查看更多>>摘要：? 2022 Elsevier B.V.Refractory high-entropy alloys (RHEAs) hold far reaching application potential in high temperature structural materials fields due to their high melting points and excellent softening resistance. However, the trade-off between strength-ductility and oxidation resistance of RHEAs has become a critical problem for their processing and application. In this work, we reported a strategy to enhance ductility of NbNiTaTi RHEA by applying the eutectic reaction of NiTi shape memory alloys. Experimentally, NbNiTaTi RHEA exhibited BCC phase and eutectic structure composed of IM phase and NiTiB2 phase. The RHEA showed a compressive strength of 2140 ± 30 MPa and a compressive plastic strain of 34 ± 2% at room temperature. Actually, the ultrafine eutectic structure with ductile NiTiB2 phase and hard IM phase could greatly enhance the ductility of NbNiTaTi RHEA while ensuring its strength. Meanwhile, The BCC phase with high solidification temperature remedied the weakness of high temperature stability of RHEA after adding non-high melting point elements. Besides, NbNiTaTi RHEA showed good corrosion resistance and its passive film remained stable across a wide range of potential. These results provided theoretical guidance for the application of ductile phase in RHEA field.
查看更多>>摘要：? 2022 Elsevier B.V.Herein, innovative visible-light-driven nano-photocatalysts for accelerated-activation of H2O2 and persulfate (PS) are explored towards degradation of ionic-dyes from wastewater. Highly-defective yttria-layers (D-Y2O3) are customized and used for stabilization of ZnO and Sm-doped ZnO (Sm-ZnO) nanoparticles. Comparing to ZnO@D-Y2O3, Sm-ZnO@D-Y2O3 nanocomposite possesses advanced surface-area and porosity with significant surface-heterogeneity, elevated negatively-charged nanoparticles (ζav = ?36.3 mV), large populations of oxygen vacancies, and enhanced visible-light absorptivity. PS-activation over visible-light-driven Sm-ZnO@D-Y2O3 photocatalyst (Sm-ZnO@D-Y2O3/PS/Vis) displays superior degradation efficiency (~100 %) of isosulfan-blue, Bismarck-brown, and methylene-blue dyes within 10 min, near-complete mineralization performance, and great cyclability. Such excellent photodegradability results from (i) synergistic combination of nanocomposite-PS-visible light, yielding highly-developed synergy-index values (SI = 3–20), (ii) abundant generation of reactive-oxidizing-species (SO4?-/h+/?OH synergistic ratio 1:1.8:1.9), and (iii) facilitated transference of photoexcited-electrons across oxygen vacancies in yttria-moiety, prohibiting electron-hole pairs recombination. Hence, Sm-ZnO@D-Y2O3/PS/Vis system is an extraordinarily candidate for complete destruction of organic-pollutants via newly photocatalytic-mechanism, whatever it treats it degrades.
查看更多>>摘要：? 2022 Elsevier B.V.Molten salt synthesis is a facile, extensible and effective way to obtain specific electrode materials with in situ carbon coating. Herein, a carbon coating Mo6S8 compounds were synthesized based on molten KCl medium, and the excellent electrochemical Mg-storage performance were demonstrated in rechargeable Mg ion batteries. Benefiting from the in situ carbon coating, the as-synthesized Mo6S8 @C delivers a high reversible capacity of 90 mAh g–1 and a superior rate performance. Further mechanism investigation via kinetics testing, ex situ XRD and XPS demonstrate that the carbon coating layer on the surface of Mo6S8 could accelerate the electron/ion transport and improve the rate performance and stability of the electrodes. This work provides a possible way to large-scale fabrication of the carbon coating Mo6S8 and lays a foundation for the practical applications of Mg ion batteries.
