查看更多>>摘要：Carbonaceous anode materials have been considered as a competitive candidate for the advanced potassium ion batteries (PIBs) owing to their high conductivity, low cost, relatively high theoretical capacity and stability. However, the poor ion transfer kinetics and undesired discharge capacity always limited their practical application. Herein, we reported the highly porous carbon nanofibers (HP-CNFs) prepared by using a facile electrospinning method for efficient K-storage. Due to its highly porous morphology, enlarged interlayer distance, N-doping, and abundant active sites, HP-CNFs can realize the rapid and reversible insertion/deinsertion of large-size K ions. HP-CNFs display reversible capacity of 311.7 mAh g?1 as an anode of PIBs even after 1000 cycles. This excellent electrochemical performance proves the feasibility of using HP-CNFs as a promising anode material for advanced PIBs.
查看更多>>摘要：During the designing stage of the laser powder bed fusion (LPBF) process for the production from a new material system, the operating variables form a large experimental parametric space. An efficient method to find the optimal parametric window of the variables is needed to enhance the essential advantage of the additive manufacturing technology – rapid prototyping. This article presents a simple analytical method to generate an optimal parametric window by estimating the melt pool dimension during the process of LPBF. By treating the well-studied INCONEL? 718 as a new system, the phase diagram, thermodynamic and thermophysical properties of the material were derived from the information available to the general public. Based on these data, a 4 × 4 parametric matrix was designed for a laser with focal diameter of 0.085 mm and 16 samples were built. The metallographic examinations of these as-built samples were performed to study the melt pool dimensions and microstructures of the samples. From the initial assessments on the structural quality of the as-built samples manufactured by the parametric matrix, it is proposed that the laser energy ranging from 45 mJ to 60 mJ, or the linear energy density from 0.53 J/mm to 0.71 J/mm, on an 85 μm × 85 μm area was the optimal operating window. From the study, it was concluded that the results of analytical calculations on the INCONEL? 718 material system agreed reasonably well with the experimental findings and the method can be applied to other new material systems to establish the optimal parametric window.
查看更多>>摘要：In the paper, the preparation process for high-entropy alloy coatings in the field of electroless plating was explored. According to the method for designable alloy coatings, Al-induced electroless plating was used to create multilayer coatings. The thermal diffusion process was used to alloy the multilayer coatings. Therefore, multilayer coatings as a predesigned basic material for alloy coatings needed to be discussed first. Then, the alloying process of high-entropy alloy coatings was primarily investigated. In this paper, the CuCoNi alloy coating was the main object of research. The alloying process was characterised and analysed by scanning electron microscopy and X-ray diffraction. The corrosion resistance of the coating was measured by electrochemical tests. The results show that the element distribution and the phase peaks of the multilayer coatings gradually became homogeneous and stable during thermal diffusion. The alloying process was confirmed by these changes in morphology and structure. Alloy coatings were created with controlled element types and element proportions in electroless plating. The element types of the coatings can be controlled by the deposition composition, and the element proportions can be controlled by the deposition thickness. The corrosion resistance of the alloy coating was better than that of the single-element coating. At 6 h of thermal diffusion (which is the optimum diffusion time for the CuCoNi alloy coating), the corrosion potential was ? 0.218 V, and the corrosion current density was 2.72 μA/cm2. Based on the preparation process results, the design methods for high-entropy alloy coatings were proposed.
查看更多>>摘要：The new nanosheet/nanorod structured of Ag–HAp/Bi2O3 plasmonic photocatalyst synthesized by in–situ sol-gel method was shown the high efficient degradation of dangerous phenolic contaminated aqueous media. It can be highlighted as the main novelty and significance of the work that morphological and structural studies shown that incorporation and grown of Bi2O3 nanorods in the crystalline structure of HAp nanosheets with oxygen–vacancy is in charge of great catalytic activity. It is proposed that growth of HAp along of c–plane resulted in the construction of nanosheets bearing the available columnar Ca2+ ions on the {001} crystal facet for replacing with Bi3+ ions and preparation of Bi2O3 nanorods. Actually, in–situ substitution of bismuth ions with calcium ones made more O–vacancy on the hydroxyapatite nanosheets. The presence of O–vacancies on the preferred crystal facet {001} of hydroxyapatite acted as active centers for capturing of electrons photogenerated, oxygen gas, and pollutant molecules. 1D–nanorods of bismuth oxide was also provided nanosized routs for transferring of photoinduced electrons which led to high photocatalytic performance. Finally, decoration with Ag nanoclusters form a plasmonic mentioned nanocomposite which completely degraded phenol molecules within photocatalytic process. The best degradation rate of 10 ppm phenolic solution was measured as high as 98.7%.
查看更多>>摘要：Facile preparation of efficient, low-cost, and stable bifunctional electrocatalysts for overall water splitting remains a big challenge. Herein, we successfully synthesized Mo-doped CoFe layered double hydroxides (Mo-doped CoFe LDH/NF) nanosheets by electrochemical transformation of Mo-doped CoFe prussian blue nanocubes on nickel foam (Mo-doped CoFe PBA/NF) for highly efficient overall water splitting. The catalyst exhibits outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance after electrochemical transformation, which is due to the abundant edge defects of Mo-doped CoFe LDH/NF can expose more active sites. Meanwhile, Mo6+ has a strong electron absorption ability, which could adjust the electronic structure and stabilize the high valence active sites. It only requires a low overpotential for OER (331 mV) and HER (227 mV) to reach 100 mA cm?2 in alkaline media, respectively. Notably, when it was employed as a bifunctional electrode, Mo-doped CoFe LDH/NF displays a low potential of 1.55 V to reach 100 mA cm?2 coupled with long-term water splitting stability in an alkaline electrolyte. This work not only developed a novel method for the synthesis of efficient double-layer hydroxide catalysts, but also paved the way for the rational design of bifunctional electrocatalysts with practical application value.
