[en] Germanium carbide (Ge_1-xC_x) films have been prepared by RF reactive sputtering a pure Ge(111) target at different flow rate ratios of CH₄/(CH₄+Ar) in a CH₄/Ar mixture discharge, and it has been found that the composition, chemical bonding, optical and mechanical properties of Ge_1-xC_x films are remarkably influenced by the flow rate ratio of CH₄/(CH₄+Ar). The effects of the chemical bonding on the optical and mechanical properties of the Ge_1-xC_x films have been explored. In addition, an antireflection Ge_1-xC_x double-layer coating deposited on both sides of the ZnS substrate wafer has been developed for application as an infrared window. It is shown that the transmittance in the wavelength region between 8 and 12 μm and the hardness of the ZnS substrate have been significantly improved by the double-layer coating

[en] Perovskite La_0.5Ca_0.5MnO₃ (LCM) based materials are promising for electrode construction but their poor conductivities often lead to limited electrochemical performances. In this work, LCM was combined with Ag through the two-step process based on sol-gel and silver mirror reaction. The as-obtained LCM@Ag composites were characterized by scanning electron microscopy and x-ray powder diffraction. The mass percent determined by energy disperse spectroscopy combined with x-ray photoelectron spectroscopy was estimated at 5%. The electrochemical measurements showed LCM@Ag to possess superior specific capacitance of 287 C g⁻¹ (179 F g⁻¹) at 1.5 A g⁻¹ while pure LCM delivered only 187 C g⁻¹ (117 F g⁻¹). The key to the improvement of performance can be attributed to the silver nanoparticle introduction, which leads to the enhancement of the electron transport capacity and ion diffusion for the composite. Meanwhile, the cycle stability slightly improved and the retention rate after 3,000 cycles at 10 A g⁻¹ reached 66%. In sum, La_0.5Ca_0.5MnO₃ perovskite system looks promising for electrode construction, where silver modification could improve the overall electrochemical properties. (paper)

[en] BiVO₄ is known for its ability to decompose water under visible light irradiation. However, BiVO₄ overall suffers from rapid recombination of photogenerated carriers, low photochemical conversion efficiency, low specific surface area, poor conductivity, and weak adsorption capacity of dye. These features limited its application in photocatalysis. In this work, ternary Z-scheme g-C₃N₄/RGO/BiVO₄ nanocomposites were successfully fabricated by in situ electrostatic adsorption of g-C₃N₄ sheets on RGO/BiVO₄ surface using hydrothermal and thermal oxidations processes. The ternary Z-scheme g-C₃N₄/RGO/BiVO₄ nanocomposites were then tested for photodegradation of Rhodamine B. The introduction of graphene into direct Z-scheme g-C₃N₄/BiVO₄ nanocomposites as an electronic accelerator efficiently enhanced the photocatalytic properties. The as-prepared g-C₃N₄/RGO/BiVO₄ composites exhibited optimal visible light responses with significantly improved photocatalytic performances toward degradation of Rhodamine B. The degradation efficiency using ternary photocatalyst reached 100% after 20 min of irradiation time. The reaction rate constant was estimated to 1.537, which was almost 29- and 20-folds higher than those of pure g-C₃N₄ and binary g-C₃N₄/BiVO₄, respectively. The synergistic effect between BiVO₄, RGO and g-C₃N₄ yielded g-C₃N₄/RGO/BiVO₄ composites with Z-scheme charge transfer mechanism, promoting rapid separation and slow recombination of photogenerated electron–hole pairs with strong photocatalytic activity. Overall, these findings look promising for design of future Z-scheme photocatalysts for environmental degradation of organic dyes.

