記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

DOI： 10.1002/anie.202414786

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記述言語：英語   出版者・発行元：Nano Letters  

An advanced materials solution utilizing the concept of “smart catalysts” could be a game changer for today’s automotive emission control technology, enabling the efficient use of precious metals via their two-way switching between metallic nanoparticle forms and ionic states in the host perovskite lattice as a result of the cyclical oxidizing/reducing atmospheres. However, direct evidence for such processes remains scarce; therefore, the underlying mechanism has been an unsettled debate. Here, we use advanced scanning transmission electron microscopy to reveal the atomic-scale behaviors for a LaFe0.95Pd0.05O3-supported Ir-Pd-Ru nanocatalyst under fluctuating redox conditions, thereby proving the reversible dissolution/exsolution for Ir and Ru but with a limited occurrence for Pd. Despite such selective dissolution during oxidation, all three elements remain cooperatively alloyed in the subsequent reduction, which is a key factor in preserving the catalytic activity of the ternary nanoalloy while displaying its self-regenerating functionality and control of particle agglomeration.

DOI： 10.1021/acs.nanolett.4c03356

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry Letters  

Amorphous materials are very attractive materials because of their unique properties, including high corrosion resistance and catalytic activity. Creating such materials on a nanoscale is very effective in maximizing their performance. However, it is difficult to synthesize amorphous nanomaterials by conventional rapid cooling methods, commonly used for bulk amorphous materials. Therefore, there are not as many reports about amorphous nanomaterials as bulk materials. Herein we report the first synthesis of Pd–Pt–P amorphous nanoparticles by a 2-step synthesis method. They were also characterized.

DOI： 10.1093/chemle/upae144

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その他リンク： https://academic.oup.com/chemlett/article-pdf/53/8/upae144/58737849/upae144.pdf

記述言語：英語   出版者・発行元：Small Methods  

Electron tomography based on scanning transmission electron microscopy (STEM) is used to analyze 3D structures of metal nanoparticles on the atomic scale. However, in the case of supported metal nanoparticle catalysts, the supporting material may interfere with the 3D reconstruction of metal nanoparticles. In this study, a deep learning-based image inpainting method is applied to high-angle annular dark field (HAADF)–STEM images of a supported metal nanoparticle to predict and remove the background image of the support. The inpainting method can separate an 11 nm Pd nanoparticle from the θ-Al2O3 support in HAADF–STEM images of the θ-Al2O3-supported Pd catalyst. 3D reconstruction of the extracted images of the Pd nanoparticle reveals that the Pd nanoparticle adopts a deformed structure of the cuboctahedron model particle, resulting in high index surfaces, which account for the high catalytic activity for methane combustion. Using the xyz coordinate of each Pd atom, the local Pd–Pd bond distance and its variance in a real supported Pd nanoparticle are visualized, showing large strain and disorder at the Pd–Al2O3 interface. The results demonstrate that 3D atomic-scale analysis enables atomic structure-based understanding and design of supported metal catalysts.

DOI： 10.1002/smtd.202301163

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Sustainable Energy and Fuels  

To realize a carbon-neutral society, developing highly active and inexpensive catalysts for ammonia (NH3) production working under moderate conditions (<400 °C, <10 MPa) using hydrogen fabricated from the electrolysis of water is demanded. Current industrial fused iron (Fe) catalysts show deficient activity under such conditions. Although Ru-based catalysts have been introduced as highly efficient catalysts working under desired conditions, they are scarce and consequently expensive. This work introduces Fe/Ba/MgO (reduced at 700 °C) as an active catalyst with a high ammonia production rate working at mild temperature and pressure (350 °C, 1.0 MPa). Ba doping to Fe nanoparticles supported on MgO and pre-reduction at high temperatures dramatically ameliorated the NH3 production rate. Due to the absence of hydrogen poisoning, the catalytic activity of the Fe/Ba/MgO increased gradually by raising the pressure from 0.1 to 3.0 MPa. The activity of this catalyst at 3.0 MPa was higher than that of two benchmark Ru catalysts. After pre-reduction at high temperature, electrons are donated from the BaO encapsulating the Fe0 nanoparticles to the N2 molecule, which promotes the rate-determining step of ammonia synthesis. We anticipate that these findings will contribute to developing inexpensive Fe catalysts for decarbonizing the ammonia synthesis process to achieve a carbon-neutral society.

