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Sample records for ru pt rh

  1. Preparation of PtSn/C, PtRu/C, PtRh/C, PtRuRh/C and PtSnRh/C electrocatalysts using an alcohol-reduction process for methanol and ethanol oxidation; Preparacao e caracterizacao de eletrocatalisadores PtRu, PtSn, PtRh, PtRuRh e PtSnRh para oxidacao direta de alcoois em celulas a combustivel tipo PEM utilizando a metodologia da reducao por alcool

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Ricardo Rodrigues

    2009-07-01

    In this work, Pt/C, PtRh (90:10), PtRh/C (50:50), PtSn/C (50:50), PtRu (50:50)/C, PtRuRh/C (50:40:10) and PtSnRh/C (50:40:10) were prepared by an alcohol-reduction process with metal loading of 20 wt.% using H{sub 2}PtCl{sub 6}.6H{sub 2}O (Aldrich), SnCl{sub 2}.2H{sub 2}O (Aldrich),and RhCl{sub 2}.XH{sub 2}O (Aldrich) as metals sources and Vulcan XC72 as support. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry (CV). The electro-oxidation of ethanol was studied by CV, chronoamperomety at room temperature in acid medium and tests at 100 deg C on a single cell of a direct methanol or ethanol fuel cell. The EDX analysis showed that the metal atomic ratios of the obtained electrocatalysts were similar to the nominal atomic ratios used in the preparation. The diffractograms of electrocatalysts prepared showed four peaks at approximately 2{theta} =40 deg, 47 deg, 67 deg and 82 deg, which are associated with the (111), (200), (220) and (311) planes, respectively, of a face cubic-centered (fcc) structure characteristic of platinum and platinum alloys. The average crystallite sizes using the Scherrer equation and the calculated values were in the range of 2-3 nm. For Pt Sn/C and PtSnRh/C two additional peaks were observed at 2 = 34 deg and 52 deg that were identified as a SnO{sub 2} phase. Pt Sn/C (50:50) and PtSnRh/C (50:40:10) electro catalyst showed the best performance for ethanol oxidation at room temperature. For methanol oxidation at room temperature Pt Ru/C, Pt Sn/C and PtRuRh/C electrocatalysts showed the best performance. Tests at 100 deg C on a single cell of a direct ethanol fuel cell PtSnRh/C showed the best performance, for methanol oxidation PtRuRh/C showed the best performance. (author)

  2. H2 splitting on Pt, Ru and Rh nanoparticles supported on sputtered HOPG

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Murphy, Shane; Nielsen, R.M.;

    2012-01-01

    nm. The rate of hydrogen exchange is measured in the temperature range 40–200°C at 1bar, by utilization of the H–D exchange reaction. We find that the rate of hydrogen exchange increases with the particle diameter for all the metals, and that the rate for Ru and Rh is higher than for Pt. In the case...... adlayers on the terraces of the larger particles. Experiments are also carried out in the presence of 10ppm CO. Pt is found to be very sensitive to CO poisoning and the H–D exchange rate drops below the detection limit when CO is added to the gas mixture. In the case of Ru and Rh nanoparticles, CO...... decreases the splitting rate significantly, also at 200°C. The variation of the sensitivity to CO poisoning with particle diameter for Ru and Rh is found to be weak....

  3. Hyperfine specific heats of PrX 2 ( X = Ir, Pt, Rh, Ru) laves phase compounds

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1980-01-01

    Specific heat data below 1 K for the C-15 compounds PrX 2 (X = Ir, Pt, Rh, Ru) reveal Schottky-type anomalies, ascribed to hyperfine interactions. Apparently the 4f-moments are magnetically ordered. The values deduced for these moments are only ≈ 70% of that for J = 4, indicating that the Pr 3+ moment is partially quenched by the crystal field.

  4. Specific heat, resistivity, and AC susceptibility of the cubic PrX 2 compounds (X = Pt, Ru, Ir, Rh)

    Science.gov (United States)

    Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; de Jongh, L. J.; Huiskamp, W. J.; Capel, H. W.; Buschow, K. H. J.

