Monodisperse ruthenium nanoparticles were prepared by reduction of RuCl3 in 1,2-propanediol. The mean particle size was controlled by appropriate choice of the reduction temperature and the acetate ion concentration. Colloidal solutions in toluene were obtained by coating the metal particles with dodecanethiol. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XANES and EXAFS for the Ru K-absorption edge) were performed on particles of two different diameters, 2 and 4 nm, and in different environments, polyol/acetate or thiol. For particles stored in polyol/acetate XPS studies revealed superficial oxidation limited to one monolayer and a surface coating containing mostly acetate ions. Analysis of the EXAFS spectra showed both oxygen and ruthenium atoms around the ruthenium atoms with a Ru-Ru coordination number N smaller than the bulk value, as expected for fine particles. In the case of 2 nm acetate-capped particles N is consistent with particles made up of a metallic core and an oxidized monolayer. For 2 nm thiol-coated particles, a Ru-S bond was evidenced by XPS and XAS. For the 4 nm particles XANES and XPS studies showed that most of the ruthenium atoms are in the zerovalent state. Nevertheless, in both cases, when capped with thiol, the Ru-Ru coordination number inferred from EXAFS is much smaller than for particles of the same size stored in polyol. This is attributed to a structural disorganization of the particles by thiol chemisorption. HRTEM studies confirm the marked dependence of the structural properties of the ruthenium particles on their chemical environment; they show the acetate-coated particles to be single crystals, whereas the thiol-coated particles appear to be polycrystalline.

Acetate- and Thiol-Capped Monodisperse Ruthenium Nanoparticles: XPS, XAS, and HRTEM Studies

Five-segment (Pt-Ru-Pt-Ru-Pt, Pt-Ni-Pt-Ni-Pt, and Pt-RuNi-Pt-RuNi-Pt) nanorods with the same overall rod length and the same total Pt segment length were prepared by sequential electrodeposition of the metals into the pores of commercially available anodic aluminum oxide (AAO) membranes. Field-emission scanning electron microscopy (FESEM) showed that the nanorods were about 210 nm in diameter and about 1.5 microm in length. The alternating Pt and oxophilic metal(s) segments could be easily differentiated in backscattered-electron images. X-ray diffraction (XRD) analysis of the nanorods indicated that Pt and Ni were polycrystalline with fcc structures, Ru was hcp, and the co-deposited RuNi adopted the nickel fcc structure with some negative shifts in the Bragg angles. The chemical states of Pt, Ru, and Ni on the nanorod surface were assayed by X-ray photoelectron spectroscopy (XPS), and the presence of Pt(0), Pt(II), Pt(IV), Ru(0), Ru(VI), Ni(0), and Ni(II) was observed. The nanorods were catalytically active for the room-temperature electrooxidation of methanol in acidic solutions. The relative rates of reaction showed the Pt-RuNi pair sites as having the lowest overpotential to dissociate water, the highest catalytic activity in methanol oxidation, and the strongest CO-tolerance in the potential window employed. The use of segmented nanorods with identifiable Pt-oxophilic metal(s) interfaces removes many of the ambiguities in the interpretation of experimental data from conventional alloy catalysts, thereby enabling a direct comparison of the activities of various types of pair sites in methanol oxidation.

Segmented Pt/Ru, Pt/Ni, and Pt/RuNi Nanorods as Model Bifunctional Catalysts for Methanol Oxidation

Terrestrial alloys of osmium-iridium-ruthenium occur in placers from depleted mantle of obducted ophiolites. Some specimens consist of intergrown metal phases having textures and compositions consistent with formation by crystallization from a melt at temperatures greater than various proposed geotherms of the earth's mantle. It is proposed that these specimens were subjected to melting in the lower mantle when the earth had temperatures higher than at present or that they melted at depths greater than 2900 km before that region was occupied by the core or that they once resided within the core. The alloys were probably transported in convecting mantle material and were subsequently incorporated into depleted mantle of lithosphere, now exposed as obducted ophiolites. It is further proposed that the alloys were originally primitive material that has remained essentially intact since accretion of the earth from the solar nebula.