查看更多>>摘要：Thermodynamic studies of the Mg-Te-O system have significant importance in improving Te recovery from pyrometallurgical processes and materials preparation in related fields. Ternary compounds, Mg3TeO6, Mg2Te3O8, MgTe2O5 and MgTe6O13, in the Mg-Te-O system have been synthesized in the present study, and their decomposition behaviors at various atmospheric conditions have been experimentally studied with the TGA-DSC technique. Obtained results showed that: 1) Mg3TeO6 started to decompose to MgO, TeO2, and O2 at 1255.9 °C in the carrying gas of 20% O2 - 80% Ar, and the initial decomposition temperature decreased along with decreasing oxygen concentration in the gas; 2) Mg2Te3O8 decomposed to MgO and TeO2, and when the O2 was rich in the gas, Mg3TeO6 was also found in the product. The initial decomposition temperature of Mg2Te3O8 was 832.1 °C, 839.2 °C, and 839.9 °C, when the O2 concentration in the carrying gas was 20%, 0.1%, and 0.0001%, respectively; 3) The decomposition products of MgTe2O5 were same with that of Mg2Te3O8, and its initial decomposition temperature decreased along with decreasing the O2 concentration in the gas; 4) MgTe6O13 decomposed to MgTe2O5 and TeO2 around 700 °C, and the initial decomposition temperature decreased with decreasing O2 concentration in the gas. Along with increasing temperature, MgTe2O5 converted to Mg3TeO6 through oxidation reactions, and Mg3TeO6 decomposed at elevated temperatures.
查看更多>>摘要：Proficient photoanode is always vital for obtaining high efficiency in dye-sensitized solar cell (DSSC). Herein, ethylenediamine functionalized TiO2 nanowires graphene oxide (TiO2 NW-NH2/GO) has been synthesized and incorporated with Ag nanoparticles. The prepared plasmonic nanocomposites are characterized by various techniques, such as, diffused reflectance, Raman and X-ray photoelectron spectroscopies, X-ray diffraction, and Scanning/transmission electron microscopies (SEM and TEM). The amine functionalized TiO2 NW-NH2/GO/Ag plasmonic nanocomposites exhibit strong light harvesting and better dye loading, leading to high efficiency. The DSSC integrated with TiO2 NW-NH2/GO/Ag nanocomposite photoanode exhibits remarkable photovoltaic performance (short-circuit current density (Jsc) of 15.09 mA cm?2 and an overall power conversion efficiency (?) of 8.76%) which is double that of the DSSC with pure TiO2 NW photoanodes (4.05%). The enhancement of efficiency, mainly due to the increased current density, is attributed to the improved electron transfer at the photoanode/electrolyte interface. Ethylenediamine gives binding interaction between TiO2 and GO/Ag.
查看更多>>摘要：Metal-organic frameworks (MOFs) have recently emerged as one class of intriguing precursors to prepare electrocatalysts that feature high porosity, good conductivity and easy functionalization with other heteroatoms. We herein report a facile synthesis of MOFs-derived Ni2P@C nanocomposite as a promising anode electrocatalyst of direct hydrazine fuel cells (DHFCs). Our study found that Ni-MOFs nanosheets could be readily anchored to the Ni foam (NF) by a solvothermal process. Phosphatization treatment of the Ni-MOFs resulted in the formation of hierarchically nanostructured Ni2P@C, wherein the catalytically active Ni2P nanoparticles was encapsulated by disordered carbon shells. The thus-prepared self-supporting Ni2P@C/NF electrocatalyst was featured by large active surface area, 3D hierarchical porous structure and good electronical conductivity. Consequently, it exhibited impressively high activity, excellent stability as well as a nearly 100% selectivity toward N2H4 electrooxidation, outperforming most reported DHFC anode electrocatalysts.
查看更多>>摘要：The microstructural changes and mechanical properties of Al-Zn-Mg-Cu-Zr alloy samples with 0.05 and 0.1 wt% Sc were investigated after conventional and quench-controlled precipitation hardening treatments. The results showed that by the addition of Sc microcontent, grain-refined microstructures with smooth precipitates were obtained. It was also revealed that aging treatment after the hot rolling process reduced grain size to 20 μm and resulted in the formation of dual-morphology precipitates. Thus, the quench-controlled samples showed a higher precipitate content than the conventionally treated samples, which was related to the increase in the diffusion rate of the dissolved atoms. Furthermore, mechanical tests demonstrated that the quench-controlled samples had the highest yield strength (600 MPa) due to finer microstructure and higher precipitate content.
查看更多>>摘要：The structural stability and high capacity of material enable a wide range of applications for asymmetric supercapacitors. In this work, we design a simple route to synthesize NiMoO4@Ni-Co LDH@NiCo2O4 composites on Ni foam. The NiMoO4@Ni-Co LDH@NiCo2O4 has a stable nanorod/nanosheet core-shell structure. In addition, the NiMoO4@Ni-Co LDH150@NiCo2O4 exhibits a high specific capacity of 1035 C g?1 and retained 80.6% of the original capacity after 5000 cycles. Moreover, the asymmetric supercapacitor is assembled by activated carbon and NiMoO4@Ni-Co LDH150@NiCo2O4 as two electrodes respectively, which shows a high energy density of 66.8 Wh kg?1 at a power density of 900 W kg?1. In the meantime, the asymmetric supercapacitor achieved a high voltage window of 1.8 V. The stable core-shell structure of NiMoO4@Ni-Co LDH@NiCo2O4 achieved a high energy density, which shows great potential for energy storage.
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Elsevier