A5036715462- Advanced Chemical Physics Studies
- Catalytic Processes in Materials Science
- Quantum, superfluid, helium dynamics
- Semiconductor materials and devices
- nanoparticles nucleation surface interactions
- Electronic and Structural Properties of Oxides
- Nuclear Physics and Applications
- Hydrogen Storage and Materials
- Ammonia Synthesis and Nitrogen Reduction
- Muon and positron interactions and applications
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Molecular Physics
- Spectroscopy and Quantum Chemical Studies
- Surface and Thin Film Phenomena
- Ion-surface interactions and analysis
- Atomic and Subatomic Physics Research
- Gas Sensing Nanomaterials and Sensors
- Silicon and Solar Cell Technologies
- Catalysis and Oxidation Reactions
- Fusion materials and technologies
- Silicon Nanostructures and Photoluminescence
- Spectroscopy and Laser Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Thin-Film Transistor Technologies
- Graphene research and applications
The University of Tokyo
2016-2025
Japan Atomic Energy Agency
2019-2024
Advanced Science Research Center
2019-2024
Tokyo University of Science
2007-2022
Meguro Parasitological Museum
2021
Nagoya University
2020
Japan Science and Technology Agency
1997-2019
Institute of Materials Structure Science
2019
Tokyo Gakugei University
2019
High Energy Accelerator Research Organization
2019
The mechanism of olefin hydrogenation on a supported noble-metal catalyst requires the presence weakly bound hydrogen atoms absorbed in volume metal particle (see picture). Co-adsorbed carbonaceous deposits affect distribution clusters and critically control their activity selectivity conversions.
Ceria (CeO2) has recently been found to be a promising catalyst in the selective hydrogenation of alkynes alkenes. This reaction occurs primarily on highly dispersed metal catalysts, but rarely oxide surfaces. The origin outstanding activity and selectivity observed CeO2 remains unclear. In this work, we show that one key aspect reaction-the interaction hydrogen with oxide-depends strongly presence O vacancies within CeO2. Through infrared reflection absorption spectroscopy well-ordered...
Significance Surfaces are gates to control the transport of energy and materials between gas phase bulk. For hydrogen storage, across surface is recognized as bottleneck, e.g., 1 H 2 in 1,000 impinging a Pd penetrates surface. Here, we demonstrate that alloying Pd(110) with submonolayer amounts Au dramatically accelerates absorption, by factor more than 40. This discovery will lead enhancement absorption kinetics, thereby improving performance hydrogen-purifying membranes hydrogen-storage...
We have succeeded in observing nuclear excitation by electron transition (NEET) ${}^{197}\mathrm{Au}$ a new method. Monochromatic x-rays of synchrotron radiation were used to ionize the $K$ shell gold atoms target foil. The internal-conversion electrons emitted from excited nuclei detected with silicon avalanche photodiode. At photon energy 80.989 keV, NEET probability was determined be $(5.0\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ comparison...
Substantial hydrogen absorption in nanometer-sized palladium crystallites on a thin film alumina support is observed at $90--350\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ under low ${\mathrm{H}}_{2}$ pressure conditions $(<2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\phantom{\rule{0.3em}{0ex}}\mathrm{Pa})$ by $^{1}\mathrm{H}(^{15}\mathrm{N},\ensuremath{\alpha}\ensuremath{\gamma})^{12}\mathrm{C}$ nuclear reaction analysis. The enthalpy of H solution varies with the absorbed content...
The fabrication of a hydrogen isotope enrichment system is essential for the development industrial, medical, life science, and nuclear fusion fields, therefore, efficient techniques with high separation factor economic feasibility are still being explored. Herein, we report hydrogen/deuterium (H/D) ability polymer electrolyte membrane electrochemical pumping (PEM-ECHP) using heterogeneous electrode consisting palladium graphene layers (PdGr). By mass spectroscopic analysis, demonstrate...
Hydrogen-associated electron-doping Mottronics for d-band correlated oxides (e.g., VO2) opens up a new paradigm to regulate the electronic functionality via directly manipulating orbital configuration and occupancy. Nevertheless, role of hydrogen in Mottronic transition VO2 is yet unclear because opposite reconfigurations toward either metallic or highly insulating states were both reported. Herein, we demonstrate root cause such hydrogen-induced multiple phase transitions by 1H...
