查看更多>>摘要：? 2022 Elsevier B.V.Designing highly efficient photocatalysts for the degradation of overused levofloxacin (LEV) antibiotics is an important and challenging task. Herein, novel atom-level heterojunction 2D MoSSe nanoplates (MSS) with various S:Se molar ratios were obtained by hydrothermal synthesis. XRD studies indicated lattice constants of these MSS catalysts were intermediate between the values for MoS2 and MoSe2, and their internal lattice distortion energy increased due to the interaction between the two types of lattice structures. Further analysis revealed the appearance of the internal electric fields in MSS catalysts, which appeared as the centers of the positive charge and the negative charge did not coincide. Due to the internal electric field, MSS catalysts had lower internal resistances, which were conducive to the transmission of internal carriers, and eventually enhanced the photoelectrochemical activity. The photocatalytic LEV degradation rate (k) of the MSS1 was 7.5 and 8.1 times superior to that of MoS2 and MoSe2, respectively. The photocurrent densities of MSS1 and MSS4 were 3.5 and 18.2 times higher than that of MoS2. In addition, the conduction band position of MSS1 shifted to the higher than O2/?O2? and that of MoS2, which could generate ?O2? for LEV degradation. Moreover, Electron Spin Resonance (ESR) analysis further revealed that the main active species in photocatalytic LEV degradation were photo-generated ?O2– and ?OH that generated from the transformation of the ?O2?. Finally, a possible photocatalytic mechanism for LEV degradation was proposed. These results confirm the advantage of the developed ternary compound.
查看更多>>摘要：? 2022 Elsevier B.V.Dielectric ceramic materials with high energy-storage density and excellent charge-discharge performance are desirable for use in dielectric capacitors. In this study, (Na0.5Bi0.5)0.75Sr0.25TiO3–xNb2O5 (denoted as NBSTNx) lead-free ceramics were prepared by a solid-state reaction method. Polarization-electric field hysteresis loops (P–E loops) reflected the energy storage characteristics of the NBSTNx ceramics. Introducing Nb into a pure NBST ceramic can reduce the large remnant polarization (Pr) and make the P–E loops slimmer. Through repeated trials and calculations, the maximum recoverable energy-storage density (Wrec ~ 3.25 J/cm3) and energy storage efficiency (η ~ 74.5%) were achieved for the NBSTN0.03 ceramic at 140 kV/cm. We also tested the stability performance of the NBSTNx ceramics, where the NBSTN0.03 ceramic exhibited the highest thermal stability (30–100 °C) and frequency stability (10–1000 Hz). The NBSTN0.03 ceramic also had a fast discharge rate (<300 ns) and a good discharge energy-storage density (Wd ~ 1.80 J/cm3). Therefore, the NBSTN0.03 ceramic with a good energy-storage density and charge-discharge performance has excellent application prospects for practical dielectric capacitors.
查看更多>>摘要：? 2022 Elsevier B.V.In the present study, a novel method for manufacturing functionally graded metal matrix composites (FGMMC) is introduced. This method is a cutting-edge combined plastic deformation process of accumulative roll bonding (ARB) and cold roll bonding (CRB) and was used to fabricate Al/Cu functionally graded composites. Several laminated composites with different content of Cu were first fabricated by the ARB process, then they were bonded by the CRB process as the volume fraction of Cu varies from the Al side to the Cu side. With an increase in Cu content, the hardness of layers rose. Furthermore, the SEM images showed the continuous changes of Cu content from the Al side to the Cu side of the composites. In addition, based on the results of the tensile test, since Cu layers act as reinforcements in the Al matrix, the strengths gradually grew with the progressive increase in the volume fractions of Cu.
