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The novel BiOBr/reduced graphene oxide/protonated g-C3N4 (BiOBr/RGO/pg-C3N4) composites were successfully synthesized by using a facile solvothermal synthesis method. The structure, ...morphology, optical and electronic properties were explored by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS), and photoelectrochemical measurement. The photocatalytic activities of as-synthesized samples were evaluated by the degradation of Rhodamine B (Rh B) and tetracycline hydrochloride (TC) aqueous solution under visible light irradiation (λ > 420nm). Compared with BiOBr, protonated g-C3N4 (pg-C3N4), BiOBr/pg-C3N4 and RGO/pg-C3N4, BiOBr/RGO/pg-C3N4 composites exhibited higher photocatalytic activity. The total organic carbon (TOC) removal ratios of Rh B and TC over 10% BiOBr/RGO/pg-C3N4 were 88% and 59%, respectively. The excellent photcatalytic performance was investigated by photoluminescence spectroscopy (PL), the radical quenching and electron spin resonance experiments. A Z-scheme charge transfer mechanism was proposed, in which RGO acted as an electron transfer mediator. It was worth pointing out that the closely contacted two-dimensional interface among the BiOBr, the RGO and pg-C3N4 promoted the separation and transfer of photo-generated charge carriers, and thus enhanced the photocatalytic efficiency.
The ternary plasmonic Ag Cl/Ag/g-C3N4 photocatalysts were successfully fabricated by a modified deposition–precipitation method, through which Ag/Ag Cl nanoparticles（5–15 nm in size） were evenly ...dispersed on the surface of g-C3N4. The Ag Cl/Ag/g-C3N4 composites exhibited higher photocatalytic activity than Ag/Ag Cl and g-C3N4. The enhanced photocatalytic performance could be attributed to an efficient separation of electron–hole pairs through a Z-scheme mechanism, in which Ag nanoparticles acted as charge separation centers.
The aluminum rechargeable battery is a desirable device for large-scale energy storage owing to the high capacity derived from the properties of the aluminum metal anode. The development of cathode ...materials is needed to compose battery systems. However, the design principles of the cathode materials have not been determined. We focus on the high capacity FeS2 cathode materials and investigate the discharge/charge reaction mechanisms in chloroaluminate ionic liquids as the electrolyte at 55°C. X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) measurements are performed for the discharged and charged samples. S 3p-orbitals are shown to play an important role in the redox reactions from the results of the S and Fe K-edge XANES spectra. As a result of the redox reaction, FeS2 is transformed into low crystalline FeS and amorphous Al2S3, as shown by the XRD and S, Al, and Fe K-edge XANES spectra. This reaction mechanism is different from the reaction observed with lithium ion.
•Electronic structural change of FeS2 was investigated by Fe and S K-edge XANES.•S 3p-orbitals in FeS2 play a significant role in the redox reactions.•FeS2 is transformed into low crystalline FeS and amorphous Al2S3 during discharging.
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•FHAp/MAO composite coating was prepared on AZ31B alloy by hydrothermal method.•The doping of F ions into HAp can change the morphology of the composite coating.•The addition of F ...ions can facilitate the formation of FHAp phase in the coating.•The composite coating significantly improved the corrosion resistance and decreased the degradation rate of the substrate.•The composite coating promoted osteoblast proliferation owing to the doping of F ions.
