查看更多>>摘要：The polysulfide shuttle and uncontrollable growth of lithium dendrites are the two fatal troubles that obstruct the practical process of lithium-sulfur batteries. Herein, a composite membrane consisting of metal-organic framework (MOF) Ce-based UiO-67 and glass fiber membrane (UiO-67-GF) is proposed as a dual-functional separator for these issues. On the one hand, the introduced Ce-UiO-67 crystals are capable of efficaciously adsorbing polysulfides and catalyzing their conversion, thereby restraining their shuttle. On the other hand, this MOF provides sufficient lithium-philic functional groups for ensuring the rapid and homogeneous transport of Li ions, and thus a stable Li plating and stripping process can be acquired. Consequently, this MOF-based separator is qualified for simultaneously resolving the challenges of polysulfide shuttle and Li dendrite. The battery with the proposed separator delivers an initial capacity of 919 mAh g(-1) and a limited decay rate of merely 0.04% per cycle for 500 cycles at 1 C. Moreover, even under a lean-electrolyte condition, a high area capacity of 6.0 mAh cm(-2) is still obtained under the increased sulfur loading of 7.0 mg cm(-2). (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：To develop effective and low-cost enzyme-like nanomaterials in the antibacterial field, we designed an easily performed and highly specific approach to obtain novel ultrathin Ni-V mixed metal oxides (MMOs) with rich oxygen vacancy. Herein, a selenium (Se) doped novel ultrathin Ni-V MMOs were derived from Ni-V layered double hydroxide (LDHs) with Se powder in N-2 instead of direct calcination in the air successfully. After Se doped, the acquired Ni-V MMOs exhibited richer oxygen vacancy and more changeable elemental state, which can drastically promote the oxidase (OXD)/peroxidase (POD)-like activity increasing nearly 2 times compared with Ni-V MMOs. Se-doping endow 3NiV-Se-350 the unique 2D hierarchical nanostructure and the richest oxygen vacancy. More interesting, Se doped Ni-V MMOs calcinated at 350 ? with a Ni/V molar ratio of 3:1 show the best OXD/POD mimic activity among different Ni/V molar ratios, and possess a good reusability for 7 cycles. Mimic activity of 3NiV-Se-350 was attributed to the reactive oxygen species (ROS), such as center dot OH and center dot O-2(-). 3NiV-Se-350 also exhibit bactericidal rate of 71.04% without H2O2 and 98.89% in the presence of H2O2 against E. coli through generating center dot O-2(-). (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The electrical conductivity and catalytic activity of the electrode materials greatly affect the photoelectric conversion performance of DSSCs. However, the commonly used Pt electrodes no longer meet the needs of long-term development at present. Herein, based on the Kirkendall effect, CoFe2O4 @C nanoparticles with core-shell structure are successfully prepared using the treatment of quasi-sol-gel method. The size of CoFe2O4 @C nanoparticles is homogenized without agglomeration through adjusting the ratio of metal salt in the precursor. The composite exhibits excellent counter electrode properties in DSSCs, which attributes to the large specific surface area and superior electro-catalytic activity. With the optimized film thickness (12 mu m) of CoFe2O4 @C, an excellent photoelectric conversion efficiency of 7.80% is finally achieved, significantly higher than that of pure carbon (PC) electrode (6.36%) and even Pt counter electrode (7.05%) under the same conditions. The composite can additionally catalyze the recycling of I-/I3- redox couple steadily, providing more possibilities for the study of Pt-free materials about DSSCs counter electrode. (c) 2022 Published by Elsevier B.V.
