Trace Ammonia Equilibrium Pressure of Zirconium Phosphate in Moisture.

Zirconium phosphate-absorbed ammonia gas and the ammonia concentration (pressure) decreased to 2 ppm (ca. 20 Pa). However, it has not been clarified what the equilibrium pressure of zirconium phosphate is during ammonia gas ab/desorption.

Isolation and characterization of blackish-brown BY2-melanin accumulated in cultured tobacco BY-2 cells.

The tobacco BY-2 cell line is one of the most utilized plant cell lines. After long-term culture, the cells turn brown to black, but the causal pigment is unknown. We successfully isolated a blackish-brown pigment from BY-2 cells cultured for 3 weeks.

Regeneration Process of Ammonia-Absorbed Zirconium Phosphate to Zirconium Phosphate.

Zirconium phosphate [Zr(HPO)·HO] absorbs 2 mol(NH)/mol[Zr(HPO)·HO] with a low equilibrium plateau ammonia concentration of around 1 ppm in water. In this study, in order to investigate the regeneration process of ammonia-absorbed zirconium phosphate [Zr(NHPO)·HO], Zr(NHPO)·HO was heat-treated above 353 K under an inert gas. Then, the structures of the heat-treated samples were evaluated using powder X-ray diffraction and thermogravimetry-mass spectrometry measurements.

Analysis of sodium generation by sodium oxide decomposition on corrosion resistance materials: a new approach towards sodium redox water-splitting cycle.

In this study, the investigation of materials with corrosion resistance was carried out to prevent side reactions caused by sodium oxide (NaO) in the Na-redox thermochemical water splitting cycle, and essential operational conditions for sodium (Na) generation from NaO were also investigated. Thermal desorption spectroscopy and X-ray diffraction techniques at altered conditions were mainly used for the experimental investigation. Numerous types of materials were tested to find materials with high resistance towards corrosion and to understand essential thermal decomposition processes of NaO.

Catalytic Activities of Various Niobium Oxides for Hydrogen Absorption/Desorption Reactions of Magnesium.

Five types of niobium(V) oxides (NbO) were synthesized by hydrothermal and heat treatment processes, and their structural properties and catalytic activities for the hydrogen absorption/desorption reactions of magnesium were characterized. The synthesized Nb oxides were dispersed on magnesium hydride (MgH), a typical hydrogen storage material, using the ball-milling method. All the synthesized Nb oxides improved the reaction kinetics of the hydrogen desorption/absorption reactions.

Temperature rise of LaNi-based alloys by hydrogen adsorption.

The temperature rise of AB-type alloys by hydrogen adsorption was limited by their critical temperatures (). We found the relation between the H desorption temperatures of metal hydrides at atmospheric pressure () and their c followed the Guldberg rule ( = 3/2 ), revealing a simple method to estimate .

Synergetic NH absorption properties of the NaBH-LiBH mixed system.

NaBH does not absorb NH below 100 kPa but transforms into a liquid state after NH absorption. On the other hand, LiBH absorbs NH at pressures lower than 100 kPa. Interestingly, mixed borohydrides absorbed NH at low pressures and were liquefied above 100 kPa due to a synergetic phenomenon.

Effective Factor on Catalysis of Niobium Oxide for Magnesium.

Magnesium is a promising hydrogen storage material but requires an efficient catalyst to enhance the sluggish kinetics of its hydrogen desorption/absorption reactions. Niobium catalysts have been shown to accomplish this, but the effective factors for catalysis on hydrogen desorption/absorption of Mg are not well understood. In order to investigate these aspects, various types of Nb oxides were synthesized and mixed with Mg, and their catalytic properties were investigated.

Surface modification effects of graphite for selective hydrogen absorption by titanium at room temperature.

Surface modification effects of graphite and organic solvents on Ti were investigated by thermogravimetry (TG), Raman spectroscopy, and transmission electron microscopy (TEM) observations to improve its hydrogen absorption properties. As a result, Ti ball-milled with graphite showed high reactivity and selectivity for hydrogen with high durability.

Concentration-composition-isotherm for the ammonia absorption process of zirconium phosphate.

The ammonia absorption process of zirconium phosphate has been studied using the concentration-composition-isotherm (CCI), X-ray diffraction and thermogravimetry-mass spectrometry (TG-MS). It was clarified that the equilibrium plateau concentration appeared due to two phase coexistence.

Eutectic Phenomenon of LiNH₂-KH Composite in MH-NH₃ Hydrogen Storage System.

Hydrogenation of a lithium-potassium (double-cation) amide (LiK(NH₂)₂), which is generated as a product by ammonolysis of litium hydride and potassium hydride (LiH-KH) composite, is investigated in details. As a result, lithium amide (LiNH₂) and KH are generated after hydrogenation at 160 °C as an intermediate. It is noteworthy that the mixture of LiH and KNH₂ has a much lower melting point than that of the individual melting points of LiNH₂ and KH, which is recognized as a eutectic phenomenon.

