查看更多>>摘要：? 2022 Elsevier B.V.Herein, we report a facile fabrication of (3-mercaptopropyl) trimethoxysilane (MPTMS) functionalized gadolinium oxide nanoparticles (Gd2O3 NPs) and their application in sensing of L-Cysteine (L-Cys). The main purpose of MPTMS was to restrict the size in 6–8 nm range with better control on the morphology and surface activities of Gd2O3 NPs. Additionally, the electro-catalytic and surface properties of MPTMS@Gd2O3 NPs were explored for the selective and sensitive detection of L-Cys by using cyclic voltammetric (CV), chronoamperometric (CA) and differential pulse voltammetric (DPV) techniques. The as formed sensor displayed a good linear response between 1 and 100 μM and possessed high peak current intensity for electro-oxidation of L-Cys with a detection limit of 30 nM. The scope of the sensor was also assessed in the presence of different interfering species. The outcomes suggested the high stability, reproducibility and electro-catalytic activity of MPTMS@Gd2O3/Au sensor. The applicability of as formed sensor in spiked human urine samples has further increased the potential prospective of developed sensor in biomedical field with good recovery rate.
查看更多>>摘要：? 2022The carbide phase in the coating can enhance the wear resistance, corrosion resistance, heat resistance, and oxidation resistance of the coating. Because the carbide-based coating can increase the service life of metal parts and further upgrade the performance of the substrate, it has been extensively studied by a large number of scientists. The carbide-based coating is widely used as a common surface strengthening technology to improve the substrate. Although a series of achievements have been made, few reviews have been made on improving the properties of carbides-based coatings. In this paper, a series of methods to improve the properties of carbides-based coatings are systematically introduced. In the first part, the necessity of studying carbide-based coatings under the current social development trend is introduced. In the second part, the common carbide coatings are introduced. In the third part, some forms of failure of carbide-based coatings are introduced. In the fourth part, a series of measures to better the performance of carbide coating are put forward. The last is a summary of the carbide coating and the prospect of future development.
查看更多>>摘要：? 2022 Elsevier B.V.The development of large-scale and highly efficiency catalysts towards oxygen reduction reaction (ORR) is of great significance for the wide application of metal–air batteries. In this work, we propose a self-sacrifice template method combined with in-situ composite technique to fabricate a novel configuration of CeO2 quantum dots embedded in hierarchical porous foliaceous N-doped carbon with both mesopores and micropores. The prepared catalyst exhibits prominent ORR electrocatalytic performance with higher half-wave potential, lower Tafel slope, and enhanced durability comparing with the commercial Pt/C catalyst. Furthermore, the Zn-air and Al–air batteries employing the prepared electrocatalysts in cathodes exhibit superior discharge performance with high open circuit voltages of 1.51 V and 1.76 V, and peak power densities of 204 and 458 mW cm?2, respectively, compared to most reported metal–air batteries. The greatly enhanced electrocatalytic performance can be ascribed to the abundant oxygen vacancies, improved redox property of Ce3+/Ce4+ as well as the three-dimensional hierarchical porous structure. This work provides a valuable chance to develop scalable quantum dot level composite catalysts in metal–air batteries.
查看更多>>摘要：? 2022 Elsevier B.V.Environment pollution caused by organics is a global issue, which have attracted much attention in sustainable development of the earth. Photocatalysis is regarded as one of efficient methods to handle this environmental problem. In this work, the g-C3N4/g-C3N5 heterostructures with strong van der Waals junction was proposed, and they showed good performance in removal of antibiotic and organic pollutants. More importantly, after further investigating the enhanced photocatalytic mechanism, PL spectra and photoelectrochemical experiment indicated that the fast charge separation could be attributed to van der Waals junctions and excitation effects between g-C3N4 nanosheets and g-C3N5 nanorods. Various of as-generated reactive oxygen species (ROS) was activated by these above factors in molecular oxygen activation process, which were confirmed by Electron Spin Resonance (ESR) and quenching experiments. Moreover, high photocatalytic stability of this as-prepared g-C3N4/g-C3N5 heterostructures was also presented. This work provides a light prospect in the photocatalyst design and the photocatalytic interface mechanism insight.
查看更多>>摘要：? 2022 The Author(s)High entropy alloys with variable silicon content were prepared by two different methods to determine the influence of the cooling rate and chemical composition on the structure and properties of the alloys. First, the structure of the alloys was investigated using X-ray diffractometry and electron microscopy and compared with M?ssbauer spectra to obtain a comprehensive description of the atom arrangement. The formation ability of the BCC and B2 phases was confirmed. The magnetic properties were examined using a vibrating sample magnetometer and M?ssbauer spectroscopy. The corrosion resistance behavior was studied by electrochemical testing. Our results show that the saturation magnetization tends to decrease with increasing silicon content and that the lowest coercive force was noted for rapidly cooled plates. The highest corrosion resistance in a 3.5% NaCl solution characterizes the AlCoCrFeNiSi0.75 alloy in the form of plates. For which Ecorr and jcorr was equal to ? 0.155 V and 0.17 μA/cm2. The addition of Si led to an increase in the hardness of the ingots and plates. For example, AlCoCrFeNiSi0.75 shows 859 HV for the ingot and 727 HV for the plate.