查看更多>>摘要：? 2022 Elsevier B.V.With the development of wearable electronic devices towards flexibility, safety, and functionality, supercapacitors are required to simultaneously possess satisfactory energy density and flexibility. Although the environmental friendliness, high theoretical capacity and tunable structure of CuS, the instability of their corresponding compounds on the flexible substrate as well as its poor conductivity limit its development. To address these issues, a pea-like hollow CuS nanoparticle structure is fabricated on the surface of carbon fiber with Cu plating, and a novel kind of flexible electrode named CPCC@CuO@CuS-H is synthesized. The inner copper plating of the electrode brings good electronic conductivity, and the hollow structure effectively improves the charge diffusion ability. CPCC@CuO@CuS-H has ultra-high mass specific capacity of 1387.1 F g?1 in an electrolyte of 2.0 M KOH solution under 2 A g?1. Moreover, the construction of disulfide bond in electrode can effectively improve the stability of hollow structure. The electrode has satisfactory rate performance and long cycle life at an ultra-high current density of 20 A g?1. Especially, by assembling a flexible all-solid-state supercapacitor (CPCC@CuO@CuS-H//CC@AC), the operating voltage closes to 1.8 V, and the energy density achieves the aim of 139.5 Wh kg?1 when the high-power density is located at 1800 W kg?1, with 82.9% electric capacity retaining after 10000 cycles, showing its promising potential in flexible devices.
查看更多>>摘要：? 2022 Elsevier B.V.The relaxor properties and energy storage performance of Bi4Ti3O12, PbBi4Ti4O15, Pb2Bi4Ti5O18 and Pb3Bi4Ti6O21 films containing 3, 4, 5 and 6 perovskite-like layers respectively were investigated. The temperature of maximum dielectric constant gradually decreases and phase transition peaks become more and more diffuse as the number of perovskite-like layers increases. The size of domains is reduced from micrometers to tens of nanometers and the boundaries between domains gradually become blurred, which makes the current peak caused by domain inversion gradually diffuse and move towards the center. These changes indicate a gradual increase in relaxor properties. The response of these changes on polarization hysteresis loops under same external electric field is that the hysteresis behavior of polarization becomes weaker and weaker. And the optimal recoverable energy densities of them are 6.8, 18.5, 30.5 and 37.2 J/cm3 with the efficiency of 23%, 60.1%, 72.6% and 76.9%, respectively, under the maximum external electric field of 1000, 1167, 1625 and 2455 kV/cm.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, we prepared (NiCoFe)86.5(AlTi)12(WMoV)1.5 HEA with excellent mechanical properties and tribological properties by vacuum arc melting technology. The results show that the fracture mechanism of the alloy at ambient temperature was ductile fracture, while at high temperature was cleavage fracture. The wear mechanisms of the alloy include abrasive wear and oxidative wear, delamination wear and adhesive wear. The alloy has the excellent tribology property and a good combination of strength and ductility. This enhancement is attributed to the alloy having a relatively high-volume fraction of nano-L12 precipitates, which can effectively hinder the movement of dislocations. The precipitates are highly coherent with the matrix, which can effectively reduce the mismatch degree and the distortion energy of HEA, so the stress concentration problem between the precipitates and the matrix is effectively avoided, thereby improving the strength and wear performance of the alloy. The existence of annealing twins can play a role in grain refinement. During plastic deformation, the dislocation movement can be effectively hindered, and the occurrence of work hardening phenomenon can be delayed to a certain extent, so that the plastic deformation can continue, and play a key role in the wear performance of the alloy. In addition, we found that the oxide film formed on the worn surface of the alloy is more brittle at low temperatures. When the temperature reaches 773 K, a tougher oxide enamel layer was formed on the worn surface, which greatly improves the wear performance of the alloy at high temperatures.
查看更多>>摘要：? 2022 Elsevier B.V.Microstructure and texture development of Al–Cu–Mg alloy with a high Cu/Mg ratio were investigated during homogenisation and hot rolling by using OM, SEM, DSC, XRD and TEM. The results showed that the Brass texture intensity increased by 2.4 times after hot rolling (90% rolling reduction), when the proportion of the second-phase particles in an area fraction and average particle size decreased from 1.32% to 0.24% and from 7.49 to 5.71 μm before hot rolling, respectively. Large particles inhibited the activation of the {111}< 110 > slip system, which led to a decrease in texture intensity. When the reduction increased, the following activated slip systems and located area of slip traces were obtained: {111}< 110 > (at grain boundaries, 35% rolling reduction), {111} + {100}< 110 > (at local area of grains, 65% rolling reduction), and {111} + {110}< 110 > (in most grains, 90% rolling reduction). In addition, the amount of the slip system corresponding slip planes increased as the spacing of the slip traces per 200 nm gradually decreased, which helped enhance the intensities of Brass- and Copper-type textures.
