查看更多>>摘要：Nickel and cobalt phosphates as a kind of low-cost inorganic materials are promising electroactive mate-rials. The structure stability and good dispersibility of micro-spherical materials make them popular in the energy storage field. Therefore, the fabrications of Ni-Co phosphate microspheres with some facile and cost-effective methods have attracted lots of attentions. In this work, we present one-step growth of Ni2Co (PO4)(2 )microspheres using urea as pH regulator. Urea decomposes into NH3 and CO2 during the hydro-thermal reaction process, resulting in the precipitation of Ni-Co phosphates. The as-prepared Ni2Co (PO4)(2) microspheres exhibit uniform and well-dispersed spherical morphology. Compared with traditional Ni2Co (PO4)(2 & nbsp;) particles, Ni2Co (PO4)(2) microspheres exhibit larger electrochemical specific surface area and smaller resistance of electrons/ions transfer. The specific capacity of Ni2Co (PO4)(2 & nbsp;) microspheres reaches as high as 153 mAh g(-1 )at a current density of 1 A g(-1), which is 1.59 times higher than that of traditional Ni2Co (PO4)(2) particles. In addition, this facile one-step synthetic method can be applied to fabricate series of Ni-Co phosphates with different Ni/Co atomic ratios. This work provides a facile synthetic method of fabricating Ni-Co phosphate materials, which has potential applications in large-scale manufacture. (C)& nbsp;& nbsp;2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Developing highly efficient strategy for fabrication of bifunctional electrocatalysts for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) is a challenging topic. In this work, we reported the in situ synthesis of N, S co-doped carbon nanorod material (N/S-C) by the facile template-free, one-step pyrolysis approach using N and S co-containing poly(ionic liquid) (PIL) of p[BZ][HSO4](2) as precursor derived from the simple chemically oxidative polymerization of ionic liquid benzidine sulfate ([BZ][HSO4](2)) in the presence of ammonium persulfate as oxidant. The N/S-C catalysts have nanorod morphology with hierarchical porous architectures of abundant micropores and well-defined mesopores featuring high specific surface areas. The ORR performance of N/S-C-800 is extremely satisfactory in alkaline media with the onset and half-potentials of 0.985 V and 0.857 V (vs. RHE), respectively, which are comparable to that of commercial Pt/C (0.990 V and 0.852 V vs. RHE). It also delivers the favorable long-term stability and methanol tolerance, significantly outperforming commercial Pt/C. Moreover, the N/S-C-800 was served as a support for Pt nanoparticles, showing the higher methanol electrooxidation activity (806.74 mA mg(Pt)(-1)) compared with commercial Pt/C (356.32 mA mg(Pt)(-1)). These results show an effective route to design the attractive metal-free carbon-based electrocatalysts for direct methanol fuel cells. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The molybdenum disulfide (MoS2) and ZnO composite system have reported as micro-nano photonic crystals in integrated optics. Based on interface engineering, their tunable nonlinear absorption (NLA) and photoelectric characteristics offer a flexible design strategies for saturation absorber and optical limiters. Nevertheless, the mechanism leading to the tunable NLA behavior has not been clearly elucidated, which were attribute to complex charge transfers and carrier regulation characteristics. In this article, MoS2/ZnO heterostructures with excellent nonlinear properties composed of ZnO nanorods (NRs) wrapped with MoS2 nanosheets were prepared by magnetron sputtering (MS) synthesis of MoS2 on highly stacked ZnO NRs. The MoS2/ZnO heterostructures exhibit an interesting brush-like morphology with abundant heterointerfaces base on optimizing sputtering time and temperature, which was beneficial to provide efficient charge transfer pathways. Due to the uneven distribution of the lowest nucleation free energy, MoS2 nanosheets possess a hybrid mode of parallel (C//) and perpendicular orientations (C) on surface of ZnO NRs, which tends to form the bending and vertical growth of layered MoS2 nanosheets. From electron-photon coupling effect, MoS2 nanosheets, ZnO NRs and MoS2/ZnO heterostructures possess favorable saturation absorption (SA), reverse saturation absorption (RSA) and coexisting absorption behavior, respectively. In addition, a changeover from RSA to SA could be realized in MoS2/ZnO heterostructures by increasing the sputtering time. The NLA coefficient of MoS2/ZnO heterostructures are in the order of 10-10 cm/W, which are about 2 times larger than those of the ZnO NRs. Thus, the MoS2/ZnO heterostructures with excellent NLA properties will be promising candidates in optoelectronic devices.