查看更多>>摘要：The interaction of NO2 gas with functionalized 2D WSe2 was investigated in this study. The liquid exfoliated pristine 2D WSe2 was functionalized with Au and Pt nanoparticles through reduction of respective metal salts at room temperature. The catalytic effect of nanoparticle functionalization was observed in gas sensing experiments. The results revealed the enhancement in sensing response upon decoration (R% = 170% for Au-decoration and 220% for Pt-decoration at 5 ppm NO2) at room temperature and most importantly, the recovery of the sensor was improved to less than 5 min for Au decorated WSe2. This work, therefore, successfully addressed the known bottleneck of recovery in 2D material-based NO2 sensors without utilizing any external energy stimulus. In fact, the response was found to be stable and reproducible while the sensor was subjected to repeated testing. The sensing characteristics and the underlying sensing mechanism have been explained in detail.
查看更多>>摘要：Fe-based metallic glasses have low magnetic induction and inferior plasticity because of inevitable doping of non-magnetic constituents. The study proposes an innovative composition design strategy considering the nature of elements, binary eutectic, atomic configuration, and mixing entropy in the alloy system. A novel composition of Fe78.9B11.8Si7.6C1Cu0.7 was adopted, adding a total of only 8.3 wt% non-magnetic elements. The critical size of Fe78.9B11.8Si7.6C1Cu0.7 bulk metallic glass was ~1 mm, and an ultra-thick ribbon of ~150 μm was obtained by twin-roll strip casting. Excellent soft magnetic properties with high saturation magnetization (Bs) of 1.68 T and low coercivity (Hc) of 7.1 A/m outperformed current conventional counterpart. Meanwhile, the high breaking strength of 2654 MPa and distinctive plastic strain of 2%, normally less than 0.5% in most Fe-based metallic glasses, was demonstrated in Fe78.9B11.8Si7.6C1Cu0.7 bulk metallic glass. This novel alloy composition and design strategy is expected to facilitate the development of next-generation magnetic materials.
查看更多>>摘要：The Al0.75CoCrFeNi alloy (Al16Co21Cr21Fe21Ni21 in at.%) presents a lamellar microstructure in the as-cast state consisting of a spinodally-decomposed B2/BCC matrix and Widmanst?tten-type FCC plates. In this study, to retain the lamellar microstructure and improve tensile strength, Al16Co21Cr21-xFe21Ni21Mox alloys with x ≤ 10 at.% were investigated. For x = 2 at.%, the Widmanst?tten microstructure changed into a vermicular one due to the stabilization of the BCC phase. With increasing the Mo/Cr ratio, the BCC phase transformed into topologically close-packed (TCP) phases, i.e., σ phase for x = 4 at.% and R phase for x ≥ 6 at.%, whose volume fractions increases with x. The as-cast alloys with x = 10 and 4 at.% presented the largest microhardness of ~600 HV0.5. The former had the highest volume fraction in TCP phases, which are hard and brittle while the latter presented the finest microstructure (enhanced phase boundary strengthening). While the alloys with x > 4 at.% were too brittle to machine tensile specimens, the others were tested between 20 and 700 °C. The ultimate tensile strength increased with increasing x up to ~1460 MPa for x = 4 at.% at 400 °C. At 700 °C, the strength of all alloys significantly decreased due to the softening of the B2 phase. Most of them had limited ductility and showed intergranular fracture except for x = 4 at.% presenting pronounced necking with ~38% ductility. The latter effect was attributed to the occurrence of interfacial sliding resulting in cavitation at grain boundaries and interphase boundaries.
