查看更多>>摘要:? 2022 Elsevier B.V.A novel EDAPbCl4 @ZIF-67 (EDA = ethylenediammonium) nanocomposite material was successfully prepared by embedding a hybrid organic-inorganic perovskites (HOIPs) into a porous zeolite imidazolate frame structure material (Zeolitic Imidazolate Frameworks, ZIFs). The electrochemical sensor was fabricated through dropping EDAPbCl4 @ZIF-67 onto the surface of glassy carbon electrode (GCE) and applied to the detection of protocatechuic acid (PCA). The results of a series of electrochemical performance tests including cyclic voltammetry (CV) and differential pulse voltammetry (DPV) showed that EDAPbCl4 @ZIF-67/GCE could amplify the signal of the electrochemical response to the oxidation of PCA. The peak current of EDAPbCl4 @ZIF-67/GCE was linearly increased with the concentration in the range of 22–337 μM. The linear regression equation was I(μA)= 0.0031 C (μM)+ 1.6968 (R2 =0.9916), the detection limit (S/N = 3) was 15 μM. Meanwhile, EDAPbCl4 @ZIF-67/GCE can effectively detect PCA in green tea and cough syrup.Its relatively excellent sensitivity indicated that the hybrid organic-inorganic perovskite (EDAPbCl4 @ZIF-67) was feasible to be used as electrochemical sensor material.
查看更多>>摘要:? 2022 Elsevier B.V.The inherent ductile-to-brittle transition (DBT) of body-centered tetragonal Sn at cryogenic temperatures restricts the use of Sn-based solders in the interconnection of cryogenic electronics, but little is known about the deformation behaviors accompanying with the transition and the underlying transition mechanism. In this work, the deformation features before cryogenic brittle fracture and the DBT mechanism in polycrystalline Sn were studied through uniaxial tensile experiments at different temperatures. Compared to the softening process stimulated by dynamic recovery and dynamic recrystallization before ductile fracture at room temperature (~293 K), a high strain hardening rate (~5% of the shear modulus) is maintained during the linear hardening period preceding brittle fracture at the liquid nitrogen temperature (~77 K) due to the pronounced intersecting of {301} deformation twins. But the irreconcilable velocity difference between dislocation glide (~3 μm/s) and twin thickening (~10 μm/s) at 77 K leads to a premature brittle fracture in the midst of the linear hardening, and indeed the DBT. The suggested specific DBT mechanism is substantiated by the fact that a significant increase in the velocity (~1500 μm/s) with the increasing temperature (123 K) allows the dislocation slip to readily accommodate the shear strains due to {301} twin thickening at the grain boundaries, thereby resulting in ductile fracture rather than brittle fracture. This deep understanding about the DBT in polycrystalline Sn may help forge a new path to design ductile and strong Sn-based solders and solder joints for cryogenic electronics by deformation twinning.
查看更多>>摘要:? 2022 Elsevier B.V.Improving the biomineralization activity of Zr-based amorphous alloys is key to advancing their use in implant materials. A nanoscale 3D porous structure was synthesized on the surface of Zr-based amorphous alloy by electrochemical dealloying in a ChCl-Thi DES. Cu and Al have the lowest corrosion potential in the DES, so the main elements eluted during dealloying are Cu and Al. After dealloying, the surface of the Zr-based amorphous alloy remained essentially amorphous, and several crystalline phases of NiZr2, Al3Ti, and CuZr2 formed simultaneously. Among the amorphous phases, Cu and Ni were present in the form of simple substances, while Zr, Al, and Ti were oxidized. The formation of the porous structure mainly included the two processes of pitting corrosion and dealloying. The pitting corrosion was controlled by Cl-, which can destroy the passivation film. In the dealloying process, thiourea played a leading role in the dissolution of active metals. A porous surface structure is beneficial for improving the biomineralization activity of Zr-based amorphous alloys.
Bertoli G.de A. Santana D.Otani L.B.Kiminami C.S....
