查看更多>>摘要：? 2022 Elsevier B.V.The development of transition metal-based materials to replace precious metal electrocatalysts in a facile and efficient approach is of great importance for water splitting. The NiS/MoS2 complex grown in situ on carbon paper (NiS/MoS2/CP) by a one-step hydrothermal method was successfully constructed as an efficient electrocatalyst. The synergetic effects of the superhydrophilic/aerophobic surface, hierarchical nanostructure and strong mechanical adhesion to a highly conductive substrate give the NiS/MoS2/CP complex outstanding catalytic activity and durability. Specifically, it exhibits relatively low overpotentials of 119 mV (at a current density of 10 mA cm?2) and 314 mV (at a current density of 100 mA cm?2) for the hydrogen evolution reaction and oxygen evolution reaction, respectively. In addition, the NiS/MoS2/CP complex can also be used as an electrolyzer that reaches a current density of 10 mA cm?2 at a cell voltage of 1.48 V without decay after 30 h of durability testing, making it an ideal electrocatalyst for water splitting towards practical application.
查看更多>>摘要：? 2022 Elsevier B.V.Bimetal oxides possess high electronic conductivity and multiple electrochemically active sites owing to their stepwise electrochemical reactions compared with the single metal oxides. However, bimetal oxides still suffer from the severe volume changes upon lithium insertion/delithiation processes, thus leading to poor cycle stability. Herein, we demonstrate the growth of novel CoMoO3 nanosheets on the cage-like carbon nanoflakes (c-CNFs) through a facile in-situ thermal decomposition strategy. The phase and morphology structures of CoMoO3 can be readily controlled by adjusting the sintering temperature under the argon atmosphere, changing from 0D CoMoO4 nanoparticles@c-CNFs (350 ℃, denoted as CoMoO4 @C) to 0D CoMoO4 nanoparticles and 2D CoMoO3 nanosheets co-existed nanohybrids@c-CNFs (450 ℃, denoted as CoMoOx @C) and 2D CoMoO3 nanosheets@c-CNFs (550 ℃, denoted as CoMoO3 @C). When examined as anode materials for LIBs, the CoMoO3 @C electrode exhibited excellent lithium storage performance. The superior performance of the CoMoO3 @C electrode could be attributed to the novel CoMoO3 nanosheet structure combined with the reduced volume change from well-fitted CoMoO3 @c-CNFs, which delivered a reversible capacity of ~706 mA h/g for 360 cycles at 500 mA/g, higher than that of the CoMoO4 @C and CoMoOx @C electrodes.
查看更多>>摘要：? 2022 Elsevier B.V.We present a detailed study of Ag7+x(P1?xGex)S6 (x = 0.1; 0.25; 0.33; 0.5; 0.75) single crystals of novel superionic conductors with argyrodite structure. The single crystals on superionic conductors Ag7+x(P1?xGex)S6 were grown by directional crystallization technique. The crystal structure of Ag7+x(P1?xGex)S6 solid solutions was studied by the Rietveld refinement method. It was found that solid solutions crystallize in three SGs: P213 (x = 0.1), F-43m (x = 0.25; 0.33) and Pna21 (x = 0.5; 0.75). Ag7+x(P1?xGex)S6 solid solutions are characterized by the presence of Ag positions with partial occupancy, which is different from the initial ternary compounds. The frequency and temperature dependences of electrical conductivity were studied by electrochemical impedance spectroscopy method. The structural disordering caused by P+5?Ge+4 heterovalent cationic substitution induces increasing ionic conductivity of the solid solutions by 5 orders of magnitude. The occurrence of favorable conditions for ion transport is explained using simple structural descriptors.
