Honeycomb Layered Frameworks with Metallophilic Bilayers

Honeycomb layered frameworks with metallophilic bilayers have garnered traction in various disciplines due to their unique configuration and numerous physicochemical and topological properties, such as fast ionic conduction, coordination chemistry, and structural defects. These properties make them attractive for energy storage applications, leading to increased attention towards their metallophilic bilayer arrangements. This Review focuses on recent advancements in this field, including characterisation techniques like X-ray absorption spectroscopy and high-resolution transmission electron microscopy, particularly for silver-based oxides. It also highlights strategies related to cationic-deficient phases induced by topology or temperature, expanding the compositional space of honeycomb layered frameworks with a focus on cationic bilayer architectures. The Review further discusses theoretical approaches for understanding the bilayered structure, especially concerning critical phenomena at the monolayer-bilayer phase transition. Honeycomb layered frameworks are described as optimised lattices within the congruent sphere packing problem, equivalent to a specific two-dimensional conformal field theory. The monolayer-bilayer phase transition involves a 2D-to-3D crossover. Overall, this Review aims to provide a panoramic view of honeycomb layered frameworks with metallophilic bilayers and their potential applications in the emerging field of quantum matter. It is valuable for recent graduates and experts alike across diverse fields, extending beyond materials science and chemistry.Comment: 68 pages, 24 figure

Genome-wide and expression analysis of protein phosphatase 2C in rice and Arabidopsis

<p>Abstract</p> <p>Background</p> <p>The protein phosphatase 2Cs (PP2Cs) from various organisms have been implicated to act as negative modulators of protein kinase pathways involved in diverse environmental stress responses and developmental processes. A genome-wide overview of the PP2C gene family in plants is not yet available.</p> <p>Results</p> <p>A comprehensive computational analysis identified 80 and 78 PP2C genes in <it>Arabidopsis thaliana </it>(AtPP2Cs) and <it>Oryza sativa </it>(OsPP2Cs), respectively, which denotes the PP2C gene family as one of the largest families identified in plants. Phylogenic analysis divided PP2Cs in Arabidopsis and rice into 13 and 11 subfamilies, respectively, which are supported by the analyses of gene structures and protein motifs. Comparative analysis between the PP2C genes in Arabidopsis and rice identified common and lineage-specific subfamilies and potential 'gene birth-and-death' events. Gene duplication analysis reveals that whole genome and chromosomal segment duplications mainly contributed to the expansion of both OsPP2Cs and AtPP2Cs, but tandem or local duplication occurred less frequently in Arabidopsis than rice. Some protein motifs are widespread among the PP2C proteins, whereas some other motifs are specific to only one or two subfamilies. Expression pattern analysis suggests that 1) most PP2C genes play functional roles in multiple tissues in both species, 2) the induced expression of most genes in subfamily A by diverse stimuli indicates their primary role in stress tolerance, especially ABA response, and 3) the expression pattern of subfamily D members suggests that they may constitute positive regulators in ABA-mediated signaling pathways. The analyses of putative upstream regulatory elements by two approaches further support the functions of subfamily A in ABA signaling, and provide insights into the shared and different transcriptional regulation machineries in dicots and monocots.</p> <p>Conclusion</p> <p>This comparative genome-wide overview of the PP2C family in Arabidopsis and rice provides insights into the functions and regulatory mechanisms, as well as the evolution and divergence of the PP2C genes in dicots and monocots. Bioinformatics analyses suggest that plant PP2C proteins from different subfamilies participate in distinct signaling pathways. Our results have established a solid foundation for future studies on the functional divergence in different PP2C subfamilies.</p

Manipulation of charge carrier flow in Bi₄NbO₈Cl nanoplate photocatalyst with metal loading

Separation of photoexcited charge carriers in semiconductors is important for efficient solar energy conversion and yet the control strategies and underlying mechanisms are not fully established. Although layered compounds have been widely studied as photocatalysts, spatial separation between oxidation and reduction reaction sites is a challenging issue due to the parallel flow of photoexcited carriers along the layers. Here we demonstrate orthogonal carrier flow in layered Bi₄NbO₈Cl by depositing a Rh cocatalyst at the edges of nanoplates, resulting in spatial charge separation and significant enhancement of the photocatalytic activity. Combined experimental and theoretical studies revealed that lighter photogenerated electrons, due to a greater in-plane dispersion of the conduction band (vs. valence band), can travel along the plane and are readily trapped by the cocatalyst, whereas the remaining holes hop perpendicular to the plane because of the anisotropic crystal geometry. Our results propose manipulating carrier flow via cocatalyst deposition to achieve desirable carrier dynamics for photocatalytic reactions in layered compounds

光・誘電機能を目指したビスマス系複合アニオン化合物の開発

京都大学新制・課程博士博士(工学)甲第23912号工博第4999号新制||工||1780(附属図書館)京都大学大学院工学研究科物質エネルギー化学専攻(主査)教授 陰山 洋, 教授 阿部 竜, 教授 安部 武志学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDGA

Effect of Fluorine Substitution in Li3YCl6 Chloride Solid Electrolytes for All-solid-state Battery

All-solid-state batteries experience irreversible capacity loss particularly in the initial potential cycle, owing to electrolyte decomposition at the electrode/electrolyte interface. A strategy for expanding the oxidation stability of electrolytes is replacing the anion with fluorine. However, fluorine substitution has a negative influence on ionic conductivity. In this study, we introduced trace amounts of fluorine into Li3YCl6 solid electrolytes which exhibit high ionic conductivities and wide potential windows. The effect of replacement on ionic conductivity, oxidation stability, and charge–discharge characteristics were studied. The trace amounts of fluorine in Li3YCl6 did not reduce the conductivity, but improved the apparent oxidation stability. The decomposed product of LiF from the fluorine-substituted electrolyte disturbed the formation of a high-resistance layer at the electrode/electrolyte interface. The initial charge–discharge efficiency of the uncoated LiCoO2 cathode was improved by the trace amount of fluorine replacement in the Li3YCl6 solid electrolyte

Fluorosulfide La2.7Ba6.3F8.7S6 with Double-Layer Honeycomb Structure Enabling Fluoride-Ion Conduction

Mixed-anion compounds comprise anion-ordered layered structures with fluoride ionic conducting layers, which are not found in conventional metal fluorides. Hence, they represent a new frontier in the search for fluoride-ion conductors. Previous studies investigated only mixed-anion compounds with known crystal structures, but failed to exploit a flexible structural design. In this study, we performed a materials search based on the ternary phase diagram of BaS-LaF3-BaF2 for new fluorosulfide phases and found an unreported fluorosulfide, La2.7Ba6.3F8.7S6, showing the fluoride ion conductivity of 4.23×10−7 S cm−1 at 343 K. La2.7Ba6.3F8.7S6 forms an anion-ordered two-dimensional crystal lattice with double-honeycomb (La-Ba)F2 fluoride-ion-conducting layers, which cannot be realized in single-anion compounds. In the (La-Ba)F2 layers, the fluoride ion conduction is realized through normal F1 site and interstitial F2 site via a vacancy mechanism. The presence of sulfide ions in the crystal structure contributes to the spreading of (La-Ba)F2 layers along the ab plane, resulting in a longer La-F distance. Material development using a systematic phase diagram search on fluorosulfides allows to increase the variation of the crystal structure for fluoride ion conductors and to discover the novel fluoride ion conducting layers that are inaccessible to single anion compounds

Honeycomb Layered Frameworks with Metallophilic Bilayers

Honeycomb layered frameworks have garnered traction in a wide range of disciplines owing not only to their unique honeycomb configuration, but also to the plenitude of physicochemical and topological properties such as fast ionic conduction, diverse coordination chemistry and structural defects amongst others typically exploited for energy storage applications. In turn, honeycomb layered frameworks manifesting metallophilic bilayer arrangements of cations sandwiched between the transition metal cation slabs have recently garnered attention due to the presence of anomalous fractional valency state of the cations always accompanied by metallophilic interactions constituting the cationic bonds within the bilayered structure. The concepts needed to characterise the aforementioned peculiarities and other phenomena such as conductor-semiconductor-insulator phase transition and magnetoresistance in these materials cut across multi-disciplines ranging from materials science and solid-state chemistry to condensed matter physics, suggesting applications that fall beyond energy storage. This Review highlights the exciting advancements in the science of honeycomb layered frameworks with metallophilic bilayers. First, the latest tactics and techniques including but not limited to X-ray absorption spectroscopy (XAS) and high-resolution transmission electron microscopy (HRTEM) particularly necessary for characterising recent honeycomb layered frameworks with metallophilic bilayers are described, with emphasis on silver-based oxides. Second, new strategies and concepts related to topochemically- or temperature-induced cationic-deficient phases expanding the compositional space of honeycomb layered frameworks focused on cationic bilayer architectures are also accentuated. Third, the latest condensed matter theoretic advances towards a full, atomistic description of the bilayered structure in such frameworks are detailed, especially related to critical phenomena at the cusp of the monolayer-bilayer phase transition. This entails, in part, describing honeycomb layered frameworks as optimised lattices within the congruent sphere packing problem, equivalent to a particular two-dimensional (2D) conformal field theory. Within this picture, the monolayer-bilayer phase transition represents the bifurcation of the honeycomb lattice into its bipartite constituents, related to a 2D-to-3D crossover. Altogether, it is hoped that this Review will give the reader a panoramic view of the honeycomb layered frameworks with important applications within the emerging field of quantum matter, potentially redefining their frontier. Thus, the scope of this Review is expected to be worthwhile for recent graduates and emerging experts alike not only in the materials science and chemistry community but also in other diverse fields of interest