查看更多>>摘要：? 2022 Elsevier B.V.Under the high current density, high cyclability and good rate performance are two major challenges for the applications of supercapacitor. How to control the composition and structure of the electrode materials is the key factor to solve these two problems. In this work, the controllable morphology Co/Ni Basic Carbonate Composites (CNBCC) were synthesized by one-step hydrothermal regulating the ratio of Co to Ni. Impressively, benefiting to its special sea urchin structure, the composite with the 1:1 ratio of Co to Ni exhibited remarkable electrochemical performance with specific capacitance (at 1 A g?1, 1682 F g?1), superior rate capability (at 1–30 A g?1, 79.3%) and cycling stability (2000 cycles, 96%). Further, a solid-state asymmetric supercapacitor Co1Ni1//AC (ASC) was constructed with a high voltage window (1.7 V). The ASC displayed a high energy density of 42.5 Wh kg?1 at power density 849.7 W kg?1, while still remained at 20.6 Wh kg?1 at a power density of 25511 W kg?1. In addition, the ASC had good flexibility, and their CV curves hardly changed after being bent into different angles; the two ASC in series could light a yellow LED for 25 min.
查看更多>>摘要：? 2022 Elsevier B.V.Electrode materials with high electrochemical activity and a favorable morphology are highly desired for improving the energy density of supercapacitors. A ternary metal sulfide with higher electrochemical activity and capacity than mono-metal sulfides offers immense promise as an energy storage material. In the present investigation, an advanced flexible hybrid electrode material composed of porous manganese molybdenum sulfide (MnMoS4) nanosheets supported on flexible carbon nanofiber (CNF) mat has been prepared via three sequential steps: (i) electrospinning, (ii) stabilization/carbonization, and (iii) hydrothermal reaction. Advantages from the rich electrochemical redox properties of MnMoS4 and the 3D interconnected network architecture of porous CNF mat, a large specific capacitance of 2187.5 F/g (at 1 A/g), and a good capacity retention ability (>87%) were achieved for the MnMoS4 @CNF hybrid electrode. In addition, asymmetric supercapacitor (ASC) devices were assembled by utilizing two different binder-free electrodes, i.e., MnMoS4 @CNF mat as the positive electrode and N, S doped CNF mat as the negative electrode, and evaluated their capacitive performances in two different electrolytes, i.e., KOH and Na2SO4. As-assembled ASC with 1 M Na2SO4 electrolyte delivered a high energy density of 72.5 Wh kg?1 and a power density of 2.7 kW kg?1 together with a capacity retention of 93.5% after 5000 cycles. The overall outcome of this investigation indicates that the binder-free nanostructured MnMoS4 @CNF hybrid mat has great potential for the development of next-generation supercapacitor devices.
查看更多>>摘要：? 2022 Elsevier B.V.Magnetocaloric cooling offers the potential to improve the efficiency of refrigeration devices and hence cut the significant CO2 emissions associated with cooling processes. A critical issue in deployment of this technology is the mechanical degradation of the magnetocaloric material during processing and operation, leading to limited service-life. The mechanical properties of hydrogenated La(Fe,Mn,Si)13-based magnetocaloric material are studied using macroscale bending tests of polycrystalline specimens and in situ micropillar compression tests of single crystal specimens. The impact of hydrogenation on the mechanical properties are quantified. Understanding of the deformation/failure mechanisms is aided by characterization with transmission electron microscopy and atom probe tomography to reveal the arrangement of hydrogen atoms in the crystal lattice. Results indicate that the intrinsic strength of this material is ~3–6 GPa and is dependent on the crystal orientation. Single crystals under compressive load exhibit shearing along specific crystallographic planes. Hydrogen deteriorates the strength of La(Fe,Mn,Si)13 through promotion of transgranular fracture. The weakening effect of hydrogen on single crystals is anisotropic; it is significant upon shearing parallel to the {111} crystallographic planes but is negligible when the shear plane is {001}-oriented. Atom probe tomography analysis suggests that this is associated with the close arrangement of hydrogen atoms on {222} planes.
