BiI3 mediated difunctionalization of α-methylstyrenes,including azidohydroxylation and azidoiodination

BiI₃ mediated vicinal azidohydroxylation of α-methylstyrenes 1 with NaN₃ in wet DMF affords β-azidoalcohols 4 in good yields. In dry DMF, β-azidoiodides 6 are also obtained by BiI₃ mediated vicinal azidoiodination of α-methylstyrenes 1 with NaN₃. This present protocol provides the bond formations of carbon-azido/carbon-hydroxy (N₃─CC─OH) bond and carbon-azido/carbon-iodo (N₃─CC─I) under water-controlled conditions.     

Elucidating the function of modified carbon blacks in high-voltage lithium-ion batteries: impact on electrolyte decomposition

We report on the improved electrochemical performance of a high-voltage LiNi_0.5Mn_1.5O₄ (LNMO) cathode using surface-modified carbon blacks (CBs) as conductive agents. Facile modifications of CBs were achieved using thermal, urea-based hydrothermal, and acid oxidation treatments. The material properties of the modified CBs, LNMO-based electrode surface, and electrolyte compositions were investigated and correlated. Based on the distribution of the decomposition deposits on the surface of the electrode, it is confirmed that CB, rather than the LNMO active material, dominates the electrolyte decomposition site at a high voltage, owing to its relatively high surface area for the reaction. Additionally, compared with the pristine CB, the hydrothermally treated N-doped CB (HCB) improves the electrochemical performance of the LNMO cathode, although the thermally treated sample exhibits the most adverse influence, followed by the oxidized one. The LNMO/HCB cathode attains optimum capacity retention (approximately 95%) for 100 cycles (1 C) and a high rate capability (70%, 5 C/0.2 C), corresponding to a lowered resistance at the cathode–electrolyte interface. Furthermore, HCB with a limited specific surface area and increased defects, as well as additional pyrrolic-N and pyridinic-N groups, substantially reduces the decomposition deposits on the surface of the electrode and the decomposition products in the electrolyte. These phenomena account for the improved electrochemical performance of the LNMO/HCB cathode.     

Viscosity of Ba-B-Si-Al-O glass measured by indentation creep test at operating temperature of IT-SOFC

Viscosity of a specific Ba-B-Si-Al-O glass used for intermediate-temperature solid oxide fuel cell was measured using indentation creep tests. Responses of shear strain to corresponding shear stress at the operating temperature of solid oxide fuel cell were analyzed, and the results revealed that the glass system possesses Newtonian flow behavior at 600-630 °C. In addition, the stress exponent and the activation energy for viscous flow at different temperatures and stresses were also determined. Finally, the absolute-rate theory was adopted to describe the viscous flow for the glass. The results were compared with other glass systems.     

Power Generation Capabilities of Microbial Fuel Cells with Different Oxygen Supplies in the Cathodic Chamber

Two microbial fuel cells (MFCs) inoculated with activated sludge of a wastewater treatment plant were constructed. Oxygen was provided by mechanical aeration in the cathodic chamber of one MFC, whereas it was obtained by the photosynthesis of algae in the other. Electrogenic capabilities of both MFCs were compared under the same operational conditions. Results showed that the MFC with mechanical aeration in the cathodic chamber displayed higher power output than the one with photosynthesis of algae. Good linear relationship between power density and chemical oxygen demand (COD) loading rate was obtained only on the MFC with mechanical aeration. Furthermore, the relationships between power density and effluent COD and between Coulombic efficiency and COD loading rate can only be expressed as binary quadratic equations for the MFC with mechanical aeration and not for the one with photosynthesis of algae.     

Bicontinuous ceramics with high surface area from block copolymer templates

Mesoporous polymers with gyroid nanochannels can be fabricated from the self-assembly of degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by hydrolysis of PLLA block. Well-defined polymer/ceramic nanohybrid materials with inorganic gyroid nanostructures in a PS matrix can be obtained by using the mesoporous PS as a template for sol-gel reaction. Titanium tetraisopropoxide (TTIP) is used as a precursor to give a model system for the fabrication of metal oxide nanostructures from reactive transition metal alkoxides. By controlling the rates of capillary-driven pore filling and sol-gel reaction, the templated synthesis can be well-developed. Also, by taking advantage of calcination, bicontinuous TiO(2) with controlled crystalline phase (i.e., anatase phase) can be fabricated after removal of the PS template and crystallization of TiO(2) by calcination leading to high photocatalytic efficiency. This new approach provides an easy way to fabricate high-surface-area and high-porosity ceramics with self-supporting structure and controlled crystalline phase for practical applications. As a result, a platform technology to fabricate precisely controlled polymer/ceramic nanohybrids and mesoporous ceramic materials can be established.