查看更多>>摘要：In this present work, a g-C3N4 decorated dual Z-scheme α-Fe2O3 and V2O5 heterojunction of magnetically recoverable GFV (g-C3N4/α-Fe2O3/V2O5) composite was rationally synthesized using facile calcination and hydrothermal approach. The crystal structure, surface morphology, chemical composition and optical properties of the as-obtained composite photocatalysts (PCs) were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra high-resolution scanning electron microscopy (HR-SEM, high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) measurement, UV-Vis diffuse reflectance spectra (DRS) and photoluminescence (PL) analyses respectively. Benefiting from these structural and compositional features, the optimum GFV heterostructured PCs sample revealed that the superior photo-degradation performance of methyl yellow (MY) and methylene blue (MB) mixed dye under visible-light, while the degradation rates were 93.4% for MY and 87.5% for MB dye at 90 min, respectively. Moreover, the enhanced photo-degradation performance of GFV composite PCs displayed an extended visible-light fascination due to lower bandgap, reduced recombination rates, high charge separation and good charge transfer capacity with the efficient dual Z-scheme heterojunction. Meanwhile, high photo-degradation stability is continued after five successive reusability tests. A possible photo-degradation mechanism of dual Z-scheme charge transfer paths was also been proposed. This study is also capable of emerging visible-light active facile heterojunction photocatalysts for various organic pollutants removal with great efficiency.
查看更多>>摘要：The α-MoO3-based materials have been intensively investigated as chemiresistive-type gas sensors due to their excellent sensing performances for gas sensing applications. However, there still remains formidable challenges for developing a simple and scalable approach to synthesize α-MoO3 with controllable structures. Herein, we demonstrated a glucose-assisted combustion synthesis strategy for the synthesis of α-MoO3 materials with controllable structures. They were obtained by heat treatment of the gels containing ammonium heptamolybdate tetrahydrate and glucose. Owing to the coordination interactions between glucose and heptamolybdate, α-MoO3-2 sample obtained by adding 1.8 g of glucose featured the highest oxygen vacancy concentration with an O/Mo atomic ratio of 2.61. The gas sensing measurements indicated that α-MoO3-2 had excellent sensing performances for detecting ethanol. Such ethanol sensor displayed the lowest detection concentration of 5 ppm ethanol, high response of 3.86 toward 20 ppm ethanol, and wide detection range of 5–100 ppm. This study sheds light on preparation of metal oxides with controllable structures on a scalable way for various applications.
查看更多>>摘要：The white light-emitting diodes (LEDs), a kind of representative multiband light emitters, which are generally manufactured by coating phosphor with InGaN-based blue LED chips, are widely used in illumination and display. However, the degradation and wavelength-conversion loss of phosphor are still issues which shorten the life of these LEDs. Herein, we demonstrate a convenient way to fabricate phosphor-free multiband-emitting LEDs without any external process or additional dielectric interlayers, utilizing only graphene as substrate for direct van deer Waals epitaxy (vdWE) of multiple-facet InGaN-based LEDs. Taking advantage of the low nucleation density of GaN on graphene, the surface morphology of the films was controlled as complete voids without flat. The morphology of InGaN/GaN multi quantum wells followed with the multiple-facet GaN, which caused the variation of indium concentration in different lattice plane of multi quantum well and led to multiband emission. Those findings reveal the roles of graphene in growth of III-nitride and provide valuable insights into the application of graphene for phosphor-free white light illumination.
查看更多>>摘要：A series of Ni3S2/C composites have been synthesized via molten salt synthesis. The microstructures, dielectric properties, magnetic properties and microwave absorption behavior of these Ni3S2/C composites were systematically investigated. The results indicate that new bonds and interfaces between C and Ni3S2 were formed via molten salt synthesis. The prepared Ni3S2/C exhibits excellent microwave absorption performance, where its microwave absorption strength reaches ?69.82 dB at 11.24 GHz. This microwave absorption performance is greatly superior to that of most current reports. A model related to conductive loss, magnetic loss and polarization relaxation loss was built to explain the multiple loss mechanism of the Ni3S2/C composite. This research expands the exploration of applying composites prepared by molten salt synthesis for the microwave absorption field.
查看更多>>摘要：In this work, a series of Co-free CrFeNiCuSix (x = 0.2, 0.3) high entropy alloys (HEAs) were designed and fabricated by suction casting, and their microstructure, mechanical properties, corrosion resistance and anti-bacterial behaviors have been systematically investigated. It is found that, all these HEAs are composed of FCC phase and have dendrite structure, while the dendrite and inter-dendrite regions are Cu-deplete and Cu-rich, respectively. Moreover, the increase in Si leads to the strengthening of this series of HEAs but would reduce their plasticity. The corrosion resistance is closely correlated with the distribution of Cu in these HEAs. The anti-bacterial rate against E. coli. is ~97% when x = 0.2, while that is ~90% when x = 0.3, indicating high anti-bacterial properties of these HEAs. This work indicates that these designed Co-free HEAs could have excellent comprehensive properties combining high ultimate tensile strength and plasticity, as well as good corrosion resistance and anti-bacterial properties, which provides a novel route in designing high-performance and low-cost anti-bacterial HEAs.
