查看更多>>摘要：? 2022 Elsevier B.V.In this study, three kinds of atomic disordered Cu50Zr50 metallic glass thin films (MGTFs) with different structural heterogeneities are prepared by controlling the substrate temperature in magnetron sputtering, i.e., controlling the thermal history. A work-hardening behavior is observed in the MGTFs by cyclic nanoindentation. The spatial distribution of structural heterogeneities, and the correlation length of the viscoelasticity of heterogeneity in three MGTFs with different thermal histories demonstrate the effect of thermal history on the viscoelasticity of three MGTFs. The activation volume of heterogeneity controlling the initiation of shear band during local deformation correlates the correlation length of viscoelastic heterogeneity, which is used to elucidate the relationship between the structural heterogeneity and the work-hardening behavior. The results show that the increase of the substrate temperature causes the viscosity of structural heterogeneity to be increased, which means the reduction of viscoelastic heterogeneity correlation length. In this case, the activation volume of heterogeneity in the MGTF is decreased, which leads the formation of shear band to be difficult.
查看更多>>摘要：? 2022 Elsevier B.V.Lead-free double perovskites have been an excellent candidate for resistive memories due to their mixed electronic-ionic properties, remarkable ambient stability and nontoxicity. However, the studies on resistive memories of rare-earth ion doping lead-free double perovskite are scarce to date. Here, we report the lead-free double perovskite Cs2AgBiBr6 films with tuning rare earth Nd3+ content by the vacuum sublimation and solution processing. The X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM) confirm that Nd-doped Cs2AgBiBr6 films show high crystallinity and phase purity. We also systematically investigate the resistive memory properties of the resulted Cs2AgBiBr6 films doped by different content Nd3+. The resistive memory devices demonstrate a typical write-once-read-many-times (WORM) behavior with low on-set voltage and long retention time. Particularly, the ON/OFF ratio of Nd-doped Cs2AgBiBr6 film is 1000 times higher than that of the undoped Cs2AgBiBr6 film. This study exhibits that Nd-doped Cs2AgBiBr6 film provide a new material platform for lead-free perovskite-based application in future electronics and optoelectronics.
查看更多>>摘要：? 2022 Elsevier B.V.Silver niobate (AgNbO3, AN) dielectric ceramics and their antiferroelectric behavior have attracted increasing attention for their potential applications in energy-storage capacitors. However, AN's inferior dielectric breakdown strength, recoverable energy storage density, and efficiency have limited its application. In this work, a combination of chemical composition design and liquid-phase sintering was considered for the fabrication of highly insulated and desensitized AN-based ceramics for enhancing Eb, Wrec, and η of AN. We design and prepare (1 ? x)AgNbO3-x(Sr0.7Bi0.2)HfO3 (AN-100xSBH, x = 0.00–0.06) ceramics with the addition of 1 mol% BaCu(B2O5) (BCB) as a sintering aid to realize this. It is found that highly desensitized ceramics can be formed at 1000–1030 °C over the course of 2 h. The electrical property characterization results indicate that the AFE state and Eb are significantly enhanced with increasing SBH concentration. High Wrec and η values of 6.1 J/cm3 and 73%, respectively, under an applied field of 330 kV/cm are achieved in the AN-5.5SBH ceramic. Meanwhile, the AN-5.5SBH ceramic shows excellent thermal stability over a wide temperature range (25–120 °C) under an externally applied field of 290 kV/cm, in which the fluctuations of Wrec and η are 3.8% and 1.5%, respectively. These results provide an effective method for obtaining AN-based ceramics with excellent electrical properties under a lower sintering temperature than that required for pure AN ceramics. This method could be further generalized to develop new lead-free energy-storage dielectric materials.