查看更多>>摘要：? 2022 Elsevier B.V.A novel nanostructure of SnO2 @polypyrrole (PPy) is grown on carbon cloth (CC) by a facile solvothermal method and subsequent chemical oxidative polymerization process in this work. Benefiting from the combination of SnO2 and PPy, the as-obtained SnO2 @PPy/CC composites show significant improvement of electrochemical performances compared to single components. Specifically, the SnO2 @PPy/CC electrode achieves a high areal capacitance of 493.8 mF cm?2 at 1.0 mA cm?2, and good rate capability. Furthermore, all solid state flexible supercapacitors (FSCs) are constructed using SnO2 @PPy/CC electrodes and polyvinyl alcohol-potassium hydroxide gel electrolyte. Remarkably, the SnO2 @PPy/CC//SnO2 @PPy/CC FSCs show a high energy density of 0.7 mWh cm?3 at a power density of 4.74 mW cm?3, superior stability (90.5% capacitance retention after 10,000 cycles at 1.0 mA cm?2) and good mechanical flexibility. This work is expected to bring up inspirations for the development of high-performance FSCs.
查看更多>>摘要：? 2022 Elsevier B.V.Photocatalytic biorefinery catches an ocean of attention because of its environmental friendliness. It is widely known that photocatalytic performance of TiO2 is poor due to the wide bandgap and sluggish electron kinetics. Herein, biochar nanosheet and anatase TiO2 (denoted as a-TiO2 @MC) were combined to accelerate the charge separation/transfer and narrow the bandgap of TiO2, which is proved by UPS and Mott-Schottky plot analysis. With improved electron kinetics, comes excellent photocatalytic performance, which gave great yield of xylonic acid (52.26%) and lactic acid (49.22%). Furthermore, h+,·OH, and 1O2 exerted positive effects on the synthesis of biomass-derived organic acids, in which the h+ plays the major role in the biorefinery over a-TiO2 @MC, whereas the·O2- is not. 1000-fold scale-up experiment indicated that 69.1% of the photocatalytic performance was achieved when compared with the similar conditions irradiated by visible light. This work provides an efficient photocatalytic biorefinery via a facile and low-cost way.
查看更多>>摘要：? 2022 Elsevier B.V.In order to develop high-strength and high-conductivity copper alloys with better comprehensive properties, the effects of Si addition on the mechanical properties, electrical conductivity and microstructure of CuCrZr alloy were investigated in this paper. The addition of Si element can improve the hardness, strength and ductility of CuCrZr alloy. The optimal peak aging parameter for CuCrZrSi alloy is 430 °C for 3 h, the hardness 228.92 HV, the tensile strength 646.76 MPa, and the elongation after fracture 10.67%. Compared with the CuCrZr alloy under the same process, the mechanical properties are increased by 10.3%, 11.9% and 16.9%, respectively. The conductivity is 4 ± 1%IACS lower than that of the sample without Si addition. The addition of Si element refines the deformation substructure and produces more Σ3n (n = 1, 2, 3) grain boundaries, thus providing more nucleation sites and higher driving forces for the precipitation phases. In both CuCrZr and CuCrZrSi alloys, the fine precipitation phases (<10 nm) fcc-Cr phase and orthorhombic-Cu8Zr3 phase, together with coarse precipitation phases (>100 nm) bcc-Cr phase and hcp-Zr phase can be observed. The orientation relationship among the two fine precipitation phases and the matrix is (1ˉ1ˉ1)[11ˉ0]Cu∥(1ˉ1ˉ1)[11ˉ0]Cr∥(133)[01ˉ1]Cu8Zr3. The Si element tends to precipitate together with the Cr phase and Zr phase, and acts to refine and spheroidize the precipitation phases.
查看更多>>摘要：? 2022 Elsevier B.V.A spongy nanostructure of graphene oxide was synthesized to enhance the porosity and surface area. Then, CoNi2S4 and MoS2 nanocomposites were fixed on the porous graphene oxide to increase the capacity and improve its performance as a substrate. Finally, they were integrated to produce the final nanocomposite. The presence of metal sulfides, as electroactive materials, promises a synergistic effect for use in supercapacitors by accelerating ion/electron diffusion rates and enlarging the active sites. The synthesized spongy nanocomposite (CoNi2S4 @MoS2 @rGO) was characterized by various techniques, including Raman spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. The results of our study showed that the spongy nanocomposite has a specific capacitance of 3268 F g?1 at 1.0 A g?1 in a 3.0 M KOH solution. In addition, it can sustain 93.6% stability of its initial capacity after 3000 consecutive charge-discharge cycles at a current density of 10.0 A g?1. Also, the optimal potential window (from zero to 1.40 V) was determined in the asymmetric configuration of this electrode. The energy density of 41 Wh kg?1 and power density of 700 W kg?1 indicate the applicability of this electrode in supercapacitor application.
