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Abstract A carbonization of metal-organic frameworks is utilized to enhance the electrochemical performance of SiO as a promising anode for Li-ion batteries. The metal-organic frameworks are synthesized by a facile and green method. The carbon-coated SiO (SiO@C composite) is characterized by X-ray diffraction (XRD), autosorb surface analyzer, high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) attaching an energy dispersive X-ray spectroscopy (EDS). The electrochemical properties of SiO@C composite and mechanically milled SiO as anodes are investigated for lithium-ion batteries. The SiO@C composite shows superior performance compared with the milled SiO, including enhanced rate capability and better capacity retention. Highlights • Porous carbon is prepared via carbonization of metal-organic frameworks. • SiO particles are uniformly covered with porous carbon. • SiO coated with porous carbon shows enhanced electrochemcial properties. [ABSTRACT FROM AUTHOR]

Atomically thin Tungsten disufide (WS 2 ) film is a promising material for flexible electronics and optoelectronics. The ability to prepare controllable and uniform WS 2 films over a large area is essential for their practical application. In this work, a two-step technique has been adopted to synthesize ultrathin WS 2 films by sulfurization of atomic-layer-deposited WO 3 films. A novel plasma enhanced atomic layer deposition (PEALD) process was employed to prepare ultrathin WO 3 films by using bis(tertbutylimido)-bis(dimethylamido)-tungsten and O 2 plasma as reactants. Smooth and atomically thin WS 2 films are easily prepared by sulfuring the ultrathin WO 3 films. It was observed that the thickness of WS 2 films can be controlled by adjusting the numbers of PEALD cycles. X-ray photo-emission spectroscopy exhibits that WS 2 films have good stoichiometry, and transmission electron microscopy reveals that WS 2 films are polycrystalline. The field effect transistor made on the as-grown WS 2 film exhibits n-type performance with an on/off current ratio of ∼10 5 and field-effect electron mobility of 4.5 cm 2 V −1 s −1 . The proposed growth technique for WS 2 film is attractive for its applications in next-generation flexible electronics and optoelectronics, and is useful for preparations of other transition metal dichalcogenides ultrathin films. [ABSTRACT FROM AUTHOR]

In this letter, hafnium (Hf) is evaluated as an alternative contact metal to monolayer tungsten diselenide (WSe 2 ) using first-principles plane-wave pseudopotential method based on density functional theory. Four configurations were considered for Hf–WSe 2 top contacts including the bridge, center, top, and upper structures. Results show that Ohmic contact between Hf metal and monolayer WSe 2 is formed and that the electron transport across Hf–WSe 2 top contacts is mainly of a resonant nature. It is found that the arrangements of Hf metal on monolayer WSe 2 play an important role on the energetic and electronic properties of Hf–WSe 2 top contacts. The order of interfacial stability of Hf–WSe 2 top contacts is upper < top < center < bridge, and Hf–WSe 2 top contacts are more stable than Ti–WSe 2 top contact because of their small lattice mismatch. The Hf–WSe 2 top contact with bridge structure has the highest electron density and the lowest tunnel barrier among the four Hf–WSe 2 top contacts. Analysis indicates that Hf metal may be proposed as an alternative electrode material for fabricating top contacts to monolayer WSe 2 due to its good stability and low contact resistance. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cu2O/Cu cermet was used as a candidate partially inert anode material to produce aluminum alloys. [•] The thermal corrosion behavior of Cu2O/Cu was investigated in molten salt at 960°C. [•] The corrosion rate is largely governed by the geometrical structures of Cu in the prepared samples. [•] The corrosion rate increases with decreasing sizes and increasing filling contents of Cu phase. [•] The corrosion rate was 1.8–9cm/y and the Cu contents is less than 6.2 wt.% in the produced aluminum. [ABSTRACT FROM AUTHOR]