[en] Objective: To evaluate the correlation between the cardiac morphological indexes on 3-D T₁-weighted MRI and CT in children with pectus excavatum. Methods: 39 children with pectus excavatum underwent chest MRI and CT preoperatively. Haller index, cardiac compression index, cardiac rotation angle, minimal antero-posterior (AP) diameter, maximal AP diameter, and transverse diameter were measured at the level of maximal sternal depression. The measurements obtained on MRI and CT were compared. Results: The correlation was significant (P < 0.05) for cardiac compression index (R = 0.88), transverse diameter (R = 0.90), Haller index (R = 0.92), cardiac rotation angle (R = 0.87), minimal AP diameter (R = 0.86), and maximal AP diameter (R = 0.49). Conclusion: The cardiac morphological indexes measured on 3-D T₁-weighted MRI correlate well with CT and can replace the CT as a noninvasive examination in children with pectus excavatum. (authors)

[en] Battery-like materials have recently been proposed as relevant bridge materials between pseudo-capacitance and battery materials. These composites have widely been used as electrodes in hybrid supercapacitors. In this account, MnCo₂O₄ (MCO), active carbon (AC) and a series of MnCo₂O₄@active carbon (MCO@AC) composites were investigated as electrodes of hybrid supercapacitors in aqueous alkaline electrolytes. MCO@AC200 achieved the highest specific capacity of 443.5 C g⁻¹ at current density of 0.5 A g⁻¹. This composite also overcame the low utilization of active material and difficult electron transport caused by thickness of high mass-loading conditions, yielding elevated volumetric capacity of 527.13 C cm⁻³ at 0.5 A g⁻¹. However, MCO@AC200 was found to suffer from poor cycle stability. To clarify the electrochemical behaviors of all hybrid electrode materials and figure out the reasons behind the short-coming, the electrochemical kinetics were analyzed by means of cyclic voltammetry, galvanostatic charge-discharge, and valence states of elements. The charge storage behaviors of MCO and AC in MCO@AC composites were found to be mutually independent. MCO as battery-like material showed irreversible phase transition, leading to deteriorated cycle stability. Overall, both electrode structure design and irreversible phase transition should be considered when developing hybrid supercapacitors with high volumetric capacity.

[en] Highlights: • The sample had merits in capacity, rate capability and potential window concurrently. • The Fe₂O₃@rGO negative electrode had high rate capability of 91.08% at 20 A g⁻¹. • The La_0.85Sr_0.15MnO₃@NiCo₂O₄//Fe₂O₃/rGO device was assembled firstly. • The device performed high energy density of 77.5 W h kg⁻¹ at 900 W kg⁻¹. -- Abstract: Battery-supercapacitor hybrid (BSH) devices are novel energy storage components for configuration engineering, which are receiving increasing attention in recent years. Fe₂O₃-based materials with wide potential windows are promising negative electrodes in aqueous electrolytes. However, Fe₂O₃-based negative electrodes exhibiting more than 90% rate capability at high current density have been rarely reported. Such high rate capability can further promote the application of BSH device for high power storage. In this study, Fe₂O₃/reduced graphene oxide (rGO) composites with potential windows ranging from −0.15 to −1.2 V and unprecedented rate capability of 91.08% are prepared by fine regulation of the component ratios. The electrode tested in 6 M KOH electrolyte provides an excellent specific capacity of 413 C g⁻¹. The electrode shows merits in capacity, rate capability and potential window simultaneously. Also, bulk charge storage leads to high specific capacity of perovskite. These features can raise the energy density of BSH device to 77.5 W h kg⁻¹ by properly matching the modified La_0.85Sr_0.15MnO₃@NiCo₂O₄ perovskite composite as positive electrode (826 C g⁻¹) and Fe₂O₃/rGO as negative electrode. The device also exhibits excellent power density (54,000 W kg⁻¹). In sum, the proposed device with superior electrochemical behavior can further promote the practical applications of perovskite-based or Fe₂O₃-based BSH devices.

[en] In this work, graphite encapsulated Fe nanoparticles and thin carbon nanotubes (CNTs) supported on the pristine CNTs, respectively, were synthesized using plasma enhanced chemical vapor deposition via efficiently controlling the flow rate of discharging CH₄ and H₂ gas. The properties of the obtained hybrid materials were characterized with superconducting quantum interference and field emission measurements. The results showed that the encapsulated Fe nanoparticles had diameters ranging from 1 to 30 nm, and this hybrid nanocomposite exhibited a ferromagnetic behavior at room temperature. Thin CNTs with an average diameter of 6 nm were attached to the surface of the prepared CNTs, which exhibited a lower turn-on field and higher emission current density than the pristine CNTs. The Fe nanoparticles either encapsulated with graphite or used as catalyst for thin CNTs growth were all originated from the pyrolysis of ferrocene. - Graphical abstract: Graphite encapsulated Fe nanoparticles and thin carbon nanotubes supported on the pristine carbon nanotubes, respectively, were synthesized using plasma enhanced chemical vapor deposition.

