•Oriented MoS2 nanoflake arrays are prepared on a Cu foil by hydrothermal method.•The growth process and mechanism of MoS2 nanoflake arrays are investigated in detail.•The capacity retention of MoS2 nanoflake arrays is 90% after 5000 cycles.•The specific capacitance of MoS2 nanoflake arrays is up to 420 F g−1 at 0.5 A g−1.Hexagonal MoS2 nanoflake arrays (h-MNFs) have been synthesized directly via hydrothermal route with Cu foil as substrate, (NH4)6Mo7O24·4H2O as the molybdenum source, CN2H4S as the sulfur source and reductant, and (CH3)2CHOH as the dispersant. The micro morphology and crystallinity of MNFs are analyzed by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman microscopy (RM). The morphological change and growth process of MNFs are investigated, basing on the samples at different hydrothermal reaction times. Moreover, the supercapacitive properties of MNFs have been examined. It is found that MNFs has a good cycling invertibility (93%) and stability (90%) after 5000 cycles, a relatively high specific capacitance (420 F g−1), a low charge transport resistance (1.8 Ω) and available energy densities ranging from 21 to 17 W h kg−1 with corresponding practical power densities ranging from 150 to 3000 W kg−1.Download high-res image (427KB)Download full-size image

•Tertiary WO3 microspheres are prepared on a Cu foil by hydrothermal method.•The growth mechanism of tertiary WO3 microspheres are investigated in detail.•The capacity retention of WO3 microsheres is 93% after 5000 cycles.•The specific capacitance of WO3 microsheres is up to 485 F g−1 at 0.5 A g−1.WO3 microspheres film with a tertiary, textured and porous structure assembled of WO3 hierarchical nanorods has been directly prepared on Cu foil using a one-step hydrothermal method. The field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectrum, X-Ray Diffraction (XRD), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) are used to reveal the surface microtopography, crystal structure, elementary composition, valence state and formation mechanism of WO3 tertiary structure. Moreover, the electrochemical properties and supercapacitive performances of WO3 microspheres film are also intensively investigated. The WO3 microspheres film has high specific capacitances of 485, 426, 372, 319 and 260 F g−1 at unit currents of 0.5, 1, 2, 5 and 10 A g−1 and exhibits good cycle stability (93% after 5000 cycles) and reversibility (98.5%), a lower charge transfer resistance (0.5 Ω) and high energy densities ranging from 21 to 17 W h kg−1 corresponded to high power densities varied from 150 to 3000 W kg−1.Download high-res image (252KB)Download full-size image

Ordered V2O5 nanobelt arrays (VNBs) vertically grown on Ni foam have been realized by one-step hydrothermal method without any additives. The obtained VNBs are a single crystal with a two-dimensional (2D) layered structure. The morphology evolution and growth mechanism of VNBs are discussed at different hydrothermal times. The morphologies, length–width ratios and sizes of materials can be controlled by simply adjusting vanadium source concentrations, pH values and hydrothermal temperatures. Moreover, these morphology parameters can significantly affect specific capacitance, cycle stability and charge transfer resistance. Due to the ordered arrangement, single-crystal, top–down and layered structure, VNBs have a relatively high ion storage capacity, specific capacitance (498 F g−1), cycling stability (88.8%) after 5000 cycles and low charge transfer resistance (14.2 Ω) as binder-free electrode materials, which reveals a great potential for practical application in energy storage devices.

Magnetically recoverable sulfur-doped CoFe2O4 nanopowders were used as photocatalyst for degradation of oxytetracycline (OTC) under visible light in aqueous solution. S doped CoFe2O4 nanopowders synthesized by a simple calcining process were characterized by XRD, TEM, VSM, FT-IR, UV-vis DRS and XPS. The results showed that introducing of S element in CoFe2O4 crystal structure narrowed its band gap and increased visible light absorption. 0.3 S-CoFe2O4 exhibited the highest magnetic property and photocatalytic activity. The maximum photocatalytic conversion ratio of OTC reached 90.4% at pH = 8.5 after 5 h irradiation. During photocatalytic process, seven intermediate products were detected, and based on that a detailed degradation path way of OTC was proposed.

