查看更多>>摘要：? 2022 Elsevier B.V.Gallium Oxide (Ga2O3) exhibits great potential in photocatalysis due to its strong redox capability. Nevertheless, working in the deep ultraviolet region and having a high recombination rate limit its application. Using magnesium powder as the reducing agent, colored Ga2O3 with different oxygen vacancy concentrations was prepared by a high temperature solid state reduction method. It is found that the band gap of Ga2O3 is related to the concentration of oxygen vacancy, which can be controlled by reducing agents. Under 30 min of simulated solar light irradiation, black Ga2O3 displays 86.2% degradation efficiency over Rhodamine B dye, which is about two times more than that for the white Ga2O3. Furthermore, after irradiation by the visible light for 120 min, the photocatalytic degradation efficiency of RhB dye for black Ga2O3 increases to approximately 40.6% (26.3% for white Ga2O3). Enhanced separation efficiency of the photogenerated carriers and local absorption of visible light are the main reasons for improved photocatalytic degradation efficiency. A novel method for studying Ga2O3 and semiconductor oxides is established by the preparation of colored Ga2O3.
查看更多>>摘要：? 2022 Elsevier B.V.In this study we investigated the nature and stability of the interfaces between Mg2.05Si0.98Bi0.02 as the TE material and Ni and Mg50Si15Ni50 as barriers. Single-leg devices of Ni/TE/Ni and Mg50Si15Ni50/TE/Mg50Si15Ni50 were prepared by the SPS process in one step and were then subjected to different aging conditions. Using Mg50Si15Ni50 as barrier provided a more stable interface with no evidence of an interaction layer. This contrasted with the case when Ni was used as a barrier. The efficiency, η, and the power output, Pout, were higher when Mg50Si15Ni50 was used as a barrier. The Ni/TE/Ni and Mg50Si15Ni50/TE/Mg50Si15Ni50 devices were aged at 673 K for up to 480 h under vacuum and an Mg vapor. For the Mg50Si15Ni50/TE/Mg50Si15Ni50 device, the Seebeck coefficient, the efficiency, and power output showed no change with aging time when aging was carried out under in an Mg vapor. The present observations showed that a stable interface can be attained when Mg50Si15Ni50 is used as a barrier for the Mg2.05Si0.98Bi0.02 TE material.
查看更多>>摘要：? 2022 Elsevier B.V.Ni3S2 materials were innovatively in-situ grown on nickel foam by the one-step reflux method. Then, a polymer PPy conductive film was successfully coated on the surface of Ni3S2 materials by electrodeposition to prepare the self-supporting Ni3S2@PPy composites on nickel foam. The content of PPy on the surface of Ni3S2 materials was controlled by changing the number of cyclic voltammetry cycles in the electrodeposition process. Ni3S2@PPy has presented the best lithium storage performance when the number of cyclic voltammetry cycles is 1. After 100 cycles (50 mA g?1), the discharge capacity remained at 396.5 mAh g?1, and the charge transfer impedance decreased with the reaction. After PPy coating on the surface of Ni3S2 material, the problem of the rapid decline of Ni3S2 electrode capacity after 50 cycles was significantly improved, and enhanced the stability of the late cycle.
查看更多>>摘要：? 2022 Elsevier B.V.Exploration visible-light-driven photocatalyst is imperative to resolve energy crisis. Hollow structure photocatalyst has attracted increasing attention due to its large surface area can greatly facilitate light harvesting and enrich the reaction sites. Based on this, a hollow core-shelled composite photocatalyst of Zn0.5Cd0.5S and copper phthalocyanine (CuPc) was synthesized by facile solution method. Under visible-light irradiation (λ > 400 nm), the as-prepared CuPc/Zn0.5Cd0.5S photocatalyst exhibits eminent hydrogen evolution up to 29.16 mmol/g·h without noble metal co-catalyst modification, which was 3.5 times higher than pristine hollow Zn0.5Cd0.5S nanoflower (8.42 mmol/g·h). Meanwhile, the lifetime of photo-carriers prolongs from 0.765 s (Zn0.5Cd0.5S) to 1.05 s (CuPc/Zn0.5Cd0.5S-4%) based on open-circuit potential calculation, and the apparent quantum yield reaches 6.95% at 400 nm wavelength. In addition, the photocorrosion of Zn0.5Cd0.5S phase dissolution is greatly restrained, ascribing to p-type CuPc with merits of fast holes transfer and high chemical stability. These results indicate that CuPc/Zn0.5Cd0.5S heterojunction possesses excellent visible-light absorption capacity and superior photocatalytic hydrogen evolution property. This study presents new insights for designing core-shelled hollow photocatalyst based on organic-inorganic nanoarchitectonics, which displays countless potential for future green energy harvesting.
