查看更多>>摘要：Photoelectrochemical (PEC) seawater splitting is an important strategy of green industrial hydrogen pro-duction on the basis of protecting fresh water resources. In this work, a floc-like BixFe(1-x)VO(4) @CNT heteronanostructure (HNS) was fabricated as the building blocks of PEC anode and demonstrated a highly enhanced PEC efficiency and stability in seawater. In BixFe(1-x)VO(4) @CNT HNS, amorphous Fe mixed BixFe(1-x)VO(4) nanoparticles (NPs) were served for visible-light absorption, photoelectric conversion, and especially conjunct nodes of carbon nanotubes (CNTs); while CNTs were employed as the high-speed channels for carrier transfer, suppressing electron-hole recombination and leading to a highly improved PEC efficiency. As a result, the as-fabricated floc-like photoanode achieves an applicable PEC photocurrent density of 0.1 mA/cm(2) at 1.5 V versus Ag/AgCl in seawater, which demonstrates the promising potential of the floc-like BixFe(1-x)VO(4) @CNT HNS in future photoconversion applications. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：The multicomponent alloys, also known as High Entropy Alloys (HEAs), have been the subject of intense exploration for over a decade now for a wide range of potential applications. To investigate microstructure and mechanical property correlation in a transformation-induced plasticity dual-phase high entropy alloy (DP-HEA) Fe50Mn30Co10Cr10 (at%), microstructural analysis, mechanical testing, and fractography were performed on the DP-HEA. The microstructural state of the alloy was analyzed by optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy, and electron backscatter diffraction (EBSD). The plastic deformation behavior of the alloy was assessed using uniaxial tensile tests. The digital image correlation (DIC) was used during the tensile test to evaluate the Young's modulus and localized strain values at different points in the gauge section of the tensile specimens as a function of time. An insight into the micromechanism of plastic deformation was gleaned from a stress relaxation test (SRT). The alloy consisted of similar to 12% (by area) of gamma-FCC and rest epsilon-HCP phases. The yield strength (YS), ultimate tensile strength, and elongation were 315 MPa, 755 MPa, and 62%, respectively. For this alloy, the plastic strain ratio was estimated to be similar to 0.75 using the DIC. The curve fitting of true stress/true strain curve using Ludwik's equation revealed the strain hardening exponent to be 0.76. The flow stress changed from 315 MPa at YS to similar to 1200 MPa at necking. From the DIC data, the maximum strain in uniformly deformed and necked regions were determined to be 0.44 and 0.68, respectively. The DIC data analysis revealed the Young's modulus of the alloy to be 180 GPa. The true activation volume of the alloy ranged from 300b(3) to 450b(3) and decreased with increase in flow stress. Overall, a good combination of strength, ductility, and work hardening behavior was noted in the HEA predominantly consisting of epsilon-HCP phase. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：MoS3 nanoparticles as well as MoS3 on graphene and multiwalled carbon nanotubes were synthesized by a solvothermal method and the prepared samples were employed as cathode material in zinc-ion batteries. With distinct advantages like low price, high safety, no environmental pollution, and high power, these batteries have promising properties for future generation battery systems. The microstructure and elec-trochemical properties of the prepared composite cathodes were investigated by XRD, TG, and XPS. The MoS3/MWCNTs have a discharge specific capacity of 368 mAh g-1 at the current density of 500 mA g(-1) and stable cycling performance, and the discharge specific capacity of MoS3/MWCNTs can still reach 321 mAh g-1 at the current density of 1 A g(-1). Making use of the outstanding mechanical, electrochemical and electronic properties of MWCNTs, the coated composite of MoS3 nanoparticles on MWCNTs can sig-nificantly improve the electrical conductivity of the materials, and enhance the charge-discharge capacity and high rate characteristics of MoS3 as aqueous zinc-ion cathode material. