查看更多>>摘要：? 2022 Elsevier B.V.This study investigates the synthesis of Ni1–2xGdxRuxO nanoparticles, with different concentrations of Gd and Ru dual dopants, in an attempt to improve their dielectric and electrical properties. These samples are synthesized via the co-precipitation method, and characterized by various structural, methods, including the X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM), and Raman spectroscopy. The XRD patterns demonstrated the formation of single NiO phase, revealing the good incorporation of (Gd, Ru) in NiO lattice. The crystallite size decreased from 21 to 10 nm with increasing the dual dopants’ concentration. The TEM images demonstrated pseudo-spherical morphology of the Ni1–2xGdxRuxO nanoparticles and the Raman spectra detected the fundamental vibrational modes of NiO. The frequency and temperature-dependent dielectric constants were augmented by the incorporation of the dual dopants, due to the induced nickel vacancies and larger surface-to-volume ratio. The Nyquist plots demonstrated depressed semicircles with smaller radii as the temperature and the dual dopants’ concentration increased. This was related to the enhancement of ac conductivity that followed different trends at room and high temperatures. The ac conductivity was tuned by varying the dual dopants concentration due to the ionic compensation mechanism, and the changes in the charge carriers’ concentrations and mobility. The correlation between the different dielectric and electric parameters suggested the dominance of the long-range conduction of the charge carriers.
查看更多>>摘要：? 2022 Elsevier B.V.It is well known that the enhanced photocatalytic performance of graphite-type carbon nitride (g-C3N4) will be limited by its microstructure, including its precursor structure, and the relationship between the precursor structure and the target catalyst structure will be an interesting question. Glutaraldehyde (GA) containing aldehyde group was introduced into melamine (MA) to form three GA/MA precursors connected by C[dbnd]N chemical bond, which cause the calcined composite catalysts of g-C3N4 and C with closer lamellar structure along with the increase of the amount of glutaraldehyde added. The study found that the C[dbnd]N chemical bond limits the conversion of melamine to melem by thermal decomposition kinetics analysis, which leads to the formation of the tighter interactions by carbonization. The resulting structure has more efficient photocatalytic performance than pure g-C3N4.
查看更多>>摘要：? 2022 Elsevier B.V.Developing efficient and economical photocatalysts was considered as an efficient and economical strategy for pollution remediation. Herein, magnetically separable ZnFe2O4/CuWO4 composites (ZW) had been developed via combining ZnFe2O4 with CuWO4. The composite with a mass ratio of 40% CuWO4 (ZW-40) performed best, and the tetracycline hydrochloride (TC) removal by adsorption-photocatalysis of ZW-40 reached 86.5%. The photocatalytic degradation rated constant of it was 9.44 × 10?3 min?1, which was approximately 5.04 and 3.28 times compared to the ZnFe2O4 and CuWO4 samples, respectively. Pseudo-second-order kinetic models could describe well the TC adsorption process, in which chemisorption was the major driving factor, with the maximum adsorption at 23.56 mg g?1. The improved photo-catalytic capability owed to the formation of Z-scheme heterojunctions with ZnFe2O4 and CuWO4, which improved the intensity of visible light absorption and enhanced the separation electron-hole pairs as well as the redox capability of the composite. ZW-40 was high stability as its removal ability of TC in different water conditions slightly dropped about 15% after 5 cycles. ZW-40 could effectively remove TC in different water matrix, its removal ability for 40 mg/L was as follows: super-pure water> municipal wastewater> swine farm wastewater. Hence, the complexation of ZnFe2O4 with CuWO4 provides a valuable strategy to improve the photocatalytic potential for ZnFe2O4-based catalysts as well as providing a promising pathway for water clarification.
