Synthesis of nanosized TiO2/SiO2 particles in the microemulsion and their photocatalytic activity on the decomposition of p-nitrophenol

Nanosized pure TiO₂ particles were prepared by hydrolysis of TTIP in the sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. TiO₂/SiO₂ nanoparticles were also prepared from TEOS as a silicon source and TTIP as a titanium source. These particles were characterized by TEM, XRD, FT-IR, BET, TGA and DTA. From thermal analysis and XRD analysis, the anatase structure of pure titania appeared in the 300–600 °C calcination temperature range and the rutile structure was showed above 700 °C. However, no rutile phase was observed for the TiO₂/SiO₂ particles up to 800 °C. The crystallite size decreased and the surface area of TiO₂/SiO₂ particles monotonically increased with an increase of the silica content. From FT-IR analysis, the band for Ti–O–Si vibration was observed and the band intensity for Si–O–Si vibration increased with an increase of the silica content. The micrographs of TEM showed that the TiO₂/SiO₂ nanoparticles had a spherical and a narrow size distribution. In addition, TiO₂/SiO₂ particles showed higher photocatalytic activity than pure TiO₂ and the TiO₂/SiO₂ (90/10) particles showed the highest activity on the photocatalytic decomposition of p-nitrophenol.     

Electrochemical performance and morphology evolution of nanosized ZnO as anode material of Ni-Zn batteries

Nanosized ZnO with prismatic form was prepared using homogeneous precipitation process and its electrochemical performance was investigated by the measurements of electrochemical cycle behaviors and passivation polarization curves. The discharge capacity delivered by nanosized ZnO still achieved about 600 mAh/g until the 250th cycle. Nanosized ZnO exhibited higher midpoint discharge voltage, better cycle stability and passivation toleration than commercial ZnO. Furthermore, nanosized ZnO showed the morphology evolution process differed slightly from that of the commercial ZnO, including morphology maintenance, orientation growth and the formation of Zn dendrites. The epitaxial growth, texture growth and crystal growth habit were put forward to illuminate the morphology evolution process.     

Zeolite Beta nanosized assemblies

Nanosized zeolite Beta assemblies are prepared by a steam assisted conversion (SAC) method from micron-sized porous amorphous silica grains soaked in clear solutions containing the alumina source and organic template. The zeolite Beta assemblies are built of closely packed uniform nanocrystals (100 nm) and retain the size and morphological features of the primary silica grains. The crystallinity and the phase purity depend strongly on the temperature and time of SAC treatment as well as on the initial aluminum content. For comparison, colloidal zeolite Beta samples with similar Si/Al ratio were prepared by a hydrothermal treatment (HT). The Raman and NMR spectroscopic data reveal that the method of preparation (SAC or HT) does not affect the local structure of Al-rich samples, while for high-silica samples the degree of disorder is higher in the ones obtained via the SAC approach. The adsorption/desorption isotherms of zeolite Beta assemblies and colloidal Beta powders indicate the presence of both micro- and mesoporosity. The catalytic behavior of the zeolite Beta assemblies and colloidal Beta powders in pentane hydroisomerization reaction is studied.     

纳米级二氧化锆的表征和应用

纳米二氧化锆是一种新型的高科技材料，有着广泛而重要的用途。本文根据国内外研究制备的最新进展及其发展趋势，综述了纳米级二氧化锆表征方法和近年来新的应用领域和研究前沿。     