DOI： 10.1039/d4se00411f

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemical Science  

Solid-solution alloys based on platinum group metals and p-block metals have attracted much attention due to their promising potential as materials with a continuously fine-tunable electronic structure. Here, we report on the first synthesis of novel solid-solution RuSn alloy nanoparticles (NPs) by electrochemical cyclic voltammetry sweeping of RuSn@SnOx NPs. High-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy maps confirmed the random and homogeneous distribution of Ru and Sn elements in the alloy NPs. Compared with monometallic Ru NPs, the RuSn alloy NPs showed improved hydrogen evolution reaction (HER) performance. The overpotentials of Ru0.94Sn0.06 NPs/C and Ru0.87Sn0.13 NPs/C to achieve a current density of 10 mA cm−2 were 43.41 and 33.19 mV, respectively, which are lower than those of monometallic Ru NPs/C (53.53 mV) and commercial Pt NPs/C (55.77 mV). The valence-band structures of the NPs investigated by hard X-ray photoelectron spectroscopy demonstrated that the d-band centre of RuSn NPs shifted downward compared with that of Ru NPs. X-ray photoelectron spectroscopy and X-ray absorption near-edge structure analyses indicated that in the RuSn alloy NPs, charge transfer occurs from Sn to Ru, which was considered to result in a downward shift of the d-band centre in RuSn NPs and to regulate the adsorption energy of intermediate Hads effectively, and thus enable the RuSn solid-solution alloy NPs to exhibit excellent HER catalytic properties.

DOI： 10.1039/d3sc06786f

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nanoscale  

The properties of solids could be largely affected by their crystal structures. We achieved, for the first time, the phase control of solid-solution RuIn nanoparticles (NPs) from face-centred cubic (fcc) to hexagonal close-packed (hcp) crystal structures by hydrogen heat treatment. The effect of the crystal structure of RuIn alloy NPs on the catalytic performance in the hydrogen evolution reaction (HER) was also investigated. In the hcp RuIn NPs, enhanced HER catalytic performance was observed compared to the fcc RuIn NPs and monometallic Ru NPs. The intrinsic electronic structures of the NPs were investigated by valence-band X-ray photoelectron spectroscopy (VB-XPS). The d-band centre of hcp RuIn NPs obtained from VB-XPS was deeper than that of fcc RuIn NPs and monometallic Ru NPs, which is considered to enable the hcp RuIn NPs to exhibit enhanced HER catalytic performance.

DOI： 10.1039/d4nr00562g

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Materials Letters  

We report the synthesis of novel RuIn solid-solution alloy nanoparticles (NPs) via the electrochemical cleaning of RuIn@InOx NPs. By alloying In to Ru, the RuIn NPs exhibited enhanced hydrogen evolution reaction (HER) activity compared with monometallic face-centered cubic (fcc) Ru NPs. Furthermore, the HER activity of RuIn NPs was comparable to that of commercial Pt catalysts. At a current density of 10 mA cm-2, RuIn NPs displayed a lower overpotential of 30.7 mV compared to monometallic fcc Ru NPs (57.8 mV) and commercial Pt NPs/C (34.1 mV). X-ray photoelectron spectroscopy and X-ray absorption near edge structure analysis revealed charge transfer from In to Ru in RuIn NPs. The results indicate that the alloying of In with Ru leads to beneficial intermetallic charge transfer, which efficiently modulates the desorption energy barrier to intermediate H* and enhances the intrinsic HER performance of monometallic fcc Ru NPs.