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：In this work, defect-enriched NiO film-coated nickel foam (NF@NiO) monolithic catalyst was prepared by an oxalic acid-assisting hydrothermal treatment without additional Ni sources and followed by a calcination treatment, which was then used as an ozonation monolithic catalyst for the first time. The formation mechanism and morphology control of NiO film, and the catalytic performance of NF@NiO were systematically investigated. It is found that the film was assembled by randomly NiO nanorods under the best conditions of 0.001 mol/L of H2C2O4, 7 mg/L of dissolved oxygen (DO), as well as the hydrothermal temperature of 120 degrees C for 18 h. Particularly, the coupling effect of H2C2O4 and DO on the morphology of NiO film and the properties of NF@NiO was revealed. Too low or too high DO would not result in a dense and complete NiO film and the absence of H2C2O4 only produced a film assembled by vertically-standing hexagonal NiO nanosheets with less vacancies (NiO nanosheets/NF). Due to the porous structure, rich defects of oxygen vacancies and undercoordinated Ni atoms, and the good redox ability, NF@NiO presented excellent catalytic performance for ozonation of toluene (about 95% of toluene removal efficiency for 350 min and 74.0% of mineralization efficiency, 7 times the breakthrough time of NiO nanosheets/NF). This work shed a light on the design and preparation of NiO monolithic catalysts for ozonation of VOCs. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Although Ni-rich cathode materials have made a great success in the field of electric vehicles due to their high capacity and low cost, many efforts are still focused on further increasing their capacity through increasing the Ni content. However, the increased Ni content usually leads to a more serious surface structure reconstruction and hence higher resistance during electrochemical cycling, which has become a major issue for Ni-rich cathodes. In order to explore a balance between surface structure stability and high energy density, a model Ni-rich material with transition metal ion gradient is prepared using a mechanical fusion and co-lithiation method, which is easy for large-scale fabrication. The gradient structure sample contains an inter bulk of LiNi0.90Co0.05Mn0.05O2 and a thin gradient outer layer with lower nickel content. The gradient sample shows a superior cycling property, rate retention, and improved safety performance. Systematic study suggests that the possible reasons for the improved electrochemical and mechanical performance of the gradient nickel-rich materials are the high stability of lower-Ni surface and the decreased surface tensile stress. This work provides an easy up-scaled method to build a gradient structure and a further in-depth understanding on its structure stabilization mechanisms, which are essential for developing high energy-density lithium-ion batteries. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Li3VO4/nitrogen doped carbon fibers (LVO/NCFs) were prepared via a low cost and scalable biomass-derived approach. High and gradually increasing capacitive lithium storage for the LVO/NCFs during cycling is induced by self-adaptive reaction kinetics, leading to outstanding cycle stability and superb rate performance. The LVO/NCFs exhibit discharge specific capacity of 774 mAh g(-1) at the current of 0.2 A g(-1) after 500 cycles, and 419 mAh g(-1) at 2.0 A g(-1) after 1000 cycles. Even after period rate testing from 0.2 to 3.0 A g(-1) over 250 cycles, the LVO/NCFs still revert to high capacity of 616 mAh g(-1) when the current is decreasing to 0.2 A g(-1). The low cost and scalable biomass-derived synthesis and the outstanding comprehensive lithium storage performance of the LVO/NCFs endow it with great promising for practical application. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Water pollution is a very serious problem concerning human health, and organic dyes are important pollution sources. Photocatalysts could convert light energy into chemical energy and photodegrade organic dyes. Thus, their potential use has been considered important. Herein, a copper-based heterojunction photocatalyst was developed through the hydrothermal method. In the heterojunction, two copper-based nanostructures, namely, nanodots CuWO4 and nanorods CuS, were used to form a composite, and all products with different ratios showed better performance for the photodegradation of Rhodamine B (RhB), especially at the ratio of 1:1 (CuWS), which possessed the best photocatalytic efficacy. Narrow bandgap, large specific surface area and efficiency of the separation of photoexcited electrons and holes were the essential factors for the enhanced photocatalytic activity. Based on the analysis of the active species trapping experiments and electron spin resonance spectra, the photogenerated holes and center dot O-2(-) over line were the essential active species during the photocatalytic degradation of RhB. Additionally, the sample CuWS could effectively photocatalytic degraded many other types of organic dyes under visible light and shows the great potential of application on environmental governance. