查看更多>>摘要：In this study, silkworm body fluid (SF), a natural biological material, was compounded with gold nanoparticles (Au NPs) to form a dielectric layer, and the biodegradable resistive random access memory (RRAM) of Al/SF:Au NPs/indium tin oxide (ITO) was fabricated. The experimental results show that embedding Au NPs increases the ON/OFF current ratio of the Al/SF:Au NPs/ITO device to 5.22 × 105. The resistances of the high resistance and low resistance states of the Al/SF:Au NPs/ITO device are well maintained, reaching 104 s. These devices can be easily fabricated using solution-based processes on substrates at room temperature, and they have reliable data storage capability. Because the compliance current is controlled, a single memory cell of a device based on SF:Au NPs has a multilevel (8 levels, 3 bits) resistance state for high-density storage, enabling multilevel data storage. Application of the device in simulating neurobehavior is further explored, and potentiation and depression of the simulated synapse can be achieved by applying pulses to the device. SF:Au NP-based RRAM shows great potential in multilevel data storage and neuromorphic computing. RRAM based on natural biomaterials has the advantages of biocompatibility, biodegradability and low cost, and it provides an important step toward the future development of bioelectronic devices.
查看更多>>摘要：Sheet-like morphology of copper cobaltite/N-doped graphene oxide materials composite was synthesized by a thermal reduction process improved by sonication. These composite nanostructured materials were confirmed by analytical methods. The composite materials were fabricated as electrode for supercapacitor applications via CV, GCD, and EIS analysis in the presence of 5 M KOH solution. The CuO@NGO and CuCo2O4@NGO composite electrodes employing excellent morphology showed improved capacitance of (196 and 475) F.g?1, respectively, at 0.5 A.g?1, and excellent cyclic stability and retention (96.5%) in the continuous 10,000 charge–discharge cycles. The electrochemical description of the synthesized CuO@NGO and CuCo2O4@NGO materials composite showed excellent electrochemical properties and cyclic stability in the presence of 5 M KOH electrolyte. The composite design of CuO@NGO and CuCo2O4@NGO materials was developed for the symmetric electrochemical supercapacitor in the presence of 5 M KOH electrolyte.
查看更多>>摘要：A facile method for the preparation of porous hollow CoxMn3-xO4 normal-reverse coexisted spinel is developed. The CoxMn3-xO4 catalysts with different morphologies can be prepared via adjusting the Co/Mn molar ratio using mixed carbonates as the precursors. The as-prepared CoxMn3-xO4 catalysts exhibit excellent catalytic activities for toluene oxidation due to the synergistic effect of abundant oxygen vacancies and the optimal molar ratio of Co3+/Mn2+–Co2+/Mn3+ coupled redox ion pairs. The porous hollow hierarchical structure of CoxMn3-xO4 is conducive to maintain good long-term structural stability and activity stabilities. The catalytic activity of CoxMn3-xO4 shows no significant loss during the 100 h of on-stream stability test and the 5 vol% water vapor inhibition test, showing excellent anti-sintering ability, high-efficiency mass transfer ability and anti-moisture ability.
查看更多>>摘要：Magnetostrictive and structural properties of sputter-prepared Fe71Co10Ga19 films on Si(100) substrates have been studied. The experimental results show that the saturation magnetostriction (λs) of the films is mainly dominated by the amount of m-D03 phase existed in the films through the modification of the sputtering parameters, including Ar gas pressure (PAr) and sputtering power (P). Large λs of 113.7 ppm is attained for the 200-nm-thick Fe71Co10Ga19 film made under the conditions of PAr = 30 mTorr and P = 40 W. Besides, the thickness (t) dependence of λs in the Fe71Co10Ga19 films is that: (a) in the region of 200 nm ≥ t ≥ 50 nm, λs increases from 113.7 to 164.7 ppm as t decreases; (b) in the region of 50 nm ≥ t ≥ 30 nm, λs decreases to 128.1 ppm as t continues to decrease. The increase of λs in the region (a) may be related to surface contribution involved by surface roughness. The decrease of λs in the region (b) results from the surface oxidation of film. The optimized λs of 113.7–164.7 ppm achieved for Fe71Co10Ga19 film in this study is superior to those (49–80 ppm) of the previously reported Fe81Ga19 thin films. The results of this work provide useful film-making information to obtain the Fe71Co10Ga19 film with outstanding structure and magnetostrictive properties for applications.