查看更多>>摘要：? 2022 Elsevier B.V.It is crucial to clarify the effects of the ceramic phase, the metal binder, and temperature on the mechanical properties of WC-Co cermets, as a typical representative of cermet materials, due to highly demanded excellent high-temperature properties under harsh service conditions. Based on uniaxial compression tests and detailed microstructural characterization, this study quantified the deformation characteristics of the ceramic phase and the metal binder at room temperature and high temperatures applying multiple analysis methods. It distinguished different contributions of the ceramic phase and metal binder to the plasticity of the cermets during deformation, and proposed the mechanisms for the plastic deformation of cermets. The results indicated that the dislocation plasticity is the dominant deformation mechanism of the cermets, and the ceramic matrix is mainly responsible for the fracture strength and contributes significantly to the plasticity of the cermets both at room temperature and high temperatures. At high temperatures, grain boundary slip and phase boundary sliding also contribute to the plastic deformation of cermets.
查看更多>>摘要：? 2022 Elsevier B.V.Aiming to obtain advanced microwave absorbing materials with high absorption efficiency, broad absorption bandwidth and low density, herein, a novel nanocomposite with irregular hollow nanostructure of Co9S8@C was successfully prepared via a soft template and annealing method. Due to the shrinkage process of the Co9S8 nanospheres by annealing, Co9S8 cores and carbon shells were easily obtained. Because of the unique microstructure with irregular outer shells and heterogeneous interfaces, improved polarization loss, multiple reflection loss as well as the impedance matching capability was achieved. As a result, greatly enhanced microwave absorption performance with a reflection loss (RL) of ? 51.3 dB at 4.12 GHz, and effective absorption bandwidth (RL<?10 dB) of 5.44 GHz at a thickness of only 1.35 mm was obtained, suggesting the unique Co9S8@C nanocomposite in this work to be an intriguing and promising microwave absorber.
查看更多>>摘要：? 2022 Elsevier B.V.Photocatalysis is an important method for degradation of antibiotics. However, the rapid recombination of photoinduced carriers limits the photoactivity. In addition, due to the small particles size of photocatalyst, it is difficult to recycle, leading to secondary pollution to environment and limited practical application. In this work, the Sn3O4/SnFe2O4 (SN/SFO) heterojunction photocatalysts were synthesized by a simple ultrasonic assisted calcination method. The prepared SN/SFO composite was analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Their photocatalytic activities to ciprofloxacin (CIP) degradation were investigated under visible light. Among SN/SFO composites with different mass ratios, SN/SFO-25% composite showed the highest degradation efficiency, and the rate constant value of SN/SFO-25% is 4.87 and 3.02 times faster than pure SFO and SN, respectively. The improved photocatalytic performance of SN/SFO can be attributed to the construction of type II heterojunction, which inhibited the recombination of electron-hole pairs. In addition, the flower-like morphology causes many pores in the material and brings more exposed surface area, which favors, to some extent, multi-reflection, enhanced sunlight absorption and boosted photocatalytic reaction. More importantly, the SN/SFO composite was easy to be separated and recovered under the action of external magnetic field. This work is expected to provide design opportunities for the construction of highly efficient magnetic photocatalysts with type-II scheme for photocatalytic degradation of CIP in water environments.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, a rare system of Sr3Co2Fe24O41/MoS2 composites has been successfully prepared via the sol-gel method and following a facile hydrothermal process, from which the flower-like MoS2 was evenly anchored on the surface of Z-type Sr3Co2Fe24O41 microplatelets. It is confirmed that the effective combination of transition metal sulfide MoS2 and multiferroic Sr3Co2Fe24O41 hexaferrite greatly optimizes the dielectric behaviors of the composites. Meanwhile, the unique hierarchical structure further enhances the microwave absorption properties. When the mass ratio of Sr3Co2Fe24O41 to MoS2 is 1:3 in composites, the smallest reflection loss value is ? 39.2 dB at the thickness of 2.0 mm, and note that the adequate absorption bandwidth can reach up to 7.6 GHz (10–17.6 GHz) with 2.2 mm. When the mass ratio is adjusted as 1:5, the optimal reflection loss of the composite reaches ? 