查看更多>>摘要：? 2022 Elsevier B.V.This study is devoted to converting an n-type mixed anion Co4Ge6Te6 skutterudite into a p-type material through partial substitution of Fe for Co. Co4-xFexGe6Te6 (x = 0, 0.04 and 0.12) samples were prepared by solid-state methods and characterized by scanning electron microscopy and powder X-ray diffraction. Thermoelectric properties of the spark plasma sintering samples were investigated in the temperature range of 50–500 °C. The positive Seebeck and Hall coefficients of Co4-xFexGe6Te6 (x = 0.04 and 0.12) suggest that the n-type Co4Ge6Te6 was successfully converted into a p-type semiconductor via the Fe substitution. Also, an increased carrier concentration in Co4-xFexGe6Te6 (x = 0.04 and 0.12) leads to a significant increase in the electrical conductivity, which improves the thermoelectric performance of the mixed anion Co4-xFexGe6Te6 skutterudite.
查看更多>>摘要：? 2022 Elsevier B.V.A Ru-Ni@Cu alloy catalyst with a well-connected two-phase or three-phase contact interface is fabricated as an alternative to a Pt-based catalyst for the hydrogen evolution reaction (HER) in water electrolysis in this study. For optimum bonding and adhesion stability, the alloy particles are grown directly on carbon paper (CP) by the hydrothermal method. The alloy particles are composed of central Cu cores, Ni nests wrapped around Cu core, and small (2.0 nm) Ru nanoparticles embedded at the Ni nests. The Ni surface readily adsorbs water, the high conductivity of Cu increases the electron density of the electrode surface to facilitate water splitting, and the Ru surface adsorbs more H+ ions, thus promoting hydrogen production in the Ru-Ni@Cu alloy. Eventually, despite the use of only 1.0 wt% Ru, the 1% Ru-Ni@Cu/CP electrode exhibits a low overpotential of ?0.15 V (η = 246 mV and 87.08 mV dec?1) at 100 mA cm?2 in a 1.0 M KOH electrolyte, similarly to the ?0.1 V overpotential of the 100% Pt/CP electrode. The electrode maintains excellent catalytic activity without deterioration for 10 days with a Faraday efficiency of 96.89% (50 h) HER and 3000th LSV cycles.
查看更多>>摘要：? 2022 Elsevier B.V.The CeO2-based electrolytes of solid oxide fuel cells (SOFCs) with high ionic conductivity have attracted considerable attention. In this study, Ca and Y co-doped Ce0.8Y0.2?xCaxO2?δ (x = 0, 0.05, 0.1, and 0.15, abbreviated as YDC, YCDC05, YCDC10, and YCDC15) electrolytes were prepared, and their properties were investigated for intermediate-temperature solid oxide fuel cells (IT-SOFCs). All samples formed a cubic fluorite structure at a low sintering temperature (600 °C). At 800 °C, the YCDC05 electrolyte exhibited the highest conductivity (0.10 S cm?1), which was approximately 54% higher than that of the YDC electrolyte. The YCDC05 had the highest grain boundary scavenging factor and the smallest blocking factor. The blocking factor of YCDC05 was reduced by 49%, compared with that of YDC at 400 °C. The density functional theory calculation results showed that the oxygen vacancy formation energy of the Y and Ca co-doped (YCDC) electrolyte was lower than that of YDC. Therefore, Ce0.8Y0.15Ca0.05O2-δ may be a potential electrolyte material for IT-SOFCs.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, HfO2-doped Si bond coats with four different compositions were fabricated on the SiC substrates by atmospheric plasma spray (APS) for environmental barrier coating bond coats. The result showed that relatively dense composite bond coats can be successfully deposited by the APS approach using reduced plasma power to avoid the formation of metastable hafnia phases and hafnium silicides. The thermal expansion behavior of the Si-HfO2 bond coat was investigated. Results indicated that plasma-sprayed Si-HfO2 bond coats showed a non-linear expansion in air environment due to the oxidation of Si and formation of HfSiO4. Thermal cycling behavior of the Si-HfO2 bond coat at 1300 ℃ was also studied. The result suggested that the Si-HfO2 bond coat with high Si concentration has relatively better thermal shock resistance, owing to its low CTE and better oxidation resistance. The HfSiO4 formation reaction between hafnia and silica alleviate the volume contraction caused by cristobalite phase transformation. The spallation of the bond coat was attributed to the formation of thermally grown oxides (TGO) and the coefficient of thermal expansion (CTE) mismatch between the bond coat and the SiC substrate.
