查看更多>>摘要：ZnSn(OH) _6/ZnO/BiOBr (ZHS/ZnO/BOB) and ZHS/ZnO/BOB loaded carbon fiber cloth (CFC) (ZHS/ZnO/ B0B@CFC) photocatalysts were successfully prepared by co-precipitation and ultrasonic method. The ultraviolet-visible diffuse reflection (UV-vis DR) spectra showed that the absorption edge of ZHS/ZnO/BOB exhibits red-shift to the visible light region, compared with the ZHS/ZnO. The conduction band position (E_(CB)) of ZHS, ZnO, and BOB were calculated to be - 0.12, - 0.22, and 0.36 eV vs. NHE, respectively, according to the Mott-Schottky (M-S) measurement. ZHS/ZnO/BOB presents flower-like spheres assembled from nanosheets. Brunauer-Emmett-Teller (BET) tested the specific surface areas of ZHS/ZnO/BOB (21.01 m~2 g~(-1)). Based on the photoluminescence spectroscopy (PL) and electrochemical impedance spectroscopy (EIS) analysis, ZHS/ZnO/BOB possesses the strongest ability to inhibit electron-hole pair recombination and the lowest charge transfer resistance, which can be mainly ascribed to the formation of heterojunction among ZHS, ZnO, and BOB. The ZHS/ZnO/BOB exhibits a high photocatalytic degradation activity for rhodamine B (RhB, 97.30%), tetracycline (TC, 83.00%), and levofloxacin (LVX, 74.50%) under 80 min irradiation, respectively. Besides, ZHS/ZnO/BOB@CFC achieved 98.8% removal efficiency towards RhB. Furthermore, high-resolution mass spectrometry (HRMS) revealed the possible degradation pathway of RhB during the photocatalysis process. Based on all the above, an easy approach for rational design of ternary photocatalyst towards the degradation of refractory pollutants was proposed.
查看更多>>摘要：This article reports the significantly improved piezoelectric and ferroelectric properties of Cu/W co-doped Ca_2Bi_2Nb_(2-x)(Cu_(1/4)W_(3/4))_xO_9 (CBNCW-x, where 0≤ x ≤ 0.150) high Curie temperature lead-free piezoelectric ceramics. The crystal structure, microstructure, and electric properties of CBNCW-x ceramics have been systematically analyzed. The results show that ceramic samples have a bismuth layered structure of m- 2, which is a single-phase of CBN. The ceramic grains show the typical plate-like structure of the bismuth layer. Cu/W co-doped CBN ceramics increased the distortion of NbO_6 octahedron, and significantly enhanced the piezoelectric constant and the remnant polarization. When x = 0.075, it shows better comprehensive properties with an excellent d_(33) of 13.8 pC/N, a high remnant polarization of 12.10 uC/cm2, the Tc of 918 °C, a dielectric loss value of 0.57%, and the Ωm value of 7099. Moreover, CBNCW-0.075 ceramic simple maintains the d_(33) of 12.7 pC/N after annealing 900 °C for 30 min, which shows good high-temperature stability. It suggests that the Cu/W co-doped CBN ceramics have good application prospects in the high-temperature piezoelectric field.
查看更多>>摘要：A novel temperature stable (l-x)MgZr_(0.85)Sn_(0.15)Nb_2O_8-xBa_3Ti_4Nb_4O_(21) -2wt% BaCu(B_2O_5) (MZSN-BTN-BCB, x = 0.12, 0.14, 0.15, 0.16, 0.18 in molar) composite ceramic was fabricated via a conventional solid-state reaction method. MZSN and BTN phase can coexist in the sintered ceramics due to the different crystal structures from the results of X-Ray diffraction and scanning electron microscopy. The sintering temperature and phase composition are especially relevant to the microwave dielectric properties. The optimal sintering temperature of MZSN-BTN ceramics was successfully reduced to 1125 °C due to the formation of BCB liquid phase. The temperature coefficient of the resonant frequency was successfully adjusted to near zero by adding an appropriate amount of BTN due to its opposite-sign τf value. Excellent microwave dielectric properties of er = 33, Q×f= 53,950 GHz (at 6.079 GHz), τf = -4.3 ppm/°C were obtained in 0.88MZSN-0.12BTN-2 wt% BCB composite ceramics when sintered at 1125 °C for 4 h.
