查看更多>>摘要：? 2022 Elsevier B.V.The core@shell structures and compositions hold greatly potential for microwave absorption. Herein, the Fe3O4@1T/2H-MoS2 nanocomposites with core@shell structures were successfully fabricated through a simple hydrothermal process. The impedance matching was significantly promoted by introducing magnetic Fe3O4 nanoparticles and designing the flower-like 1 T/2 H-MoS2 with core@shell structures. It can be seen that the regulation of Fe3O4 contents play an important role in electromagnetic parameters and microwave absorption performances of the Fe3O4@1T/2H-MoS2 nanocomposites with core@shell structures. The Fe3O4@1T/2H-MoS2 nanocomposites with core@shell structures with corresponding thickness of 2.67 mm display the minimum reflection loss (RLmin) value of ? 56.22 dB at 10.36 GHz (in X band), and the maximum absorption bandwidth (ABmax) extend up to 4.76 GHz with thickness of only 1.89 mm. This result is of great significance for improving microwave absorbing performance, and the nanocomposites can be regarded as candidates for high-quality absorbing materials.
查看更多>>摘要：? 2022 Elsevier B.V.Bi4O5Br2 has received considerable interests for energy conversion and environment remediation in recent years. Fabrication of oxygen vacancies (OVs) is effective to improve the photocatalytic activity of Bi4O5Br2. However, OVs are instable and easy to deactivate during continuous photocatalytic process. In this paper, Bi4O5Br2 modified by metal Bi and OVs (Bi-OVs-Bi4O5Br2) have been prepared to improve the stability of OVs and the photocatalytic activity in H2 evolution. Bi-OVs-Bi4O5Br2 exhibited excellent photocatalytic activity with a H2 evolution rate of 67.9 μmol·g?1·h?1, which was 2.1 times higher than that of pure Bi4O5Br2. The enhancement may be attributed to the narrowed band gap, facilitated separation of photogenerated charge carriers, increased adsorption sites for H2O and reduced H2 adsorption energy on the surface of Bi4O5Br2. Notably, the metal Bi could act as reactive sites to activate H2O, so as to avoid OVs to be filled with H2O. As a result, Bi-OVs-Bi4O5Br2 exhibited high photocatalytic stability in continuous test. Results from this study clarified the intrinsic functionality of metal Bi and OVs in Bi4O5Br2 and provided new insights into rational design of highly-efficient Bi-based photocatalyst.
查看更多>>摘要：? 2022 Elsevier B.V.A comprehensive analysis of the phase constituent, microstructure and mechanical/damping properties of Fe3Cr2NiCuAlx (x = 0, 0.125, 0.25, 0.5) alloys by tuning the Al mole ratio is presented in the paper. The results show that the phase constitutions of the alloys are the face centered cubic (FCC) and body centered cubic (BCC) phases and the volume fractions of the two phases are changed with the Al content. For the alloys with the Al mole ratios of 0 and 0.125, the FCC phase predominates as the matrix and the FCC2 nanoparticles are precipitated in the matrix, while for the alloys with the Al mole ratios of 0.25 and 0.5, the BCC phase predominates as the matrix and the B2 nanoparticles are precipitated in the matrix. The highest damping capacity of 0.056 was found for the Fe3Cr2NiCuAl0.25 alloy with 70.1 vol% of the BCC phase in the form of the dendrites and 29.9 vol% of the FCC phase in the form of the interdendrites. This alloy also has a high yield strength of 1069 MPa with the plastic strain being over 50% without fracture under compression.
查看更多>>摘要：? 2022 Elsevier B.V.One-dimensional hierarchical porous carbon nanofibers (CNFs) embedded with Co3O4 nanoparticles in a hollow channel (PPMCo) are fabricated by coaxial electrospinning followed by thermal treatment. The degree to which the CNF surface is exposed to Co3O4 nanoparticles was controlled by the cobalt(II) acetate concentration. The well-controlled structure of PPMCo with porous structure, heteroatoms, and amorphous Co3O4 nanoparticles provided fast ion transport and large reaction surface area, resulting in effective ion migration to the active site and a high rate capacity of the electrode. Benefitting from the unique structure, the PPMCo supercapacitor electrodes displays a high specific capacitance of 188 Fg?1 at 1 mAcm?2, rate capability of 82% when the current density is increased from 1 to 20 mAcm?2, and cycling stability of 93% for 10,000 cycles. The good capacitive performance of the PPMCo electrode is attributed to the synergistic effect of the hierarchical porosity, electroactive material of Co3O4, high effective surface area, and polar effects by heteroatoms.
查看更多>>摘要：? 2022 Elsevier B.V.PVDF@TiO2 NPs hybrid membranes with different hybrid modes were fabricated. The chemical structure, surface characteristic features and optical properties of the hybrid membranes were characterised. The effects of different hybrid modes on photocatalytic performance are discussed for the first time. The results indicated that the membrane with both chemical bonding and coordination between TiO2 NPs and polymer matrix showed the best photocatalytic performance. Furthermore, the aggregation tendency of TiO2 NPs on the hybrid membrane surface was effectively suppressed and the band gap of TiO2 NPs was significantly reduced. The photogenerated electron-hole recombination rate was significantly decreased by the strongly electronegative fluorine (F), carboxyl and ester groups. Additionally, the negatively charged carboxyl groups on the surface of hybrid membrane facilitated the adsorption of methylene blue (MB) dye and promoted the adsorption-photocatalytic degradation of the MB. The photocatalytic degradation efficiency (η) of MB was higher than 95.4% and the η remained greater than 90% after 5 recycling cycles. Compared with membranes prepared by dip coating or blending, the grafted membrane exhibited higher degradation efficiency and improved recyclability. Therefore, this membrane provided a simple method for preparing stable hybrid membranes with better photocatalytic performance.