DOI： 10.1021/acsmaterialslett.3c01218

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Chemical Society  

The use of nanotubes in the solution state is crucial not only for the exploration of physical and chemical behaviors at the molecular level but also for application such as thin-film fabrication. Surface modification is generally used to solubilize carbon nanotubes (CNTs) and various synthetic nanotubes; however, this method may affect the surface properties of the original nanotubes, and the detailed crystal structure obtained after modification is unclear. Here, we report the synthesis of a crystalline and soluble metal-organic nanotube consisting of a cationic tubular framework and an anion with a long alkyl chain. The nanotubular structures are formed not only in the solid state but also in the solution state, as confirmed by an X-ray structural analysis, optical measurements, and electron microscopy studies. This nanotube system is realized in different states without any surface modification, which is quite different from typical CNTs and synthetic nanotubes. In addition, self-assembled crystalline bundles are directly observed using transmission electron microscopy (TEM) for the first time in a metal-organic nanotube system. The bundle structures are also confirmed by atomic force microscopy (AFM) observations of thin nanotube films. We envisage a systematic design of such soluble metal-organic nanotubes that will enable direct observation of mass transport behavior in channels of bundles or a single nanotube, as well as a wide range of thin-film applications.

DOI： 10.1021/jacs.3c02252

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Small  

Highly efficient thermoelectric materials require, including point defects within the host matrix, secondary phases generating positive effects on lowering lattice thermal conductivity (κL). Amongst effective dopants for a functional thermoelectric material, SnTe, Cu doping realizes the ultra-low κL approaching the SnTe amorphous limit. Such effective κL reduction is first attributed to strong phonon scattering by substitutional Cu atoms at Sn sites and interstitial defects in the host SnTe. However, other crystallographic defects in secondary phases have been unfocused. Here, this work reports micro- to atomic-scale characterization on secondary phases of Cu-doped SnTe using advanced microscopes. It is found that Cu-rich secondary phases begin precipitation ≈1.7 at% Cu (x = 0.034 where Sn1−xCuxTe). The Cu-rich secondary phases encapsulate two distinct solids: Cu2SnTe3 ((Formula presented.)) has semi-coherent interfaces with SnTe ((Formula presented.)) such that they minimize lattice mismatch to favor the thermoelectric transport; the other resembles a stoichiometric Cu2Te model, yet is so meta-stable that it demonstrates not only various defects such as dislocation cores and ordered/disordered Cu vacancies, but also dynamic grain-boundary migration with heating and a subsequent phase transition ≈350 °C. The atomic-scale analysis on the Cu-rich secondary phases offers viable strategies for reducing κL through Cu addition to SnTe.

DOI： 10.1002/smll.202204225

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ChemCatChem  

Supported Ru catalysts were prepared by using different Ru precursors and examined for the hydrogenation of benzaldehyde to CHM. The catalyst prepared from Ru3(CO)12 precursor and HT support exhibited high yield of CHM. Moderate acidic and basic nature of HT was favourable to control the selectivity for CHM. The physicochemical properties analysis revealed that highly dispersed Ru nanoparticles were effective for the hydrogenation of benzaldehyde. RuCO/HT catalyst was tolerant to different functional groups and was stable until 7th cycle of recycle study.

DOI： 10.1002/cctc.202200241

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出版者・発行元：Journal of the American Chemical Society  

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 of HEA NPs have been developed recently, synthesizing HEA NPs with ultrasmall particle size and narrow size distribution remains challenging because most of the reported synthesis methods require high temperatures that accelerate particle growth. This work provides a new methodology for the fabrication of ultrasmall and homogeneous HEA NPs using a continuous-flow reactor with a liquid-phase reduction method. We successfully synthesized ultrasmall IrPdPtRhRu HEA NPs (1.32 ± 0.41 nm), theoretically each consisting of approximately 50 atoms. This average size is the smallest ever reported for HEA NPs. All five elements are homogeneously mixed at the atomic level in each particle. The obtained HEA NPs marked a significantly high hydrogen evolution reaction (HER) activity with a very small 6 mV overpotential at 10 mA/cm-2 in acid, which is one-third of the overpotential of commercial Pt/C. In addition, although mass production of HEA NPs is still difficult, this flow synthesis can provide high productivity with high reproducibility, which is more energy efficient and suitable for mass production. Therefore, this study reports the 1 nm-sized HEA NPs with remarkably high HER activity and establishes a platform for the production of ultrasmall and homogeneous HEA NPs.