To improve the corrosion resistance, bioactivity and bonding strength of magnesium alloys, fluoride doped hydroxyapatite (FHAp) coating was fabricated on micro-arc oxidation (MAO) treated AZ31B magnesium alloy by a simple hydrothermal treatment. The surface morphology, phase composition, electrochemical property, degradation behavior and cytocompatibility of the prepared coatings were investigated in this study. The effect of the doping amount of fluoride ion on the morphology and phase composition of the composited coating was also studied. Through controlling the doping amount of fluoride ions, a uniform and dense FHAp coating composed of many nanorods was successfully prepared on MAO treated AZ31B magnesium alloy. And the the addition of fluoride ions in hydrothermal solution can facilitate the formation of FHAp phase in the coating. The thickness of FHAp/MAO composite coating was about 20 μm and the coating showed good adhesion to the substrate. And the composite coating showed higher corrosion resistance and lower degradation rate than Ca-P/MAO composite coating and the uncoated substrate. Moreover, osteoblasts cellular tests proved that the FHAp/MAO composite coating significantly improved the cell adhesion and spreading, proliferation and expression of alkaline phosphatase due to the doping of fluoride ion.
The Daxing’anling forest region represents a crucial forestry hub in China and confronts some of the nation’s most severe freezing–thawing hazards. This study delved into the temporal trends and ...spatial distributions of various parameters related to freezing and thawing, including air temperature, ground surface temperature, freezing index, thawing index, and freezing–thawing frequency. Furthermore, this study assessed and delineated freezing–thawing hazards within the research area. The findings revealed a rapid increase in air temperature and ground surface temperature within the Daxing’anling forest region yet a lower rate of increase in ground surface temperature compared to Northeast China. Latitude had the strongest influence on mean annual air temperature, mean annual ground surface temperature, air freezing index, air thawing index, ground surface freezing index, ground surface thawing index, air freezing–thawing frequency, and ground surface freezing–thawing frequency, followed by longitude and elevation. Overall, freezing index, and air freezing–thawing frequency increased from south to north, whereas mean annual air temperature, mean annual ground surface temperature, air thawing index, ground surface thawing index, and ground surface freezing–thawing frequency decreased from south to north. The assessment outcomes underscore the importance of closely monitoring freezing–thawing hazards in regions north of the 50th parallel.
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•A facile simultaneous sulfidation and nitridation process was developed.•Rod-like Fe-N-Fe1-xS@C composites were synthesized.•Low-valence FeNC species serve as polysulfide adsorbent ...and electrocatalysts.•The composites exhibit superior high-rate performance and cycling stability.
Iron mono-sulfide anodes suffer from severe irreversible capacity loss due to their poor electronic conductivity and the formation of lithium polysulfide intermediates during cycles. Here, rod-like iron-nitrogen-carbon species integrated Fe1-xS@C composites (r-Fe-N-Fe1-xS@C) are successfully prepared via a one-step simultaneous sulfidation and nitridation of MIL-88A-Fe precursors. The low valence iron-nitrogen-carbon species may serve as polysulfide adsorbent and electrocatalysts, boosting the conversion reaction between lithium polysulfides and Fe1-xS. Its porosity with nano-sized architectures not only enhance the Fe1-xS redox kinetics, but also can mitigate volume expansion stresses. As expected, the r-Fe-N-Fe1-xS@C electrodes exhibit superior charge/discharge performances at high current density (800 mAh g−1 at 5 A g−1) and remarkable long-term cycling stability. Delicately-designed low valence metallic polysulfide electrocatalysts may shed some light on the rational design of high performance sulfur-based and metal sulfide-based electrodes for lithium and/or sodium ion batteries.
In this study, carbonate saline soil in the Duerbote of Songnen Plain was improved by adding lime and fly ash. The improved soil was exposed to 0, 30, and 60 freeze-thaw cycles, and ordinary triaxial ...compression tests (UU) were conducted under confining pressures of 100, 200, and 300 kPa. The effects of freeze-thaw cycles, lime content, fly ash content, and confining pressure on the peak deviatoric stress, cohesion, and internal friction angle on the lime-ash improved carbonate saline soil were analysed. The incorporation of lime and fly ash in carbonate saline soil transformed the stress-strain curves from the strain hardening type to strain softening type and also changed the strain corresponding to the peak deviatoric stress of the soil. The effect of lime on the shear strength of the soil was the most significant, and it significantly increased the peak deviatoric stress, cohesion, and internal friction angle of the soil. Similarly, the effect of fly ash on the peak deviatoric stress and internal friction angle of the soil was significant, but the effect on cohesion was very limited. A small amount of fly ash increased the peak deviatoric stress and internal friction angle of carbonate saline soil, but an excessive amount had the opposite effects. The freeze-thaw cycles cause the shear strength of the carbonate saline soil to decrease, but the incorporation of lime and fly ash alleviated this decrease.