查看更多>>摘要：Investigations on the high-performance flexible ultraviolet photodetectors have been becoming one of the interesting research focuses in recent years. ZnO is considered as suitable material for ultraviolet photodetection due to its wide bandgap (~3.37 eV). In this work, ZnO nanorod arrays were prepared using the hydrothermal method at the temperature of 70 ℃ on flexible substrates. Polyethyleneimine (PEI) was added into hydrothermal solution as the growth additive to achieve the performance improvement of the ZnO nanorod arrays ultraviolet photodetector. SEM, XRD, absorption spectroscopy, Raman spectroscopy and XPS were employed to characterize the morphology, crystallinity, optical properties and chemical composition. The introduction of PEI adjusts the growth process of ZnO nanorod arrays and affects the distribution of defect states, which brings out the improvement of the optoelectronic performance of ZnO nanorod arrays ultraviolet photodetectors. Compared with pure ZnO, the higher photo to dark current ratio and responsivity, and quicker time response speed are demonstrated in the PEI-assisted ZnO nanorod arrays photodetectors. And more photoresponse parameters are also discussed and compared. Furthermore, the photodetectors also display outstanding mechanical flexibility and robustness under multiple bending cycle tests. Our work presents a potential approach for improving the optoelectronic performance of simple-operated flexible ultraviolet photodetectors.
查看更多>>摘要：Magnetic nanoparticles (MNPs) have emerged as efficient materials for thermo-therapeutic modalities viz. magnetic fluid hyperthermia (MFH) and photo-thermal therapy (PTT). Nevertheless, the quest to further enhance the effectiveness of such materials is a major challenge to their successful endeavour. In the present work, we have synthesised MnFe2O4 nano-flowers utilising solvo-thermal method to be employed as nano-heat generators during MFH and PTT. The material, in addition to effective heating under an alternating magnetic field (AMF), demonstrated impressive heating ability under near infra-red (NIR) irradiation. Various techniques, such as, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photo-electron spectroscopy (XPS) and M?ssbauer spectroscopy were used to study the structural features and chemical composition of the sample. The photoluminescence spectroscopy (PLS) has further corroborated the efficient heating behaviour of the sample under NIR irradiation. The observed intrinsic loss power value of 5.31 ± 0.079 nH m2 kg?1 is significantly higher than the commercially available ferro-fluids and comparable to previously reported values for iron oxide nano-flowers. A substantial SiHa cells death during photo-thermal treatment was noticed at a concentration of 500 μg/mL of MnFe2O4 nano-flowers after exposure to 808 nm laser of 0.66 W cm-2 power density for only 10 min. However, at the same concentration of nanoflowers (i.e. 500 μg/mL) and exposure time (i.e. 10 min) during MHT with SiHa cells, a significant decrease in cell viability was not observed.
查看更多>>摘要：To enhance the rate capability and cyclic stability, we develop few layered graphene wrapped nanocrystalline/amorphous Sn4P3 (named as Sn4P3@FLG) by ball milling. The high energy output of vibrational ball milling enables tight contact of Sn4P3 with FLG via P[sbnd]O[sbnd]C bonding as well as compact structure with a high tap density of 4.5 g cm?3. The constraint of FLG not only enhances kinetics of electron and Li+ transfer, but also relieves the volume variation and particle aggregation of Sn4P3 during the lithiation/delithiation process. Therefore, Sn4P3@FLG exhibits superior rate and cyclic performance when evaluated as anode material for lithium-ion batteries. At 0.1 A g?1, it delivers a high reversible capacity of 1077.6 mA h g?1 with a high coulombic efficiency of 89.0% in the first cycle. Even at 1 A g?1, it still retains 929.6 mA h g?1 after 830 cycles. Furthermore, when matched with commercial LiFePO4 cathode in a full cell, it delivers a reversible capacity of 778.0 mA h g?1, with a coulombic efficiency of 79.4%. Considering the high tap density of 4.5 g cm?3, the volumetric capacity of Sn4P3@FLG can be as high as 3500 A h dm?3. Therefore, Sn4P3@FLG can be a promising anode material for high performance lithium-ion batteries.