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查看更多>>摘要:? 2022 Elsevier B.V.The almost infinite compositional space is one of the most attractive aspects of High Entropy Alloys (HEAs), but finding promising compositions is usually a great challenge. The most studied families of HEAs include the 3d transition metals, in which promising face-centered cubic alloys have been found, but few single-phase body-centered cubic (BCC) alloys were designed and produced with these elements. In the present work, a systematic exploratory study was performed within the VCrMnFeCo system, a vast compositional space currently underexplored and prone to form BCC solid solutions. It is shown that the brittle and usually undesirable sigma phase is often observed in this HEA family and, therefore, predicting its formation is essential in alloy design. The phase equilibria were studied in a wide range of compositions by the CALPHAD method and the combination of two empirical methods proposed by Tsai et al. (2013; 2016) for predicting the sigma phase. Six compositions were produced and characterized in the as-cast and annealed condition (1150 oC, 4 h), namely V42Cr41Mn17, VCrFe, VCrMnFe, V37Mn25Fe38, VCrMnCo, and VCrMnFeCo. The first three alloys presented a single-phase BCC microstructure, while the others were sigma dominant. The CALPHAD and Tsai criteria disagreed on some predictions, and both were partially accurate when compared to the experimental characterization. Considerations on alloy design of 3d transition metal HEAs were discussed, as well as the advantages and limitations of these predictive methods when applied in the proposed system. The simultaneous application of CALPHAD and Tsai criteria is recommended for the sigma-prone 3d transition metal HEAs. This work collaborates to a better understanding of the dimension of compositional fields in 3d transition metal HEAs.
查看更多>>摘要:? 2022 Elsevier B.V.Combination of liquid ultrasonication and facile hydrothermal approach were used for synthesis of novel highly efficient WO3/g-C3N4-WS2 ternary photocatalyst. The presence of noble metal free WS2 as cocatalyst induced localized surface plasma resonance (LSPR) and extended the light utilizing spectrum of the ternary composite towards the NIR. An electrochemical property reveals that it follows combined S-Scheme/Type-1 mode of changer transfer mechanism in the ternary. Transient photocurrent validated the excitation of charge carriers in the presence of light with 18.18% increases in photocurrent for ternary. Formation of internal electric field at the interface of heterojunction restricted the recombination rate. The reduction in the charge transfer resistance by the introduction of WS2 was established through LSPR effect. Pore size varies from 2 to 30 nm confirms mesoporous structure. Highest donor density of 4.24 × 1023 was found in WOCNS. This has significantly enhanced photocatalysing ability and established successful degradation of both MB and MO under the direct sunlight and artificial NIR light source. AQY of WOCNS composite was found to be 66.67% higher than pristine g-C3N4 in the NIR region. The dominance of reactive oxygen species (ROS) such as superoxide radicals (.O2-) and holes (h+) were primarily responsible for decomposition of MB and MO. The ternary exhibited high stability and reusability with a removal efficiency of 87% for up to 5th consecutive cycles. This study demonstrates the novel S-scheme/Type-1 strategy for harnessing full solar spectrum with application towards water purification and industrial wastewater treatment.
查看更多>>摘要:? 2022 Elsevier B.V.Negative current collectors play vital roles in the electrochemical performance of liquid metal batteries (LMBs). Employing a three-dimensional (3D) current collector is an effective approach to host molten lithium and reduce the effective current density. The Ni-Fe foam is a frequently used 3D current collector for the negative electrode. However, the corrosion of molten lithium towards the Ni-Fe foam skeleton devastates the 3D structure of the current collector and so deteriorates seriously the electrochemical performance of LMB. To enhance the corrosion resistivity, herein, the graphite layer coated Ni-Fe foam (Graphite@Ni-Fe) is prepared by the chemical vapor deposition method. The prepared scaly-like graphite layer plays a bifunctional role in chemistry, preventing corrosion as an effective barrier and improving remarkably the surface lithiophilicity of Ni-Fe foam. The assembled Li||Bi batteries with Graphite@Ni-Fe foam as negative current collector exhibit stable cycling performance with capacity retention of 98.10% and high Coulombic efficiencies over 98.3% at 0.4 A cm?2 over 100 cycles at 500 °C. More importantly, outstanding rate capability is achieved and almost no capacity degradation is observed upon current density change from 0.2 to 2.0 A cm?2. This work highlights the importance of the lithiophilicity and the corrosion resistance ability of the negative current collectors for LMBs.
