAPbX3 (X]Br, Cl, I), are being investigated as a sub-stitute to commonly used metal oxide semiconductor-based sensors for the detection of various volatile organic compounds and toxic gases at room temperature. The present work provides detailed insights into chlorine halide incorporation on the ammonia sensing performance of the most popular MAPbI3 (MAPI) perovskite thin films. Here, we shown that the MAPbI3-xClx (MAPIC) sensor exhibits a high response of 591%, nearly13 times larger than the MAPI sensor for 10 ppm of ammonia exposure at room temperature. This work demonstrates excellent potential of MAPIC as an ultra-sensitive, stable and reversible NH3 sensor vis-a-vis MAPI sensor for early detection of NH3. The proposed sensing mechanism suggests that by en-gineering the morphology at the nanoscale and doping induced excellent charge carrier diffusion length could enhance ammonia sensor responsivity. (c) 2021 Elsevier B.V. All rights reserved
查看更多>>摘要：Transition metal sulfides are extensively studied as the watchful member of Faradic supercapacitive electrode materials because of their evidently enhanced electronic conductivity. Meanwhile, delicate development and manipulation of such novel nanostructured materials are required to achieve the desired electrochemical behaviors. Therefore, in this work a novel 3D hierarchical manganese sulfide (MS) multilayer nanoflakes grown on Ni foam are designed and fabricated through the Kirkendall effect and applied as supercapacitors electrode. An advantage of such special 3D electrode architectures and unique compositional feature is in the fact that the as-prepared MS electrode presents greatly enhanced supercapacitive performances with ultrahigh specific capacity of 1.22 C cm-2 at 1 mV s-1 and fantastic cycling properties with the capacitance retention 100% after 1000 cycles. In addition, the electrochemical reaction of the MS electrode is a diffusion-controlled Faradaic redox process, while the diffusion coefficient is about 1.3 times larger than that of the manganese oxide (MO) electrode prepared under the same condition, suggesting the higher ion mobility of the MS electrode materials. These promising electrochemical behaviors demonstrate the great potential for application in high performance supercapacitors. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Rechargeable aqueous zinc ion batteries (ZIBs) are highly desired for future energy storage due to their low cost and high safety, yet the development of suitable cathode materials for ZIBs is still a main challenge. Herein, for the first time, we demonstrate 1T-WS2 nanosheets can be a promising cathode candidate for rechargeable ZIBs. Benefiting from the large inter-layer spacing and high conductivity of 1T phase, the assynthesized WS-200 delivers reversible discharge capacities of 233.26, 206.25 and 179.99 mAh/g at the current densities of 50, 100 and 200 mA/g, respectively, while the discharge capacity of commercial WS2 is only similar to 22 mAh/g (current density: 200 mA/g). Even at a high current density of 1000 mA/g, WS2-200 still exhibits the initial discharge capacity of 85.11 mAh/g. Moreover, the zinc ion's storage mechanism was analyzed by electrochemical impedance spectra (EIS) and cyclic voltammetry (CV) measurements. On the one hand, WS2-200 with 1T phase displays the improved ion diffusion. On the other hand, the small diameter of nanosheets and expanded inter-layer spacing increases the capacitive capacity of WS2. This work lays the foundation for the research of WS2, which is expected to become one of the competitive cathode materials for zinc-ion batteries. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The semiconductor-to-metal transition (SMT) is reported in nanocomposite films of wide bandgap semiconducting oxides. This study offers insight into the existing models of temperature-dependent charge transport by tailoring the defects induced disorder into the lattice by swift heavy ions irradiation. The structural studies show the presence of both cadmium oxide and zinc oxides phases and confirm the nanocomposite nature of films. Temperature-dependent charge transport properties of the nanocomposite films were studied by carrying out four-probe resistivity measurements in the wide temperature range of 35-300 K. Here, the swift heavy ions irradiated films demonstrated the tuning of SMT phenomena and its transition temperature upon increasing fluence of irradiation. These irradiation effects are discussed in terms of irradiation-induced defects/disorders into the lattice. The change in the nature of temperaturedependent resistivity in pristine and irradiated films has been envisaged with a quantitative fit of experimental data by invoking quantum correction to conductivity (QCC). Our results are consistent with QCC model, which essentially depends on weak localization and renormalized electron-electron interactions. Thus, this work extends the validity of the weak localization model to composite systems. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A non-precious metal electrocatalyst for oxygen evolution reaction (OER) is achieved by synergistically coupling layered double hydroxides (LDH) and hybrid supports(reduced graphene oxide (rGO) and Ti3C2Tx-MXene). The NiFe LDH/Ti3C2Tx-rGO catalyst exhibits superior activity with a promising low overpotential of 235 mV at a current density of 10 mA cm(-2) in alkaline medium. The strong interfacial interaction and electronic coupling with prominent charge-transfer between the NiFe LDH and Ti3C2Tx is identified, which not only improves the conductivity and stability and of the hybrids, but also greatly accelerates the redox process of NiFe LDH for OER. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The effect of strain rate on stress-induced alpha ' phase transformation and room temperature tensile deformation flow behavior of a metastable beta-type Ti-30Zr-5Mo alloy at strain rates ranging from 3 x 10(-5) to 10(3) s(-1) was investigated. The trigger stress for alpha ' phase transformation increases from 190 to 632 MPa with the strain rate increasing from 3 x 10(-5) to 10(3) s(-1), while the transformed volume of alpha ' phase decreases at the same time. The true strain at which stress-induced alpha ' phase transformation occurs also increases from 0.01 to 0.035 with the strain rate increasing from 3 x 10(-5) to 10(3) s(-1). Ultrahigh strain hardening rate of 8.7 GPa is observed at the strain rate of 3 x 10(-5) s(-1) due to the stress-induced alpha ' phase transformation. At a high strain rate of 10(3) s(-1), the planar slip bands also form during deformation, indicating that the deformation becomes more localized with increasing strain rate. The ultimate tensile strength increases from 722 to 853 MPa with increasing the strain rate from 3 x 10(-3) s(-1) to 10(1) s(-1) without sacrificing the elongation to fracture. The improved mechanical properties are attributed to the dislocation hindering mechanism of short-range obstacles associated with the stress-induced alpha ' phase transformation during deformation, and the adiabatic temperature rise caused by the deformation. (C) 2021 Elsevier B.V. All rights reserved.
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