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Nickel is a promising candidate as an alternative to ruthenium for an ammonia decomposition catalyst. However, the performance of Ni‐based catalysts for ammonia decomposition is still not sufficient to achieve a good hydrogen production rate under low‐temperature because the weak nitrogen affinity of Ni reduces the frequency of the ammonia decomposition reaction. Here, it is reported that Ni supported on barium titanium oxynitride (Ni/h‐BaTiO3−xNy) with a hexagonal structure acts as a highly active and water‐durable catalyst for ammonia decomposition. The operation temperature is reduced by over 140 °C when N3− ions are substituted onto the O2− sites of the BaTiO3 lattice, and the Ni/h‐BaTiO3−xNy catalyst significantly outperforms conventional oxide‐supported Ni catalysts for ammonia decomposition. Furthermore, the activity of Ni/h‐BaTiO3−xNy remains unchanged after exposure to water. The 15NH3 decomposition reaction and Fourier transform‐infrared spectroscopy (FT‐IR) measurements reveal that lattice nitrogen vacancy sites on h‐BaTiO3−xNy function as the active sites for ammonia decomposition. The ammonia decomposition activity of Ni/h‐BaTiO3−xNy is also higher than that of the Ni/h‐BaTiO3−xHy oxyhydride catalyst, making a contrast to the activity trend in ammonia synthesis. [ABSTRACT FROM AUTHOR]

Metal nitride complexes have recently been proposed as an efficient noble‐metal‐free catalyst for ammonia synthesis utilizing a dual active site concept. However, their high sensitivity to air and moisture has restricted potential applications. We report that their chemical sensitivity can be improved by introducing Al into the LaN lattice, thereby forming La−Al metallic bonds (La−Al−N). The catalytic activity and mechanism of the resulting TM/La−Al−N (TM=Ni, Co) are comparable to the previously reported TM/LaN catalyst. Notably, the catalytic activity did not degrade after exposure to air and moisture. Kinetic analysis and isotopic experiment showed that La−Al−N is responsible for N2 absorption and activation despite substantial Al being introduced into its lattice because the local coordination of the lattice N remained largely unchanged. These findings show the effectiveness of metallic bond formation, which can support the chemical stability of rare‐earth nitrides with retention of catalytic functionality. [ABSTRACT FROM AUTHOR]

The Hybrid Ring with a superconducting‐linac injector as a highly flexible synchrotron radiation source to enable new experimental techniques and enhance many existing ones is proposed. It is designed to be operated with the coexistence of the storage (SR) bunches characterized by the performance of the storage ring, and the single‐pass (SP) bunches characterized by the performance of the superconducting linac. Unique experiments can be performed by simultaneous use of the SR and SP beams, in addition to research with various experimental techniques utilizing the versatile SR beam and research in the field of ultrafast dynamics utilizing the ultrashort pulse of the SP beam. The extendability of the Hybrid Ring will allow it to be developed into a synchrotron radiation complex. [ABSTRACT FROM AUTHOR]

Lanthanum oxyhydrides were recently reported to be fast hydride ion conductors with the highest conductivity at 100–400 °C. Here, the relationship between the hydride‐ion conduction and the ammonia synthesis activity of ruthenium‐loaded lanthanum oxyhydrides (Ru/LaH3−2xOx) is investigated. The onset ammonia formation temperature by the Ru/LaH3−2xOx is lower by 100 °C when compared to the Ru‐loaded lanthanum oxides. The apparent activation energy of ammonia synthesis over Ru/LaH3−2xOx is 64 kJ mol−1, which is much smaller than that of hydride‐ion conductivity (≈100 kJ mol−1), indicating no direct relationship between the catalytic activity and the bulk hydride‐ion conductivity. However, the catalytic performance is strongly correlated with the surface H− ion mobility of Ru/LaH3−2xOx, which gives rise to the formation of low work function electrons at H− ion vacancies near the Ru‐support interface and high resistance for H2 poisoning on the Ru catalyst. Moreover, LaH3−2xOx has high nitridation resistance as compared with lanthanum hydride (LaH3) under ammonia synthesis condition. As a result, the high surface H− concentration of Ru/LaH3−2xOx is preserved during ammonia synthesis, exhibiting more robust activity than Ru/LaH3. Almost the same results are obtained for Ru/CeH3−2xOx implicating the common characteristics of rare‐earth oxyhydride support. [ABSTRACT FROM AUTHOR]