[en] A novel hedgehog-like core/shell structure, consisting of a high density of vertically aligned graphene sheets and a thin graphene shell/a copper core (VGs-GS/CC), has been synthesized via a simple one-step synthesis route using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Scanning and transmission electron microscopy investigations show that the morphology of this core/shell material could be controlled by deposition time. For a short deposition time, only multilayer graphene shell tightly surrounds the copper particle, while as the deposition time is relative long, graphene sheets extend from the surface of GS/CC. The GS can protect CC particles from oxidation. The growth mechanism for the obtained GS/CC and VGs-GS/CC has been revealed. Compared to VGs, VGs-GS/CC material exhibits a better electron field emission property. This investigation opens a possibility for designing a core/shell structure of different carbon–metal hybrid materials for a wide variety of practical applications. - Graphical abstract: With increasing deposition time, graphene sheets extend from the surface of GS/CC, causing the multilayer graphene encapsulated copper to be converted into vertically aligned graphene sheets–graphene shell/copper core structure. Highlights: ► A novel hedgehog-like core/shell structure has been synthesized. ► The structure consists of vertical graphene sheets-graphene shell and copper core. ► The morphology of VGs-GS/CC can be controlled by choosing a proper deposition time. ► With increasing deposition time, graphene sheets extend from the surface of GS/CC. ► VGs-GS/CC exhibits a better electron field emission property as compared with VGs.

[en] Highlights: ► One-step solvothermal route to RGO/CdS hybrid materials. ► The hybrid materials exhibit an enhanced photocatalytic degradation activity for MB. ► The optimum loading amount of RGO is 5.0 wt%. ► The RGO retards the charge recombination of CdS enhancing the degradation efficiency. - Abstract: Reduced graphene oxide/cadmium sulfide (RGO/CdS) hybrid material was synthesized by a one-step solvothermal method, wherein graphene oxide (GO) was a supporting material on which CdS nanoparticles were distributed homogeneously, and cadmium acetate (Cd(Ac)₂·2H₂O) was used as the CdS precursor. The supporting material RGO for CdS nanoparticles effectively enhanced their photocatalytic activities for the photodegradation of methylene blue in the aqueous solution. The optimum weight ratio of the GO to CdS in the hybrid material was 5.0%, which exhibited an excellent photodegradation efficiency (94%) and a better removal efficiency of total organic carbon (TOC) (57%), about 2.5 times and 5.1 times higher than that of pure CdS nanoparticles, respectively, under visible light (VL) irradiation. This improved photodegradation efficiency could be attributed to the increased adsorbability for methylene blue molecules, light absorption levels located in visible region, high charge transfer and separation ability, due to the introduction of a two-dimensional RGO network.

[en] LaMnO₃ is a promising candidate for used in supercapacitor because of its unique anion-based intercalation capacitive behavior. Its electrochemical performance, however, is still seriously limited by the intrinsically poor electrical conductivity and the exudation of Mn species during reversible intercalation. Herein, we demonstrate that the hybridization of LaMnO₃ with NiCo₂O₄ to form hierarchical core–shell nanosheet-assembled architectures on Ni foam can efficiently suppress the leaching of Mn species and evidently improve the electronic conductivity, thus optimizing its physicochemical properties for supercapacitance. As expected, superior capacitive performance is achieved with ultrahigh specific capacity of 811 C g⁻¹ at 0.5 A g⁻¹, and the capacity still reached 555 C g⁻¹ even at the largest current density of 16 A g⁻¹ with a high rate capability of 68%. When assembled with activated carbon (AC) as an hybrid supercapacitor device, it delivers not only maximum energy density of 36.6 Wh·kg⁻¹ at a power density of 800 W kg⁻¹ and ultrahigh power density of 25,600 W kg⁻¹ at an energy density of 19.4 Wh·kg⁻¹, but also robust cycling stability (up to 10,000 cycles), holding great potential for future energy storage devices.