Exhibiting thickness-dependent change in the critical temperature (Tc) for the onset of superconductivity, Mo2C has emerged as an important new member in the family of two-dimensional atomic ...crystals. Controllable growth in terms of morphology and thickness is necessary to elucidate its intrinsic properties at the 2D limit. Here we demonstrate the chemical vapor deposition of ultrathin Mo2C crystals on liquid Cu surface where the morphology of the crystals can be controlled by tuning the carbon supersaturation. A unique staggered carbon vacancy ordering is discovered in Mo2C crystals having particular geometries. Thickness engineering of the crystal can be achieved by controlling the thickness of the Cu catalyst layer, which affords a facile route to grow ultrathin 2D samples. Ultrathin Mo2C crystals so obtained, have been characterized using aberration corrected scanning transmission electron microscopy annular dark field imaging, where the co-existence of both AA and AB stacking modes is observed. The high crystallinity of the Mo2C crystals synthesized in this work is attested by its characteristic sharp superconducting transition.
Large‐sized MoS2 crystals can be grown on SiO2/Si substrates via a two‐stage chemical vapor deposition method. The maximum size of MoS2 crystals can be up to about 305 μm. The growth method can be ...used to grow other transition metal dichalcogenide crystals and lateral heterojunctions. The electron mobility of the MoS2 crystals can reach ≈30 cm2 V−1 s−1, which is comparable to those of exfoliated flakes.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The electrochemical performances of TiS2 in potassium ion batteries (KIBs) are poor due to the large size of K ions, which induces irreversible structural changes and poor kinetics. To obtain ...detailed insights into the kinetics of phase changes, we investigated the electrochemical properties, phase transformations, and stability of potassium-intercalated TiS2 (K x TiS2, 0 ≤ x ≤ 0.88). In situ XRD reveals staged transitions corresponding to distinct crystalline phases during K ion intercalation, which are distinct from those of Li and Na ions. Electrochemical (cyclic voltammetry and galvanostatic charge/discharge) studies show that the phase transitions among various intercalated stages slow down the kinetics of the discharge/charge in bulk TiS2 hosts. By chemically prepotassiating the bulk TiS2 (K0.25TiS2) to reduce the domain size of the crystal, these phase transitions are bypassed and more facile ion insertion kinetics can be obtained, which leads to improved Coulombic efficiency, rate capability, and cycling stability.
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IJS, KILJ, NUK, PNG, UL, UM
The water ecological environment plays an important role in the development of Xinjiang. Dense industrial areas have certain pollution to surface water. In this study, surface water samples from ...Manas River Basin near Shihezi City were collected in May 2019 to study the pollution characteristics of heavy metals Cd, As, Cr, Cu, Ni, Zn, Fe, and Pb in this section of the river. The content of Zn in this basin is the highest, and the content of Cd is the lowest. In this study, Nemerow pollution index results show that the single-factor pollution index of 8 kinds of heavy metals at each sampling point of the Manas River is less than 1; the grade is “clean.” The comprehensive pollution index of all sampling points is less than 0.7, and the heavy metal pollution grade of the surface water of Manas river is “no pollution.” The human health risk assessment model results show that the total health risk of children is higher than that of adults. Cr, Fe, Ni, Zn, Cu, Cd, and Pb are mainly affected by domestic and industrial wastewater discharge and non-point source pollution, and As is controlled by the natural source of the soil parent material layer.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Li metal batteries (LMBs) are known as the ideal energy storage candidates for the future rechargeable batteries due to the high energy density. However, uncontrolled Li dendrites growing during ...charge/discharge process causes extremely low coulombic efficiency and short lifespan. In this work, a thin lithiophilic layer of Ag was coated on the bare Li surface via a thermal evaporation method, which alleviated volume variations and suppressed Li dendrites growth during cycling. As a result, a long lifespan of 250 h at a current density of 1 mA cm
was achieved in the symmetric cell when using the Ag-modified Li foil (Ag@Li). The LiFePO
|Li full cell demonstrated an excellent cycling performance with a high specific capacity of 131 mAh g
even after 300 cycles at 0.5 C. This study offers a suitable method for stabilizing Li metal anodes in LMBs.
