The catalytic effect of nanosized MgO on the decomposition of ammonium perchlorate

MgO nanoparticles with an average size of 30 nm were prepared by a traditional sol-gel method using magnesium chloride and NaOH aqueous solution as the raw materials. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the products. The catalytic effect of the MgO prepared on the decomposition of ammonium perchlorate (AP) was investigated by differential thermal analysis (DTA). The results indicate that MgO nanoparticles have a good dispersibility and a uniform crystallite size, also have an intense catalytic effect on the decomposition of AP comparing with commercial product.     

Nanoparticle dispersion-strengthened coatings and electrode materials for electrospark deposition

Advanced electrode compositions were developed using self-propagating high-temperature synthesis (SHS). Electrospark deposition (ESD) was applied to produce tribological coatings which were disperse-strengthened by incorporation of nanosized particles. Nanostructured electrodes of cemented carbides were produced using powder metallurgy technologies. They allow increasing the coatings density, thickness, hardness, Young's modulus and wear resistance. Positive effects of the nanostructure of electrodes on the deposition process and structure and properties of the coatings are discussed. In that case the tungsten carbide phases become predominant in the coatings. A mechanism of the dissolution reaction of WC with Ni at the contact surface of electrode was proposed. It was shown that the formation of the coating structure starts on the electrode and is accomplished on the substrate.     

Hydrothermal synthesis of titanium dioxides from peroxotitanate solution using different amine group-containing organics and their photocatalytic activity

Nanosized TiO₂ particles were prepared by hydrothermal method of the amorphous powders which were precipitated in an aqueous peroxotitanate solution using different amine group-containing organics. The physical properties of prepared nanosized TiO₂ particles were investigated. We also examined the activity of TiO₂ particles as a photocatalyst for the decomposition of orange II. The TiO₂ particles calcined at 400 °C were shown to have a stable anatase phase which has no organic compounds. The particles size of titania particles decreased from 15 to 10 nm as the carbon chain length increased. The titania nanoparticles were shown to have a polygonal shape prepared using NH₄OH and tetramethylammonium hydroxide (TMAOH) as additives, however, the micrographs showed the spherical and narrow size distribution prepared using tetraethyl-ammonium hydroxide (TEAOH) and tetrabutylammonium hydroxide (TBAOH). The titania particles prepared using TEAOH as an amine group-containing organic showed the highest activity on the photocatalytic decomposition of orange II. In addition, the titania particles calcined at 500 °C showed the highest activity on the photocatalytic decomposition of orange II.     

溶胶-凝胶法制备透明无机-有机纳米复合硬质薄膜

利用旋覆法通过溶胶－凝胶（Ｓｏｌ－ｇｅｌ）法在有机玻璃（ＰＭＭＡ）表面制备无机－有机硬质薄膜，产品具备致密、透明、耐擦伤等性能．纳米氧化物颗粒在体系中均匀分布，使硬度及耐擦伤性能较有机玻璃均有较大提高．     

Electrochemical characterization of single cell and short stack PEM electrolyzers based on a nanosized IrO2 anode electrocatalyst

A nanosized IrO₂ anode electrocatalyst was prepared by a sulfite-complex route for application in a proton exchange membrane (PEM) water electrolyzer. The physico-chemical properties of the IrO₂ catalyst were studied by termogravimetry–differential scanning calorimetry (TG–DSC), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The electrochemical activity of this catalyst for oxygen evolution was investigated in a single cell PEM electrolyzer consisting of a Pt/C cathode and a Nafion^® membrane. A current density of 1.26 A cm⁻² was obtained at 1.8 V and a stable behavior during steady-state operation at 80 °C was recorded. The Tafel plots for the overall electrochemical process indicated a slope of about 80 mV dec⁻¹ in a temperature range from 25 °C to 80 °C. The kinetic and ohmic activation energies for the electrochemical process were 70.46 kJ mol⁻¹ and 13.45 kJ mol⁻¹, respectively. A short stack (3 cells of 100 cm² geometrical area) PEM electrolyzer was investigated by linear voltammetry, impedance spectroscopy and chrono-amperometric measurements. The amount of H₂ produced was 80 l h⁻¹ at 60 A under 330 W of applied electrical power. The stack electrical efficiency at 60 A and 75 °C was 70% and 81% with respect to the low and high heating value of hydrogen, respectively.