查看更多>>摘要：? 2022 Elsevier B.V.The coating with a porous structure, having a good adhesion to the substrate and containing titanium dioxide in the modifications of rutile and anatase, has been obtained by plasma electrolytic oxidation of VT1–0 technically pure titanium in a 0.1 M neutral aqueous solution of Na2SO4. Gold 10-nm-layer has been deposited on surface by electron-beam evaporation to obtain Ti/TiO2/Au composite. This gold layer consists of 5 nm gold nanoparticles, which has been determined based on the coherent scattering regions for the diffraction peak (111) using the Debye-Scherrer method. Deposition of 10-nm gold layer on the surface of Ti/TiO2 results in increase in photocurrent densities from 3·10?9 A/cm2 to 4·10?6 A/cm2. Calculation from the slopes of the Mott-Schottky plots enable one to estimate the number of charge carriers (donors) and the flat band potential vs Ag/AgCl, which are ND = 3.9·1019 cm?3, Efb = – 0.14 V for Ti/TiO2 and ND = 3.0·1020 cm?3, Efb = – 0.4 V for Ti/TiO2/Au composite.
查看更多>>摘要：? 2022 Elsevier B.V.Potassium (K) metal batteries are attractive alternatives beyond lithium-ion batteries because of the large abundance, high theoretical specific capacity and low electrochemical potential of the K metal. However, K metal anode have been restrained by the uncontrollable K dendrite growth. A high-activity K metal anodes achieved by confining K metal into a Bismuth compound hollow carbon tube (Bi@CNT) freestanding matrix is reported. The homogeneous K ionic flux and reduced local current density during plating/stripping processes are enabled by the high electronic transport in the Bi@CNT matrix. Moreover, the “K-philic” Bi in the Bi@CNT can induce the nucleation of K metal and induce K to uniformly distribute in the electrode during cycling. Therefore, the obtained Bi@CNT composite K anode shows more excellent electrochemical performance in electroplating/stripping, greatly improves the stability (500 h at 0.5 mA cm?2 - 0.5 mA h cm?2and a low overpotential of 53 mV), and provides more choices for the development of potassium metal batteries. Furthermore, K@Bi@CNT||PTCDA full batteries exhibit excellent electrochemical performance with good rate capability and long cycling stability (103.3 mA h g?1 after 150 cycle at 0.1 A g?1).
查看更多>>摘要：? 2022 Elsevier B.V.Molecular hydrogen has been considered as ideal energy carrier due to its high calorific value and clean product, which also requires eco-friendly generation process. Electrocatalytic H2 evolution from water splitting represents a compelling sustainable and green energy technology, but it is severely hindered by the large overpotential needed, especially for non-noble metal electrocatalysts. In this study, an interface engineering strategy is extended to improve the catalytic hydrogen evolution reaction (HER) performance of CoP by introducing CeO2 component. The novel heterostructure of CoP/CeO2 is successfully fabricated by a selective phosphidation treatment of pre-synthesized Co-PBA/CeO2 hybrid precursor. The introduced CoP/CeO2 hetero-interface would regulate the electronic structure, accelerate charge transfer and enhance the intrinsic activity of the active sites. By optimizing the content of functional CeO2 entity, the CoP/CeO2-2.5 is the most active electrocatalyst with the lowest overpotential of 152 mV to reach 10 mA cm?2 current in 1.0 M KOH, as well as a Tafel slope of 83.5 mV dec?1. Besides, CoP/CeO2-2.5 can also continuously operate well for more than 16 h, demonstrating the good durability of this electrocatalyst. This work would broaden the advanced HER electrocatalysts by fabricating hetero-interface with different functional components.
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