Tetracycline is an organic compound that poses a significant threat to both the ecological environment and human health during its long-term production and use. Advanced oxidation processes based on sulfate radicals (SR-AOP) have been recognized as effective techniques for treating antibiotic contamination. However, The urgent demand for a green, efficient, and recyclable catalyst to effectively facilitate persulfate treatment of tetracycline pollution is evident. Magnetic Fe 3 O 4 -C@MoS 2 composite were synthesized using hydrothermal and pyrolysis methods. Degradation experiments, free radical quenching experiments, EPR analysis were carried out to investigate the degradation performance and mechanisms of Fe 3 O 4 -C@MoS 2 composite. Results showed that the degradation efficiency of 100 mL of 20 mg/L tetracycline solution reached up to 97% within 40 mins with the dosage of 20 mg Fe 3 O 4 -C@MoS 2 and 30.7 mg peroxmonosulfate. Furthermore, this degradation system exhibited excellent efficiency even over a wide pH range of 3–9. The transformation of Mo (IV) and S2-/S n 2- species valence states facilitated the conversion between Fe(III)/Fe(II). Both free radical (S O 4 ⋅ − , ⋅ O H and O 2 ⋅ −) as well as non-free radical species (O 2 1) were found to accelerate the catalytic reaction during the tetracycline degradation. The possible pathways of tetracycline degradation were proposed, and the toxicity of the intermediate products were proved to be lower than that of tetracycline. Finally, magnetic Fe 3 O 4 -C@MoS 2 composites possessed good reusability and stability after 4 cycles of degradation. [Display omitted] • Fe 3 O 4 -C@MoS 2 -2/PMS achieved 97% of TC degradation efficiency within 40 mins. • Mo (IV) and S2-/S n 2- species promoted the redox cycle of Fe(III)/Fe(II). • Synergistic effects of free radicals (S O 4 ⋅ − , ⋅ O H and O 2 ⋅ −) and non-free radical (O 2 1) species enhanced the high degradation efficiency of TC. • Fe 3 O 4 -C@MoS 2 -2 with magnetism exhibited favorable reusability and stability. [ABSTRACT FROM AUTHOR]

Abstract: Novel oxyfluoride glasses SiO2–Al2O3–Na2O–ZnF2 doped with Tm3+ and Tm3+/Yb3+ were fabricated. The optical properties of the synthesized glasses were experimentally and theoretically investigated in detail. According to the Judd–Ofelt theory, the Judd–Ofelt intensity parameters were calculated. With these intensity parameters, the radiative transition probabilities, fluorescence branching ratios and radiative lifetimes were obtained. The fluorescence lifetime and quantum efficiency for 1D2 → 3F4 emission of Tm3+-singly doped glass were determined to be 12μs, and 35.3%, respectively. The up-conversion luminescence was observed upon excitation with 980nm diode laser. The dependence of the up-conversion emission intensity upon the excitation power was examined, and the up-conversion mechanisms were discussed. [Copyright &y& Elsevier]

Development of highly active, durable electrocatalysts involving cheap and earth-abundant non-precious metals for the electrocatalytic hydrogen evolution reaction (HER) is of great significance for green hydrogen fuel production. Herein, we report a novel ultrafine VN nanoparticle (2–4 nm) dispersedly confined in Co-encapsulated N-doped carbon nanotubes (VN/Co@NCNT) by a facile one-pot NH 3 -free pyrolysis method. When applied for the electrocatalytic HER, the as-obtained VN/Co@NCNT material exhibits greatly improved catalytic activity compared to bulk VN and Co@NCNT counterparts, with a quite low overpotential of 180 mV at 10 mA cm−2 (VN: 342 mV; Co@NCNT: 313 mV), accompanying a remarkable catalytic durability for over 60 h and approximately 100% Faradaic efficiency in alkaline media. The enhanced electrocatalytic HER performance of VN/Co@NCNT can be mainly attributed to the exposed high-density catalytically active sites of ultrafine VN nanoparticles, the fast mass and electron transport over Co-embedded graphitic carbon nanotubes, as well as the enhanced electrical conductivity by the graphitic and pyridinic N-doping effects. Image 1 • A facile one-pot NH 3 -free pyrolysis approach is reported to synthesize carbon tube-supported ultrafine VN nanoparticles. • The ultrafine nanostructure of VN favors the full exposure of catalytically active sites on its surface. • The as-obtained material can function as a highly active and stable nonprecious metal containing electrocatalyst of HER. • The findings put forward new insights into the rational design of efficient VN-based HER electrocatalysts. [ABSTRACT FROM AUTHOR]

We have studied the structure, composition and electrical properties of the MoSe x films deposited at different substrate temperature ranging from 298 to 573 K and the electrical characteristics of the back-gated MoSe x field effect transistors (FETs). Results show that these characteristics depend deeply on the substrate temperature. With the increment of the substrate temperature, the MoSe x films transfer from amorphous state to crystalline state, the concentration of the bond Mo and Se decreases first and then increases, and the bonding atomic ratio of Se/Mo increases. When the substrate temperature is at 423 K, the MoSe x film has the highest Hall mobility (6.71 cm 2 V −1 s −1 ) and the lowest room temperature resistivity (3.28 Ω cm). Moreover, MoSe x FET fabricated by amorphous MoSe x film channel has higher I on / I off ratio and field-effect mobility. Using the MoSe x channel deposited at 423 K, the highest I on / I off ratio and field-effect mobility of the FET are about 10 5 and 15.7 cm 2 V −1 s −1 , respectively. [ABSTRACT FROM AUTHOR]