查看更多>>摘要：The effect of TiO2 addition on densification, microstructure, and mechanical behaviour of Ceria Stabilized Zirconia Toughened Alumina (CSZTA) was studied in the present work. CSZTA powders with various concentrations (0–10 wt%) of TiO2 were synthesized using the co-precipitation method. The powders were compacted into ? 10 mm pellets using a uniaxial hydraulic press and sintered in the presence of air at various sintering schedules. The TiO2 content and sintering schedule were optimized based on density, phases present, microstructure, and mechanical properties of the sintered sample. X-ray Diffraction (XRD) was used to identify the phases present, and the Rietveld refinement method was used to quantify phases from the XRD patterns. Microstructures of sintered samples were studied using Scanning Electron Microscope (SEM). The hardness and indentation fracture toughness was determined using a Vickers hardness tester. It was found that the addition of TiO2 to CSZTA improved sinterability and reduced the sintering temperature from 1600 °C to 1400 °C. The maximum Vickers hardness of up to 1591 HV10 with an optimum fracture toughness of 7.42 MPa.√m was observed for 4 wt%TiO2 - CSZTA sample sintered at 1400 °C for 3 h.
查看更多>>摘要：A robust and bright red emitter is recognized as a key enabler for high-quality warm white light-emitting diode (w-LED). Herein, triple molybdate scheelite-type NaCaLa1-x(MoO4)3:xEu3+ (NCLM:xEu3+) phosphors derived from NaCaLa(MoO4)3 host by the equivalent-valent substitution strategy are successfully synthesized and systematically studied. Impressively, the NCLM:Eu3+ phosphors (λem = 615 nm) can be effectively stimulated by 395 and 466 nm light, exhibiting an ultra-high color purity and quantum efficiency close to 100%. The structure-related emission characteristics were analyzed based on the Judd-Oflet theory. The packaged white LED device used tri-color phosphors displays a superior color rendering index of 86.0 and low correlated color temperature of 2797 K. Moreover, the NCLM-based polydimethylsiloxane film maintains an impressive luminescent performance when it is folded or bent, demonstrating the potential applications in the field of flexible display and other light-emitting devices.
查看更多>>摘要：In this study, CoCrFeNiAl0.2(TiC)x (x = 0,0.06,0.12,0.2) composites were prepared by high-gravity combustion synthesis (HGCS). The mixture powders of several low-cost metal oxides (Co2O3, Cr2O3, Fe2O3, NiO), Al, Ti and C were used as raw materials. In the high-gravity field, the CoCrFeNiAl0.2 high-entropy alloys (HEAs) were obtained by inducing a thermic reaction between the several low-cost metal oxides (Co2O3, Cr2O3, Fe2O3, NiO) and Al powders. Then the TiC was in-situ synthesized by Ti and C powders. The results show that the size and distribution of the in-situ synthesized TiC can be controlled by adjusting the Ti and C additions and the value of high-gravity field. When the high-gravity field rises to 1200 g, the bending strength, compressive strength and specific strength of CoCrFeNiAl0.2(TiC)0.12 composites respectively up to 1.17 GPa, 2.13 GPa, 0.3 MPa·Kg?1·m?3. Therefore, the HGCS with ‘green’ and efficiency characteristics offers an alternative pathway to control the structure and properties of the ceramic/ HEAs composites.
查看更多>>摘要：Designing highly active and cost-effective electrocatalysts for ORR (oxygen reduction reaction) and revealing their activity origin are indispensable for energy conversion technologies. Herein, atomically distributed Co over S, N co-doped hierarchical porous carbon matrix (Co/S,N-C) is prepared by a sacrificial template strategy. The Co/S,N-C provides abundant active sites for the ORR due to its mesopore structure and large specific surface area. The S, N co-doping can modify the charges around Co active center. As a result, the Co/S,N-C exhibits prominent electrocatalytic activity with comparable half wave potential to commercial Pt/C (0.84 V vs RHE) in alkaline condition. Furthermore, the Zn-air battery based on the Co/S,N-C shows a high specific power of 147.4 mW cm?2 and superior long-term stability.
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Elsevier