查看更多>>摘要：Pyrite (FeS2) is a promising photocatalyst because of its high optical absorption coefficient, suitable band gap and low cost. However, the low conductivity and weak stability of FeS2 limits its application. Herein, two-dimensional (2D) hetero-structured FeS2/reduced graphene (FeS2/rGO) photocatalyst was synthesized by a facile sodium-oleate-assisted two-phase solvothermal method. The optimized FeS2/rGO hybrids possessed excellent initial conversion frequency (TOF, 10.96 μmolO2 molmetal?1 s?1) and oxygen evolution amount (21.2 μmol), which was 2.5 times higher than of pure FeS2. Further studies revealed that the excellent catalytic property was attributed to the 2D heterojunction between FeS2 and rGO, which improved the optical adsorption of the hybrids and accelerated the rapid transfer of photogenerated charges from FeS2 surface to water molecules. The FeS2/rGO hybrids remained stable even after three runs photocatalytic reaction under the strong oxidation conditions. This study provides a facile strategy for the design of FeS2/rGO hybrids as a highly efficient water oxidation catalyst, improving the development of solar energy conversion.
查看更多>>摘要：A crystalline phase diagram of a Nd–Fe–B–Cu sintered magnet up to 1100 °C was determined through in-situ synchrotron X-ray diffraction using a new sample mounting method that prevents high-temperature contact reactions between the sample and the quartz capillary tube container. Using this newly developed method, we successfully observed almost identical phase diagrams during heating and cooling, indicating thermodynamic equilibrium. In addition, we obtained changes in the constituent phase fraction after quenching. Temperature-reversible changes in the dhcp-Nd fraction were observed from 475 °C to 650 °C, corresponding to a eutectic reaction in the Nd–Cu phase. The fcc-NdOx fraction decreased with the increase in the Nd2O3 fraction above 1000 °C, which behavior was attributed to a phase change from fcc-NdOx to high-temperature liquid and hcp-Nd2O3 phases. The measurements verify the thermodynamic database recently constructed for CALPHAD calculations of the Nd–Fe–B–Cu–O system by assuming the local thermodynamic equilibrium of the Nd oxides within the microstructure of the magnet.
查看更多>>摘要：The remarkable magnetocaloric effect demonstrated in Ni-Mn-based multi-functional alloys benefits a lot from large magnetization difference ΔM and low thermal hysteresis ΔHhys upon the magnetostructural transformation. Here, we present the effective manipulation of the magnetostructural transformation as well as the related magnetocaloric effect through simultaneously introducing Co and Si to ternary Ni-Mn-Sn alloys. Such co-doping method allows not only large magnetization difference but also low thermal hysteresis, yielding giant inverse magnetocaloric effect in a Ni39Co9Mn42Sn9Si1 alloy. Under the magnetic field change of 5T, the field-induced entropy change ΔSM up to 23.5 Jkg?1 K?1 and the reversible ΔSM of 23.4 Jkg?1 K?1 are obtained. Moreover, giant refrigeration capacity up to 402 Jkg?1 is also achieved, being much higher than those reported previously. Furthermore, large field-induced adiabatic temperature change ΔTad up to ?4.0 K and reversible ΔTad of ?1.8 K are demonstrated through the direct measurements under a low magnetic field change of 1.5 T. Thus, multi-component alloying could be employed as an effective route towards the design of high-performance Heusler-type magnetocaloric materials.