•Conversion/deconversion mechanism of (Fe,Cr)-binary oxide thin film is reported.•Influence of substituting iron by chromium (CrxFe2−xO3 phase) is evaluated.•Inferior electrochemical conversion ...activity of chromium vs iron oxide is shown.•Decreased lithium transport caused by presence of chromium oxide is evidenced.•SEI layer uptake and thin film electrode volume expansion upon cycling are shown.
(Fe,Cr)-binary oxide thin film electrodes were prepared as negative electrode material for lithium-ion micro-batteries by thermal growth on a stainless steel (AISI 410, FeCr12.5) current collector. The mechanisms of lithiation/delithiation were investigated by means of electrochemical (CV, galvanostatic cycling), spectroscopic (XPS, ToF-SIMS) and microscopic (SEM, AFM) analytical techniques. The as-prepared (Fe, Cr)-binary oxide electrodes exhibit a good cycling performance except the first discharge/charge cycle where a high irreversible capacity is observed due to formation of a solid electrolyte interphase (SEI) layer. The influence of substituting an oxidized iron by an oxidized chromium (CrxFe2−xO3 phase) was evaluated. The data show that the inferior electrochemical conversion activity of substituted oxidized chromium results in hindering lithium transport in the bulk thin film electrode. It was observed that the irreversible morphology modifications together with SEI evolution are critical to capacity degradation while retaining good coulombic efficiency.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Chiral perovskites have attracted considerable attention as excellent spin-emitting materials for applications in spintronics, quantum optics, and biological. Especially in drug development of ...biological, weak chirality molecules are frequently selected to reduce the side effects of toxics, and there is a common defect for accurately detecting the weak chirality with common methods at room temperature. In this study, formamidine lead bromide perovskite nanocrystals (FAPbBr
NCs) were coated with chiral ligands, whose chirality was too weak to be observed in the visible region at room temperature. Thus, by characterizing the transverse shift of photonic spin Hall effect (SHE), the accurate discrimination of weak chirality in the visible region was achieved successfully. By measuring the shift value and light spot splitting of photonic SHE at the same concentration, NEA-coated FAPbBr
NCs can effectively enhance the chirality of naphthalene ethylamine (NEA) ligands when under the mutually reinforcement of chiral molecular and inorganic parts. In addition, we furtherly clearly distinguished the tiny chiral distinction of NEA-coated FAPbBr
NCs with different particle sizes, which revealed that the chirality decreases with the increase of particle size. These findings could provide effective solutions for the detection and application of weak chirality in hybrid perovskite nanocrystals in universal environment.
With the ever-increasing demands of grid-scale energy storage, aqueous zinc-ion batteries (ZIBs) have garnered increasing attention around the world. However, limited Zn
2+
host materials have ...hindered the commercialization of ZIBs. Hence, Mo-V oxides with different phase structures (orth-, tri-, and tetra-MoVO) were precisely constructed to develop phase-dependent Mo-V oxide cathodes for Zn
2+
storage in ZIBs. The open frameworks and varied tunnel structures formed a favorable alternative for achieving suitable Zn
2+
diffusion kinetics. With optimized phase engineering, the high specific capacity of approximately 400 mA h g
−1
and excellent cyclic stability of 1000 cycles were achieved with orth-MoVO as the cathode. The large amount of six- and seven-member rings in the orth-MoVO phase, which allow for alternative Zn
2+
insertion, play a vital role in hosting Zn
2+
ions reversibly. The proposed phase engineering strategy provides a new approach toward cathode design in ZIBs.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In article number 1900579, Jilei Liu, Jiaxu Yan, Xiaofeng Fan, Yizhong Huang, Ze Xiang Shen and co‐workers utilize operando techniques including Raman mapping and X‐ray diffraction (XRD), in ...combination with theoretical simulations, to enable the direct visualization of potassium‐intercalated graphite intercalation compounds staging evolution during electrochemical operations, with high temporal and spatial resolution. Moreover, solid evidence for a new stoichiometric formula of KC16 and an intrastage transition within stage 2 are found.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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