DOI： 10.1021/jacs.2c02755

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Omega  

Ruthenium catalysts may allow for realization of renewable energy-based ammonia synthesis processes using mild reaction conditions (<400 °C, <10 MPa). However, ruthenium is relatively rare and therefore expensive. Here, we report a Co nanoparticle catalyst loaded on a basic Ba/La2O3support and prereduced at 700 °C (Co/Ba/La2O3_700red) that showed higher ammonia synthesis activity at 350 °C and 1.0-3.0 MPa than two benchmark Ru catalysts, Cs+/Ru/MgO and Ru/CeO2. The synthesis rate of the catalyst at 350 °C and 1.0 MPa (19.3 mmol h-1g-1) was 8.0 times that of Co/Ba/La2O3_500red and 6.9 times that of Co/La2O3_700red. The catalyst showed ammonia synthesis activity at temperatures down to 200 °C. Reduction at the high temperature induced the formation of BaO-La2O3nanofractions around the Co nanoparticles by decomposition of BaCO3, which increased turnover frequency, inhibited the sintering of Co nanoparticles, and suppressed ammonia poisoning. These strategies may also be applicable to other non-noble metal catalysts, such as nickel.

DOI： 10.1021/acsomega.2c01973

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Chemical Society  

The crystal structure significantly affects the physical and chemical properties of solids. However, the crystal structure-dependent properties of alloys are rarely studied because controlling the crystal structure of an alloy at the same composition is extremely difficult. Here, for the first time, we successfully demonstrate the synthesis of binary Ru-Pt (Ru/Pt = 7:3) and Ru-Ir (Ru/Ir = 7:3) and ternary Ru-Ir-Pt (Ru/Ir/Pt = 7:1.5:1.5) solid-solution alloy nanoparticles (NPs) with well-controlled hexagonal close-packed (hcp) and face-centered cubic (fcc) phases, through the chemical reduction method. The crystal structure control is realized by precisely tunning the reduction speeds of the metal precursors. The effect of the crystal structure on the catalytic performance of solid-solution alloy NPs is systematically investigated. Impressively, all the hcp alloy NPs show superior electrocatalytic activities for the hydrogen evolution reaction in alkaline solution compared with the fcc alloy NPs. In particular, hcp-RuIrPt exhibits extremely high intrinsic (mass) activity, which is 3.1 (3.2) and 6.7 (6.9) times enhanced compared to that of fcc-RuIrPt and commercial Pt/C.

DOI： 10.1021/jacs.2c00583

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Materials Au  

The crystal structure, which intrinsically affects the properties of solids, is determined by the constituent elements and composition of solids. Therefore, it cannot be easily controlled beyond the phase diagram because of thermodynamic limitations. Here, we demonstrate the first example of controlling the crystal structures of a solid-solution nanoparticle (NP) entirely without changing its composition and size. We synthesized face-centered cubic (fcc) or hexagonal close-packed (hcp) structured PdxRu1-x NPs (x = 0.4, 0.5, and 0.6), although they cannot be synthesized as bulk materials. Crystal-structure control greatly improves the catalytic properties; that is, the hcp-PdxRu1-x NPs exceed their fcc counterparts toward the oxygen evolution reaction (OER) in corrosive acid. These NPs only require an overpotential (η) of 200 mV at 10 mA cm-2, can maintain the activity for more than 20 h, greatly outperforming the fcc-Pd0.4Ru0.6 NPs (η = 280 mV, 9 min), and are among the most efficient OER catalysts reported. Synchrotron X-ray-based spectroscopy, atomic-resolution electron microscopy, and density functional theory (DFT) calculations suggest that the enhanced OER performance of hcp-PdRu originates from the high stability against oxidative dissolution.