•Melted aluminosilicate glass filled with surface cracks to form a dense coating.•The coating shows high oxidation resistance performance at high temperature stage.•High infrared emissivity is good for cooling down at high-temperature stage.A multicomponent coating composed of ZrSiO4 and aluminosilicate glass was designed and prepared by slurry dipping and subsequent sintering on the surface of SiC substrate to improve the anti-oxidation ability of substrate. At appropriate temperature, the molten aluminosilicate glass carrying the stable ZrSiO4 particles will spread over the substrate’s surface to form a dense and stable coating. Among them, the flowing aluminosilicate glass will fill the crack and micro-pores of ZrSiO4, which inform a dense coating. Glass phase and ceramic phase could inhibit the propagation of the cracks together. This coating shows high infrared emissivity at broad bands, reaching more than 0.93. Wonderfully, the coating was endowed high oxidation resistance performance at high temperature in the air, which was mainly attributed to the compact and stable structure of coating, coupled with the high thermal expansion coefficient.

Well-oriented hexagonal WO3 nanorod arrays (h-WNRs) with an average diameter of 150 ± 50 nm and a length of 2.0–3.0 μm have been successfully realized on a Cu substrate on a large scale via a simple hydrothermal method without organic additives and substrate pre-treatment. The morphology, crystallinity, atomic composition and chemical state of WNRs are investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The morphology evolution and growth mechanism of well-aligned WNRs are intensively studied. Moreover, the supercapacitive properties of WNRs with different diameters and aspect ratios are also examined. WNRs exhibit excellent cycling stability and reversibility (97%), a high specific capacitance (463 F g−1) at a current density of 1.0 A g−1, and a lower charge transfer resistance (0.8 Ω).

•The mechanochemical route was employed to produce the polyoxometalate-based hybrids.•The porous structure of POM-based hybrid particles can be fabricated by this route.•The hybrid maintains the characteristic electrochemical properties of polyanions.Based on the Keggin-type silicotungstic acid and thiourea, a new inorganic-organic hybrid with lamellar shape has been synthesized by a mechanochemical route at room temperature. The heteropolyanions still retained the Keggin-type structure in the hybrid. It was designed as a carbon paste electrode to investigate its electrochemical properties. The sample shows the characteristic electrochemical properties of Keggin-type polyanions, holding three couples of stable and reversible redox peaks in the range of −0.15~−0.73 V, which may arise from the maintenance of Keggin-type polyanions and the pore structure of lamina. This work proposed a new synthetic route for polyoxometalates-based hybrid, and offered an effective method to investigate the property of polyoxometalate-based hybrid under the solid state condition.The lamel-shaped organic-POM hybrid has been synthesized by a simple mechanochemical route at room temperature. A three-dimensional bulk-modified carbon paste electrode (I-CPE) was constructed. It shows the characteristic electrochemical properties of Keggin-type polyanions, holding three couples of stable and reversible redox peaks.Download full-size image

C/C composite material is widely used in aerospace field and others, however, it is easy to be oxidized at high temperature. In order to improve the oxidation resistance, ZrC is introduced as an oxidation inhibitor used in matrix modification of C/C composite material. Flat plate samples of ZrC/C composite materials were prepared by hot-pressing sintering. The degree of graphitization increases with rising sintering temperature, and layer structure of carbon matrix is observed clearly in the sample treated at 2273 K. Diffusion behavior of Zr in C matrix at high temperature is studied, which can be generally expressed as D=3.382×10−11 exp[2.029×105/(RT)]. The diffusion of Zr in C matrix leads to the over-saturation of C in the micro area and the oversaturated C precipitates as graphite. This continuous process promotes the transformation of carbon to graphite.