查看更多>>摘要：? 2022 Elsevier B.V.The carbon-based hole transport layer-free (HTL-free) PSCs show promising potential for commercialization stemming from the economy and chemical inertia of carbon electrodes. While the huge energy barrier between the perovskite layer and carbon electrode results in severe energy loss and poor stability simultaneously. Herein, 2D perovskite as a passivation layer is successfully constructed with the help of 3-chlorobenzylamine (3Cl-BA), which is anchored on the surface of methylamine lead iodine (MAPbI3) perovskites by forming NH–I hydrogen, forming Cl–I bond and filling the halide vacancies, thereby suppressing the energy loss and protecting perovskites from moisture ingress. Detailed experimental characterizations prove that the 3Cl-BA passivation layer could optimize energy level and prolong the carrier lifetime of the perovskites. As a result, a gratifying power conversion efficiency (PCE) of 13.22 % is obtained for carbon-based HTM-free PSCs based on the 3Cl-BA treated MAPbI3 perovskite by optimizing the post-treatment conditions. What's more, owing to the existence of the hydrophobic 2D structure, the unencapsulated PSC exhibits better long-term moisture stability. It remains at 95 % of the original PCE after aged under the environment of the nitrogen for 800 h. This post-treatment based on 3Cl-BA provides a bright road to preparing efficient and stable PSCs via forming 2D/3D perovskite structures.
查看更多>>摘要：? 2022 Elsevier B.V.Choosing Two-Dimensional (2-D) layered semiconductor material MoS2 as the insulator, FeSiAl/MoS2 composites were synthesized by mixing MoS2 and aerosolized FeSiAl in a certain mass ratio. The structure, morphology and magnetic properties of FeSiAl/MoS2 composites were measured by XRD, SEM, XPS, VSM and B-H analyzer. The SEM results show that high-speed ball milling breaks the binding of weak Van der Waals force between MoS2 layers, and nano-thick MoS2 micron flakes wrapped on the FeSiAl spherical surface. The results of magnetic properties show that not only the FeSiAl/MoS2 composite achieves a higher magnetic permeability due to the thin MoS2 flakes clinging to the FeSiAl particle surface, but also the eddy current between the metallic particles is blocked, resulting in a great reduction of eddy current loss. The permeability results show that the relaxation frequency of FeSiAl/MoS2 composites exceeds 1 MHz, which is suitable for application at high frequency. The magnetic loss of FeSiAl/1 wt%MoS2 composite reaches 454kWm?3 under the condition of f= 0.1 MHz and B= 0.1 T, which is about three quarters of that of FeSiAl soft magnetic composites for commercial application.
查看更多>>摘要：? 2022 Elsevier B.V.In the present work, the effects of Gd on hot tearing susceptibility (HTS) of as-cast Mg96.94-Zn1-Y(2?x)-Gdx-Zr0.06 (x = 0, 0.5, 1, 1.5, 2 at%) alloys reinforced with long-period stacking ordered (LPSO) phase was studied. The HTS of the alloys was predicted and confirmed by differential thermal analysis system and hot tearing test system, respectively. Based on the cooling curves, shrinkage stress curves and microstructure evolution observed by SEM, TEM and EBSD, the hot tearing mechanism of the alloys was explored. The results showed that the HTS of Mg96.94-Zn1-Y(2?x)-Gdx-Zr0.06 alloys significantly decreased with the increasing of Gd content. When Gd content was 0.5 and then increased to 1 at%, the decrease in HTS of the alloys was attributed to the combined effects of grain refinement and increased secondary phase amount. When Gd content increased to 1.5 and then to 2 at%, the grain size of the alloys increased instead, and the HTS continued to decrease. This was attributed to the increase of pinning effect of LPSO phase and the increase of residual liquid feeding capacity caused by the increase of precipitation amount of the secondary phase. The combined effects of the two made up for the negative effects of grain coarsening. In Mg96.94-Zn1-Gd2-Zr0.06 alloy, the amount of LPSO phase was the most, and the pinning effect on grain boundaries was the strongest. The intergranular bridges composed of LPSO phase hindered the initiation and propagation of hot tearing, thus, the alloy had the lowest HTS.
