A5015612819- Catalytic Processes in Materials Science
- Electrocatalysts for Energy Conversion
- Nanomaterials for catalytic reactions
- Ammonia Synthesis and Nitrogen Reduction
- Nuclear materials and radiation effects
- Hydrogen Storage and Materials
- Ion-surface interactions and analysis
- Metal-Organic Frameworks: Synthesis and Applications
- Nuclear Materials and Properties
- Catalysis and Oxidation Reactions
- nanoparticles nucleation surface interactions
- High Entropy Alloys Studies
- Advanced Materials Characterization Techniques
- Electron and X-Ray Spectroscopy Techniques
- Chalcogenide Semiconductor Thin Films
- Catalysts for Methane Reforming
- Radioactive element chemistry and processing
- Machine Learning in Materials Science
- Laser-Ablation Synthesis of Nanoparticles
- Electronic Packaging and Soldering Technologies
- Catalysis and Hydrodesulfurization Studies
- High-Temperature Coating Behaviors
- Semiconductor materials and devices
- Advanced Photocatalysis Techniques
- Advanced Electron Microscopy Techniques and Applications
Kyushu University
2016-2025
Kirinyaga University
2021
Graduate School USA
2018-2021
Oita University
2021
Hokkaido University
2021
Kyoto University
2021
Japan Science and Technology Agency
2013-2018
Kawaguchi Junior College
2015
Kobe University
2007
Kumamoto University
2001-2003
The platinum-group metals (PGMs) are six neighboring elements in the periodic table of elements. Each PGM can efficiently promote unique reactions, and therefore, alloying PGMs would create ideal catalysts for complex or multistep reactions that involve several reactants intermediates. Thus, high-entropy-alloy (HEA) nanoparticles (NPs) all (denoted as PGM-HEA) having a great variety adsorption sites on their surfaces could be candidates to catalyze reactions. Here, we report first time...
We report the first discovery of pure face-centered-cubic (fcc) Ru nanoparticles. Although fcc structure does not exist in bulk phase diagram, was obtained at room temperature because nanosize effect. succeeded separately synthesizing uniformly sized nanoparticles both and hcp having diameters 2-5.5 nm by simple chemical reduction methods with different metal precursors. The prepared were supported on γ-Al2O3, their catalytic activities CO oxidation investigated found to depend size.
Pd(x)Ru(1-x) solid solution alloy nanoparticles were successfully synthesized over the whole composition range through a chemical reduction method, although Ru and Pd are immiscible at atomic level in bulk state. From XRD measurement, it was found that dominant structure of changes from fcc to hcp with increasing content. The structures 30-70% consisted both structures, phases coexist single particle. In addition, reaction hydrogen changed exothermic endothermic as content increased....
RuRhPdIrPt high-entropy-alloy nanoparticles with a broad and featureless valence band spectrum show high hydrogen evolution reaction activity.
Abstract Water is the only available fossil-free source of hydrogen. Splitting water electrochemically among most used techniques, however, it accounts for 4% global hydrogen production. One reasons high cost and low performance catalysts promoting oxygen evolution reaction (OER). Here, we report a highly efficient catalyst in acid, that is, solid-solution Ru‒Ir nanosized-coral (RuIr-NC) consisting 3 nm-thick sheets with 6 at.% Ir. Among OER catalysts, RuIr-NC shows highest intrinsic...
The compositional space of high-entropy-alloy nanoparticles (HEA NPs) significantly expands the diversity materials library. Every atom in HEA NPs has a different elemental coordination environment, which requires knowledge local electronic structure at an atomic level. However, such not been disclosed experimentally or theoretically. We synthesized composed all eight noble-metal-group elements (NM-HEA) for first time. Their was revealed by hard X-ray photoelectron spectroscopy and density...
A Ru/La<sub>0.5</sub>Ce<sub>0.5</sub>O<sub>1.75</sub>catalyst pre-reduced at an unusually high temperature (650 °C) catalyses ammonia synthesis a rate under mild conditions.
High-entropy alloy nanoparticles (HEA NPs) emerged as catalysts with superior performances that are not shown in monometallic catalysts. Although many kinds of synthesis techniques HEA NPs have been developed recently, synthesizing ultrasmall particle size and narrow distribution remains challenging because most the reported methods require high temperatures accelerate growth. This work provides a new methodology for fabrication homogeneous using continuous-flow reactor liquid-phase...
Low-crystalline Ru nano-layers and the strong basicity of Ru/Pr<sub>2</sub>O<sub>3</sub>synergistically accelerated rate-determining step ammonia synthesis.
We report novel PtW solid-solution nanoparticles (NPs) produced through electrochemical cleaning of core/shell PtW@WO3 NPs. The resulting NPs achieved a record hydrogen evolution reaction (HER) performance as class Pt-based alloys. A current density 10 mA cm-2 was reached with an overpotential 19.4 mV, which is significantly lower than that commercial Pt catalyst (26.3 mV). also exhibited long-term stability. Theoretical calculations revealed negatively charged atoms adjacent to W atom...