查看更多>>摘要：Zeolitic imidazolate framework 67 (ZIF67) is widely considered as potential active material for supercapacitors (SC) due to large surface area and tunable structures, but small electrical conductivity limits its energy storage ability. Fluoride with high electrical conductivity is reported to be beneficial on reducing charge-transfer resistance of SC. In this study, ZIF67-derived perovskite fluoride is synthesized using ammonium fluoride (NH4F) as electroactive material of SC at the first time. Different NH4F amounts are used to produce perovskite ZIF67-derived fluorides (ZIF67-N). The optimized ZIF67-N electrode shows specific capacitance (CF) of 636.8 F/g at 10 mV/s, owing to small particle size and suitable F- to 2-methylimidazole ratio for providing high electronegativity. The ZIF67 and cobalt nickel fluoride prepared using NH4F but no 2-methylimidazole (CoNi-N) are synthesized to understand roles of fluorine and 2-methylimidazole on energy storage. The ZIF67 electrode shows much smaller CF (1.6 F/g) than ZIF67-N electrode, owing to largely enhanced pore width of ZIF67-N even if surface area is largely reduced when NH4F is added during synthesis. The SC comprising optimized ZIF67-N electrodes shows maximum energy density of 27.2 Wh/kg at 650.0 W/kg as well as CF retention of 86% and Coulombic efficiency of 100% in 8000 times charge/discharge process.
查看更多>>摘要：Wire arc additive manufacturing (WAAM) has been proved to be a promising method to fabricate large expensive NiTi shape memory alloys with complex geometry. In this study, five layers of NiTi alloy with dimensions of 80 × 12 × 15 mm were deposited by the cold metal transfer (CMT) welding based WAAM process. The macroscopic morphology, microstructure evolution, phase transformation and mechanical properties of each layer were investigated and compared with each other. Each layer of the as-deposited NiTi wall shows a one-step B2→B19′ transformation during cooling and the martensitic transformation temperature (Ms) is lower than that of the as-received wire. For the first three layers, the columnar grains growing along the building direction have a larger length-to-diameter ratio and B2 is the main constituent phase. Coarse dendritic Ti2Ni/Ti4Ni2O precipitates are precipitated at the interior of the grains besides grain boundaries. However, grains in the subsequent layers become finer and the region near the top surface are characterized by equiaxed grains, and elliptical Ti2Ni/Ti4Ni2O precipitates mainly concentrate at grain boundaries. The heat-affected zone exhibits the lowest hardness of 233.34HV, followed by a gradually increase among the as-deposited layers and the highest hardness of 331.27HV was obtained at the 5th layer. The highest ultimate tensile strength of 652.46Mpa, together with the elongation of 13.66% and recoverable strain of 2.39% was obtained in the sample which is located at 11.5 mm height away from the substrate. This research provides an innovative method and insights for additive manufacturing NiTi shape memory alloys by introducing CMT based WAAM method.
查看更多>>摘要：The construction of three-dimensional (3D) hierarchically porous nanostructures is an effective microstructural design strategy for the fabrication of lightweight electromagnetic wave (EMW) absorption materials. In this work, 3D hierarchically porous Ti3C2Tx MXene@polyaniline (PANI) hybrids are prepared via a self-assembly process. The as-prepared hybrids possess excellent microwave absorption performance with the minimum reflection loss (RLmin) of the optimal Ti3C2Tx MXene@PANI hybrid reaching ? 53.79 dB at 12.67 GHz with a thickness of 1.33 mm and a loading amount of 10 wt% in paraffin. The light weight and high-efficiency microwave absorption properties of the hybrids result from their 3D hierarchically porous structure and well-matched impedance characteristics, which provide multiple reflection channels and loss mechanisms for incident EMWs. This strategy offers a rational, simple and practical design approach for high-performance MXene-based EMW absorbers.
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Elsevier