44.5 dB at 9.28 GHz with a thickness of 3.0 mm. The high-efficiency microwave absorption performance of the composites is attributed to the synergistic effect of dielectric materials and multiferroic materials. The calculation results on delta and attenuation constant display that impedance matching degree and attenuation ability of composites are balanced, which not only reduces the reflection of electromagnetic waves on the absorber surface, but also enhances its consumption. At the same time, the flower-shaped MoS2 is stacked on the surface of Sr3Co2Fe24O41 microplatelets which is conductive to the multiple reflections and scattering of electromagnetic waves between layers, greatly promoting the attenuation of electromagnetic waves. This work opens up an updated pathway for the design of magnetic/dielectric microwave absorbers with vigorous absorption and ultra-wideband.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, non equiatomic FeCrNiCoMoW MEA composite coatings were successfully prepared by electron beam cladding Fe-based amorphous powders. The effects of WC-10Co amounts (0–30 wt%) on the microstructure, mechanical properties, and electrochemical property of the MEA composite coatings were investigated. The added WC-10Co decomposed, and the original amorphous alloy was completely crystallised. The composite coatings primarily comprised the face-centred cubic (FCC) matrix, M23C6 (M = Cr, Mo, Fe, or W) and WC particles. The average hardness of the composite coatings gradually increased with increased WC-10Co amounts from 5.66 ± 1.09 GPa to 8.02 ± 2.54 GPa. The composite coating with 30 wt%WC-10Co showed optimal hardness and wear resistance, which were approximately 4 and 2 times that of the substrate, respectively. The wear mechanism changed from severe adhesive wear for 0 wt% WC-10Co composite coating to abrasive and slight adhesive wear for 10–30 wt% WC-10Co composite coatings. The 10 wt% WC-10Co coating exhibited the best corrosion resistance in 3.5 wt% NaCl solution. The number of corrosion pits decreased with the addition of WC-10Co increased, and corrosion occurred in the Cr-depleted regions. Solid solution, dislocation, WC particles and M23C6 nanoprecipitates were responsible for the improvement in mechanical properties and corrosion resistance of the coatings.
查看更多>>摘要：? 2022 Elsevier B.V.The grain boundary α (αGB) in titanium alloys is believed to significantly impact the subsequent β → α transformation, the evolution of α microtexture and the final mechanical properties. The αGB with remained β phase has been generally observed in Ti-6Al-2Sn-4Zr-6Mo and other α + β titanium alloys. In this study, the growth behavior and variant selection of αGB formed by β processing were investigated by the interrupted furnace cooling experiment. In the early growth period of the αGB, discontinuous chevrons αGB particles grew, which was significantly associated with Mo element distribution. Besides, the double-Burgers orientation relationship (2-BOR) variant selection criterion according to the θ2-BOR (misorientation of the close-oriented αGB variant pair of parent β1 and β2) deviation is refined in this study. At β grain boundary with θ2-BOR deviation below 8o, the αGB orientation is 100% predicted. In this case, the αGB grains are always close to the closest theoretical variant pair of both sides β grains. When θ2-BOR is over 14o, the criterion is not predictive.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, a new low loss Ba3Ti4-x(Mn1/3Nb2/3)xNb4O21 (MN-BTN, 0 ≤ x ≤ 12 mol%) ceramics configuration was presented through preparing by the solid-state route. The XRD patterns, Rietveld refinement, microstructure, and microwave properties were systematically analyzed. All the fabricated MN-BTN ceramics belonged to the hexagonal structure with a P63/mcm space group. More specifically, the 6MN-BTN ceramic exhibited a high relative density of ~92.3 %, homogeneous grains distribution with an average size of ~71.95 μm, and several excellent microwave dielectric properties: εr = 59.67, Q×f= 16,226 GHz, τf= +103.9 ppm/℃ sintered at 1220 ℃. The incorporation of 1.5 wt% BaCu(B2O5) (BCB) compound within the 6MN-BTN ceramic not only effectively reduced the sintering temperature from 1220 ℃ to 950 ℃, but also the excellent microwave dielectric properties were maintained: εr = 42.33, Q×f= 11,300 GHz, τf= +24.7 ppm/℃. Interestingly, the 6MN-BTN + 1.5 wt% BCB ceramic showed better chemical compatibility with Ag. The proposed 6MN-BTN + 1.5 wt% BCB ceramic configuration could be regarded as a promising material for LTCC applications.
NSTL
Elsevier