    1983-04-01

    Specific-heat, differential-susceptibility and electrical-resistivity measurements on PrX 2 (X = Ir, Pt, Rh, Ru) compounds reveal phase transitions at Tc = 11.2±0.5 K, 7.7±0.5 K, 7.9±0.5 Kand 33.9±0.5 K for X = Ir, Pt, Rh, and Ru, respective ly. From earlier neutron inelastic scattering experiments, the crystalline electric field levels of these compounds have been determined. The specific-heat results are compared with the results of a mean-field calculation, assuming bilinear exchange interactions. The presence of broad secondary maxima in the temperature dependence of the specific heat of PrRh 2, PrRu 2 and especially PrIr 2 can qualitatively be explained by the presence of biquadratic (quadrupolar) interactions. The behaviour of the susceptibility is in agreement with ferromagnetic ordering. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  5. Screening of electrocatalysts for direct ammonia fuel cell: Ammonia oxidation on PtMe (Me: Ir, Rh, Pd, Ru) and preferentially oriented Pt(1 0 0) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Vidal-Iglesias, F.J.; Solla-Gullon, J.; Montiel, V.; Feliu, J.M.; Aldaz, A. [Instituto de Electroquimica, Universidad de Alicante, Apartado 99, 03080 Alicante (Spain)

    2007-09-27

    Ammonia has attracted attention as a possible fuel for direct fuel cells since it is easy to handle and to transport as liquid or as concentrated aqueous solution. However, on noble metal electrodes ammonia oxidation is a sluggish reaction and the electrocatalyst needs to be improved for developing efficient ammonia fuel cells. In this work, ammonia electrooxidation reaction on 3-4-nm bimetallic PtMe (Ir, Rh, Pd, Ru) and on preferentially oriented Pt(1 0 0) nanoparticles is reported. PtMe nanoparticles have been prepared by using water-in-oil microemulsions to obtain a narrow size distribution whereas preferentially oriented Pt nanoparticles have been prepared through colloidal routes. Among all the bimetallic samples tested, only Pt{sub 75}Ir{sub 25} and Pt{sub 75}Rh{sub 25} nanoparticles show, at the low potential range, an enhancement of the oxidation density current with respect to the behaviour found for pure platinum nanoparticles prepared by the same method. In addition, two Pt(1 0 0) preferentially oriented nanoparticles of different particle size (4 and 9 nm) have been also studied. These oriented nanoparticles show higher current densities than polycrystalline Pt nanoparticles due to the sensitivity of ammonia oxidation toward the presence of surface sites with square symmetry. The reactivity of the different 4-nm nanoparticles parallels well with that expected from bulk PtMe alloys and Pt single crystal electrodes. (author)

  6. Epitaxial Growth of Multimetallic Pd@PtM (M = Ni, Rh, Ru) Core-Shell Nanoplates Realized by in Situ-Produced CO from Interfacial Catalytic Reactions.

    Science.gov (United States)

    Yan, Yucong; Shan, Hao; Li, Ge; Xiao, Fan; Jiang, Yingying; Yan, Youyi; Jin, Chuanhong; Zhang, Hui; Wu, Jianbo; Yang, Deren

    2016-12-14

    Pt-based multimetallic core-shell nanoplates have received great attention as advanced catalysts, but the synthesis is still challenging. Here we report the synthesis of multimetallic Pd@PtM (M = Ni, Rh, Ru) nanoplates including Pd@Pt nanoplates, in which Pt or Pt alloy shells with controlled thickness epitaxially grow on plate-like Pd seeds. The key to achieve high-quality Pt-based multimetallic nanoplates is in situ generation of CO through interfacial catalytic reactions associated with Pd nanoplates and benzyl alcohol. In addition, the accurate control in a trace amount of CO is also of great importance for conformal growth of multimetallic core-shell nanoplates. The Pd@PtNi nanoplates exhibit substantially improved activity and stability for methanol oxidation reaction (MOR) compared to the Pd@Pt nanoplates and commercial Pt catalysts due to the advantages arising from plate-like, core-shell, and alloy structures.

  7. New neutron diffraction results on magnetic properties of the cubic rare earth compounds HoP and PrX/sub 2/ (X = Ru, Rh, Ir, Pt)

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, P.; Haelg, W.; Kaldis, E.; Greidanus, F.J.A.M.; Buschow, K.H.J.