Electron-doping Mottronics within correlated vanadium dioxide (e.g., VO2) opens up a paradigm to abruptly regulate the Mottronic phase transitions via adjusting d-orbital occupancy and configuration. Nevertheless, potential impact of high-valence elementary substitution in hydrogen-associated VO2 is yet unclear. Herein, we demonstrate role W6+) regulating hydrogen-triggered VO2, assisted by quantitative hydrogen analysis using nuclear reaction analysis. Substituting with transitional metal...
The conditions enabling the transition of surface-adsorbed hydrogen atoms into bulk metals are explored by comparing response chemisorbed H on Pd(100) and Ti(0001) single crystals to thermal activation in vacuum. Thermal desorption spectroscopy $^{1}\text{H}(^{15}\text{N},\ensuremath{\alpha}\ensuremath{\gamma})^{12}\text{C}$ nuclear reaction analysis reveal that heating causes ${\text{H}}_{2}$ from Pd(100), whereas reversibly exchange between surface Ti with negligible loss ${\text{H}}_{2}$....
The microscopic mechanism of low-temperature (80 K &lt; T 160 K) hydrogen (H) ingress into the H2 (&lt;2.66 × 10−3 Pa) exposed Pd(110) surface is explored by H depth profiling with 15N nuclear reaction analysis (NRA) and thermal desorption spectroscopy (TDS) isotope (H, D) labeled hydrogen. NRA TDS reveal two types absorbed states distinctly different distributions. Between 80 ∼145 a near-surface hydride phase evolving as α1 feature at forms, which initially extends only several...
Quantum-state-selective thermal desorption of ${\mathrm{H}}_{2}$ weakly physisorbed on Ag(111) demonstrates significantly different features between the nuclear-spin modifications. An energy shift due to rotational-symmetry breaking induced by an anisotropic interaction affects not only enthalpy but also entropy adsorption. The preexponential factor for ortho-${\mathrm{H}}_{2}$ is about three times as large that para-${\mathrm{H}}_{2}$. difference indicates a perpendicular orientation...
The Pd-catalyzed hydrogenation of C═C double bonds is one the most important synthetic routes in organic chemistry. This catalytic surface reaction known to require hydrogen interior Pd catalyst, but mechanistic role Pd-dissolved H has remained elusive. To shed new light into this fundamental problem, we visualized distribution near a single crystal charged with absorbed during typical conversion butene (C4H8) butane (C4H10), using depth profiling via nuclear analysis. revealed that (1)...
Currently, no known material retains its photoinduced metallic conductivity over a long time while also exhibiting repeatable metal-to-insulator recovery. Here, we demonstrate such highly insulator-to-metal transition in yttrium oxyhydride (YOxHy) epitaxial thin films. The temperature (T) dependence of the electrical resistivity (ρ) films transforms from insulating to state (dρ/dT > 0) under ultraviolet laser illumination. YOxHy film recovers original when heated (125 °C) an Ar atmosphere...
Formation of an electrolyte–electrode interface that allows smooth Li-ion transport is essential for the further development all-solid-state Li batteries. Water vapor recognized as one critical origin increased resistance at interface. However, detailed mechanism degradation remains unclarified. This study uses a thin-film battery with LiCoO2 electrode to investigate how protons contribute degradation. Protons were introduced by exposing surface water vapor. Electrochemical, compositional,...
Hydrogen atoms adsorbed on Si(111) and Pt(111) were investigated by nuclear reaction analysis (NRA) using 1H(15N,alphagamma)12C. From measurements of the NRA spectrum at normal tilted ion incidences zero-point vibrational energies H in perpendicular parallel directions found to be 123.4+/-4.6 44.6+/-6.2 meV, respectively, which are consistent with harmonic potentials. The obtained for Pt(111)-H 80.8+/-3.9 62.1+/-6.0 meV directions, respectively. These results indicate that stretching mode is...
Alloying Pd with Au has remarkable features of enhancement hydrogen solubility compared to and catalytic activity for reactions such as partial hydrogenation unsaturated hydrocarbons. A key understanding these phenomena is clarification behavior in the near-surface region. In present work, by applying nuclear reaction analysis high-resolution depth profiling combination thermal desorption spectroscopy, we show that substantially accumulates region absorbed bulk a single-crystal Pd70Au30(110)...