Continuous-Flow Chemical Synthesis for Sub-2 nm Ultra-Multielement Alloy Nanoparticles Consisting of Group IV to XV Elements.

Multielement alloy nanoparticles have attracted much attention due to their attractive catalytic properties derived from the multiple interactions of adjacent multielement atoms. However, mixing multiple elements in ultrasmall nanoparticles from a wide range of elements on the periodic table is still challenging because the elements have different properties and miscibility. Herein, we developed a benchtop 4-way flow reactor for chemical synthesis of ultra-multielement alloy (UMEA) nanoparticles composed of d-block and p-block elements.

Continuous-Flow Reactor Synthesis for Homogeneous 1 nm-Sized Extremely Small High-Entropy Alloy Nanoparticles.

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.

Highly Stable and Active Solid-Solution-Alloy Three-Way Catalyst by Utilizing Configurational-Entropy Effect.

Since 1970, people have been making every endeavor to reduce toxic emissions from automobiles. After the development of a three-way catalyst (TWC) that concurrently converts three harmful gases, carbon monoxide (CO), hydrocarbons (HCs), and nitrogen oxides (NO ), Rh became an essential element in automobile technology because only Rh works efficiently for catalytic NO reduction. However, due to the sharp price spike in 2007, numerous efforts have been made to replace Rh in TWCs.

Rational Synthesis for a Noble Metal Carbide.

Transition metal carbides have attractive physical and chemical properties that are much different from their parent metals. Particularly, noble metal carbides are expected to be promising materials for a variety of applications, particularly as efficient catalysts. However, noble metal carbides have rarely been obtained because carbide phases do not appear in noble metal-carbon phase diagrams and a reasonable synthesis method to make noble metal carbides has not yet been established.

Reverse Monte Carlo modeling for local structures of noble metal nanoparticles using high-energy XRD and EXAFS.

Reverse Monte Carlo (RMC) modeling based on the total structure factor () obtained from high-energy X-ray diffraction (HEXRD) and the () obtained from extended X-ray absorption fine structure (EXAFS) measurements was employed to determine the 3-dimensional (3D) atomic-scale structure of Pt, Pd, and Rh nanoparticles, with sizes less than 5 nm, synthesized by photoreduction. The total structure factor and Fourier-transformed PDF showed that the first nearest neighbor peak is in accordance with that obtained from conventional EXAFS analysis. RMC constructed 3D models were analyzed in terms of prime structural characteristics such as metal-to-metal bond lengths, first-shell coordination numbers and bond angle distributions.

The relationship between crystalline disorder and electronic structure of Pd nanoparticles and their hydrogen storage properties.

We investigated the relationship between crystalline disorder and electronic structure deviations of Pd nanoparticles (NPs) and their hydrogen storage properties as a function of their particle diameter (2.0, 4.6 and 7.

Correlation between the electronic/local structure and CO-oxidation activity of Pd Ru alloy nanoparticles.

Pd Ru nanoparticles (NPs) were observed to display enhanced CO oxidation activity with the maximum performance obtained at the composition = 0.5. To unveil the origin of this superior CO oxidation activity, we investigated the local structure, valence state, and electronic properties of Pd Ru NPs using synchrotron-based X-ray techniques.

Local Geometry and Electronic Properties of Nickel Nanoparticles Prepared via Thermal Decomposition of Ni-MOF-74.

Metal-organic frameworks (MOFs) provide highly selective catalytic activity because of their porous crystalline structure. There is particular interest in metal nanoparticle-MOF composites (MNP@MOF) that could take advantage of synergistic effects for enhanced catalytic properties. We present an investigation into the local geometry and electronic properties of thermally decomposed Ni-MOF-74 calcined at different temperatures and time durations.

Size effects on rhodium nanoparticles related to hydrogen-storage capability.

To unveil the origin of the hydrogen-storage properties of rhodium nanoparticles (Rh NPs), we investigated the electronic and crystal structures of the Rh NPs using various synchrotron based X-ray techniques. Electronic structure studies revealed that the hydrogen-storage capability of Rh NPs could be attributed to their more unoccupied d-DOSs than that of the bulk near the Fermi level. Crystal structure studies indicated that lattice distortion and mean-square displacement increase while coordination number decreases with decreasing particle size and the hydrogen-absorption capability of Rh NPs improves to a greater extent with increased structural disorder in the local structure than with that in the mean structure.