X‐ray absorption fine structure (XAFS) spectroscopy is one of the most widely used methods at synchrotron radiation facilities. XAFS gives us information on chemical states and local structures. Fundamentally, XAFS is bulk sensitive, not surface sensitive. If a surface sensitive XAFS method was available, surface chemical reactions can be observed under realistic conditions. Here, we report the development and present status of a type of surface sensitive x‐ray spectroscopy, which is named total reflection x‐ray spectroscopy, TREXS. [ABSTRACT FROM AUTHOR]

Macroscopic properties of carbon fiber‐reinforced plastic (CFRP) and environmental barrier coating (EBC), widely used for airplanes, can be deteriorated by local cracks or degradation ("trigger sites"). We have tried to find these trigger sites using x‐ray microscopy (XM), which can provide the 2D or 3D images of the chemical states and microstructures. Crack initiation in CFRP was observed in a non‐destructive manner in multi‐scales (nm‐mm). 3D chemical‐state mapping of Yb in EBC was achieved with high resolution (<50 nm). In addition to XM, in‐situ observations at high temperatures were conducted for obtaining complementary information. X‐ray absorption spectroscopy (XAS) and x‐ray diffraction (XRD) analysis were performed simultaneously up to 1773 K. Dynamic XAS with short time‐resolution (<10 ns) was conducted to investigate changes in the local structure of metal. These approaches can help us identify degradation trigger sites in the materials. [ABSTRACT FROM AUTHOR]

Abstract: Ammonia decomposition is an important technology for extracting hydrogen from ammonia toward the realization of a hydrogen economy. Herein, it is reported that large oblate hemispheroidal Ru particles on Ca(NH2)2 function as efficient catalysts for ammonia decomposition. The turnover frequency of Ru/Ca(NH2)2 increased by two orders of magnitude when the Ru particle size was increased from 1.5 to 8.4 nm. More than 90 % ammonia decomposition was achieved over Ru/Ca(NH2)2 with large oblate hemispheroidal Ru particles at 360 °C, which is comparable to that of alkali‐promoted Ru catalysts with small Ru particle sizes. XAFS analyses revealed that Ru particles are immobilized on Ca(NH2)2 by Ru−N bonds formed at the metal/support interface, which lead to oblate hemispheroidal Ru particles. Such a strong metal–support interaction in Ru/Ca(NH2)2 is also substantiated by DFT calculations. The high activity of Ru/Ca(NH2)2 with large Ru particles primarily originates from the shape and appropriate size of the Ru particles with a high density of active sites rather than the electron‐donating ability of Ca(NH2)2. [ABSTRACT FROM AUTHOR]

The dynamics of the local electronic and geometric structures of WO3 following photoexcitation were studied by femtosecond time-resolved X-ray absorption fine structure (XAFS) spectroscopy using an X-ray free electron laser (XFEL). We found that the electronic state was the first to change followed by the local structure, which was affected within 200 ps of photoexcitation. [ABSTRACT FROM AUTHOR]

Ammonia Synthesis: Ruthenium Catalysts Promoted by Lanthanide Oxyhydrides with High Hydride-Ion Mobility for Low-Temperature Ammonia Synthesis (Adv. Keywords: ammonia synthesis; hydride ion conductivity; oxyhydride; ruthenium catalysts EN ammonia synthesis hydride ion conductivity oxyhydride ruthenium catalysts 1 1 1 01/29/21 20210127 NES 210127 In article number 2003723 Masaaki Kitano, Hideo Hosono and co-workers show that lanthanide oxyhydrides such as LaH SB 3-2 I x i sb O SB I x i sb and CeH SB 3-2 I x i sb O SB I x i sb , with a high hydride-ion conductivity effectively promote the activity of a Ru catalyst for low-temperature ammmonia synthesis. Ammonia synthesis, hydride ion conductivity, oxyhydride, ruthenium catalysts. [Extracted from the article]