Evidence of a deep mantle history in terrestrial osmium-iridium-ruthenium alloys

The sensitivity of X-ray absorption spectroscopy (XAS) can be increased by using the modulated excitation approach, where the sample is excited with a periodic external stimulation (e.g., changes in temperature, gas/liquid concentration, etc.) and the corresponding spectra are filtered with the frequency of the excitation. The resulting demodulated spectra contain similar spectral features as difference spectra but to much higher k values because of the isolation of the structural change that occurs with the same frequency as that of the excitation. Furthermore, multiple intermediate species that occur with a phase delay can uniquely be differentiated. We present a robust approach for the quantitative analysis of demodulated extended X-ray absorption fine structure (EXAFS) spectra. Simulations show that the proposed fitting approach resolves small changes in the sample’s structure with greatly enhanced precision. Experimentally, this is demonstrated by the formation of ruthenium oxide species upon partial...

Quantitative Analysis of Modulated Excitation X-ray Absorption Spectra: Enhanced Precision of EXAFS Fitting

Multisegment PtRu nanorods (Pt-Ru, Pt-Ru-Pt, Pt-Ru-Pt-Ru, Pt-Ru-Pt-Ru-Pt, Pt-Ru-Pt-Ru-Pt-Ru) with customizable lengths of the individual metals are obtained by the sequential electrodeposition of the metals into the poresof anodic aluminum oxide (AAO) membranes. Field-emission scanning electron microscopy (FESEM) shows that the nanorods are about 200 nm in diameter and 1.2 μm long, with 900 nm of total platinum-segment length. The alternating platinum and ruthenium segments can be easily differentiated using FESEM. X-ray diffractometry reveals that the platinum and ruthenium in the bimetallic nanorods are polycrystalline with face-centered cubic and hexagonal close-packed crystal lattice structures, respectively. The presence of Pt°, Pt I I , Pt I V , Ru°, and RU V I on the surface of the bimetallic nanorods is demonstrated via X-ray photoelectron spectroscopy. The nanorods are catalytically active in the room-temperature electro-oxidation of methanol. The relative rates of reaction, recorded using chronoamperometry, show a linear relationship between the long-time (near-steady-state) current density and the number of Pt-Ru interfaces. The use of segmented nanorods with a controlled number of Pt-Ru interfaces removes many of the ambiguities in the interpretation of experimental data from conventional alloy catalysts and has provided a direct demonstration of the role of pair sites in bifunctional catalysis.

Multisegment PtRu Nanorods: Electrocatalysts with Adjustable Bimetallic Pair Sites

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Ruthenium, a new mineral from Horokanai, Hokkaido, Japan

Background: We recently proposed that IgG4-positive interstitial pneumonia (IgG4+ IP) differs in clinical characteristics from IgG4-related disease (RD) (ERJ Open Res 2021;7). Aims and objectives: This study aimed to assess and identify the characteristics of patients with IgG4+ interstitial lung disease (ILD) according to the American College of Rheumatology and European League Against Rheumatism classification criteria for IgG4-RD, 2019. Methods: This was a retrospective nationwide multicentre study in Japan. We reviewed 28 patients, who demonstrated ILD on high-resolution computed tomography of the chest, elevated serum IgG4 concentrations, and infiltration of numerous IgG4+ cells in the lungs and analysed their clinico-radiolo-histopathological findings. After expert multidisciplinary discussions, the patients were classified as definite-IgG4-RD (d-IgG4-RD) or mimickers. Thereafter, the patients were assessed according to the classification criteria. Results: Among the 28 patients included, seven were diagnosed with d-IgG4-RD, and 21 as mimickers, including 16 patients with IgG4+ IP. Five of seven patients with d-IgG4-RD were classified as IgG4-RD, while 12 of 16 patients with IgG4+ IP were excluded by the classification criteria. Conclusion: Most cases of IgG4+ IP were excluded by the classification criteria; they should be treated differently from IgG4-RD.

Yasunori Terasaki

Papers

Ruthenium, a new mineral from Horokanai, Hokkaido, Japan

Respiratory lesions of IgG4-related disease classified by 2019 ACR/EULAR criteria: A retrospective study