비만아 부모의 돌봄 경험: q 방법론

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

Coordinatively unsaturated (CUS) iron sites are highly active in catalytic oxidation reactions; however, maintaining the CUS structure of iron during heterogeneous catalytic reactions is a great challenge. Here, we report a strategy to stabilize single-atom CUS iron sites by embedding highly dispersed FeN4 centers in the graphene matrix. The atomic structure of FeN4 centers in graphene was revealed for the first time by combining high-resolution transmission electron microscopy/high-angle annular dark-field scanning transmission electron microscopy with low-temperature scanning tunneling microscopy. These confined single-atom iron sites exhibit high performance in the direct catalytic oxidation of benzene to phenol at room temperature, with a conversion of 23.4% and a yield of 18.7%, and can even proceed efficiently at 0°C with a phenol yield of 8.3% after 24 hours. Both experimental measurements and density functional theory calculations indicate that the formation of the Fe═O intermediate structure is a key step to promoting the conversion of benzene to phenol. These findings could pave the way toward highly efficient nonprecious catalysts for low-temperature oxidation reactions in heterogeneous catalysis and electrocatalysis.

A single iron site confined in a graphene matrix for the catalytic oxidation of benzene at room temperature.

Emerging trends in spin crossover (SCO) based functional materials and devices

Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high overall abundance of precursors, their even geographical distribution, and low cost. Apart from inherent thermodynamic disadvantages, SIBs have to overcome multiple kinetic problems, such as fast capacity decay, low rate capacities and low Coulombic efficiencies. A special case is sodium super ion conductor (NASICON)-based electrode materials as they exhibit - besides pronounced structural stability - exceptionally high ion conductivity, rendering them most promising for sodium storage. Owing to the limiting, comparatively low electronic conductivity, nano-structuring is a prerequisite for achieving satisfactory rate-capability. In this review, we analyze advantages and disadvantages of NASICON-type electrode materials and highlight electrode structure design principles for obtaining the desired electrochemical performance. Moreover, we give an overview of recent approaches to enhance electrical conductivity and structural stability of cathode and anode materials based on NASICON structure. We believe that this review provides a pertinent insight into relevant design principles and inspires further research in this respect.

Challenges and Perspectives for NASICON-Type Electrode Materials for Advanced Sodium-Ion Batteries

Alkali atom doping is an efficient way to induce charge transfer and Fermi level tuning in layered materials through intercalation. However, there is a general lack of microscopic understanding of the effect of doping inhomogeneity in geometric and electronic aspects. Here, we report surface doping of a bulk VSe2 crystal by sodium. Na atoms form intercalated subsurface islands that modify the electronic phase of the top layer of VSe2. In addition to n‐doping, the charge density wave of the intercalated VSe2 surface layer changes from the (4 × 4) bulk phase to the ( 3×7$\sqrt 3 {\bm{ \times }}\sqrt 7 $ ) known in monolayer phase of VSe2. Surprisingly, an electronic state at the edges of Na‐intercalated area shift anomalously upward in energy as detected by scanning tunneling spectroscopy. This is explained by a local gating effect resulting from local dipoles at the edges. The study illustrates a clear example of intercalation effect that should be general in alkali‐intercalated bulk layered materials.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/admi.202201680

Formation of Monolayer Charge Density Waves and Anomalous Edge Doping in Na Doped Bulk VSe2

Growth and local electronic properties of Cobalt nanodots underneath graphene on SiC(0001)

Order-disorder transition of the epitaxial surface alloy of bulk immiscible elements ${\mathrm{Au}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}$ on Ru(0001) is studied using complementary experiments of scanning tunneling microscopy and grazing incidence x-ray diffraction. For $x\ensuremath{\simeq}1/3$, we evidence an apparent continuous transition towards disorder with increasing temperature from 550 to 700 K. An ordered ${\mathrm{Au}}_{2}\mathrm{Fe}$ two-dimensional alloy is found to be composed of nanometer size domains of the three variants that switch to a two-dimensional solid solution with temperature. A two-levels model is developed to analyze those results which conducts to interpret this phase transition as the result of an order-disorder transition within two dimensional uncorrelated grains, or domains, with nearly fixed size. This system is a good candidate in order to study two-dimensional phase transitions of surface alloy, a largely unexplored domain but crucial to understanding thermal stability of bimetallic nanoparticles.

Amandine Bellec

Papers

Formation of Monolayer Charge Density Waves and Anomalous Edge Doping in Na Doped Bulk VSe2

Growth and local electronic properties of Cobalt nanodots underneath graphene on SiC(0001)

Order-disorder phase transition in Au 2 Fe on Ru(0001)