查看更多>>摘要:? 2022 Elsevier B.V.In this study, crystalline graphene quantum dots (GQDs) is prepared using agro waste of paddy straw via hydrothermal route and GQDs reinforced fly ash polymer nanocomposites was prepared for the first time. HR-TEM and XRD investigations confirmed the formation of hexagonal GQDs with average diameter of 8 nm. Nanocomposite prepared with GQDs reinforcement in fly ash waste under epoxy system was fabricated through the compressive molding machine. Graphene quantum dots-fly ash polymer nanocomposites showed a substantial and concurrent increase in dielectric constant (?') up to ~ 350 compared to fly ash based polymer composites (?'~13). The GQDs-reinforced fly ash based nanocomposites possess the high flexural strength of 60 MPa, whereas pristine fly ash polymer hybrid composite exhibited flexural strength of 35 MPa. The unconventional dielectric enhancement and flexural strength of agro waste derived GQDs reinforced fly ash polymer nanocomposite is attributed to the sudden increase in the electric dipoles and improved interfacial and chemical bonding of crystalline GQDs with fly ash and epoxy.
查看更多>>摘要:? 2022 Elsevier B.V.In this article, the TaOx/Ta stacked sensing films as sensing membranes were deposited onto n+-type Si substrate by a radio-frequency (RF) magnetron sputtering technique for solid-state extended-gate field-effect transistor (EGFET) pH sensors. The effect of rapid thermal annealing (RTA) treatment (300–700 °C) on structural properties of the TaOx/Ta stacked sensing films was investigated in detail. The chemical compositions, element profiles, crystallographic structures, surface morphologies, and film microstructures of the TaOx/Ta stacked sensing films were characterized by X-ray photoelectron spectroscopy, Auger electron spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy, respectively. The sensing performance of the TaOx/Ta stacked sensing films is most closely correlated with their relative structural features. Among these RTA temperatures, the best sensing performance including pH sensitivity, hysteresis and drift was achieved at the RTA temperature of 500 °C. The obtained experimental results showed that the TaOx/Ta stacked sensing film is considered a feasible alternative for pH sensor and biosensor applications.
查看更多>>摘要:? 2022 Elsevier B.V.In this study, even if excess electrolyte is injected, stable performance is maintained because SDC (Sm0.2Ce0.8O2?δ) coated on the surface of the anode induces electrolyte redistribution. In addition, the SDC coating is intended to increase the performance and lifetime of the cell by improving the thermal stability of the anode at high temperatures. An SDC-coated Ni-based anode is manufactured by dip-coating SDC (Sm0.2Ce0.8O2 ?δ) sol on a Ni-based anode. As a result of operating the cell in which excess electrolyte (pore filling ratio 115–120%) is injected, the “flooding” phenomenon caused by excessive electrolyte injection is suppressed within 72 h of cell operation, and the cell performance maintains a high performance of 0.72 V at 150 mA/cm2. In addition, the thermal stability of the Ni-based anode is increased due to the SDC coating, and stable performance is maintained for more than 1000 h of operation.
查看更多>>摘要:? 2022 Elsevier B.V.Among various perovskite proton conducting oxides, Y-doped BaZrO3 perovskite is a promising material for electrochemical hydrogen devices due to its good chemical stability and higher proton conductivity at higher operating temperatures like 500–800 °C. For the practical application of the functional BaZrO3 proton conductors in electrochemical hydrogen devices like tritium purification and recovery systems in a nuclear fusion reactor (where deuterium and tritium isotopes are utilized as fuel), it's necessary to understand the isotopic effect of proton conductivity. To understand the isotopic effect of proton conductivity in the barium zirconates, in this study, the proton conductivities in the Ar, (Ar + 4% H2), (Ar + 4% D2), (Ar + H2O), (Ar + D2O), and O2 atmospheres were measured for two different compositions: BaZr0.9Y0.1O2.95 (BZY), and BaZr0.955Y0.03Co0.015O2.97 (BZYC) in the temperature range from 500 °C to 1000 °C. By comparing the obtained results, a significant difference in sinterability, conductivity, and the isotopic effect was observed due to the co-doping of the Co element in the BaZr1?xYxO3-α proton conductor.