查看更多>>摘要：? 2022 Elsevier B.V.Large lattice distortion is the design idea to obtain a high elastocaloric effect of shape memory alloys. In the present work, a new method of He ion irradiation is used to obtain a large lattice distortion, resulting in a 6.5 K of adiabatic temperature in Ti-Ni microwires, compared to the 2.9 K of the unirradiated sample. In addition, the isothermal entropy change is 68 J/kg·K at 293 K, which is twice as high as that of unirradiated alternatives. The microwires have a larger unit cell lattice distortion after irradiation across the stress-induced martensite transformation, therefore, the irradiated sample has a larger lattice entropy change, resulting in the improvement of the phase transformation entropy change. This is the main reason that the elastocaloric effect of Ti-Ni shape memory microwires is significantly improved after He ion irradiation. This method will provide a new idea for the design of colossal elastocaloric effect materials and provide the possibility for the application of solid-state refrigeration.
查看更多>>摘要：? 2022 Elsevier B.V.To study the effects of Al and Ti additions on the formation of inclusions in nickel-based superalloys, laboratory experiments were carried out at 1823 K. We observed mainly pure Al2O3 inclusions and some Al2O3–TixOy and Al2O3(–TixOy)–titanium nitride (TiN) composite inclusions in the nickel-based alloy with initial deoxidants of 0.3–0.7% Al and 0.7–1.2% Ti (wt%). The total Ti content in the inclusions increased slightly with an increasing amount of added Ti. Thermodynamic calculations were conducted to understand the formation mechanism of the inclusions and control the inclusions. The predominance diagram obtained for the Al–Ti–O inclusions in the nickel-based superalloy system was based on Factsage and classical thermodynamic calculations. The inclusions obtained from experiments were not completely consistent with the Factsage calculated results; however, they agreed well with the classical thermodynamic calculation. The calculated results indicated that the thermodynamic stable inclusion was Al2O3 in liquid K4169 alloy at 1823 K. The oxygen content should be controlled to< 10 ppm to avoid the formation of Al2O3 inclusions in the superalloy. Thermodynamic results indicated the initial precipitation of TiN in the FCC phase of the superalloy from 963 to 1403 K. The precipitation temperature of TiN decreased with the decrease of N content and increase in Ti content in the superalloy. The precipitation of TiN was not only dependent on the contents of Ti and N in a sample but also on the cooling conditions.
查看更多>>摘要：? 2022 Elsevier B.V.Composition-modified bilayer channel configuration was introduced for enhancing the device performance of In-Ga-Zn-O (IGZO) thin film transistors (TFTs), which was composed of 3-nm-thick In-rich prompt-IGZO and 12-nm-thick prime-IGZO layers for the formation of two-dimensional electron gas (2DEG) at interfaces. The cationic compositions of bilayer IGZO channels were designed by modulating the sub-cyclic ratios among the precursors during atomic-layer deposition process. To properly control the effect of modified compositions in bilayer channels, the oxidant for the formation of Al2O3 protection and gate insulator layers were chosen as ozone. The IGZO TFTs fabricated with bilayer channel configurations exhibited the carrier mobility of 45.5 cm2/Vs and the subthreshold swing of 0.24 V/dec, keeping the turn-on position at near 0 V of gate bias without performing additional heat treatments including post-annealing process at higher temperatures. From the investigations on the temperature-dependent variations in electrical conductivity and band alignments of bi-layered IGZO channels, composition controls of prime and prompt IGZO layers were found to be crucial for initiating the quantum confinement effect of 2DEG. Thus, the optimum compositions (In:Ga:Zn) of both layers were 1.4:1.0:2.0 and 5.0:1.0:3.4, respectively. The device using optimum bilayer channel composition exhibited excellent positive bias stress (PBS) stability due to the implementation of confinement barrier at interface between the prime and prompt layers, in which the threshold voltage shifts (?VTH) were estimated to be as low as 1.34 V. Furthermore, it was found that the PBS instability was anomalously compensated even at higher temperature stresses owing to long-term hydrogen diffusion from the ozone-processed gate stacks. The ?VTH was finally stabilized to 0.22 V at 80 °C with a lapse of stress time for 104 s.
NSTL
Elsevier