    1982-01-01

    Neutron diffraction studies performed on polycrystalline, NaCl type HoP in external magnetic fields yield <100> as easy directions of magnetization in the ferromagnetic state. The magnetic ordering of the MgCu/sub 2/ type Laves phase systems PrX/sub 2/ (X = Ru, Rh, Ir, Pt) was investigated on powdered samples by means of neutron diffraction. Simple ferromagnetic structures were observed. The determined Curie temperatures confirm bulk measurements, and the values of the ordered magnetic moments indicate crystal field effects.

  8. New neutron diffraction results on magnetic properties of the cubic rare earth compounds HoP and PrX2 (X=Ru, Rh, Ir, Pt)

    Science.gov (United States)

    Fischer, P.; Hälg, W.; Kaldis, E.; Greidanus, F. J. A. M.; Buschow, K. H. J.

    1982-09-01

    Neutron diffraction studies performed on polycrystalline, NaCl type HoP in external magnetic fields yield as easy directions of magnetization in the ferromagnetic state. The magnetic ordering of the MgCu2 type Laves phase systems PrX2 (X=Ru, Rh, Ir, Pt) was investigated on powdered samples by means of neutron diffraction. Simple ferromagnetic structures were observed. The determined Curie temperatures confirm bulk measurements, and the values of the ordered magnetic moments indicate crystal field effects.

  9. Room temperature biogenic synthesis of multiple nanoparticles (Ag, Pd, Fe, Rh, Ni, Ru, Pt, Co, and Li) by Pseudomonas aeruginosa SM1

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Sarvesh Kumar; Constanti, Magda, E-mail: magdalena.constanti@urv.cat [Universitat Rovira i Virgili, Departament d' Enginyeria Quimica (Spain)

    2012-03-15

    Room temperature biosynthesis of Ag, Pd, Fe, Rh, Ni, Ru, Pt, Co, and Li nanoparticles was achieved using Pseudomonas aeruginosa SM1 without the addition of growth media, electron donors, stabilizing agents, preparation of cell/cell-free extract or temperature, and pH adjustments. The resulting nanoparticles were characterized by Transmission electron microscopy and X-ray diffraction. It was observed that P. aeruginosa SM1 is capable of producing both intracellular (Co and Li) and extracellular (Ag, Pd, Fe, Rh, Ni, Ru, and Pt) nanoparticles in both crystalline and amorphous state. The FT-IR spectra clearly showed the presence of primary and secondary amines which may be responsible for the reduction and subsequent stabilization of the resulting extracellular nanoparticles which were obtained as a one-step process. This suggests toward an unknown 'selection mechanism' that reduces certain metal ions and allows others to enter the cell membrane. Finally, in this first of its kind study, single strain of bacteria was used to produce several different mono-metallic nanoparticles.

  10. Room temperature biogenic synthesis of multiple nanoparticles (Ag, Pd, Fe, Rh, Ni, Ru, Pt, Co, and Li) by Pseudomonas aeruginosa SM1

    Science.gov (United States)

    Srivastava, Sarvesh Kumar; Constanti, Magda

    2012-03-01

    Room temperature biosynthesis of Ag, Pd, Fe, Rh, Ni, Ru, Pt, Co, and Li nanoparticles was achieved using Pseudomonas aeruginosa SM1 without the addition of growth media, electron donors, stabilizing agents, preparation of cell/cell-free extract or temperature, and pH adjustments. The resulting nanoparticles were characterized by Transmission electron microscopy and X-ray diffraction. It was observed that P. aeruginosa SM1 is capable of producing both intracellular (Co and Li) and extracellular (Ag, Pd, Fe, Rh, Ni, Ru, and Pt) nanoparticles in both crystalline and amorphous state. The FT-IR spectra clearly showed the presence of primary and secondary amines which may be responsible for the reduction and subsequent stabilization of the resulting extracellular nanoparticles which were obtained as a one-step process. This suggests toward an unknown "selection mechanism" that reduces certain metal ions and allows others to enter the cell membrane. Finally, in this first of its kind study, single strain of bacteria was used to produce several different mono-metallic nanoparticles.

  11. Synthesis, crystal structure, and electronic properties of high-pressure PdF2-type oxides MO2 (M = Ru, Rh, Os, Ir, Pt).