查看更多>>摘要：? 2022 Elsevier B.V.A hybrid metal-semiconductor can be utilized as an attractive photocatalyst which demonstrates unique synergistic properties stemming from the materials combination. One of the essential advancements is precisely controllable for each geometrical factor in metal and its semiconductive support. Herein, we synthesized Sr0.9Ti0.9Ru0.1O3-δ (STRO) fibers by the electrospinning method and tailored the morphology by in-situ exsolved Ru nanoparticles (NPs). Thus, a metal-semiconductor heterostructure is formed. The hierarchical Ru-STRO catalyst manifested a remarkable enhancement of solar-assisted photocatalytic activity with a 5-fold increase in hydrogen evolution rate, attributed to enhanced charge separation, reaction sites, and light absorption. Theoretical simulations and Kelvin probe force microscopy (KPFM) explained the reaction pathways of photogenerated carriers and how their partitioning and transportation are tuned by Ru NPs. Our work provides a novel method to easily fabricate metal-semiconductor heterostructure via an in-situ growth method for the development of high-performance photocatalysts.
查看更多>>摘要：? 2022 Elsevier B.V.Electrocatalytic hydrogen production by water splitting is highly energy-intensive due to poor electrocatalysts and sluggish four-electron oxygen evolution reaction (OER) kinetics. Herein, MnO2 and sulfur-doped MnO2 (S-MnO2) are prepared by a simple hydrothermal method. The results show that S-MnO2 exhibits a higher OER activity than MnO2 because the sulfur doping gives rise to more Mn3+ active sites, oxygen vacancies (VO) and electrochemically active surface areas. Density functional theory (DFT) calculation further confirms that the abundant VO leads to a higher surface energy of S-MnO2, which is conducive to the adsorptions of H2O and OH- on Mn3+ sites. Moreover, formaldehyde oxidation reaction (FOR) is employed to substitute for sluggish OER to improve hydrogen evolution reaction (HER). Compared to OER-based electrolyzer (3.354 V), the cell voltage of FOR-based electrolyzer (2.778 V) at 100 mA cm?2 has decreased by 17.17 %, and the Faradic efficiency of hydrogen production increases from 89.6 % to 98.6 %. The results indicates that to produce the same amount of hydrogen, 17.17 % of electric energy can be economized. Thus the cost of hydrogen production decreases greatly. The HER efficiency is greatly improved because FOR has faster kinetics than OER. Meanwhile, after running for 2 h at 1.75 V, 52 % of formaldehyde has been degraded. The results demonstrate that the innovative electrolyzer can not only greatly improve the HER efficiency, but also efficiently degrade formaldehyde pollutants.
查看更多>>摘要：? 2022 Elsevier B.V.Introducing an external energy field into water electrolysis is considered as an innovative strategy to improve electrocatalysis for water splitting. However, rationally modulating these external energy fields to synergize electrocatalytic processes remains a great challenge. Herein, phosphate-incorporated iron oxide nanosheet arrays (P-FeOx/IF) are constructed as multifunctional photothermal-electrocatalytic electrodes for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The as-prepared P-FeOx/IF exhibits excellent photothermal conversion performance and enables in-situ surface self-heating under near-infrared (NIR) light irradiation, resulting in a gradual increase in local temperature on the electrode surface. Impressively, the photothermal P-FeOx/IF electrode exposed to NIR light irradiation shows significantly improved electrocatalytic performances with relatively low overpotentials for OER (η10: 280 mV) and HER (η10: 104 mV) to deliver a current density of 10 mA cm?2. Furthermore, a two-electrode system using photothermal P-FeOx/IF as anode achieves a low cell voltage of 1.685 V. This study provides a new avenue for developing high-performance electrocatalysts incorporating photothermal effects.
查看更多>>摘要：? 2022 Elsevier B.V.In order to design and develop new marine structural materials with a balance of strength-toughness-corrosion resistance, in this work, the synergistic effects of Al and Ti on the microstructure, mechanical and corrosion resistance properties of CoCrFeNi(Al0.3Ti0.2)x high-entropy alloys were systematically investigated. With the addition of Al and Ti, the L12-γ' phase formed in the alloys significantly improves the mechanical properties, but excessive addition will lead to the formation of Al-Ti-rich B2 phase structure, which reduces the ductility of the alloy. For the corrosion resistance of the alloys in 3.5 wt. % NaCl solution, the increase of Al and Ti contents improves the stability of the passive film, while effectively reduces the corrosion current density and passivation current density of the alloys. However, the precipitation with a large number of strengthening phases aggravates the segregation of elements, resulting in a decrease in the pitting corrosion resistance and the resistance to the pit propagation of the alloy. In addition, compared with conventional structural alloys, the L12-strengthened dual-phase CoCrFeNiAl0.15Ti0.1 high-entropy alloy possesses an excellent balance of strength-toughness-corrosion resistance. This work also provides guidance for the future development of high-performance high-entropy alloy systems for marine engineering.
