Nobuko Hanada

Synthesis of alkylidene pyrrolo[3,4-b]pyridin-7-one derivatives via RhIII-catalyzed cascade oxidative alkenylation/annulation of picolinamides

A novel tunnel Na(0.61)Ti(0.48)Mn(0.52)O2 material is explored as a cathode for sodium-ion batteries for the first time. It can deliver a reversible discharge capacity of 86 mA h g(-1) with an average voltage of 2.9 V at 0.2 C rate in a sodium half cell, exhibiting good rate capability and capacity retention at a cut-off voltage of 1.5-4 V. These results indicate that tunnel Na(0.61)Ti(0.48)Mn(0.52)O2 has a great potential application in large scale energy storage.

Hydrogen generation by electrolysis of liquid ammonia

Hydrogen gas is generated by the electrolysis of liquid ammonia which has high hydrogen capacity of 17.8 mass%. The metal amides are used as supporting electrolytes to dissolve the amide ion in liquid ammonia. The results presented here indicate that liquid ammonia is promising as an energy medium for hydrogen storage and generation.

Hydriding properties of ordered-/disordered-Mg-based ternary Laves phase structures

Abstract Ternary Laves phase structures with compositions MgYNi 4 , MgCaNi 4 and CaYNi 4 were prepared, and the relationship between the structures and hydriding properties was studied in detail. Only in MgYNi 4 are Mg and Y found to be ordered and a plateau pressure is clearly observed in the P–C isotherm during the dehydriding process. In MgCaNi 4 , however, Mg and Ca are disordered, and hydrogen content of MgCaNi 4 is ∼30% larger than that of MgYNi 4 . Control of their order/disorder in Laves phase structures may provide the hydriding properties with higher hydrogen concentrations and flatter plateau regions.

The existing state of hydrogen in electrochemically charged commercial purity aluminum and its effect on the tensile properties

Hydrogen was introduced in commercial-purity (99%) aluminum by electrochemical charging to study the existing state of hydrogen and its effects on the mechanical properties of aluminum. Electrochemical charging was conducted in an aqueous H2SO4 solution with 0.1% NH4SCN as a hydrogen recombination poison. The potential and pH during the charging were determined from the immune, passive, and corrosive regions in the Pourbaix diagram to determine the optimum conditions for the charging. The maximum amount of hydrogen absorbed was obtained in the immune region. The amount of hydrogen and its existing state were examined using hydrogen desorption curves, which were obtained by thermal desorption spectroscopy. The curves showed distinctive peaks corresponding to trapping sites of hydrogen in the material. One of the peaks was observed at approximately 100 � C, and it corresponds to vacancies and dislocations in the material; another peak was observed at approximately 400 � C and it corresponds to molecular hydrogen in blisters. It was presumed that charged hydrogen diffuses into the bulk of the material to form hydrogen-vacancy pairs, and then these pairs cluster to form blisters. The fracture strain of charged aluminum in the immune region decreased with decreasing strain rate, showing an inverse dependence on the fracture strain of the uncharged material. This phenomenon was considered to be caused by hydrogen transport by dislocations through the interaction between hydrogen and dislocations. The phenomenon was further confirmed by the observation of hydrogen release during tensile deformation, where the amount of hydrogen was high in the strain rate range where the interaction between dislocations and hydrogen was prominent. [doi:10.2320/matertrans.M2011035]

Electrochemical Charge for the Formation of Metal Hydrides from LiH+M (M=Mg, Al)

For a formation of metal hydride of MgH 2 or AlH 3 under room temperature and ambient pressure, the cathode electrodes of metal and lithium hydride are electrochemically charged with Li anode electrodes in the system of Li-ion extraction. For MgH 2 formation, the VC (Voltage-Composition) curve of Mg + 2LiH during charge shows a plateau voltage at 0.6 V until the final composition of 1.05 Li extraction. After charge MgH 2 phase is observed by the XRD measurement. Therefore MgH 2 is produced by the electrochemical charge from Mg and LiH. For AlH 3 formation, Al + 3LiH is charged until the final composition of 0.6 Li at a plateau voltage of 0.8 V which corresponds to the reaction between Al and LiH for the formation of AlH 3 . In the XRD profile after charge AlH 3 phase is not detected although the intensities of Al and LiH decrease compared with these before charge, which suggests the reaction leading to the formation of AlH 3 .