Preparation and characterization of SnS nanocrystals by a triethanolamine-assisted diethylene glycol solution synthesis

Stoichiometric, phase-controllable SnS nanocrystals (NCs) were prepared by a solution chemical synthesis using triethanolamine-assisted diethylene glycol solvent, tin(II) chloride and thioacetamide as precursors at injection temperature of 180-220 °C. The influences of triethanolamine adding amounts, injection temperature, refluxing time on crystal phase, growth morphology and optical property of the synthesized SnS NCs were investigated. The results showed that both orthorhombic (OR) and zinc-blende (ZB) phase of SnS NCs could be formed by altering triethanolamine amounts.     

Preparation of highly efficient Al-doped ZnO photocatalyst by combustion synthesis

Novel Al-doped ZnO (AZO) photocatalysts with different Al concentrations (0.5–6.0 mol%) were prepared through a facile combustion method and followed by calcination at 500 °C for 3 h. The obtained nanopowders were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) combined with EDX, transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and photoluminescence spectroscopy. The XRD patterns of AZO nanopowders were assigned to wurtzite structure of ZnO with the smallest crystallite size about 11 nm consistent with the results from TEM. The doping of Al in ZnO crystal structure successfully suppressed the growth of ZnO nanoparticles confirmed by XRD patterns. The absorption spectra analysis showed that the optical band gap energy (E_g) for the AZO nanopowders were in the range of 3.12–3.21 eV and decreased with increasing of Al dopant. The photocatalytic activities of the samples were evaluated by photocatalytic degradation of methyl orange under visible light (λ ≥ 420 nm) and sunlight irradiation. The results showed that the AZO photocatalyst doped with 4.0 mol% Al exhibited five times enhanced photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity could be attributed to extended visible light absorption, inhibition of the electron–hole pair's recombination and enhanced adsorptivity of MO dye molecule on the surface of AZO nanopowders.     

Ca_(1-x)Zn_xTiO_3∶Pr~(3+)的固溶特性及其发光性能

通过高温固相合成法制备了名义组成为Ca1-xZnxTiO3∶0.002Pr3+(x=0.0~0.20)的红色发光材料,采用XRD和光谱等手段研究微量Zn掺杂的单相Ca1-xZnxTiO3∶0.002Pr3+材料的晶体结构参数与发光性能,分析了等价Zn2+的掺杂对固溶体结构参数与发光性能的影响规律。结果表明,在x≤0.01微量Zn掺杂时,Zn取代Ca形成单相Ca1-xZnxTiO3∶0.002Pr3+固溶;其晶胞参数和晶胞体积,260和330 nm两激发带以及610nm发射峰强度均随Zn掺量增加快速减小,且发光强度与晶胞参数的变化规律相吻合。分析表明这种变化与Zn取代Ca形成的固溶结构有关。     

Synthesis of high-temperature resistant monolithic zirconia-based aerogel via facile water glass assisted sol–gel method

Zirconia aerogel monolith was prepared by a facile co-hydrolysis method, which adopts ZrOCl₂ as the precursor and water glass (Na₂SiO₃) as the gel initiator. ZrO₂ aerogel was formed by rational controlling of the hydrolysis rate of Zr⁴⁺ ions by Na₂SiO₃. The obtained aerogel consists of ZrO₂ nanoparticles surrounded by amorphous SiO₂ nano shell. The density and the surface area can be well tuned by adjusting the ratio of ZrOCl₂ to Na₂SiO₃. The in-situ introduced SiO₂ nano shell layer acts as the particle boundary reinforcement phase, which not only strengths the ZrO₂ particle connections to form monolith, but also significantly mitigates the sintering of ZrO₂ nanoparticles at high temperature. As a result, the zirconia aerogel prepared by such method could maintain its nanoporous microstructure up to 1000?°C.