DOI： 10.1021/acsmaterialsau.1c00048

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Chemical Society  

The compositional space of high-entropy-alloy nanoparticles (HEA NPs) significantly expands the diversity of the materials library. Every atom in HEA NPs has a different elemental coordination environment, which requires knowledge of the local electronic structure at an atomic level. However, such structure has not been disclosed experimentally or theoretically. We synthesized HEA NPs composed of all eight noble-metal-group elements (NM-HEA) for the first time. Their electronic structure was revealed by hard X-ray photoelectron spectroscopy and density function theory calculations with NP models. The NM-HEA NPs have a lower degeneracy in energy level compared with the monometallic NPs, which is a common feature of HEA NPs. The local density of states (LDOS) of every surface atom was first revealed. Some atoms of the same constituent element in HEA NPs have different LDOS profiles, whereas atoms of other elements have similar LDOS profiles. In other words, one atom in HEA loses its elemental identity and it may be possible to create an ideal LDOS by adjusting the neighboring atoms. The tendency of the electronic structure change was shown by supervised learning. The NM-HEA NPs showed 10.8-times higher intrinsic activity for hydrogen evolution reaction than commercial Pt/C, which is one of the best catalysts.

DOI： 10.1021/jacs.1c13616

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Catalysis Science and Technology  

Catalytic hydrogenation of nitriles is a cost-effective and green method for synthesizing amines and imines, which have many industrial applications. However, this reaction generally requires harsh reaction conditions and produces a mixture of amine and imine products due to its chemodiversity. Therefore, it is a challenge to selectively hydrogenate nitriles to a single product under ambient conditions (1 bar of H2 at 25 °C). Here, we report an effective method for selective hydrogenation of nitriles that does not require heat, pressurization, or long reaction times. We achieved this by means of bimetalization between palladium (Pd) and platinum (Pt) nanoparticles, which resulted in a catalyst that showed high yield of secondary amines. Although Pd and Pt are thermodynamically immiscible, we have successfully alloyed the two metals by means of rapid chemical reduction assisted by microwave heating. X-ray absorption spectroscopy suggested the formation of heteroatomic Pdδ+Ptδ− sites via charge transfer between neighboring Pd and Pt atoms in the alloy structure. Moreover, Fourier transform IR spectroscopy and scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy indicated that decreasing the size of the PdPt (50 : 50) nanoparticles improved the degree of alloying and facilitated the formation of electron-enriched Ptδ− species. On the basis of kinetics studies and density functional theory calculations, we concluded that cyano group activation, which was the rate-determining step over monometallic Pd and Pt catalysts, was accelerated over the heteroatomic Pdδ+Ptδ− sites because of strong back-donation from electron-enriched Ptδ− species to the carbon atom of the cyano groups. The PdPt random alloy nanoparticles catalyzed the reactions of various aromatic and heterocyclic nitriles, and the corresponding secondary amines were selectively obtained in just a few hours.

DOI： 10.1039/d1cy02302k

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nuclear Materials and Energy  

The sink strengths of precipitate/matrix interfaces in Cu alloys, were investigated by performing in-situ observation of electron irradiation in high-voltage electron microscopy (HVEM). Fine black spot defects, which seemed to be dislocation loops were observed at irradiation temperature ranging between RT and 373 K in Cu–Cr–Zr, Cu–Cr and GlidCop Al–60 alloys with low number density. In Cu–Cr, loops formed on a part of precipitates interfaces. Hence, a part of precipitate/matrix interfaces is a sink with interstitial bias. Whereas, most of the interfaces are neutral sinks for point defects. In the case of Cu–Cr–Zr and GlidCop Al–60, black spots formed around dislocation, which were induced during two-step heat treatment. The results showed that the precipitate/matrix interface of Cr-rich precipitates in Cu alloys serve as a strong sink for point defects.

DOI： 10.1016/j.nme.2022.101144

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chem Catalysis  

The photocatalytic dry reforming of methane (photoDRM: CH4 + CO2 = 2CO + 2H2) converts greenhouse gases into valuable synthesis gas with photon energy. However, previous photoDRM catalysts comprising supported metal nanoparticles hardly avoid the recombination of photoexcited charges. Herein, we report that significant photoDRM performance can be achieved by a metal-oxide nanocomposite consisting of nanometer-thick, intertwined networks of fibrous rhodium metal and cerium dioxide, i.e., Rh#CeO2. The Rh#CeO2 nanocomposite exhibits the world-highest conversion and yield in photoDRM under UV light irradiation, being accompanied with no other side reactions such as reverse water gas shift reaction. Theoretical simulations and Kelvin probe force microscopy demonstrate that the photoexcited electrons and holes in Rh#CeO2 are efficiently partitioned into the Rh- and CeO2 nanophases, respectively. The efficient charge partitioning in Rh#CeO2 accounts for the selective photoDRM reaction.