查看更多>>摘要：? 2022 Elsevier B.V.Manganese and europium doped zinc sulphide (Mn2+/Eu3+@ZnS) quantum dots (QDs) were prepared via direct aqueous route in order to broaden tunable emission. We report a new strategy featuring enhanced photoluminescence through Mn2+/Eu3+@ZnS QDs leading to an intense orange-red emission and thus remarkably enhancing PL QY up to 41.35%. The X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) studies revealed the cubic crystalline structure with average crystalline sizes in the range of 1.5–2.5 nm. The Mn2+/Eu3+@ ZnS QDs was applied as an exceptional chemical sensor for Cu2+ via quenching mechanism due to competitive coordination between QDs and Cu2+ with the limit of detection (LOD) of 0.036 μM. Furthermore, the proposed approach is capable of detecting Cu2+ in water samples with satisfactory recoveries highlighting viability and prospective applications of the sensing platform. We finally demonstrate from CIE Chromaticity diagram that doped QDs show meliorated colorimetric properties which render this new class of QDs a promising prospect to be employed in white LEDs.
查看更多>>摘要：? 2022 Elsevier B.V.The thermal and athermal influence of electric current on dislocation motion is the fundamental mechanism for the electroplastic effect in different metals. Due to the significant scale difference between dislocation evolution and macroscopic deformation, it is difficult to figure out how the electric current affects the dislocation motion and further leads to the macroscopic electroplastic behavior since several interweaving mobile and immobile dislocations are involved. As a macroscopic manifestation of the interaction between dislocations and interstitial atoms, the Portevin–Le Chatelier (PLC) effect provides a satisfying entry point for solving the above problems by connecting the microscopic dislocation mechanism to the macro-scale electroplastic effect in a straightforward manner. Experiments of Al6061 in the tensile process show that the introduction of current causes two opposite effects, i.e., an increase of the pinning strength and a reduction of the time for dislocations to escape from pinning. Further microscopic characterization reveals that the reasons for the above phenomena include two aspects: (1) Promotion of the dissolution of the precipitated phase and increases in the concentration of interstitial atoms in the system. (2) Promotion of the motion of dislocations and the activation of additional slip systems. Those changes are closely related to the thermal and athermal effects of the current. Based on the observation results in this paper, the contradictions in the existing literature can be well explained.
查看更多>>摘要：? 2022 Elsevier B.V.Rapid and efficient detection of acetone gas at room temperature is of great importance for non-invasive screening of diseases as well as environmental and industrial safety. In this work, we have demonstrated a resistive room temperature acetone gas sensor based on molybdenum disulfide (MoS2)-copper oxide (CuO) nanocomposites. The morphological and structural characteristics, crystalline nature, and attachment of CuO nanoparticles on MoS2 nanosheets were investigated using various standard material characterization techniques. The sensing properties of the MoS2-CuO nanocomposite sensor were investigated systematically by exposing to various acetone gas concentrations. It was found that the sensor showed excellent response towards acetone with high sensitivity and fast response and recovery time with a detection limit of 93 ppb. Furthermore, the sensor also showed good repeatability, reproducibility and stability, and portended enormous potential for acetone gas monitoring in the fields of health care, environmental, and industrial applications. The probable sensing mechanism of the MoS2-CuO nanocomposite based acetone sensor has been discussed in detail.
查看更多>>摘要：? 2022 Elsevier B.V.In recent years, chiral organic-inorganic hybrid metal halides have attracted more and more attention from researchers. However, most chiral metal halides are based on toxic Pb elements. In this work, we first successfully prepared a pair of lead-free manganese-based metal halide enantiomers (R/S-1-PPA)2MnBr4 (R/S-1-PPA=R/S-1-Phenylpropan-1-amine). Under the excitation of 365 nm UV light, (R/S-1-PPA)2MnBr4 exhibited bright green emission, which can be attributed to the spin-forbidden d-d transition of Mn2+. In addition, the decay lifetimes were as high as 32.57 μs and 33.60 μs for (R-1-PPA)2MnBr4 and (S-1-PPA)2MnBr4, respectively. (R/S-1-PPA)2MnBr4 showed notable circular dichroism (CD) signals and displayed highly efficient circularly polarized photoluminescence (CPPL) at room temperature with the large glum of ? 0.01 and 0.008, respectively. The high glum enables them to be a series of very promising materials for the development of chiral optoelectronic devices based on chiral hybrid metal halides. Finally, the white LED device constructed with (R-1-PPA)2MnBr4 also showed a wide color gamut, as high as 107% of NTSC, and a “warm” white light-correlated color temperature of 6883 K, which indicated it has good competitiveness in the application of white light LED devices.
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