查看更多>>摘要：Rational design of metal oxide heterostructures is of great importance for gas sensors to be applicable in the detection of inflammable, explosive and toxic gases. Herein, we designed CuO/In_2O_3 heterostructures with flower-like structures via a highly efficient one-step hydrothermal technique and constructed optimal structures to improve formaldehyde sensing properties. Consequently, the obtained 7-CuO/In_2O_3 flowerlike structures with uniform p-n heterostructure and a large quantity of oxygen vacancies exhibits the best sensing properties for detecting formaldehyde. The corresponding response value is 11.67-10 ppm formaldehyde at a low operating temperature of 100 °C, which is approximately 2.97 times higher than that of pure ln_2O_3 sensor (3.93 at 200 °C). Besides, the 7-CuO/In_2O_3 sensor also exhibits good reproducibility and stability, sub-ppm-level detection limit (1.38-0.5 ppm), high selectivity, and outstanding long-term stability, which benefits from the synergistic effect of strong oxygen adsorption capacity, p-n heterojunction between CuO and ln_2O_3, catalytic effect of CuO, and the unique flower-like structures, showing the great potential for practical formaldehyde detection.
查看更多>>摘要：The cylindrical Sn: β-Ga_2O_3 crystal with high crystalline quality was successfully designed and grown by the innovative edge-defined film-fed growth (EFG) method equipped with a cylindrical Iridium die. The challenges for the growth of Sn: β-Ga_2O_3 crystals were overcome by optimizing the design of an afterheater. The growth morphology of cylindrical β-Ga_2O_3 crystal was studied using a theoretical model and the results from experimental crystal growth. The order of importance of growth conditions affecting β-Ga_2O_3 crystal growth morphology was examined, based on the morphological features of cylindrical β-Ga_2O_3 crystals obtained by the EFG and Czochralski methods. The iridium inclusions with three shapes were observed in bulk β-Ga_2O_3 crystal, and the formation mechanism was carefully discussed. The optical bandgap and valence band maximum (VBM) of Sn: β-Ga_2O_3 crystal were calculated to be 4.74 eV and 3.49 eV by absorption spectra and X-ray photoelectron spectroscopy (XPS), respectively. The corresponding surface barrier height (φ_(surf)) was 1.25 eV. The carrier concentration of 5.95× 10~(18) cm~(-3) was characterized by capacitance-voltage (C-V) measurement. By the Hall measurement, the carrier mobility and resistivity were estimated to be around 51 cm~2 V~(-2) s~(-1) and 3.55 ×10~(-2) Ω cm, respectively.
查看更多>>摘要：Rotary swaging (RS), as a widely used industrial method for severe plastic deformation (SPD), is a near net forming process which uses high-speed pulse hammer of multi-hammer to process solid shaft parts or hollow variable cross-section forgings. Initially RS is mainly used to manufacture difficult-to-deform metals with poor plasticity (such as W and Mg alloys, etc.). Recently, because RS process can enable large hydrostatic stresses and facilitate the accumulation of large strain, it is also allowing for high-throughput mass production of different metals with enhanced mechanical properties. This paper first introduces the RS working principle and unique characteristics, then systematically summarized the microstructural characteristics (grain size, texture, etc.), mechanical properties (such as strength, ductility, etc.), physical and chemical properties of various ultrafine grained metals prepared by RS, finally compares the advantages and disadvantages of swaging with other deformation methods, and looks forward to the future development and application fields of rotary swaging.
Reda M. AbdelhameedMahmoud El-ShahatMahmoud A. Abd El-Ghaffar
14页
查看更多>>摘要：Metal-organic frameworks (MOFs) have shown a great potential for producing efficient and eco-friendly photocatalysts. Furthermore, phthalocyanines (PCs) are promising materials in photocatalytic reactions because of their unique adsorption and photosensitizing properties. Here, three phthalocyanines (Pcs) derivatives with Al~(3+) and Co~(2+) ions as the central metal were prepared to attach them to the MOFs matrix. The photocatalytic decay performance of methylene blue (MB) and methyl orange (MO) and their mixtures were investigated under visible light illumination. The photocatalyst NH_2-MIL-125, Al-PcCl@NH_2-MIL-125, CoPc@NH_2-MIL-125, and CoPcPA@NH_2-MIL-125 show 0.01, 0.012, 0.035, and 0.046 min~(-1) MB degradation rate, respectively, while, the degradation rates of MO were 0.021, 0.027, 0.052 and 0.082, respectively. Amazingly, the degradation rates of MB in presence of MO showed boosted photocatalytic decomposition with the degradation rate of 0.066, 0.069, 0.085, and 0.120 min~(-1), respectively. This study illustrates a high performance for utilizing porous MOF-based materials not only as supports but as electron acceptors that enhance both photostability and photocatalytic activity.