Operando spectroscopic analyses for the ammonia absorption process of sodium borohydride.

The ammonia absorption process of sodium borohydride for ammonia storage has been studied by using the operando NMR and FT-IR measurements under various ammonia pressures. As a result, the characteristic variation in the chemical states of both materials due to the liquefaction has been clarified.

MgH-CoO: a conversion-type composite electrode for LiBH-based all-solid-state lithium ion batteries.

Several studies have demonstrated that MgH is a promising conversion-type anode toward Li. A major obstacle is the reversible capacity during cycling. Electrochemical co-existence of a mixed metal hydride-oxide conversion type anode is demonstrated for lithium ion batteries using a solid-state electrolyte.

Nitrogen Dissociation via Reaction with Lithium Alloys.

Lithium alloys are synthesized by reactions between lithium metal and group 14 elements, such as carbon, silicon, germanium, and tin. The nitrogenation and denitrogenation properties are investigated by thermal and structural analyses. All alloys dissociate the nitrogen triple bond of gaseous molecules to form atomic state as nitrides below 500 °C, which is lower than those required for conventional thermochemical and catalytic processes on nitride syntheses.

Bulk-Type All-Solid-State Lithium-Ion Batteries: Remarkable Performances of a Carbon Nanofiber-Supported MgH Composite Electrode.

Magnesium hydride, MgH, a recently developed compound for lithium-ion batteries, is considered to be a promising conversion-type negative electrode material due to its high theoretical lithium storage capacity of over 2000 mA h g, suitable working potential, and relatively small volume expansion. Nevertheless, it suffers from unsatisfactory cyclability, poor reversibility, and slow kinetics in conventional nonaqueous electrolyte systems, which greatly limit the practical application of MgH. In this work, a vapor-grown carbon nanofiber was used to enhance the electrical conductivity of MgH using LiBH as the solid-state electrolyte.

Kinetic Modification on Hydrogen Desorption of Lithium Hydride and Magnesium Amide System.

Various synthesis and rehydrogenation processes of lithium hydride (LiH) and magnesium amide (Mg(NH₂)₂) system with 8:3 molar ratio are investigated to understand the kinetic factors and effectively utilize the essential hydrogen desorption properties. For the hydrogen desorption with a solid-solid reaction, it is expected that the kinetic properties become worse by the sintering and phase separation. In fact, it is experimentally found that the low crystalline size and the close contact of LiH and Mg(NH₂)₂ lead to the fast hydrogen desorption.

Metal hydride-based materials towards high performance negative electrodes for all-solid-state lithium-ion batteries.

Electrode performances of MgH2-LiBH4 composite materials for lithium-ion batteries have been studied using LiBH4 as the solid-state electrolyte, which shows a high reversible capacity of 1650 mA h g(-1) with an extremely low polarization of 0.05 V, durable cyclability and robust rate capability.

Catalytic modification in dehydrogenation properties of KSiH3.

A number of known catalysts, which have been proven to be very effective for several hydrogen species, were studied in order to determine their effects on the hydrogen ab/desorption properties of KSiH3. Among all the catalysts used in this work, mesoporous Nb2O5 is found to be quite effective, with a reduction in activation energy from 142 kJ mol(-1) for pristine KSi to 63 kJ mol(-1) for mesoporous-Nb2O5-added KSi, thus allowing desorption to start at 100-120 °C. Any disproportionation is not observed in the controlled hydrogenation process.

Anode properties of magnesium hydride catalyzed with niobium oxide for an all solid-state lithium-ion battery.

The anode properties of pristine MgH2 and MgH2 catalyzed with Nb2O5 have been investigated for an all solid-state lithium-ion battery. The catalytic effect stabilizes the plateau voltage as a result of kinetic improvement of the hydrogen transfer from the Mg phase to the Li phase.

Improvement of hydrogen desorption kinetics in the LiH-NH3 system by addition of KH.

It was found that, when a little amount of KH (5 mol%) was added in the LiH-NH(3) hydrogen storage system, the hydrogen desorption kinetics of this system at 100 °C was drastically improved by the KH "pseudo-catalytic" effect.

The reaction process of hydrogen absorption and desorption on the nanocomposite of hydrogenated graphite and lithium hydride.

The lithium-carbon-hydrogen (Li-C-H) system is composed of hydrogenated nanostructural graphite (C(nano)Hx) and lithium hydride (LiH). C(nano)Hx is synthesized by ball-milling of graphite under a hydrogen atmosphere. In this work, the reaction process of hydrogen absorption and desorption on the Li-C-H system is investigated.