查看更多>>摘要：? 2022 Elsevier B.V.The AlCoCrFeNi high entropy alloy (HEA) has been regarded as a potential candidate for refractory material due to its uniqueness, and its brittleness can be tuned by heat treatment. In this work, we propose a new heat treatment process to tailor the phases of AlCoCrFeNi HEA, and reach the optimum trade-off of strength and ductility. The results show that normalizing treatment in air can be used to instead of quenching in water to obtain the same phase composition and even better performance of AlCoCrFeNi HEA, then avoiding the shortcomings of quenching, reducing production costs, improving production efficiency and expanding its application prospects. The detailed phase compositions and required temperature of normalizing treatment are B2 + BCC (as-cast) → B2 + BCC + little FCC + little σ (700 °C) → B2 + BCC + FCC + σ (900 °C) → B2 + BCC + little FCC (1100 °C) → B2 + BCC (1300 °C). The 1100 °C treated alloy has the highest ultimate compressive strength (3429 MPa) and compression ratio (33.6 %), and reaches the best strength-ductility trade-off due to its special phase composition and microstructure.
查看更多>>摘要：? 2022 Elsevier B.V.0.5–5 % (atom percent) Nd3+-doped SrF2 transparent ceramics were fabricated by hot-pressed sintering and the effects of Nd3+ doping content on microstructure and spectral properties were studied. With Nd3+ content increased from 0.5 % to 5 %, in-line transmittance of Nd:SrF2 ceramic at 1060 nm increased from 15.8 % to 85.3 %. FE-SEM micrographs showed the grain growth was inhibited and the microstructure became more compact and homogenous. Emission spectra revealed that concentration quenching was occurred at Nd3+ content of 1–2 %. Emission lifetime of 4F3/2 energy level monotonously decreased from 1805.4 μs to 19.6 μs. Evolution profiles of emission intensity and lifetime of Nd:SrF2 transparent ceramic with Nd3+ doping content were proposed. The appropriate Nd3+ content for spectral properties of Nd:SrF2 transparent ceramic was found around 1 %. The results demonstrated Nd:SrF2 transparent ceramic has large emission lifetime and mild concentration quenching effect, indicating that Nd3+-doped SrF2 transparent ceramics could be more promising gain media for all-solid-state lasers than other Nd3+-doped alkaline-earth fluorides.
查看更多>>摘要：? 2022 Elsevier B.V.Metal-organic frameworks (MOFs) with tunable nano-micro structures ikhas been widely employed on developing electromagnetic wave (EMW) absorption materials (MAMs). However, the electromagnetic (EM) response and EMW absorption mechanism of heterogeneous metallic MOFs derivatives have not been systematically studied. In this work, a series of Ag/ZnO@C hybrid materials with metal-semiconductor heterostructures were prepared by using ZIF-L with adjustable cation exchange. As Zn2+ is replaced by Ag+, the structure of ZIF-L changes gradually, which determined the crystal and structure of Ag/ZnO@C hybrid materials. Finally, the minimum reflection loss (RLmin) of the product obtained at 60 ℃ reached ? 37.13 dB at 3.0 mm, and the maximum absorption bandwidth (fE) reached 6.8 GHz at 4.0 mm (loading content = 33 wt%). Therefore, this work can provide guidance for the design of hybrid structural MAMs by phase transformation MOFs.
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