•The Ba1.0Co0.7Fe0.2Nb0.1O3 − δ (BCFN) nanopowder were successfully prepared by the sol–gel method.•The obtained powders exhibited a cubic perovskite-type structure, and the average crystallite size was ~ 60 nm.•Investigate the pH condition to form sol system.Using metal nitrates, Nb2O5, citric acid and Ethylenediamine Tetraacetic Acid (EDTA) as raw materials, Ba1.0Co0.7Fe0.2Nb0.1O3 − δ (BCFN) nanopowders were successfully prepared by an EDTA-citric acid complex method. The synthesis process, thermal decomposition behavior, phase variation and micro-morphology of the precursor and obtained nanopowders were characterized by TG/DSC, FTIR, XRD and TEM combined with selected area electron diffraction (SAED) techniques. The cubic perovskite-type structure BCFN nanopowders could be obtained at 950 °C with an average crystallite size of ~ 60 nm. The redox performance was studied using O2 temperature programmed desorption (O2-TPD) and H2 temperature programmed reduction (H2 –TPR). BCFN nanopowders exhibited better oxygen reduction ability than micron powders at lower temperature. Both BCFN nanopowders and micron powders were mixed with Ce0.8Y0.2O2 − δ (YDC) nanopowders with mass ratio of 1:1, respectively. The mixed powders were coated on a BCFN-Ce0.8Gd0.2O2 − δ (GDC) composite cathode in order to lower its polarization resistance. The results showed that the BCFN-GDC/GDC/BCFN-GDC symmetric cell with BCFN-YDC nanocoating exhibited lower polarization resistance compared to samples with BCFN-YDC micron size coating or without coating.

Fluorite Ce0.8Sm0.2O2-δ (SDC) nanopowder with a crystallite size of 15 nm was synthesized by a co-precipitation method. An SDC porous layer was coated onto a BaCo0.7Fe0.2Nb0.1O3-δ (BCFN) mixed conductor to improve its oxygen transport behavior. The results show that the SDC-coated BCFN membrane exhibits a remarkably higher oxygen permeation flux (\({J_{{O_2}}}\)) than the uncoated BCFN in the partial oxidation of coke oven gas (COG). The maximum \({J_{{O_2}}}\) value of the SDC-coated BCFN is 18.28 mL·min-1·cm-2 under a COG/air flux of 177 mL·min-1/353 mL·min-1 at 875°C when the thickness of the BCFN membrane is 1 mm; this \({J_{{O_2}}}\) value is 23% higher than that of the uncoated BCFN membrane. This enhancement is likely because of the higher oxygen ionic conductivity of SDC, which supplies oxygen vacancies and accelerates oxygen exchange on the membrane/coating layer/gas three-phase boundary.

The degradation behavior of oxytetracycline (OTC) in aqueous solution using Fe2O3–TiO2 nanopowders (Fe2O3–TiO2 NPs) as photocatalysts under UV/visible light was investigated in this paper. Fe2O3–TiO2 NPs photocatalysts synthesized using co-precipitation were characterized by XRD, TEM, FT-IR and UV-vis DRS. Fe2O3–TiO2 NPs with 45 wt% Fe2O3 exhibited higher photocatalytic activity than others. The photocatalytic degradation of OTC shows a maximum efficiency at pH = 5.5 under both UV/visible light due to the surface adsorption. The intermediate products during the photocatalytic degradation of OTC were detected by LC-MS/TOF. Seven main intermediates were formed, and their evolution was discussed. On the basis of the evidence oxidative intermediate formation and a detailed degradation path way of OTC by 45 Fe2O3–TiO2 NPs are proposed.

A mild method has been developed for the hydroboration of arylalkenes using Cu2O as catalyst with PPh3 as ligand in methanol at room temperature. A gram-scale reaction under this condition was also achieved with high yield.