查看更多>>摘要：? 2022 Elsevier B.V.The thermoelectric properties and transport mechanism of Cu0.5In0.5Cr2Se4 and its Zn-doped samples were studied. In the middle and low temperature range, the electrical resistivity of Cu0.5In0.5Cr2Se4 decreases and Seebeck coefficient increases with the increase of temperature, indicating the fixed range hopping behavior of Anderson's localization. Two abnormal declines emerge simultaneously in resistivity and Seebeck coefficient at high temperatures, indicating a band regulation by temperature. After slight Zn-doping, the carrier concentration decreases slightly and the carrier mobility increases obviously, realizing electron delocalization. Both of resistivity and Seebeck coefficient decrease with further increasing Zn doping content due to the enhanced carrier concentration, resulting in the improved power factor. The thermal conductivity is extremely low in the pristine Cu0.5In0.5Cr2Se4 and increases with increasing Zn-doping. Due to the significant enlargement of power factor and relatively weak increase of thermal conductivity, the ZT value is enhanced by Zn doping from 0.30 of the pristine sample to 0.40 for the sample with 3.5% Zn doping at 773 K. Moreover, a factor of about 60% improvement of the average ZT is reported on the Zn-doped Cu0.5In0.5Cr2Se4 sample, reaching 0.26 over the temperature range between 323 K and 773 K.
查看更多>>摘要：? 2022 Elsevier B.V.Additive manufacturing (AM) of metallic materials usually results in columnar grains that grow epitaxially along the building direction, which usually results in anisotropy of mechanical properties. This common phenomenon is a severe challenge to the engineering application of AM components. Herein, we use ultrasound to assist the wire and arc additive manufacturing (WAAM) process of Inconel 625 alloy. The results show that ultrasound successfully breaks the growth of columnar grains and promotes the transformation from columnar grains to equiaxed grains. At the same time, the< 001 > orientation texture is eliminated and the grain orientation tends to be a random distribution. The refinement of grain structure significantly increased the YS of Inconel 625 (13.2% and 23.8%) and reduced the anisotropy. In addition, the cavitation effect and convection of ultrasound increased the molten pool temperature and reduced the temperature gradient, which led to a significant decrease in the Nb content in the Laves phase. This exciting result is expected to be applied to alloys that are prone to columnar grains in WAAM.
查看更多>>摘要：? 2022 Elsevier B.V.Cu2?xS nanochains network (NCNW) with tunable diameter in the range of 5–9 nm is prepared by a self-assembly strategy. Control experiments reveal that poly (sodium 4-styrenesulfonate) plays a key role in guiding the assembly of the nanochains. The Cu2?xS NCNW demonstrates a broad localized surface plasmon resonance (LSPR) band in the near-infrared-Ⅱ region, which matches the optical window of biological tissues. The LSPR band of the Cu2?xS NCNW red-shifts and intensifies with the increase of diameter. The Cu2?xS NCNW with an average diameter of 8.7 nm exhibits a high photothermal conversion efficiency of 80.7% under 808 nm laser (0.75 W cm?2). Furthermore, the thermal effect stability of the Cu2?xS NCNW is also good. In vitro experiments demonstrate that all the nanochains possess low cell cytotoxicity. The 8.7 nm Cu2?xS NCNW own the maximum cellular uptake, and can cause> 90% apoptosis rate of Hela cells under low power density laser (808 nm, 0.75 W cm?2), demonstrating its promising application in photothermal therapy.
查看更多>>摘要：? 2022 Elsevier B.V.The resistive switching (RS) characteristics of amorphous Sm2Ti2O7 thin films prepared by using RF sputtering were investigated and the effect of post-metallization annealing (PMA) on the RS properties were analysed. Comparison of as-deposited Sm2Ti2O7 thin film device and the device after PMA treatment, the latter exhibits better RS properties, including more uniform set voltages, switching cycle times and higher Ron/Roff ratio. The prepared samples all revealed bipolar resistive switching (BRS) behaviour. The results indicated that the conductive mechanism in terms of the concentration of oxygen vacancies can be controlled by different deposition atmosphere (Ar/O2) ratio and film thickness. Additionally, the resistive switching properties can be enhanced by PMA treatment due to the formation of AlOx interface layer, which prevents the oxygen ions from out-diffusion through the boundaries. At the PMA temperature of 350 °C, the two resistance states can be distinguished in a range of> 10 over 8099 switching cycles along with a retention of 104 s at room temperature and 85oC, showing promise for non-volatile memory applications.