•Porous LiNi1/3Co1/3Mn1/3O2 microspheres were prepared by a co-precipitation method.•Phosphate coating layer was formed by H3PO4 etching and then annealing treatment.•Phosphate-coated ...LiNi1/3Co1/3Mn1/3O2 exhibited good electrochemical performances.
Porous LiNi1/3Co1/3Mn1/3O2 microspheres were synthesized by a co-precipitation approach combined with high-temperature calcination. To improve the electrochemical performances, phosphate coating was formed on the surfaces of porous LiNi1/3Co1/3Mn1/3O2 microspheres by H3PO4 etching and subsequent annealing treatment. As anticipated, phosphate-coated LiNi1/3Co1/3Mn1/3O2 microspheres (2mol.% H3PO4) delivered discharge capacity of 100. 1mAhg−1 at 5°C, which was higher than that of pristine LiNi1/3Co1/3Mn1/3O2 microspheres (64.8mAhg−1). The improvement of rate capability and cycle stability of LiNi1/3Co1/3Mn1/3O2 microspheres could be attributed to the phosphate coating, which suppressed the side reaction between cathode and electrolyte. The phosphate surface modification has a promising application in improving the performance of layered oxide cathode materials for lithium ion batteries.
A novel hollow urchin-like α-FeOOH hierarchical structure was fabricated via a one-pot hydrothermal procedure without using any templates, surfactants or organic raw materials. An inside-out ...amorphous ripening mechanism was proposed to unravel its structural evolution. The kinetics, equilibrium and thermodynamics of its adsorptive removal of Cr(vi) from wastewater were comprehensively investigated. It was found that the adsorption process can be depicted using a pseudo-second-order model, and a high adsorption capacity of 58.97 mg g(-1) was obtained from the equilibrium adsorption isotherm. Also, the thermodynamic parameters (i.e., enthalpy, entropy and Gibbs free energy) at different temperatures were acquired to reveal a spontaneous adsorption process, with both physical and chemical characteristics.
Flower-like hydrogenated TiO2(B) nanostructures have been synthesized via a facile solvothermal approach combined with hydrogenation treatment. The obtained TiO2(B) nanostructures show uniform and ...hierarchical flower-like morphology with a diameter of 124 ± 5 nm, which are further constructed by primary nanosheets with a thickness of 10 ± 1.2 nm. The Ti3+ species and/or oxygen vacancies are well introduced into the structures of TiO2(B) after hydrogen reduction, resulting in an enhancement in the electronic conductivity (up to 2.79 × 10−3 S cm−1) and the modified surface electrochemical activity. When evaluated for lithium storage capacity, the hydrogenated TiO2(B) nanostructures exhibit enhanced electrochemical energy storage performances compared to the pristine TiO2(B) nanostructures, including high capacity (292.3 mA h g−1 at 0.5C), excellent rate capability (179.6 mA h g−1 at 10C), and good cyclic stability (98.4% capacity retention after 200 cycles at 10C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of oxygen vacancies and the unique flower-like morphologies.
Flower-like hydrogenated TiO2(B) nanostructures exhibit enhanced specific capacity, excellent rate performance and superior cycling stability. Display omitted
•H-TiO2(B) nanostructures are obtained by the solvothermal and hydrogenation method.•The thin TiO2(B) nanosheets are advantageous for the Li+ transport.•Ti3+ species in TiO2(B) structure can in situ monitor its electrical conductivity.•H-TiO2(B) nanostructures exhibited excellent electrochemical performances.
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