In this paper, two kinds of perovskite-type mixed conductor materials, Ba0.5Sr0.5Co0.8Fe0.2O3 − δ and BaCo0.7Fe0.2Nb0.1O3 − δ, were prepared by solid state synthesis. By combination of thermal gravimetric analysis, XRD and SEM, the high-temperature chemical stability of these two materials in pure Ar, 10% CO2 + Ar and 40% H2 + Ar atmosphere was studied. In addition, oxygen permeation tests were also conducted in order to study the two materials' long term stability under service condition of coke oven gas (COG) partial oxidation reforming. The results show that BaCo0.7Fe0.2Nb0.1O3 − δ material, in which Ba occupied all A-site and B-site is partly substituted by a small amount of Nb, has a better chemical and structural stability than Ba0.5Sr0.5Co0.8Fe0.2O3 − δ at high temperature under rather high oxygen concentration gradient through the membrane. At 875 °C, when COG flow rate was 88 ml/min and air flow was fixed at 76.89 ml/min, oxygen permeation flux through a BaCo0.7Fe0.2Nb0.1O3 − δ membrane of 1 mm in thickness reached 11.5 ml/min1 cm2, which could meet the industrial conditions of the COG partial oxidation reforming in industrial applications.Research Highlights► BCFN sample shows a high decomposition temperature in strong reduction atmosphere. ► BCFN’s crystal structure annealed in 10% CO2 + 90% Ar was more stable than BSCF’s. ► Nb in B-site plays a positive role in improving the stability of BCFN. ► Both membranes were increasing oxygen permeation flux with COG flow rate increase.

Processing of nanocrystalline Bi2O3-HfO2-Y2O3 ceramic having high density has been investigated and reported in this paper. Nanopowders of mixed bismuth oxide, hafnia and yttrium oxide have been prepared by a reverse titration chemical coprecipitation from Bi3+, Hf4+ and Y3+ containing aqueous solution. The high density, nanocrystalline Bi2O3-HfO2-Y2O3 ceramic has been synthesized by microwave plasma sintering. The XRD results of grain growth behavior indicates that growth of both δ-Bi2O3 and c-HfO2 crystallites obeys the parabolic rate law, expressed as (D–D0)2 = Kt, during sintering process. After sintering at 700 °C for 60 min, the relative density of the samples sintered by microwave plasma has been found to be greater than 97%, and the samples exhibit considerably finer microstructure with an average size between 60 and 70 nm and equiaxed morphology and better density comparing with that of samples sintered by conventional pressureless sintering. In addition, mechanical properties of nanocrystalline Bi2O3-HfO2-Y2O3 ceramic has been improved greatly compareing with nanocrystalline Bi2O3-Y2O3 ceramic.

•V2O5 was prepared by hydrothermal method followed by a post-annealing treatment.•Different morphologies of V2O5 can be controlled by surfactants.•Microstructure of products has great influence on infrared emissivity.Vanadium pentoxide (V2O5) with different morphologies including nanorods, nanoparticles and microparticles have successfully been synthesized by surfactants assisted hydrothermal method combined with a post-annealing process. Structure, morphology and emissivity of the obtained V2O5 have been investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and infrared emissivity (IR-2). The results show that the morphologies of V2O5 play a key role in affecting the infrared emissivity. V2O5 nanorods show more excellent infrared emissivity (0.908 in wavelength of 3–5 μm, 0.986 in wavelength of 8–14 μm and 0.965 in wavelength of 1–22 μm) than that of V2O5 nanoparticles and microparticles.

The effect of B4C addition (0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%) on properties and microstructure of Al2O3-SiC-C (ASC) based trough castables was studied in this paper. The results showed that the bulk density of samples after firing at 1450 °C decreased when the addition of B4C was over 1 wt%. The cold modulus of rupture of samples improved significantly with the addition of B4C when the treating temperature was over 1100 °C. Among them, sample with 1.5 wt% of B4C had the best anti-slag performance and thermal shock resistance. The SiC fibers were formed in the non-oxidized zone of ASC castables with addition of B4C after firing at 1450 °C in air condition. The obtained fibers rooted in the walls of inner micropores of samples with the diameter of 50–200 nm, and the lengths of 10–50 µm. The experiment revealed the nucleation of SiC started at about 1000 °C, and then the growth of SiC fibers happened at higher temperature in a favorable condition. A stepped twin structure perpendicular to the growth direction of fibers could be observed. Finally, the growth mechanism was interpreted by thermodynamic calculations.