查看更多>>摘要：? 2022 Elsevier B.V.Owing to sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), it is still challenging to rationally design and construct bifunctional electrocatalysts with high performance, low-cost and good stability to substitute precious-metal catalysts. Herein, we introduce Ni ions to obtain spherical Prussian blue analog (PBA) doped with Co/Fe/Ni and further to synthesize nitrogen and Co/Fe/Ni co-doped carbon nanotubes (denoted as CoFeNi-CNTs) with small diameters (20–30 nm) by pyrolyzing the mixture of melamine and PBA. The optimized CoFeNi-CNTs have abundant metal-nitrogen-carbon (M-N-C) structures and CoFeNi nanoparticles respectively as effective ORR and OER active sites, which lead to outstanding electrocatalytic activities and durability with a half-wave potential of 0.85 V for ORR and an overpotential of 440 mV for OER. Especially, the rechargeable Zn-air battery based on CoFeNi-CNTs catalyst delivers a high peak power density of 138.7 mW cm-2, specific capacity of 793 mAh gZn-1 and stable charge-discharge cycling over 500 h, outperforming the Pt/C-RuO2 based devices. And all-solid-state Zn-air battery also displays excellent discharge-charge performance and stability. This work explores the optimization of oxygen catalytic activity for carbon nanotubes by reducing diameters and constructing dual-active-sites strategy.
查看更多>>摘要：? 2022 Elsevier B.V.Co-modified ZnO (Co@ZnO) nanorods are successfully prepared by hydrothermal synthesis method without secondary pollution. The element distribution, microstructure, crystal plane spacing, and other related parameters of Co@ZnO nanorods are systematically studied by adopting different material characterization methods. It can be concluded that Co nanoparticles are decorated on the outside of ZnO nanorods. Gas sensing tests demonstrate that Co@ZnO sensor has a significant improvement for the detection of n-propanol in response time, response value, and detection lower limit. In particular, the response value of 1 mol% Co@ZnO sensor to 100 ppm n-propanol is 491 at 250 °C, which is about 3 times than the response value of ZnO sensor at 275 °C. The minimum detection limit of 1 mol% Co@ZnO sensor for n-propanol has been reduced to 10 ppb with the response value of 3.14, which has reached the minimum detection limit for n-propanol by contrast with other literature report for the detection of n-propanol. The improvement of gas sensing properties of Co@ZnO nanorods is discussed by its catalytic oxidation of n-propanol, special nanorods morphology, and fermi level shift of ZnO triggered by Co doping.
查看更多>>摘要：? 2022 Elsevier B.V.To effectively boost the dielectric loss, herein, mixed-dimensional Ni foam (NF)/ZnCo2O4 @NiO conductive network heterostructures consisting of three-dimensional (3D) NF, one-dimensional (1D) ZnCo2O4 nanowires and two-dimensional (2D) NiO nanosheets were designed and produced by a simple two-step method. The growth of 1D ZnCo2O4 nanowires on the surface of 3D NF was done by a hydrothermal process, followed by the chemical bath deposition (CBD) of 2D NiO nanosheets. The obtained results indicated that the NiO content in the as-prepared NF/ZnCo2O4 @NiO network heterostructures could be promoted by increasing the CBD time, which improved their specific surface areas. Owing to utilizing the multiple interfaces for enhancing the interfacial polarization, the as-prepared NF/ZnCo2O4 @NiO network heterostructures presented the remarkably enhanced electromagnetic wave absorption performances (EMWAPs) compared to NF/ZnCo2O4 nanowire arrays. Moreover, the EMWAPs of mixed-dimensional NF/ZnCo2O4 @NiO network heterostructures could be further optimized by increasing the NiO content, which was demonstrated to promote the interfacial polarization. Generally, the findings demonstrated that taking full advantage of interface engineering in constructing the mixed-dimensional conductive network heterostructures is a very effective strategy to aggrandize dielectric loss, which provided an efficient and promising strategy to develop the novel and high-efficient microwave absorbers.
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