DOI： 10.1016/j.checat.2021.11.015

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry C  

Catalytic oxidation of methane to formaldehyde and methanol has attracted attention because of its advantage in energy efficiency over the conventional multistep reaction process involving endothermic steam reforming of CH4; however, it is challenging to selectively obtain the partial oxidation products in the direct oxidation of CH4. In the present study, Co/SiO2 with various Co loadings was tested for the CH4/O2/H2O gas flow reaction. As a result, Co/SiO2 with a low loading of ≤0.1 wt % showed high selectivity for the partial oxidation reaction and mainly produced HCHO, while Co/SiO2 with high Co loadings proceeded to complete oxidation. Structural analysis using X-ray absorption fine-structure spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and scanning transmission electron microscopy suggested that single Co atoms generated at low Co loadings were effective in the selective oxidation of CH4 to HCHO, while Co3O4 nanoparticles generated at high Co loadings promoted the complete oxidation.

DOI： 10.1021/acs.jpcc.1c08739

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その他リンク： https://doi.org/10.1021/acs.jpcc.1c08739

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d1sc06578e

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Acta Materialia  

The Cu6Sn5 intermetallic, which commonly forms at the solder interconnects, is a critical component contributing to the reliability of today's electronic products. It has been established that the structural control of its hexagonal η-Cu6Sn5 polymorph can be achieved over a wide temperature range of service conditions via chemical doping with Ni or Au, effectively suppressing the undesirable hexagonal to monoclinic (ƞ → ƞ′) phase transition at 186 °C and its associated volume change. In this study, we further investigate the effects of Ni (26.5 at%) and Au (9 at%), with high doping/alloying contents, on the atomic-scale structure of η-Cu6Sn5 using a suite of microscopy techniques including atomic-resolution imaging, chemical mapping, electron diffraction, and in-situ heating, coupled with advanced data informatics. Our study reveals that while Ni occupancy takes place in both the Cu1 and Cu2 sites of η-Cu6Sn5 in substantial amounts, Au is mostly substituted at the Cu1 sites of η-Cu6Sn5. Most interestingly, characteristic occupational modulations of the Cu6Sn5 structure arise with each type of dopants: a three-fold ordered structure for Ni accompanied by a displacive modulation of the constituent atoms, but a two-fold layer-like structure for Au. Moreover, with a high content of Ni, the unit cell of η-Cu6Sn5 is found to contract along its hexagonal ah axis relative to the Ni-dilute case, but anisotropically expands the ch axis in a bimodal fashion; in contrast, the effect of Au appears to be of an isotropically expanding nature.

DOI： 10.1016/j.actamat.2021.117513

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Nano  

Compositional and structural arrangements of constituent elements, especially those at the surface and near-surface layers, are known to greatly influence the catalytic performance of alloyed nanoparticles (NPs). Although much research effort often focuses on the ability to tailor these important aspects in the design stage, their stability under realistic operating conditions remains a major technical challenge. Here, the compositional stability and associated structural evolution of a ternary iridium-palladium-ruthenium (Ir-Pd-Ru) nanoalloy at elevated temperatures have been studied using interrupted in situ scanning transmission electron microscopy and theoretical modeling. The results are based on a combinatory approach of statistical sampling at the sub-nanometer scale for large groups of NPs as well as tracking individual NPs. We find that the solid solution Ir-Pd-Ru NPs (?5.6 nm) evolved into a Pd-enriched shell supported on an alloyed Ir-Ru-rich core, most notably when the temperature exceeds 500 °C, concurrently with the development of expansive atomic strain in the outer surface and subsurface layers with respect to the core regions. Theoretically, we identify the weak interatomic bonds, low surface energy, and large atomic sizes associated with Pd as the key factors responsible for such observed features.