Pd octahedrons and cubes enclosed by {111} {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, solid-state (2)H NMR hydrogen pressure-composition isotherm measurements. With these measurements, it was found that exposed facets do not affect hydrogen-storage capacity; however, they significantly absorption speed, with octahedral...
Binary solid-solution alloys generally adopt one of three principal crystal lattices-body-centred cubic (bcc), hexagonal close-packed (hcp) or face-centred (fcc) structures-in which the structure is dominated by constituent elements and compositions. Therefore, it a significant challenge to selectively control in with certain composition. Here, we propose an approach for selective using chemical reduction method. By precisely tuning speed metal precursors, alloy nanoparticles, are able...
We report on novel solid-solution alloy nanoparticles (NPs) of Ru and Cu that are completely immiscible even above melting point in bulk phase. Powder X-ray diffraction, scanning transmission electron microscopy, energy-dispersive measurements demonstrated atoms were homogeneously distributed the NPs. Ru0.5Cu0.5 NPs higher CO oxidation activity than fcc-Ru NPs, which known as one best monometallic catalysts.
Abstract For the first time, we synthesize solid‐solution alloy nanoparticles of Ir and Cu with a size ca. 2 nm, despite being immiscible in bulk up to their melting over whole composition range. We performed systematic characterization on nature x 1− alloys using powder X‐ray diffraction, scanning transmission electron microscopy coupled energy‐dispersive spectroscopy photoelectron spectroscopy. The results showed that had face‐centered‐cubic structure; charge transfer from occurred...
We report the charge transfer dependence on CO<sub>2</sub> hydrogenation activity to methanol in Cu nanoparticles covered with metal–organic framework systems.
The crystal structure significantly affects the physical and chemical properties of solids. However, structure-dependent alloys are rarely studied because controlling an alloy at same composition is extremely difficult. Here, for first time, we successfully demonstrate synthesis binary Ru-Pt (Ru/Pt = 7:3) Ru-Ir (Ru/Ir ternary Ru-Ir-Pt (Ru/Ir/Pt 7:1.5:1.5) solid-solution nanoparticles (NPs) with well-controlled hexagonal close-packed (hcp) face-centered cubic (fcc) phases, through reduction...
Multielement alloy nanoparticles have attracted much attention due to their attractive catalytic properties derived from the multiple interactions of adjacent multielement atoms. However, mixing elements in ultrasmall a wide range on periodic table is still challenging because different and miscibility. Herein, we developed benchtop 4-way flow reactor for chemical synthesis ultra-multielement (UMEA) composed d-block p-block elements. BiCoCuFeGaInIrNiPdPtRhRuSbSnTi 15-element group IV XV were...
High-entropy oxide nanoparticles (HEO NPs) have been intensively studied because of their attractive properties, such as high stability and enhanced catalytic activity. In this work, for the first time, denary HEO NPs were successfully synthesized using a continuous supercritical hydrothermal flow process without calcination. Interestingly, allows formation on order seconds at relatively lower temperature. The contained 10 metal elements, La, Ca, Sr, Ba, Fe, Mn, Co, Ru, Pd, Ir, had...
We demonstrate a novel, simple synthetic method for metal (Ni) NPs in MOF using the partial thermal decomposition of nickel(II) 2,5-dihydroxyterephthalate (Ni-MOF-74). The Ni inside Ni-MOF-74 are several nanometers size, and size can be precisely controlled by heating conditions.
Abstract Hydrogen has the potential to power much of modern world with only water as a by-product, but storing hydrogen safely and efficiently in solid form such magnesium hydride remains major obstacle. A significant challenge been difficulty proving hydriding/dehydriding mechanisms and, therefore, have long subject debate. Here we use situ ultra-high voltage transmission electron microscopy (TEM) directly verify decomposition bulk MgH 2 Mg-Ni alloys. We find that release mechanism from (2...
Ru is an important catalyst in many types of reactions. Specifically, well known as the best monometallic for oxidation carbon monoxide (CO) and has been practically used residential fuel cell systems. However, a minor metal, supply risk often causes violent fluctuations price Ru. Performance-improved cost-reduced solid-solution alloy nanoparticles Cu-Ru system CO are now presented. Over whole composition range, all Cux Ru1-x exhibit significantly enhanced activities, even at 70 %...
To mitigate global problems related to energy and warming, it is helpful develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show the activity per weight of catalyst Ru/Ba/LaCeOx, prereduced at 700 °C, highest among reported oxide-supported Ru catalysts, 52.3 mmol h–1 gcat–1 350 1.0 MPa. The turnover frequency Ru/Ba/LaCeOx °C was more than 8 times Cs+/Ru/MgO, which a well-known used as benchmark; furthermore, hydrogen poisoning, typical...