查看更多>>摘要：The photocatalytic hydrogen (H2) evolution of photocatalyst generally requires the assistance of cocatalysts, which are mainly centered on noble metals, such as Pt and Au. However, noble metals cocatalysts often suffer from the uneven distribution and severe aggregation, as well as scarcity. Herein, we reported nickelsalen (Ni-salen) molecules on the promotion of photocatalytic H2 evolution with polymeric carbon nitride (PCN)/CdS heterojunction, in which the noble metal free Ni-salen molecules are soluble and highly dispersed during photocatalytic H2 evolution under visible light irradiation (lambda >= 420 nm). Under optimized loading concentration of the Ni-salen molecules (0.03 mM), the highest H2 evolution rate is up to 23.3 mmol g-1 h-1, which is more than 4 times higher than that by using PCN/CdS heterojunction alone. In addition, Ni-salen molecules are highly stable and can offer a durable H2 evolution with 28 h. The enhancement on H2 evolution is the result of efficient photogenerated electrons transfer from photoexcited PCN/CdS heterojunction to the coordination unsaturated Ni active centers of Ni-salen molecules. This work demonstrates the great potential of soluble noble metal free Ni-salen molecules on the promotion of photocatalytic H2 evolution.
查看更多>>摘要：The novel La(1-x)Ca(x)Ti(1-y)TayO(3-delta) nano perovskites with high oxygen vacancies have been prepared for solid oxide fuel cells (SOFCs) by facile hydrothermal method. To enhance the oxygen vacancies, structural, thermal and chemical stability, the phase composition of the materials was varied with multiple x & y values like (0, 0.2, 0.4, 0.6, 0.8 and 1). All the as prepared compositions of La(1-x)Ca(x)Ti(1-y)TayO(3-delta) were undergone heat treatments in autoclave, calcined at 700 & DEG;C and sintered at 1000 C. These modified perovskite oxides can add in hefty point defects, such as oxygen vacancies that compensate dopants or are part of an inherent off-stoichiometry. These defects have high mobilities in La(1-x)Ca(x)Ti(1-y)TayO(3-delta) perovskites, making it most suitable for electrochemical energy conversion devices. The appropriate phase purity, structural properties, lattice parameters and morphology of the perovskite were inspected. Electrical conductivity of sintered pellets was analyzed using electrochemical impedance spectroscopy. The electrical behavior of La(1-x)Ca(x)Ti(1-y)TayO(3-delta) is enhanced at lower operating temperature and long-term structural stability, phase purity is also improved owing to the inclusion of Calcium and Tantalum (La(1-x)Ca(x)Ti(1-y)TayO(3-delta)). The enhancement in electrical conductivity, electro-catalytic activity is credited by means of partial replacement of Ca and Ta in the perovskite structure. Among them, La0.6Ca0.4Ti0.6Ta0.4O3-delta showed the maximum conductivity of 9.18 x 10(-2) S cm(-1) at 750 C. These results demonstrate that the La(1-x)Ca(x)Ti(1-y)TayO(3-delta) perovskites are capable as electrode material intermediate temperatures SOFCs fabrication. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：High-valent or equivalent foreign element doping could improve the charge separation of the hematite (alpha-Fe2O3) for enhancing the photoelectrochemical (PEC) water oxidation. However, the induced extra surface states would anodically shift the onset potential. This work reported a two-step hydrothermal method to prepare the low-valent Li doped alpha-Fe2O3 that alleviated the charge recombination and partially removed the surface states. Thus, the photocurrent density of optimized Li-doped alpha-Fe(2)O(3)was 0.75 mA/cm(2) (1.23 VRHE), up to 3.6 times higher than that of pristine alpha-Fe2O3 (0.21 mA/cm(2)). Meanwhile, the onset potential also shifted negatively to 0.68 VRHE by 100 mV. The Density Functional Theory (DFT) revealed the Li atoms occupied the interstitial sites of the oxygen octahedron, and the introduced halffilled states in the bandgap can expand the light absorbance and improve the charge transport. The synergetic effects of enhanced charge separation efficiency and removal of surface states contributed to efficient PEC water oxidation. (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：A new titanium matrix composites (TMCs) with distinctive architecture consisting of isolated fiber-like structural composites region (FLSCR) within continuously Ti region were designed and fabricated by powder metallurgy, hot extrusion, and subsequent hot rolling. This work systematically investigated the important role of TiB contents on microstructural