DOI： 10.1021/acsnano.1c10414

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acscatal.1c02887

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acsnano.1c03413

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d1ta03480d

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d1cc02154k

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.200861

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/adma.202005206

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.200779

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/ejic.202001141

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41467-021-20956-4

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/bcsj.20210007

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acsanm.1c00006

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d0sc02351e

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<p>Recyclable Pd_0.5Ru_0.5–PVP catalyst showed higher activity than monometallic Pd or Ru catalyst for the hydrogenation of quinoline. Furthermore, Pd_0.5Ru_0.5–PVP was able to hydrogenate different arenes.</p>

DOI： 10.1039/d0ra09981c

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d0cc05958g

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d0sc03373a

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/jacs.0c07143

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.jpcc.0c06813

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/jace.17101

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/jacs.0c04807

記述言語：その他   掲載種別：研究論文（学術雑誌）  

© 2020 American Physical Society. Chemical modification using only small amounts of elements such as Zn, In, Sb, or Ni has proven to be an effective means to control the desirable crystal structure of hexagonal η-Cu6Sn5 over a wide thermally operating window, typically found in Pb-free Sn-based soldering or Li-ion battery anode applications. Though appealing, the underlying mechanisms on the role of these dopants remain incomplete and their atomic arrangements within the η-Cu6Sn5 lattices have not yet been experimentally determined. In the current study, we directly reveal the atomic positions of Zn, In, and Sb at the Sn sites of η-Cu6Sn5 via atomic-scale x-ray energy dispersive spectroscopy (XEDS) maps utilizing advanced Cs-corrected scanning transmission electron microscopy. The use of advanced statistical algorithms including Poisson non-local principal component analysis and lattice averaging enables the fine resolution of weak XEDS maps from trace dopant elements. Our first-principles calculations further identify the influence of dopants at these atomic sites on the overall energetics, electronic structures, as well as local bonding environments, leading to the most favorable situations for η-Cu6Sn5 stabilization.

DOI： 10.1103/PhysRevMaterials.4.065002

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/ente.202000264

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/d0cc00566e

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41929-019-0419-z

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acssuschemeng.9b06299

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/jacs.9b09219

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s42004-019-0148-x

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.190830

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c9cc09192k

記述言語：その他   掲載種別：研究論文（学術雑誌）  

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim There is interest in minimizing or eliminating the use of Pt in catalysts by replacing it with more widely abundant and cost-effective elements. The alloying of Pt with non-noble metals is a potential strategy for reducing Pt use because interactions between Pt and non-noble metals can modify the catalyst structure and electronic properties. Here, a γ-Al2O3-supported bimetallic catalyst [Pt(0.1)Co(1)/Al2O3] was prepared which contained 0.1 wt % Pt and 1 wt % Co and thus featured an extremely low Pt : Co ratio (<1 : 30 mol/mol). The Pt and Co in this catalyst formed alloy nanoparticles in which isolated electron-rich Pt atoms were present on the nanoparticle surface. The activity of this Pt(0.1)Co(1)/Al2O3 catalyst for the purification of automotive exhaust was comparable to the activities of 0.3 and 0.5 wt % Pt/γ-Al2O3 catalysts. Electron-rich Pt and metallic Co promoted activation of NOx and oxidization of CO and hydrocarbons, respectively. This strategy of tuning the surrounding structure and electronic state of a noble metal by alloying it with an excess of a non-noble metal will enable reduced noble metal use in catalysts for exhaust purification and other environmentally important reactions.

DOI： 10.1002/cplu.201800542

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/jmicro/dfy136

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c9sc00496c

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.jpcc.8b11380

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/anie.201812325

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c8sc05441j

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c9cc00174c

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acssuschemeng.8b04683

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c8sc04135k

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.180931

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.carbon.2018.05.026

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/chem.201800936

記述言語：その他   掲載種別：研究論文（学術雑誌）  

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim For the first time, we synthesize solid-solution alloy nanoparticles of Ir and Cu with a size of ca. 2 nm, despite Ir and Cu being immiscible in the bulk up to their melting over the whole composition range. We performed a systematic characterization on the nature of the IrxCu1−x solid-solution alloys using powder X-ray diffraction, scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results showed that the IrxCu1−x alloys had a face-centered-cubic structure; charge transfer from Cu to Ir occurred in the alloy nanoparticles, as the core-level Ir 4f peaks shifted to lower energy region with the increase in Cu content. Furthermore, we observed that the alloying of Ir with Cu enhanced both the electrocatalytic oxygen evolution and oxygen reduction reactions. The enhanced activities could be attributed to the electronic interaction between Ir and Cu arising from the alloying effect at atomic-level.