查看更多>>摘要：? 2022 Elsevier B.V.To expand the application range of electromagnetic interference (EMI) shielding materials, it has become an urgent issue to achieve the excellent shielding effectiveness (SE) in extreme environment. In this paper, an ultralight, compressible and superhydrophobic foam composed of melamine foam (MF), Ti3C2Tx MXene and polydimethylsiloxane (PDMS) was constructed via the facile dipping and vacuum-assisted impregnation method. The MF as a skeleton can provide coated substrate for MXene sheets to realize the 3D conductive network. Meanwhile, the PDMS layer of MF/MXene/PDMS (MFMP) foam can enhance the stability and durability of its structure and capability. The obtained MFMP foam possesses the very low reduction (less than 10%) of compressive stress at a high strain of 60% after 200th compression cycles. More importantly, the MFMP foam also shows an ultrahigh absolute SE of 29088 dB cm2 g?1 due to its excellent SE of 44.66 dB and ultralow density of 9.22 mg cm?3. The retention rate of SE can be maintained over 85% under the different treatment of serve environment. This strategy offers a promising idea to construct the ultralight porous materials for highly efficient EMI shielding applications in damping and high humidity environment.
查看更多>>摘要：? 2022 Elsevier B.V.Green phosphor has become increasingly an attractive focus owing to its multifunctional applications in illumination, display, anti-counterfeiting, and even bio-labeling. In this paper, trivalent terbium (Tb3+)-activated Ba3(ZnB5O10)PO4 (BZBP) green phosphors were synthesized at 1050 K for 1 h via a microwave-assisted sintering route. The structural study, influence of dopant Tb3+ content and working temperature on photoluminescence behavior, and colorimetric properties were performed comprehensively. Tb3+ successfully substitutes Ba2+ in the BZBP lattice. Under 378 nm near-ultraviolet (NUV) excitation, the emission bands peak at 488, 542, 585, and 623 nm, corresponding to the 5D4→7F6, 5D4→7F5, 5D4→7F4, and 5D4→7F3 transitions of Tb3+, respectively. Despite the working temperature increases, the title phosphor maintains the high emission intensity and low chromaticity shifting, exhibiting robust thermostability and color stability. This work provides a simple and rapid synthesis method for borophosphate-based phosphor. The application of NUV-excited white light-emitting diodes fabricated with the title product and commercial phosphors (red, blue) indicates that the developed green phosphor BZBP:Tb3+ is a promising candidate material in illumination and display applications.
查看更多>>摘要：? 2022 Elsevier B.V.Ferromagnetic Weyl semimetal Co3Sn2S2 has recently attracted a lot of interest on account of its large non-saturating magnetoresistance and the high carrier mobility common to topological semimetals. Moreover, the material also provides a platform for studying the interplay between the intrinsic magnetism and topological band structures, which generates a significant anomalous Hall effect. Chemical doping is the usual approach to adjust materials’ properties, and it can lead to fascinating results. Here, we present the influence of Fe-doping on the magnetic and transport properties of polycrystalline Co3Sn2S2. The Fe-doping suppresses the sample's magnetic order, increases the electrical resistivity, results in a skew-scattering contribution to the anomalous Hall effect and Fe impurities cause the Kondo effect. In addition, we report on the impact of Fe-doping on the magnetoresistance of Co3Sn2S2, where Fe-doping leads to a dramatic decline in magnetoresistance. Furthermore, the hysteresis behavior in the low magnetic field region, detected previously in nanoflake samples only, is observed in both pure and Fe-doped Co3Sn2S2 bulk samples. Our findings serve as a reference and source of inspiration for future chemical doping research on topological semimetals.
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