查看更多>>摘要：? 2022 Elsevier B.V.Developing high-efficient and stable electrocatalysts for oxygen evolution reaction (OER) is crucial for water splitting and metal-air batteries. Herein, ternary CoFe1?XMnX (0 <X < 1) layered double hydroxides (LDHs) grown on nickel form (NF) with nanosheet-nanowires (1D/2D) hierarchical nanostructure are synthesized. The introduction of Mn causes the change of crystal phase, morphology, and electronic structure of CoFe-LDH through electron transfer from Co/Fe to Mn, which provides the whole merit structural features and synergistic effect. Further experimental results exhibit that CoFe0.75Mn0.25-LDH possesses superior OER performance, which only requires overpotentials of 243 and 298 mV to reach 20 and 100 mA cm?2. The remodeling of LDHs in the OER process is also discussed to further explore the OER catalytic mechanism. In addition, CoFe0.75Mn0.25-LDH can also be utilized to the urea oxidation reaction (UOR), which requests a low potential of 1.367 V to reach 10 mA cm?2. A solar driven water splitting system is assembled and acquires the current density of 10 mA cm?2 at the low cell voltage of 1.58 V. This work offers an effective approach to boost the OER and UOR performance of CoFe-LDH based bifunctional electrocatalysts.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, the mechanical properties, microstructural characteristics and deformation behavior of a novel high-strength metastable β alloy Ti-6.5Cr-4.5Sn-4.5Mo (wt %) were investigated. By obtaining α phase mixed microstructure with different size, morphology and orientation combinations in β matrix, a good combination of tensile strength σb~1305 MPa and total elongation ?f~13.4 % was achieved. The microstructural characteristics of α phase consisting of discontinuous thin grain boundary α phase (αGB), lamellar α colonies and acicular αs precipitates were obtained by the solution treatment above β transus for a short time plus subsequent aging treatment after the heavy cold rolling. Detailed TEM analysis shows that it is difficult to deform for acicular αs precipitates due to their fine-scale, leading to a large number of α/β interfaces acting as dislocation barriers, which may ultimately result in an improvement on strength of the alloy. Compared with αs, the αGB and lamellar α colonies are soft, which could produce the large enough deformation and allow dislocations to generate and accumulate within them, so that it is beneficial to improve the mechanical properties of the alloy. Stress-relaxation experiments show that the sample with a uniform and finer distribution of α precipitate has a larger value of mobile dislocation ρm/ρm0 after relaxation, implying that most of the mobile dislocations remains in the sample, which results in the ultrahigh strength meanwhile accepted ductility in the specimen.
查看更多>>摘要：? 2022More efficient power conversion devices are able to transmit greater electrical power across larger distances to satisfy growing global electrical needs. A critical requirement to achieve more efficient power conversion are the soft magnetic materials used as core materials in transformers, inductors, and motors. To that effect it is well known that the use of non-equilibrium microstructures, which are, for example, nanocrystalline or consist of single phase solid solutions, can yield high saturation magnetic polarization and high electrical resistivity necessary for more efficient soft magnetic materials. In this work, we synthesized CoFe – P soft magnetic alloys containing nanocrystalline, single phase solid solution microstructures and studied the effect of a secondary intermetallic phase on the saturation magnetic polarization and electrical resistivity of the consolidated alloy. Single phase solid solution CoFe – P alloys were prepared through mechanically alloying metal powders and phase decomposition was observed after subsequent consolidation via spark plasma sintering (SPS) at various temperatures. The secondary intermetallic phase was identified as the orthorhombic (CoxFe1?x)2P phase and the magnetic properties of the (CoxFe1?x)2P intermetallic phase were found to be detrimental to the soft magnetic properties of the targeted CoFe – P alloy.
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