Influences of temperature on thermal properties of monolayer MoS 2 were investigated using first-principles calculations based on the density-functional perturbation theory. The calculated equilibrium vibration properties and Grüneisen parameters γ of monolayer MoS 2 are in good agreement with the available experimental and theoretical values. Interestingly, γ of acoustic modes show an evidently asymmetric character due to the sandwiched structure of monolayer MoS 2 while γ of optical modes display an approximate symmetry in the first Brillouin zone. Thermal properties analysis shows that temperature has a great effect on Debye temperature θ D , isochoric specific heat capacity C V , relaxations time τ , mean free path l , and thermal conductivity κ of monolayer MoS 2 . With the increasing temperature, θ D and C V increase rapidly and then reach saturation, whereas τ and l decrease sharply and then become moderate. The saturation value of θ D and C V of monolayer MoS 2 is 603 K and 17.6 cal/cell K, respectively. The κ of monolayer MoS 2 illustrates the expected T −1 dependence in the range from 47 to 603 K, and it is dominated by longitudinal acoustic (LA) mode which has the maximum value of τ and l . At room temperature, the calculated κ of monolayer MoS 2 of 29.2 W m −1 K −1 is higher than 1.35 W m −1 K −1 that was obtained by Molecular dynamics, but it is in agreement with the experimental value of 34.5 ± 4 W m −1 K −1 . [ABSTRACT FROM AUTHOR]

(TiCp + TiBw)/Ti composite was firstly prepared by spark plasma sintering (SPS) and hot extrusion from Ti-B4C system, and then isothermally heat treated at 400-700 °C for 24 h, respectively. The elevated temperature tensile strength was tested at temperatures corresponding to isothermal heat treatments. Microstructure characterizations were carried out by using SEM, EPMA, XRD, EBSD and TEM. Results show that, the microstructure of (TiCp + TiBw)/Ti composite consists of Ti matrix, particle-like TiC and whisker-like TiB. TiCp and TiBw are stable at elevated temperatures and can prevent Ti matrix from coarsening. On the other hand, the strength of the composite decreases significantly with the increase of testing temperature, but it is always in proportion to that of pure Ti tested at the same temperature, indicating the strengthening effect of in situ formed TiCp and TiBw is stable at elevated temperature. The decrease of elevated temperature strength of (TiCp + TiBw)/Ti composite can be mainly attributed to the high temperature softening of Ti matrix. [ABSTRACT FROM AUTHOR]

Two-dimensional metal-organic framework nanosheets (2D MONs) are excellent heterogeneous catalysts owing to their high density and accessible catalytic sites, reduced diffusion pathways for reactants/products, and fast electron transport. Moreover, the employment of 2D MONs as supports to encapsulate noble nanoparticles can not only stabilize the noble nanoparticles, but also significantly improve their catalytic activity through the synergetic effect between 2D MONs and noble nanoparticles. Herein, we reported a microwave-assisted method for the rapid preparation of 2D UiO-67 metal-organic framework nanosheets (named UiO-67 NS). The Au nanoparticles modified UiO-67 nanocomposites (denoted as Au/UiO-67 NS nanocomposites) are formed by the in situ reduction of HAuCl 4 in the pores of UiO-67 NS. The Au/UiO-67 NS nanocomposites show excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol, and only 20 equivalent sodium borohydride can completely reduce 10 mM 4-NP in 100 s, thanks to highly exposed Au NPs and reduced diffusion distance. In addition, XPS characterizations showed that the binding energy of Au 4 f in Au/UiO-67 NS nanocomposites displays a 0.48 eV less than that of Au nanoparticles on UiO-67 octahedral microcrystals (denoted as Au@UiO-67 OM), which is believed to be responsible for the enhanced catalytic activity toward the reduction of 4-nitrophenol. [Display omitted] • Microwave-assisted method allows efficient, rapid and reproducible preparation of 2D Zr-MOFs UiO-67 nanosheets (UiO-67 NS). • In situ reduction of impregnated HAuCl4 by NaBH4 results in highly dispersed and accessible Au nanoparticles on UiO-67 NS. • The Au/UiO-67 NS shows higher catalytic activity than Au nanoparticles decorated UiO-67 octahedral microcrystals. • The reduction products of 4-aminophenol can be further converted into 4-acetoxyacetanilide in one-pot reaction. [ABSTRACT FROM AUTHOR]

