Gas-Phase Catalysis by Micelle Derived Au Nanoparticles on Oxide Supports

The reactivity of gold clusters (8–22 nm diameter) supported on different metal oxides (titanium dioxide (TiO₂), zinc oxide (ZnO), zirconium oxide (ZrO₂), and silicon dioxide (SiO₂)) was investigated in a continuous flow reactor. Clusters were encapsulated within polymer in toluene solution, impregnated onto the bulk supports, and reduced by calcination at 300 °C. Support dependent sintering (TiO₂>ZrO₂>ZnO) was observed following heating in air at 300 °C. For both CO oxidation and propylene hydrogenation, Au nanoclusters on TiO₂ exhibit the highest activity compared to other supports.     

Epoxidation of Propylene with Hydrogen Peroxide Over TS-1 Catalyst Synthesized in the Presence of Polystyrene

Titanium silicalite-1 (TS-1) catalyst was synthesized in the presence of polystyrene (PS) particles (denoted as TS-1_PS catalyst) for use in the epoxidation of propylene with hydrogen peroxide. For the purpose of comparison, TS-1 catalyst was also synthesized by a conventional method (in the absence of polystyrene particles). In the epoxidation of propylene, the TS-1_PS catalyst showed a higher conversion of hydrogen peroxide and a higher selectivity for propylene oxide (PO) than the TS-1 catalyst. Consequently, the TS-1_PS catalyst showed a higher yield for PO than the TS-1 catalyst. Characterization results showed that the high catalytic performance of TS-1_PS was attributed to the enhanced hydrophobic property of the catalyst and the suppressed formation of anatase TiO₂ in the catalyst.     

Electroless coating of tungsten oxide on the surface of copper powder

Tungsten oxide was successfully deposited on the surface of copper powder and the thickness of coating layer was dependent on deposition time. Because a spontaneous reaction occurred on the interface between copper and tungsten-peroxo electrolyte, there was a maximum thickness that could be obtained, as confirmed from XRD and EDX results. Mesoporous tungsten oxide was also deposited using SDS as a structure directing agent. As-synthesized tungsten oxide was amorphous and, after calcination at 450 °C, crystallized tungsten oxide was produced. Compared to pure tungsten oxide, the tungsten oxide coated copper oxide showed enhanced absorption in the visible region.     

A facile synthesis, in vitro and in vivo MR studies of d-glucuronic acid-coated ultrasmall Ln₂O₃ (Ln = Eu, Gd, Dy, Ho, and Er) nanoparticles as a new potential MRI contrast agent

A facile one-pot synthesis of d-glucuronic acid-coated ultrasmall Ln(2)O(3) (Ln = Eu, Gd, Dy, Ho, and Er) nanoparticles is presented. Their water proton relaxivities were studied to address their possibility as a new potential MRI contrast agent. We focused on the d-glucuronic acid-coated ultrasmall Dy(2)O(3) nanoparticle because it showed the highest r(2) relaxivity among studied nanoparticles. Its performance as a T(2) MRI contrast agent was for the first time proved in vivo through its 3 T T(2) MR images of a mouse, showing that it can be further exploited for the rational design of a new T(2) MRI contrast agent at high MR fields.     

Nano-sized Ni-doped carbon aerogel for supercapacitor

Carbon aerogel was prepared by polycondensation of resorcinol with formaldehyde using sodium carbonate as a catalyst in ambient conditions. Nano-sized Ni-doped carbon aerogel was then prepared by a precipitation method in an ethanol solvent. In order to elucidate the effect of nickel content on electrochemical properties, Ni-doped carbon aerogels (21, 35, 60, and 82 wt%) were prepared and their performance for supercapacitor electrode was investigated. Electrochemical properties of Ni-doped carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. Among the samples prepared, 35 wt% Ni-doped carbon aerogel (Ni/CA-35) showed the highest capacitance (110 F/g) and excellent charge/discharge behavior. The enhanced capacitance of Ni-doped carbon aerogel was attributed to the faradaic redox reactions of nano-sized nickel oxide. Moreover, Ni-doped carbon aerogel exhibited quite stable cyclability, indicating long-term electrochemical stability.     

Rapid synthesis of Pt-based alloy/carbon nanotube catalysts for a direct methanol fuel cell using flash light irradiation

We synthesized Pt, Pt–Ru alloy and Pt–Ru–Mo alloy nanoparticles on the multi-walled carbon nanotubes (MWCNTs) using flash light irradiation and characterized these catalysts. Pt₁₀₀, Pt₅₀-Ru₅₀ alloy and Pt₄₃-Ru₄₃-Mo₁₄ alloy are coated onto MWCNTs followed by flash light irradiation to facilitate the formation of nanoparticle-alloys. The fabricated pure Pt and Pt-based alloy nanoparticle/MWCNTs were characterized by X-ray diffraction (XRD), raman spectroscopy and scanning electron microscopy (SEM). Cyclic voltammetry (CV) studies and electrochemical impedance spectroscopy (EIS) results revealed that the Pt₄₃-Ru₄₃-Mo₁₄/MWCNT catalyst has higher activity and stability with regard to methanol electro-oxidation than the Pt₁₀₀/MWCNT and Pt₅₀-Ru₅₀/MWCNT catalysts.     

Influence of graphene nanoplatelets content on the structure and properties of macroporous carbon foams prepared by organic colloidal templates

Graphene nanoplatelets (GNPs)-reinforced carbon foams have been fabricated by polycondensation of resorcinol–formaldehyde resin as a carbon precursor and GNPs as a reinforcing material. The pore structure, mechanical properties, and electrical conductivity were investigated in terms of the amount of the GNPs. The results show that the amount of GNPs has a considerable influence on compressive strength, electrical conductivity, and specific capacitance. Although the amount of GNPs added does not influence the pore structure, the mechanical properties, electrical conductivity, and specific capacitance of carbon foams were improved with increasing the GNPs content. With 5 wt% addition of GNPs, the compressive strength, electrical conductivity, and specific capacitance increased by 75.2, 240.26, and 53.36 %, respectively.     

Fabrication of mesoporous cerium dioxide films by cathodic electrodeposition

Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.