查看更多>>摘要：Spinel metal oxides, prepared at high temperature, have shown excellent gas sensing properties among metal oxide sensing materials. Herein, a series of porous spinel gallate nanospheres, including CdGa_2O_4, NiGa_2O_4, CoGa_2O_4, CuGa_2O_4, ZnGa_2O_4, and MgGa_2O_4 were prepared by solvothermal method and followed low temperature calcination. XRD, SEM, XPS and N_2 adsorption-desorption have been carried out to determine their structure, morphology, chemical state and surface area, respectively. These nanospheres are all composed of tiny nanoparticles, giving meso-porous characters. Furthermore, the sensor based on CdGa_2O_4 exhibits excellent formaldehyde sensing performance, including good selectivity, short response time, and excellent stability at the low working temperature of 120 °C.
查看更多>>摘要：Colloids consisting of the CoCrCuFeNi high-entropy alloy nanoparticles in ionic liquid with the l-butyl-3-methylimidazolium ([BMIM]~+) cation and the tetrafluorborate ([BF4]~-) anion were obtained by the DC magnetron sputtering of high-entropy alloy target in vacuum, onto the surface of [BMIM.BF4] ionic liquid. The method of the nanoparticle colloid preparation is based on negligibly small vapour pressure of the ionic liquid, which allows its application in vacuum. The high-entropy alloy nanoparticle colloids were studied by HRTEM microscopy and SQUID magnetometry. Results of the structural and magnetic analyses show that the colloids contain ultra-small single-crystalline nanoparticles of an uneven shape and typical size of (2-3) nm. The nanoparticles have relatively narrow size distribution which is typical for this preparation method. The high-entropy alloy nanocolloids show complex magnetic properties that are a function of temperature, applied magnetic field and mass content of the nanoparticles in the colloids. The obtained results imply significant magnetic interactions between the ionic liquid and the high-entropy alloy nanoparticles.
查看更多>>摘要：Compared with single-component electrode materials, multi-component composite materials are more capable to promote the electrochemical performance of electrode materials because of the synergistic effect of different components. In this work, a binary FeOOH/Fe_2O_3 composite is fabricated by a facile and low-cost hydrothermal method with FeCl_3*6 H_2O and C0(NH_2)_2 as raw materials. The microstructure and composition of the as-prepared sample is characterized by XRD, SEM, TEM, FT-IR, and XPS. The electrochemical performance of the binary FeOOH/Fe_2O_3 composite is investigated by CV, EIS, charge-discharge test, and GITT measurement. Compared to single-component FeOOH or Fe_2O_3, this binary FeOOH/Fe_2O_3 composite exhibits outstanding high-rate capability (645 mA h g~(-1) at 1 A g~(-1)) and superior long-term cycling stability (779 mA h g~(-1) after 300 cycles at 0.5 A g~(-1)) due to the synergetic effect between FeOOH and Fe_2O_3. EIS analysis reveals that the electrochemical reaction resistance in binary FeOOH/Fe_2O_3 composite is lower than that in single-component FeOOH or Fe_2O_3. CV analysis demonstrates that the binary FeOOH/Fe_2O_3 composite has a certain pseudocapacitive behavior during discharge and charge processes. The lithium ion diffusion coefficient of the binary FeOOH/Fe_2O_3 composite derived from GITT data ranges from 4.0 ×10~(-12) to 1.0 × 10~(-14) cm~2 s~(-1). Ex-situ SEM observations revealed that the binary FeOOH/Fe_2O_3 composite has good structural integrity upon cycling, which partially accounts for the superior electrochemical performance of the electrode. The reported method could provide a facile avenue for the ingredient design of high-performance anode materials for next-generation lithium-ion batteries (LIBs).
NSTL
Elsevier