evolution and mechanical response of the as-rolled fiberlike structural TMCs. The designed FLSCR-5% and FLSCR-10% with fiber-like structure obtain high ductility of 24.4% and 19%, respectively, which shows a better combination of strength and ductility. The strengthening is attributed to the refinement of the equiaxed alpha grains and the load-bearing effect of TiB whiskers. Meanwhile, continuously Ti region significantly reflects and blunts the crack propagation which is supposed to improve the static toughness of the fiber-like structural TMCs, but the ductility would be decreased by increasing TiB content in the FLSCR, which is attributed to the decreasing volume fraction of titanium matrix and the increasing crack initiation rate. Additionally, due to the fiber-like composites region, the strain hardening rate of the FLSCR-10% (from ~0.05 to ~0.135 strain) is significantly strengthened by the hetero-deformation induced back stress, which is beneficial to the ductility. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：This paper focuses on the corrosion behavior of Mg-5.7Gd-1.9Ag alloy sheets with high strength-ductility synergy in the 3.5 wt% NaCl solution prepared by a combined route of rolling and aging. Electrochemical measurements indicate that the rolled sheet exhibits a significantly improved corrosion resistance as compared to its as-cast counterpart. Subsequent aging, as a widely used strengthening method, decreases corrosion resistance to a certain extent. However, the aged sheet still has enhanced corrosion resistance as compared to its as-cast counterpart. The observed corrosion migration in the present Mg-5.7Gd-1.9Ag Mg alloy mainly stems from the evolution of second phases, but not the grain size and texture. A small number of the micron beta phase particles is incapable of promoting severe galvanic corrosion and thus endows the rolled sheet with good corrosion resistance, while the massive submicron beta phase particles along grain boundaries and dense gamma '' nanoplates within grains in the aged sheet bring out severe galvanic corrosion and thus accelerate corrosion. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Si(3)N(4 )nanowires doped with rare earth ions (such as Ce3+, Tb3+, Eu2+ and Eu3+) were synthesized by plasma assisted direct nitridation method using Si, rare earth oxides and N2 as raw materials. The prepared doped Si(3)N(4 )nanowires were characterized by XRD, EDS, XPS, SEM and TEM. The obtained single-crystal doped Si(3)N(4 )nanowires have uniform diameters of about 50-100 nm and lengths of more than 10 mu m. The photoluminescence (PL), PL decay curves as well as thermal quenching behaviors of doped Si3N3 nanowires were systematically investigated. This work provides an effective strategy for doping large-size functional atoms in Si(3)N(4 )nanowires. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The hot deformation behavior and microstructural evolution of Inconel 625 superalloy sheet under different conditions were investigated. The hot tensile tests under the temperature ranging from 800 degrees C to 950 degrees C with the increment of 50 degrees C and the strain rates between 0.001 and 0.1 s-1 were performed on a Gleeble 3500 machine. The experimental results indicated that the plastic flow behavior of the Inconel 625 sheet changes from work hardening to hot softening with the rise of experimental temperature and the decline of strain rate. Furthermore, the elongation is decreased with the rise of deformation temperature and decline of strain rate. According to the principle of dynamic material model (DMM), the process maps at various strains were constructed, and the optimal domain with the highest power dissipation was determined. The optimal domain appears at the temperature range of 925 and 950 degrees C and the strain rate between 0.001 and 0.1 s-1 with the power dissipation efficiency of about 46.5%. The grain size, grain boundary and texture of the deformed samples under typical conditions was analyzed by electron backscatter diffraction (EBSD) and transmission electron microscope (TEM), which reflected that the dynamic recrystallization (DRX) occurs in the optimal hot working window, and the preferred orientation for DRX nucleation of the Inconel 625 superalloy sheet is the < 001 > direction. The deformation behavior of Inconel 625 sheet under the longterm service temperature range is affected by the coupled effect of DDRX and CDRX. (c) 2022 Elsevier B.V. All rights reserved.
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