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The high reaction tendency between graphene and titanium (Ti) matrix during fabrication of graphene/Ti composites aggravates the structural integrity of graphene and limits its outstanding strengthening potential. In order to solve this problem, in this study, few-layered graphene (FLG) decorated with SiC nanoparticles (SiCp@FLG) was synthesized to reinforce Ti-6Al-4V (Ti64) alloy via a powder metallurgy route. Microstructure and Vickers hardness of the developed SiCp@FLG/Ti64 composites were studied systematically. Results showed that the SiCp decoration changed the morphology of FLG/Ti interface from continuous TiC reaction layer to discontinuous TiC nanoparticles during hot-press sintering. This discontinuous interface not only kept the integrity of FLG by suppressing its reaction with Ti matrix but also led to direct bonding between FLG and Ti. This designing strategy of protecting the reinforcement by secondary particle decoration can be potentially applied to the development of high-performance metal matrix composites. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The targeted research of equiaxed alpha particles and lamellar alpha colonies in duplex microstructure of Ti60 alloy was conducted to more reveal the related mechanisms. For this purpose, in-situ tensile test, the electron probe microanalysis (EPMA), microhardness test, electron backscatter diffraction (EBSD), and Transmission Electron Microscopy (TEM) technologies were used to carry out relevant research in this work. The in-situ tensile result shows that the slip line preferentially occurs in the equiaxed alpha particle. Prism slip of the (10 (1) over bar0) plane and [1 (2) over bar 10] direction is the most activated slip system in the equiaxed alpha particle according to the calculation result of the movement slip system. Single slip was operated in individual equiaxed alpha particle, as the stress concentration at the grain boundary increases, multiple slips could be activated in the adjacent equiaxed alpha particle while the slip line was hardly found in colonies. With the deformation amount increases, pyramidal slip mode with high critical resolved shear stress (CRSS) in lamellar alpha had to be activated to accommodate the deformation. It is concluded from the in-situ tensile observation and EBSD analysis that the lamellar microstructure contributes less to the deformation at room temperature which is attributed to the large size of colonies and limited range of slip systems. Cracks nucleate mainly at the grain boundary of the equiaxed alpha particle and the colony since the existence of non-deformation area. TEM analysis shows that the dislocation networks were pinning by the silicide at the grain boundary of the equiaxed alpha particle, thus induces the stress concentration and promotes the crack nucleation. In addition, the blocking effect of the alpha(2)-Ti3Al particles on the dislocation was also found, indicating that the microcrack could nucleate within the equiaxed alpha particle. On this basis, two diverse crack initial modes of intergranular fracture at the grain boundary and transgranular with in the equiaxed alpha particle fracture were proposed. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：SnO2 has become one of the hot materials for research at this stage due to the advantages of simple preparation, low cost and stable properties. In this study, SnO2/SiO2 nanocomposites were prepared by the sol-gel method. The structure, properties and morphology of the SnO2 nanoparticles were determined by HRTEM, SEM, XPS FTIR and XRD characterization. Compared with the pure SnO2 material, the SnO2/SiO2 composite has superior gas sensing properties to triethylamine. The test results demonstrate that the optimal temperature of the SnO2/SiO2 sensor is 280 degrees C, which is 45 degrees C lower than before doping. At 280 degrees C, the sensitivity to 100 ppm triethylamine was 18, which was 2.4 times higher than that before doping. The SnO2/SiO2 sensor can detect triethylamine with a minimum concentration of 500 ppb. In addition, the gas-sensitive mechanism of SnO2/SiO2 to triethylamine was illustrated. (C) 2021 Elsevier B.V. All rights reserved.
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