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TiO2 Microboxes with Controlled Internal Porosity for High‐Performance Lithium Storage

Titanium dioxide (TiO₂) is considered a promising anode material for high‐power lithium ion batteries (LIBs) because of its low cost, high thermal/chemical stability, and good safety performance without solid electrolyte interface formation. However, the poor electronic conductivity and low lithium ion diffusivity of TiO₂ result in poor cyclability and lithium ion depletion at high current rates, which hinder them from practical applications. Herein we demonstrate that hierarchically structured TiO₂ microboxes with controlled internal porosity can address the aforementioned problems for high‐power, long‐life LIB anodes. A self‐templating method for the synthesis of mesoporous microboxes was developed through Na₂EDTA‐assisted ion exchange of CaTiO₃ microcubes. The resulting TiO₂ nanorods were organized into microboxes that resemble the microcube precursors. This nanostructured TiO₂ material has superior lithium storage properties with a capacity of 187 mAh g⁻¹ after 300 cycles at 1 C and good rate capabilities up to 20 C.     

Mesoporous carbon nanofiber network derived from agarose for supercapacitor electrode

Great efforts have been devoted on searching for sustainable and earth-abundant precursors to prepare activated carbon suitable for supercapacitor electrode applications. In this paper, we demonstrated the preparation of mesoporous carbon nanofiber network (~?10 nm in diameter of the nanofibers) from agarose precursors. With the aid of zinc acetate, the nanofiber network structure existing in natural agarose gel can be well retained after the carbonization process and the yielded mesoporous carbon nanofiber networks have high surface area and large pore volume without further activation. Supercapacitor electrodes were made from such mesoporous carbon nanofiber networks and specific capacitance of 157 F g^?1 can be achieved with the optimized zinc acetate concentration and carbonization temperature.     

The formation mechanism of Bi2Sr2Ca2Cu3Ox superconducting phase

The mechanism and dynamic model of the formation of 2223 phase are presented and verified in the paper. It reveals that with the solubilization of part of the 2212 phase, 2223 phase is formed by the reaction being carried out according to a nucleation and growth mechanism in the presence of liquid phase, which conforms to the JMA dynamics equation. The addition of a little 2223 phase as nucleator, regrinding and resintering can promote the formation of 2223 phase. But the quick formation rate of 2223 phase may lead to irregularity of the 2223 phase structure, which degrades its electric and magnetic properties, while annealing treatment can improve its superconductivity.     

Enhanced photocatalytic activity of graphene–TiO2 composite under visible light irradiation

Novel graphene–TiO₂ (GR–TiO₂) composite photocatalysts were synthesized by hydrothermal method. During the hydrothermal process, both the reduction of graphene oxide and loading of TiO₂ nanoparticles on graphene were achieved. The structure, surface morphology, chemical composition and optical properties of composites were studied using XRD, TEM, XPS, DRS and PL spectroscopy. The absorption edge of TiO₂ shifted to visible-light region with increasing amount of graphene in the composite samples. The photocatalytic degradation of methyl orange (MO) was carried out using graphene–TiO₂ composite catalysts in order to study the photocatalytic efficiency. The results showed that GR–TiO₂ composites can efficiently photodegrade MO, showing an enhanced photocatalytic activity over pure TiO₂ under visible-light irradiation. The enhanced photocatalytic activity of the composite catalysts might be attributed to great adsorptivity of dyes, extended light absorption range and efficient charge separation due to giant π-conjugation system and two-dimensional planar structure of graphene.     

Green synthesis by diethylene glycol based solution process and characterization of SnS nanoparticles

Uniform near‐spherical SnS nanoparticles were prepared by a hydrazine hydrate‐assisted diethylene glycol solution synthesis based on the reaction of tin dichloride (SnCl₂·2H₂O) with thioacetamide (H₃CCSNH₂). The as‐prepared SnS nanoparticles were characterized by XRD, FETEM, EDS, XPS and UV‐vis‐NIR spectrophotometer. The results showed that the SnS nanoparticles had orthorhombic crystal structure, good stoichiometry and indirect bandgap of ∼1.1 eV. The nanoparticle size could be controlled by changing injection temperature. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)