DOI： 10.1002/anie.201800650

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.4028/www.scientific.net/SSP.273.95

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c8sc01460d

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.4028/www.scientific.net/SSP.273.95

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c7sc05343f

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c7cp07591j

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c7sc05343f

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.scriptamat.2017.03.013

記述言語：その他  

DOI： 10.1038/srep43720

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/jacs.7b01186

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jpowsour.2016.11.105

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/chem.201604286

記述言語：英語   掲載種別：研究論文（学術雑誌）  

We report on hexagonal close-packed (hcp) palladium (Pd)–boron (B) nanocrystals (NCs) by heavy B doping into face-centered cubic (fcc) Pd NCs. Scanning transmission electron microscopy–electron energy loss spectroscopy and synchrotron powder X-ray diffraction measurements demonstrated that the B atoms are homogeneously distributed inside the hcp Pd lattice. The large paramagnetic susceptibility of Pd is significantly suppressed in Pd–B NCs in good agreement with the reduction of density of states at Fermi energy suggested by X-ray absorption near-edge structure and theoretical calculations.

DOI： 10.1002/anie.201703209

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/cl.170440

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The realization of metal nanoparticles (NPs) with bimetallic character and distinct composition for specific catalytic applications is an intensively studied field. Due to the synergy between metals, most bimetallic particles exhibit unique properties that are hardly provided by the individual monometallic counterparts. However, as small-sized NPs possess high surface energy, agglomeration during catalytic reactions is favored. Sufficient stabilization can be achieved by confinement of NPs in porous support materials. In this sense, metal–organic frameworks (MOFs) in particular have gained a lot of attention during the last years; however, encapsulation of bimetallic species remains challenging. Herein, the exclusive embedding of preformed core–shell PdPt and RuPt NPs into chemically robust Zr-based MOFs is presented. Microstructural characterization manifests partial retention of the core–shell systems after successful encapsulation without harming the crystallinity of the microporous support. The resulting chemically robust NP@UiO-66 materials exhibit enhanced catalytic activity towards the liquidphase hydrogenation of nitrobenzene, competitive with commercially used Pt on activated carbon, but with superior size-selectivity for sterically varied substrates.

DOI： 10.1002/chem.201603984

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/jmicro/dfw018

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.pnucene.2016.07.013

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/srep28265

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2320/matertrans.M2016021

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/C6SC02382G

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/cctc.201500758

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c5cc04663g

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c5dt02815a

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c5cp00954e

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/srep08450

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/ejic.201402409

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c4cc05941g

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.1017/S1431927614004127

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/nmat4030

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/srep05620

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ja504699u

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.nimb.2013.10.077

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ja409464g

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/jmicro/dfu012

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.1557/opl.2013.199

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ultramic.2012.10.006

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.nimb.2013.04.069

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ja311261s

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ja311261s

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.actamat.2012.08.024

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.actamat.2012.03.031

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3139/146.110564

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.1016/j.nimb.2010.05.022

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jnucmat.2008.06.027

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.nimb.2008.03.127

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s11837-007-0050-3

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.nimb.2006.04.164

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.1016/j.nimb.2005.11.108

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

DOI： 10.1016/j.jnucmat.2004.04.160

開催年月日： 2023年6月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2023年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：東京大学　駒場キャンパス   国名：日本国  

開催年月日： 2022年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：JA長野県ビル   国名：日本国  

開催年月日： 2022年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：早稲田大学 西早稲田キャンパス   国名：日本国  

開催年月日： 2022年5月

記述言語：英語   会議種別：口頭発表（一般）  

国名：日本国