查看更多>>摘要：? 2022 Elsevier B.V.In order to improve the damping capacity of aluminum matrix composites (AMCs) and overcome the mutual exclusive of strengthening and damping capacity, a new strategy that combined additive manufacturing (AM) and vacuum infiltration process to prepare AMC was developed. The prepared AMC was AlSi10Mg-NiTi lattice structure interpenetrating phase composite (IPC), and its damping capacity was increased by more than 94% and the compressive strength was increased by 100%, compared with those of AlSi10Mg. The mechanism of IPC's high damping capacity is mainly the improvement of interface damping with the combined effects of grain boundary damping and stacking faults (SFs). The mechanism of the effectively improved compressive strength is the continuous three-dimensional interpenetrating phase structure with good interface and the strengthening of SFs and nano-scale Ti7Al5Si12 grains. The present findings may provide an alternative and effective way to obtain multifunctional structure-damping materials.
查看更多>>摘要：? 2022To achieve high device performance and high reliability for the gallium nitride (GaN)-based high electron mobility transistors (HEMTs), efficient heat dissipation is important but remains challenging. Enormous efforts have been made to transfer a GaN device layer onto a diamond substrate with a high thermal conductivity by bonding. In this work, two GaN-diamond bonded composites are prepared via modified surface activated bonding (SAB) at room temperature with silicon interlayers of different thicknesses (15 nm and 22 nm). Before and after post annealing process at 800 °C, thermal boundary conductance (TBC) across the bonded interface including the interlayer and the stress of GaN layer are investigated by time-domain thermoreflectance and Raman spectroscopy, respectively. In the case of as-bonded samples, TBC of the 15 nm Si interlayer (32.4 MW/m2-K) was higher than that of the 22 nm (28.0 MW/m2-K); but after annealing, TBC of the 15 nm Si interlayer (71.3 MW/m2-K) became lower than that of the 22 nm (85.9 MW/m2-K), because the annealing is especially effective for thicker interlayer to improved interfacial TBC. The obtained stress was less than 230 MPa for both before and after the annealing, and this high thermal stability indicates that the room-temperature bonding can realize a GaN-on-diamond template suitable for further epitaxial growth or device process.
查看更多>>摘要：? 2022 Elsevier B.V.This investigation is aimed at obtaining superior electromagnetic wave (EMW) absorbers and we successfully prepared the core–shell-structured Co/C@MoS2 nanocubes comprising Co/C nanocubes tightly coated with uniform MoS2 nanosheets for the first time. The MoS2 nanoshells of the Co/C@MoS2 enabled the optimization of the impedance matching and generation of dipolar polarizations. The Co/C cores also increased the conductivity of the resultant Co/C@MoS2 composites, thus promoting the attenuation ability of the EMW. The synergetic contributions of improved impedance matching and multiple loss mechanisms led to excellent EMW absorption of the Co/C@MoS2. In particular, the reflection loss of the Co/C@MoS2 reached ? 52.76 dB at 8.88 GHz for a 2.5-mm-thick absorber while the effective attenuation bandwidth under ? 10 dB was 3.84 GHz for a 1.5-mm-thick absorber. Accordingly, the prepared Co/C@MoS2 with enhanced absorption performance is a promising absorber and we also proposed a facile design and synthesis strategy for new EMW absorbers in this paper.
查看更多>>摘要：? 2022 Elsevier B.V.Nonlinear optical (NLO) crystals can produce tunable lasers through the direct second-harmonic generation (SHG) process, which is of great significance in modern laser technology. Herein, a new chalcogenide β-PbGa2S4 (1) crystallized in space group of Pna21 was synthesized via high-temperature solid-state reactions. Compound 1 is composed of a three-dimensional framework [Ga8S16]8? with hexagonal voids filled by Pb atoms via covalent Pb–S interactions. Importantly, it exhibits promising NLO performances, such as phase-matchable SHG efficiency (0.6×AgGaS2@1200 nm and 0.1×AgGaS2@1910 nm), moderate band-gap (2.46 eV), suitable laser-induced damage threshold (3.0×AgGaS2), and a broad IR transparency window (0.5–25.0 μm). SHG response of 1 is mainly attributable to the occupied S–3p and Ga–4p states and unoccupied S–3p and Pb–6p states.
查看更多>>摘要：? 2022The work performed highlights the switching mechanism of MoSe2/PVA polymer nanocomposites (PNCs) at different concentrations of MoSe2 nanoparticles in the PVA matrix (1%, 3%, and 4%). The ex-situ approach had been used to synthesize MoSe2/PVA PNCs. XRD spectrum revealed the rise of crystallinity with the presence of MoSe2 nanoparticles in PVA. The bandgap calculated from UV–vis spectroscopy was 2.73 eV (1 wt%), 2.27 eV (3 wt%) and 2.19 eV (4 wt%). The quenching of photoluminescence (PL) spectra revealed an increase in trap states with the addition of MoSe2 while creating oxygen vacancies. FT-IR spectra showed the complete coverage of MoSe2 nanoparticles by PVA. FESEM showed the good dispersion of nanoparticles in the PVA matrix. The third-order non-linear susceptibility (χ(3)) was measured by the Z-scan technique and exhibited the presence of saturable and two-photon absorption phenomenon. An increase in χ(3) verified the rise of electron population density in trap states. The increase in non-linearity indicated the fabrication of a good non-volatile Ag/ MoSe2-PVA/FTO memory device. I-V and WRER cycles were used to examine the electrical switching in a two-terminal memory device. The Ion/Ioff ratio observed in endurance characteristics at 3 wt% concentration is ~9.28 × 102. The findings revealed the prospect of improving memory device performance using MoSe2/PVA PNCs by investigating the dynamics of linear, non-linear, and electrical responses in the material that are trap controlled.
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