BiCuSeO-based oxyselenide compounds show promising thermoelectric properties, but its thermal stability and oxidation behavior are unknown, which were investigated in the present work with a PbTe-based thermoelectric alloy as a comparison. It was revealed that the BiCuSeO polycrystalline materials displayed much better thermal stability in air than the PbTe-based alloys that were severely oxidized at 573 K, resulting in a decreased density and significantly reduced electrical conductivity. Nevertheless, it was found that the BiCuSeO-based thermoelectric materials could not be used in air for a long time as a conventional oxide at high temperatures; apparent decomposition occurred in the BiCuSeO samples when heated at 773 K, although at 573 K the oxidation was limited to the surface accompanied by the formation of bismuth oxide. [ABSTRACT FROM AUTHOR]

• CoMn 2 O 4 @CoMn 2 S 4 nanocomposites were firstly prepared via in-situ growth method. • The specific capacity of the CoMn 2 O 4 @CoMn 2 S 4 reaches 1542.0 C g−1 at 1 A g−1. • The capacity retention of the CoMn 2 O 4 @CoMn 2 S 4 is 95.81% after 5000 cycles at 20 A g−1. • The symmetric capacitor (CoMn 2 O 4 @CoMn 2 S 4 //AC) exhibits excellent performance. In this work, a novel CoMn 2 O 4 @CoMn 2 S 4 core-shell nanocluster@nanosheet was successfully grown onto Ni foam via a hydrothermal reaction, which omitted the addition of a binder and conductive additive and the need for a complicated electrode preparation process. CoMn 2 S 4 nanosheets as "shells" were found to be uniformly distributed on the surface of CoMn 2 O 4 nanoclusters as "cores" to form a typical core-shell structure. These structures possess a high specific surface area and abundant active sites, which not only shorten the transmission path for electrons and ions, but also prevent collapse of the structure, thus improving its cycling stability. The specific capacity of CoMn 2 O 4 @CoMn 2 S 4 is 1542.0 C g−1 at a current density of 1 A g−1, which is 3.1 times higher than that obtained for CoMn 2 O 4. Moreover, CoMn 2 O 4 @CoMn 2 S 4 shows excellent electrochemical cycling performance, and the specific capacity retention rate for CoMn 2 O 4 @CoMn 2 S 4 reaches 95.81% after 5000 cycles at a current density of 20 A g−1. The specific energy of the CoMn 2 O 4 @CoMn 2 S 4 reaches 44.30 Wh kg−1 at a specific power of 774.98 W kg−1. Therefore, the CoMn 2 O 4 @CoMn 2 S 4 //AC device shows excellent practical application capability. [ABSTRACT FROM AUTHOR]

• Rh single atoms were loaded onto the surface of Cu 2 MoS 4 nanoparticles. • The photocatalytic efficiency of the Cu 2 MoS 4 /Rh composites was evaluated. • Rh single atoms could prevent electron/hole recombination during photocatalytic reaction. In this study, hollow cubic Cu 2 MoS 4 nanoparticles were synthesized via a facile hydrothermal method. Following that, Rh single atoms were loaded onto the surface of Cu 2 MoS 4 nanoparticles to prevent electron/hole recombination. The cubic morphology of Cu 2 MoS 4 nanoparticles and the presence of Rh atoms were investigated by Transmitting Electron Microscope (TEM). The crystal structure of the synthesized Rh-loaded Cu 2 MoS 4 was studied by X-ray diffraction (XRD). The shift in Rh X-ray Photoelectron Spectroscopy (XPS) peaks indicated the intimate interaction between Rh and Cu 2 MoS 4 , providing a pathway for the charge transfer. The photocatalytic efficiency of the synthesized photocatalysts was significantly enhanced by introducing Rh single atoms onto the Cu 2 MoS 4 surface. Consecutive photocatalytic dye degradation experiments revealed that Rh-loaded Cu 2 MoS 4 nanoparticles could be recycled and reused multiple times with no drop in the photocatalytic efficiency. The improved photocatalytic performance of Rh-loaded Cu 2 MoS 4 was attributed to a lower charge transfer resistance, higher charge transfer rate, and longer charge carrier lifetime. The most crucial reactive radical was detected to be ⋅O 2 - while e - and h + are also playing an essential role in the photocatalytic degradation of RhB on Rh-loaded Cu 2 MoS 4. This study highlighted the importance of forming a Schottky junction between Rh and Cu 2 MoS 4 to enhance charge carrier separation and improve photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monodisperse CIS NCs have been obtained via thermal decomposition of metal–thiolate. [•] The XRD pattern revealed that CIS NCs have chalcopyrite and wurtzite structures. [•] Pyramid-like (chalcopyrite) and nanospheres (wurtzite) were determined by TEM. [•] The third-order optical nonlinearity is investigated by using Z-scan technique. [Copyright &y& Elsevier]