(C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Electrochemical deposition of rhenium-iron alloy from water-in-salt electrolytes containing a super-high concentration of lithium chloride is investigated. Different techniques, including cyclic voltammetry, chronoamperometry, X-ray fluorescence, scanning electron microscope, X-Ray diffraction, and electrical measurements at cryogenic temperature are used to characterize the alloy electrochemical system and the deposited films. The catalytic effect of iron on rhenium deposition is observed, where the deposition rate of rhenium significantly increases in the presence of iron. Alloying rhenium with iron significantly inhibits the recrystallization of the as-deposited amorphous films. At the same time, it also greatly suppresses the superconductivity of rhenium.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The anchor of functional materials on metal-organic frameworks (MOFs) nanosheets to precisely construct fascinated heterostructures for electrocatalysis is highly promising but challenging owing to the different interfacial thermodynamics and nucleation kinetics. In this work, we design and synthesize ultrafine metal oxides nanoparticles (NPs) homogenously distributed on cobalt-based MOF (Co-MOF) nanosheets for oxygen evolution reaction (OER) by a facile solvothermal reaction and subsequent partially controlled pyrolysis. The ultrafine Co3O4 NPs with a particle size of about 1.5 nm can be obtained from the dispersed elemental Co in Co-MOF and uniformly generated on the surface of the MOF, which is crucial for the for-mation of the unique heterostructure. The well-designed Co-MOF-350 exhibits an efficient electrocatalytic activity with a low overpotential of 239 mV at a current density of 10 mA cm(-2) and a small Tafel slope of 63 mV dec(-1), and an outstanding catalytic stability for OER, much superior to the pure Co-MOF and Co3O4 electrocatalyst. The intriguing OER performance mainly originates from the desirable combination of the abundant active sites, the extended electron transport channel between ultrafine metal oxides and Co-MOF nanosheets. More importantly, the work will help to design novel heteroarchitectured MOFs-based composites as efficient and robust electrocatalysts for practical applications. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In the present work, effect of heat treatment on microstructure and corrosion behaviour of a high Mo containing alpha + beta titanium alloy (Ti-6Al-1 V-4Mo-0.1Si) has been investigated. Heat treatment results in the formation of wide variety of microstructure depending on the heating temperature (below or above the beta transus) and cooling conditions. Martensite was observed after oil quenching (OQ), Widmanstatten alpha (alpha(WS)) + beta after air cooling (AC) and lamellar alpha (alpha(L)) + beta after furnace cooling (FC). The corrosion behaviour of the heat-treated specimens were studied in simulated body fluid (SBF) at 37 & nbsp;C using open circuit potential time (OCP), electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarization tests. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical nature of the corroded surfaces. The study revealed that, in general, OQed samples had increased corrosion resistance than the ACed and FCed samples. XPS confirmed the presence of TiO2 and Al2O3 on the corroded sample. The alloy's improved corrosion resistance was attributed to stable inert TiO2 film. Samples heat treated at 950 & nbsp;C were found to have better corrosion resistance in general.(C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The flow behavior and dynamic transformation of near beta TC17 alloy with a bimodal structure were investigated by hot compression with the high strain rate range from 1 s-1 to 20 s-1 and in the temperature range from 840 degrees C to 900 degrees C in this study. The most evident discontinuous yielding and post strain hardening occur at 840 degrees C-20 s(-1 )due to its high alpha p volume fraction before compression and the subsequent strong work hardening effect. High strain rate can slightly promote dynamic transformation when alloy is compressed at 840 degrees C and 870 degrees C due to domination of the high flow stress and temperature raising. However, more dramatic dynamic transformation is obtained for 1 s(-1) at 900 degrees C because the deformation heating at higher temperature/lower strain rate is less evident, and the deformation time thus maters more greatly on the phase transformation. The fine alpha s shows an obvious phase transformation priority than the coarse alpha p under all conditions due to the enhanced alloy element (Al) diffusivity resulting from enlarged alpha/beta interface and higher dislocation (diffusion channel) density around it. The alpha p promotes the dynamic re crystallization of beta phase while this effect becomes weaker when dynamic transformation is progressed greatly, mainly due to the inevitable stored energy consumption and reduced alpha p volume fraction caused by phase transformation. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The Zn3V3O8@N-graphene (ZnVO@NG) hybrid was successfully prepared by hydrothermal method as anode material for lithium-ion batteries (LIBs). The introduced N-graphene (NG) was used as a conductive carbonaceous matrix for encapsulating Zn3V3O8 (ZnVO) flowers due to good mechanical properties. The ZnVO@NG electrode has better rate performance and higher cyclic stability than most ZnxVyOz-based anode reported before. The reversible discharge capacity of the composite maintains 601 mAh g(-l) after 1200 cycles at the rate of 4 A g(-1). The enhanced performance owes to the fast lithium ion/electron transport kinetics, highly surface-controlled pseudocapacitive behavior, and improved interfacial storage of the composite. The density functional theory (DFT) calculations have demonstrated that the interfaces between the ZnVO and graphene sheets provide active sites for the adsorption of Li+ ions. In addition, charges redistribution occurring at the interface of the composite confirms the built-in electric field, which could accelerate Li+/electron diffusion. (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：At present, passivated emitter and rear cell (PERC) solar cells dominate the photovoltaic industry. However, light and elevated temperature-induced degradation (LeTID) is an important issue responsible for the reduction of PERC efficiency, which may lead to up to 16% relative performance losses in multicrystalline silicon solar cells, and this degradation occurs in almost all types of silicon wafers. Even in next-generation silicon solar cells like Tunnelling oxide passivated contact (TOPCon) and Heterojunction with Intrinsic Thinlayer (HJT) solar cells, LeTID can still cause an efficiency loss up to 1% relative. LeTID is a long process in terms of time during the whole cycle of degradation and regeneration, which will seriously affect the conversion efficiency and stability of solar modules, and hence increase the cost of electricity generated by solar cells. Furthermore, after years of research on LeTID, researchers are yet to determine the specific cause of LeTID. In this paper, we refer to specific literature, briefly describe the development history of LeTID, introduce the phenomena of LeTID in crystalline silicon solar cells, and describe its characteristics. In addition, we also analyzed the fundamental causes of LeTID, and found that the cause may be related to metal impurities or hydrogen contained in solar cells. At present, in view of the participation of hydrogen in LeTID and other existing related theories, this paper introduces several methods to inhibit LeTID in crystalline silicon. Finally, the content of this paper is summarized, and the development of solar cells in the future is prospected.
查看更多>>摘要：In this work, a gas atomized feedstock was used to fabricate an AlCoCrFeNi HEA coating using the high-velocity oxygen fuel (HVOF) process. The coating's resistance to room temperature surface degradation was evaluated using dry sliding wear and seawater corrosion testing. The coating retained the feedstock phase structure with negligible in-flight oxidation and was composed of a majority BCC phase with a minor B2 phase, resulting in a high micro-and nano-hardness of ~7 GPa. These observed phase compositions were consistent with thermodynamically calculated phase predictions using a CALPHAD model. Microstructure-mechanical property mapping revealed uniform microstructural characteristics. However, the multiscale wear resistance of the coating was critically affected by the presence of the hard BCC/B2 phase composition, which led to severe brittleness. Combinatorial assessment of the worn surface, wear debris and counter body indicated that wear was dictated by a combination of abrasive, surface fatigue, tribo-oxidation and adhesive wear. In addition, the coating exhibited superior general corrosion resistance compared with conventional SS316L, but the selective dissolution of the B2 phase preceded poor localized corrosion re-sistance, ultimately leading to pitting corrosion.(c) 2022 Published by Elsevier B.V.
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