纳米TiO2的液相制备方法及其在涂料工业中的应用

综述了液相法合成纳米TiO2的制备方法，评价了各种方法的优缺点。介绍了纳米TiO2在涂料中的应用，指出了在纳米TiO2合成及应用研究中存在的问题和发展方向。     

Production of Higher Hydrocarbons from CO2 over Nanosized Iron Catalysts

The effects of the particle size of a Fe/Cu/K catalyst on CO and CO₂ hydrogenation reactions as well as the variation of crucial factors such as surface area and basicity, reduction, carburization, and catalytic behavior of precipitated Fe/Cu/K catalysts were evaluated. Hematite nanoparticle catalysts with various surface tensions were produced by homogeneous precipitation in alcohol/water solvents. The basicity of the K‐promoted iron catalyst was higher in iron catalysts with lower particle size. The increase in K‐basic sites at the surface of catalysts with smaller particle size was attributed to their higher surface areas. Elevation of catalyst basicity led to considerably stronger dissociative CO adsorption. Shifting the oxygen removal pattern to lower temperature was the consequence of faster nucleation of FeCx crystallites on promoted surface oxides. CO₂ hydrogenation can occur in two distinct direct and indirect routes via the Fischer‐Tropsch mechanism.     

Nano Li4Ti5O12–LiMn2O4 batteries with high power capability and improved cycle-life

We report the effects of electrode thickness, cathode particle size and morphology, cathode carbon coating matching ratio and laminate structure on the electrochemical characteristics of nanosized Li₄Ti₅O₁₂–LiMn₂O₄ batteries. We show that a correct adjustment of these parameters resulted in significant improvements in power capability and cycle-life of such devices, making them competitive, low-cost and safe battery chemistry for next generation Li-ion batteries. In addition, Li₄Ti₅O₁₂ reversible specific capacity beyond three Li-ions intercalation is reported.     

Antagonistic effects of copper on the electrochemical performance of LiFePO4

In the last few years, several strategies towards boosting the electrochemical performance of LiFePO₄ cathodes have been envisaged. Copper addition to the phosphate seems to be a simple, inexpensive method for this purpose. However, it has a serious drawback: at voltages slightly higher than that required for lithium extraction from LiFePO₄, the copper is oxidized to either Cu(I) or Cu(II) with partial decomposition of the electrolyte. XRD patterns are consistent with the disappearance of copper from pristine composites upon charging at up to 4.0 V. Moreover, a copper deposit is formed on the lithium surface in the discharged state that creates a barrier hindering the release of Li ion from the electrode. Therefore, copper electroactivity strongly influences the capacity and cycling life of the cell.     

Nanosized Silica-Reinforced Maleimido Terminal Triaryl Pyridine Core Polybenzoxazine (nSiO2/PBZ) Nanocomposites

A new series of nanosized silica-reinforced polybenzoxazine (nSiO₂/PBZ) hybrid nanocomposites were prepared from three types of maleimido terminal benzoxazine monomers and nSiO₂. The successive increment of nSiO₂ into the PBZ matrices exhibited lower dielectric constant, superior thermal stability and higher glass transition temperature. The hydrophobic nature due to the presence of a less polar Si-O-Si linkage in the composites reduced water uptake properties. The incorporation of nSiO₂ particles also retains their luminescence properties. The homogeneous morphology of the nanocomposites caused from the good interfacial interaction between the embedded nSiO₂ and PBZ matrix as evidenced by SEM and AFM images.     

Nanosized α-LiFeO2 as electrochemical supercapacitor electrode in neutral sulfate electrolytes

In this work we have explored the electrochemical properties of two lithiated iron oxide powders for supercapacitor purposes. These samples mainly consisted of α-LiFeO₂ in nanosized or micrometric form. Electrolyte was an aqueous 0.5 M Li₂SO₄ solution and voltage range studied was between 0 and −0.7 V vs. a Ag/AgCl reference electrode. As expected, electrochemical performance was dependent on the particle size. When electrolyte was deaerated a stable capacitance of ≈50 F g⁻¹ is provided by the nanosized sample for several hundred cycles. Other sulfate based salts (Na₂SO₄, K₂SO₄, Cs₂SO₄) were investigated as electrolytes but only Li₂SO₄ leads to a stable capacitance upon cycling, probably due to lithium intercalation. An hybrid cell consisting of this sample and MnO₂ as negative and positive electrodes, respectively, delivered 0.3 F cm⁻² (10 F g⁻¹). Although these values are lower than reported for other aqueous hybrid cell, α-LiFeO₂/MnO₂ asymmetric capacitor is interesting from both, an economic and an environmental point of view.