查看更多>>摘要：Graphene aerogel and graphene-magnetite hybrid aerogel were prepared using hydrothermal method followed by a freeze-drying process. Magnetite nanoparticles were encapsulated by graphene sheets in an electrostatic self-assembly process. The morphology and properties of aerogels were characterized by several techniques including UV-Vis spectroscopy, Raman spectroscopy, FESEM, TEM and XRD. The mechanical and thermal behavior of the aerogels were evaluated at different concentration levels of Fe3O4 nanoparticles (0, 10, 20 and 30 wt%). The compressive strengths of the hybrid aerogels at the strain of 80% for graphene aerogels containing 0, 10, 20 and 30 wt% Fe3O4 nanoparticles were determined to be 5.93, 12.96, 6.85, and 6.15 kPa, respectively. The highest mechanical properties were achieved for the sample containing 10 wt% Fe3O4 nanoparticles (FGA10). Thermal analysis revealed that FGA10 sample had a 15% less weight loss when heated up to 600 °C compared with that for the bare graphene aerogel, indicating the formation of a more thermally stable structure. Furthermore, adding Fe3O4 nanoparticles improved the thermal insulation performance of the graphene aerogel, since the dynamic heat transfer rate and heat dissipation rate of FGA10 were lower than those for the bare graphene aerogel.
查看更多>>摘要：To evaluate the effect of homogenization conditions on the possible loss of low-melting-point Pb and Bi to the surface in the free-cutting AA6026 alloy, three homogenization regimes were applied: 480 °C/12 h, 530 °C/12 h, and 550 °C/6 h. The microstructural characterization by optical, scanning, and transmission electron microscopy coupled with EDS analysis, macroanalysis of chemical composition by ICP-AES as well tensile tests at room and 500 °C, and Charpy impact test were employed to evaluate the different homogenization regimes. It was found that the choice of homogenization temperature had no significant effect on the level of loss of low-melting point elements. The optimal homogenization regime appeared to be 550 °C/6 h as it led to almost complete β-AlFeSi → α-AlFe(Mn)Si transformation and β-Mg2Si dissolution resulting in improved mechanical properties. The presence of the liquid phase did not lead to catastrophic failure due to the liquid metal embrittlement of the aluminum matrix, but the wetting of Fe,Mn – bearing constituents by molten Pb led to decohesion of the constituents. The morphological change to globular α-AlFe(Mn)Si decreased the surface area and interconnectivity of the microconstituents, which improved the hot ductility. During cooling after homogenization at T > 500 °C, the Q-phase precipitated, pointing up the potential quench sensitivity of the alloy. However, precipitation of the Q-phase laths in dispersoid-free zones reduced strain localization and improved room temperature ductility and impact toughness.
查看更多>>摘要：LiFePO4 (LFP) is a well-known material used in cathodes for the application of lithium-ion batteries as a result of its increased stability in thermal and structural aspects. Nonetheless, the low conductivity of LFP in terms of electronic and ionic are major disadvantages of this material. The LFP's surface has been coated with nitrogen-doped carbon to solve these disadvantages. Sericin is the coating material utilized and it is one of the components of silk cocoon which is abundant in carbon and nitrogen and readily available. The nitrogen-doped carbon-coated LFP, particularly for 1.0 wt% N-C@LFP, has exhibited excellent discharge capacity delivering 113.51 mAh g?1 at 1 C rate whereas bare LFP with no coating merely 94.27 mAh g?1, confirming approximately 20% improvement of the discharge capacity. This indicates that the electrochemical performance of LFP is enhanced when nitrogen-doped carbon derived from sericin is used as a coating material for LFP.
查看更多>>摘要：Relaxor ferroelectrics (RFEs) with superior energy storage properties are the commonly selected materials for energy storage capacitors. In this work, a relaxor end-member of Bi(Mg0.5Sn0.5)O3 (BMS) was introduced into ferroelectric (FE) Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics, which remarkably inhibited grain growth and triggered a FE-to-RFE phase transition, as well as improved breakdown strength. An ultrahigh energy efficiency (η) of 97.6% with a high recoverable energy density (Wrec) of 1.703 J/cm3, and excellent temperature stability (30–130 °C) have been achieved in (1-x)Ba0.85Ca0.15Zr0.1Ti0.9O3-xBi(Mg0.5Sn0.5)O3 with x = 0.08 (BCZT-BMS8) ceramic, which is mainly due to the slim P-E loop and enhanced breakdown strength. It should be noted that the ultrahigh η of 97.6% for BCZT-BMS8 is quite attractive for further applications. Electron paramagnetic resonance signal of oxygen vacancies (g ~ 1.955) was detected in BCZT-based ceramics for the first time, which could be helpful to explore novel lead-free ceramics for energy storage capacitors.
查看更多>>摘要：The solidification behavior close to the ternary Vss-V3Si-V5SiB2 eutectic reaction in the V-Si-B system has been experimentally investigated via arc-melting. According to the microstructure investigation, which is performed by SEM observations, EDS and EBSD measurements and XRD analysis, the composition of the ternary eutectic reaction has been determined at V-9Si-6.5B (at%). Its microstructures in two different sample sections with different cooling rates were further investigated and compared with the calculated result of the developed eutectic growth theory based on the Jackson-Hunt model to reveal the competitive solidification behavior between the two-phase Vss-V5SiB2 and three-phase Vss-V3Si-V5SiB2 eutectic growth. As a result, the liquidus projection around the ternary eutectic reaction was modified and the cross section of the ternary Vss-V3Si-V5SiB2 eutectic coupled zone along the monovariant Vss-V5SiB2 and V3Si-V5SiB2 reaction lines was schematically proposed.
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Elsevier