Publisher Correction: Hydrogen storage and stability properties of Pd-Pt solid-solution nanoparticles revealed via atomic and electronic structure.

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Hydrogen storage and stability properties of Pd-Pt solid-solution nanoparticles revealed via atomic and electronic structure.

Bimetallic Pd Pt solid-solution nanoparticles (NPs) display charging/discharging of hydrogen gas, which has relevance for fuel cell technologies; however, the constituent elements are immiscible in the bulk phase. We examined these material systems using high-energy synchrotron X-ray diffraction, X-ray absorption fine structure and hard X-ray photoelectron spectroscopy techniques. Recent studies have demonstrated the hydrogen storage properties and catalytic activities of Pd-Pt alloys; however, comprehensive details of their structural and electronic functionality at the atomic scale have yet to be reported.

Disappearance of the Superionic Phase Transition in Sub-5 nm Silver Iodide Nanoparticles.

Bulk silver iodide (AgI) is known to show a phase transition from the poorly conducting β/γ-phases into the superionic conducting α-phase at 147 °C. Its transition temperature decreases with decreasing the size of AgI, and the α-phase exists stably at 37 °C in AgI nanoparticles with a diameter of 6.3 nm.

Electronic Structure Evolution with Composition Alteration of RhCu Alloy Nanoparticles.

The change in electronic structure of extremely small RhCu alloy nanoparticles (NPs) with composition variation was investigated by core-level (CL) and valence-band (VB) hard X-ray photoelectron spectroscopy. A combination of CL and VB spectra analyses confirmed that intermetallic charge transfer occurs between Rh and Cu. This is an important compensation mechanism that helps to explain the relationship between the catalytic activity and composition of RhCu alloy NPs.

Origin of the catalytic activity of face-centered-cubic ruthenium nanoparticles determined from an atomic-scale structure.

The 3-dimensional (3D) atomic-scale structure of newly discovered face-centered cubic (fcc) and conventional hexagonal close packed (hcp) type ruthenium (Ru) nanoparticles (NPs) of 2.2 to 5.4 nm diameter were studied using X-ray pair distribution function (PDF) analysis and reverse Monte Carlo (RMC) modeling.

Size dependence of structural parameters in fcc and hcp Ru nanoparticles, revealed by Rietveld refinement analysis of high-energy X-ray diffraction data.

To reveal the origin of the CO oxidation activity of Ruthenium nanoparticles (Ru NPs), we structurally characterized Ru NPs through Rietveld refinement analysis of high-energy X-ray diffraction data. For hexagonal close-packed (hcp) Ru NPs, the CO oxidation activity decreased with decreasing domain surface area. However, for face-centered cubic (fcc) Ru NPs, the CO oxidation activity became stronger with decreasing domain surface area.

Drawstring lichen planus: A unique case of Koebnerization.

Drawstring dermatitis is a type of frictional dermatitis that can result from a traditional tightly worn garments such as sari or salwaar-kameez. We report a 54-year-old female patient presented with lichen planus of the drawstring site that was confirmed histopathologically. This case is rare and demonstrates how sociocultural practices can influence the presentation of common dermatoses such as LP.

Atomic disorder of LiNiO thin films caused by Li doping: estimation from X-ray Debye-Waller factors.

Cubic type room-temperature (RT) epitaxial LiNiO and NiO thin films with [111] orientation grown on ultra-smooth sapphire (0001) substrates were examined using synchrotron-based thin-film X-ray diffraction. The 1[Formula: see text]1 and 2[Formula: see text]2 rocking curves including six respective equivalent reflections of the LiNiO and NiO thin films were recorded. The RT factor, which appears in the Debye-Waller factor, of a cubic LiNiO thin film was estimated to be 1.

Hard X-ray photoelectron spectroscopy of LixNi1-xO epitaxial thin films with a high lithium content.

The core-level and valence-band electronic structures of LixNi1-xO epitaxial thin films with x = 0, 0.27, and 0.48 were studied by hard X-ray photoelectron spectroscopy.