查看更多>>摘要：Cobalt hexacyanoferrate (CoHCF) as a promising cathode material of asymmetrical supercapacitors gen-erally undergoes a single redox reaction of Fe(II)/Fe(III) couple to store energy in neutral aqueous elec-trolytes. Its framework Co ions are electrochemically inactivated, leading to a limited electrochemical capacity. Herein, we develop a strategy to activate the reversible Co(II)/Co(III) redox reaction through tuning the microenvironment of Co ions. A carbon nanodots/CoHCF (C-dots/CoHCF) hybrid nanostructure has been successfully fabricated via a simple co-precipitation reaction of Co2+ and [Fe(CN)(6)](3-) ions in the presence of carboxylate-rich C-dots. Impressively, electrochemical results and X-Ray photoelectron spectroscopy (XPS) reveal the charge storage of C-dots/CoHCFs due to two-specie (Fe and Co) redox reactions, which render an enhanced electrochemical capacity. It is considered that the activation of reversible Co(II)/Co(III) redox reaction is due to the strong coordination interaction between the terminated framework Co ions and carboxylate groups of C-dots. In addition, this nanostructure offers increased active sites and promotes electron conductivity, thereby achieving a remarkable high specific capacitance (394 F g(-1) at 1 A g(-1)) and excellent rate performance. The C-dots/CoHCF cathode is paired with an activated carbon anode to assemble an aqueous asymmetrical supercapacitor, which can deliver a high energy density of 48.6 Wh kg(-1) (488 W kg(-1)) and retain 88.3% of its initial capacitance over 5000 charge/discharge cycles. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：AA1050 metal matrix composites (MMCs) reinforced by Al0.5CoCrFeNi high-entropy alloy particles (HEAp) were prepared by stir casting and subsequent rolling (room temperature rolling (RTR) and cryorolling (CR)). The mechanical properties and microstructures of the AA1050-HEAp MMCs were studied. By adding 3 wt% HEAp, the ultimate tensile strength of the stir-casted AA1050-HEAp MMCs increased by 74.3% compared with AA1050. After rolling, the mechanical properties of the CR AA1050-HEAp MMCs were better than those obtained by RTR. The differences of the mechanical properties of the AA1050-HEAp MMCs obtained by CR and RTR increased with a higher rolling deformation and a lower mass fraction of HEAp. After RTR, there were various voids in AA1050-HEAp MMCs, which were not observed in CR MMCs through both scanning electron microscopy and transmission electron microscopy. Finally, the effect of cryogenic temperature on microviods and mechanical properties of MMCs were discussed. (C) 2021 Elsevier B.V. All rights reserved.
Bin Humam, SamiGyawali, GobindaKim, Tae HoLee, Soo Wohn...
11页
查看更多>>摘要：This study investigated the effects of two different carbide ceramic particles (WC and TaC), which were co deposited separately, on the microstructure of the Ni-W alloy. Besides, this work also tried to show an overview of the structural model and address the probability distribution of atoms in Ni-W alloy system, WC, and TaC particles based on obtained results and theoretical conception. Furthermore, the coating properties have been examined using different tools such as XRD, EDS, TEM, SEM, and surface roughness tests to analyze the microstructure and surface properties of the composite coatings. The obtained results revealed that incorporating WC into the matrix induced the porosity in the coating. On the contrary, the inclusion of TaC particles on the Ni-W microstructure promoted the coating strength and improved the scratch resistance behaviors against both lower (0-50 N) and the higher (50-120 N) load ranges. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A new Bi2WO6/BiOI/Ag heterojunction composite was fabricated by the deposition of Ag nanoparticles on Bi2WO6/BiOI via two-step hydrothermal process and characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron micro-scope (SEM) and high resolution transmission electron microscope (HRTEM) analyses. The photoelectric properties of the as-prepared composites were investigated by UV-vis diffuse reflectance spectrum (DRS), transient photocurrent response, electrochemical impedance spectroscopy (EIS) and photoluminescence spectrum (PLS). It was found that the amount of Ag in Bi2WO6/BiOI/Ag exhibited an evident influence on photoelectric properties and photocatalytic activity. Compared with the other as-prepared photocatalysts, Bi2WO6/BiOI/Ag-8 presented the highest photocatalytic activity for tetracycline degradation ascribed to the heterojunction structure and the surface plasmon resonance (SPR) action, which evidently enhanced the visible-light absorbance, and promoted the separation/transfer of photo-generated electron/hole (e(-)/h(+)) pairs. The organic intermediates formed during tetracycline photocatalytic degradation were identified and the degradation pathway was proposed. For the recommended photocatalyst, the hydroxyl radical ((OH)-O-center dot) and superoxide anion radical (O-center dot(2)-) produced by the Z-scheme photocatalytic mechanism with Ag as co-catalyst were responsible for the degradation. In addition, the photocatalytic degradation of tetracycline evidently reduced the solution toxicity and enhanced the biodegradability. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The electrodeposition of lithium on heterogeneous substrates is often loose and uneven owing to the lithiophobic nature of most substrates, which causes deterioration of cell performance and ultimately cell failure. In this paper, a simple high current density induced uniform nucleation of Li on Cu substrate is presented to solve this problem. The as-obtained Li seeds with small and uniform size fully cover the surface of Cu, which is conducive to dense and even electrodeposition of Li afterwards. The LiF-rich solid electrolyte interface generated by the high current density on the Li seeds also helps to inhibit the formation of dendritic lithium. The pouch cell employing this strategy demonstrates remarkable improvement in cycling stability. (c) 2021 Elsevier B.V. All rights reserved.
Ye, ZhengweiWang, KejunLi, XiaoqiongYang, Jianjian...
8页
查看更多>>摘要：Ferrite/carbon aerogel composites have been fabricated via vacuum impregnation and coprecipitation of iron ions. The resultant Fe3O4/carbon aerogels possess high specific surface area, electronic conductive interconnected network and uniformly dispersed magnetic nanoparticles, showing an excellent electromagnetic wave absorption performance, which can be tactfully regulated by the pyrolysis temperature and incorporated Fe3O4 content. The minimum reflection loss of -57 dB is achieved with a filler loading of 10 wt%, and the effective absorption bandwidth can cover 5.2 GHz with a thickness of 1.8 mm. Furthermore, the electromagnetic energy dissipation mechanism has been discussed to provide a new route for preparing electromagnetic wave absorption materials. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, thermoelectric properties of the nanocomposite materials produced via ball milling followed by spark plasma sintering from In0.2Yb0.2Co4Sb12 double filled skutterudite (SKT) with silicon and tungsten carbide inclusions are investigated. The nanocomposites with low volume ratios of beta-SiC and '-WC have a significantly increased power factor, while the lattice thermal conductivity is lowered only for beta-SiC composites. The power factor enhancement in '-WC/SKT composite compensates the increase of its thermal conductivity, and as a consequence, the maximum value of the figure of merit, 0.97, is attained for 0.33 v% 'WC at 450 degrees C, with 15% higher than that of the simple skutterudite sample. (c) 2021 Elsevier B.V. All rights reserved.
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