    Science.gov (United States)

    Shirako, Yuichi; Wang, Xia; Tsujimoto, Yoshihiro; Tanaka, Kie; Guo, Yanfeng; Matsushita, Yoshitaka; Nemoto, Yoshihiro; Katsuya, Yoshio; Shi, Youguo; Mori, Daisuke; Kojitani, Hiroshi; Yamaura, Kazunari; Inaguma, Yoshiyuki; Akaogi, Masaki

    2014-11-03

    The polycrystalline MO2's (HP-PdF2-type MO2, M = Rh, Os, Pt) with high-pressure PdF2 compounds were successfully synthesized under high-pressure conditions for the first time, to the best of our knowledge. The crystal structures and electromagnetic properties were studied. Previously unreported electronic properties of the polycrystalline HP-PdF2-type RuO2 and IrO2 were also studied. The refined structures clearly indicated that all compounds crystallized into the HP-PdF2-type structure, M(4+)O(2-)2, rather than the pyrite-type structure, M(n+)(O2)(n-) (n superconductivity nor a magnetic transition was detected down to a temperature of 2 K, unlike the case of 3d transition metal chalcogenide pyrites.

  12. Coexistence of magnetic order, heavy fermion and intermediate valence behaviour in Ce{sub 7}X{sub 3} (X=Ni, Ru, Pd, Pt, Ir and Rh)

    Energy Technology Data Exchange (ETDEWEB)

    Trovarelli, O. [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche; Sereni, J.G. [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche; Schmerber, G. [IPCMS-GEMM, 23 rue du Loess, 67037 Strasbourg (France); Kappler, J.P. [IPCMS-GEMM, 23 rue du Loess, 67037 Strasbourg (France)

    1995-02-01

    Low temperature specific heat, AC magnetic susceptibility and magnetization measurements were performed on the Ce{sub 7}X{sub 3} compounds (X=Ni, Ru, Rh, Pd, Ir and Pt). They exhibit coexistence of magnetic order (MO), heavy fermion (HF) and intermediate valence (IV) behaviour and the results are interpreted in terms of the three Ce sublattices (1Ce{sub I}, 3Ce{sub II} and 3Ce{sub III}) present in the Th{sub 7}Fe{sub 3}-type structure. From entropic considerations it is found that sublattice Ce{sub III} presents an IV behaviour in all these compounds and Ce{sub II} show MO or have a HF behaviour depending on the Ce-ligand electronic structure. The Ce{sub I} atoms (more than 6A distant from each other) exhibit MO only when the Ce{sub II} sublattice provides a high density of electronic states. ((orig.)).

  13. Magnetic properties of PrX 2 compounds (X = Pt, Rh, Ru, Ir) studied by hyperfine specific heat, magnetization and neutron-diffraction measurements

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Fischer, P.; Furrer, A.; Buschow, K. H. J.

    1983-04-01

    Magnetic ordering phenomena in rare-earth intermetallic compounds can be unravelled most advantageously in the case of simple crystallographic structure and when a combination of microscopic techniques is applied. Here we shall present the temperature and magnetic field dependence of the magnetic moment of the cubic PrX 2 compounds (X = Pt, Rh, Ru, Ir), as inferred from hyperfine specific-heat, magnetization and neutron-diffraction measurements. The results are compared with a mean-field calculation, taking crystalline electric field and bilinear (dipolar) exchange interactions into account. Adopting experimental values of the Lea, Leask and Wolf parameters x and W from inelastic neutron scattering results, we find satisfactory agreement between our magnetic data and the mean-field theory. An observed discrepancy of about 15% between the calculated and measured saturation values of the spontaneous magnetization can be explained by the presence of quadrupolar interactions.

  14. Specific heat, differential susceptibility and electrical resistivity of PrX2 (X = Ir, Pt, Rh and Ru) laves phase compounds at temperatures 1.4 K < T < 40 K

    Science.gov (United States)

    van Dongen, J. C. M.; van der Linden, H. W. M.; Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; Mydosh, J. A.; Buschow, K. H. J.

    1980-01-01

    Specific heat and differential susceptibility data of PrX 2 (X = Ir, Pt, Rh, and Ru) compounds reveal phase transitions at Tc = (11.2 ± 0.5) K, (7.7 ± 0.5) K, (7.9 ± 0.5) K and (33.9 ± 0.5) K for X = Ir, Pt, RhandRu, resp. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  15. Hydrogen Adsorption on Pt, Rh and Pt-Rh Electrodes

    Institute of Scientific and Technical Information of China (English)

    贾梦秋; A.M.Meretskyi

    2005-01-01

    The hydrogen adsorption on Pt-Rh alloys in sulfuric acid aqueous solutions was studied by the method of cathode pulses. Hydrogen adsorption on the electrode with all ratio of alloy components (ωRh = 0-100%) is well described by the Temkin logarithmic isotherm. The surface coverage by adsorbed hydrogen at the same potential is decreased with increasing content of rhodium in the system. A linear dependence of adsorption peak potential on the alloy compositions in the case of weakly bonded adsorbed hydrogen is established. Hydrogen adsorption heat as a function of surface coverage for Pt-Rh-electrodes was obtained. The shape of the current-potential curve and position of the weakly bonded hydrogen adsorption on the potential scale are all related to alloy compositions, thus can serve as the basis for the determination surface composition of allovs.

  16. Analytical results for crystalline electric field eigenvalues of trivalent rare-earth ions using computer algebra: application to the magnetism of PrX2 ( X = Mg, Al, Ru, Rh, Pt)

    Science.gov (United States)

    Sobral, R. R.; Guimarães, A. P.; da Silva, X. A.

    1994-10-01

    The eigenvalues of the Crystalline Electric Field (CEF) Hamiltonian with cubic symmetry are analytically obtained for trivalent rare-earth ions of ground state J= {5}/{2}, {7}/{2}, 4, {9}/{2}, 6, {15}/{2} and 8, via a Computer Algebra approach. In the presence of both CEF and an effective exchange field, Computer Algebra still allows a partial factorization of the characteristic polynomial equation associated to the total Hamiltonian, a result of interest to the study of the magnetic behavior of rare-earth intermetallics. An application to the PrX2 intermetallic compounds ( X = Mg, Al, Ru, Rh, Pt) is reported.

  17. Eosin Y/M/SiO2(M=Pt,Rh,Ru)催化剂可见光催化还原水制氢%Photocatalytic Reduction of Water to Hydrogen over Eosin Y / M / SiO2 Catalysts(M =Pt, Rh, Ru)

    Institute of Scientific and Technical Information of China (English)

    张晓杰; 王保玉; 汤长青

    2012-01-01

    通过人工模拟光合作用,构建了具有较高可见光还原水制氢性能的Eosin Y/M/SiO2(M=Pt,Rh,Ru)催化体系,详细考察了析氢助催化剂、二氧化硅表面性质以及曙红与二氧化硅的混合方式等因素对光敏化催化剂制氢性能的影响.实验结果表明:钌作为析氢助催化剂,析氢速率和表观量子效率可分别高达90μmol h-1和23.8%;二氧化硅的比表面积增大,析氢速率随之增高;与曙红Y浸渍法吸附在二氧化硅表面制备的催化剂相比,原位物理混合制备的催化剂光敏化析氢速率和稳定性均有显著提高.

  18. Crystal field splittings of PrX 2 compounds (X=Pt, Rh, Ir, Ru, Ni) studied by inelastic neutron scattering

    Science.gov (United States)

    Greidanus, F. J. A. M.; De Jongh, L. J.; Huiskamp, W. J.; Furrer, A.; Buschow, K. H. J.

    1983-01-01

    Neutron inelastic scattering experiments have been performed on polycrystalline samples of the cubic Laves phase compounds PrX 2(X=Pt, Rh, Ir, Ni). Measurements in the paramagnetic state yield LLW parameters 0.6< x<1 and W<0. In this region various levels cross at an x value 0.86 and as a consequence the electronic ground state in the paramagnetic regime is either the singlet Γ 1, or the non-magnetic doublet Γ 3. Measurements in the ferromagnetic state support these conclusions. The crystal-field parameters obtained can be used in model calculations of some macroscopic quantities, in particular the specific heat and the spontaneous magnetization. The variation of the x values in the present series of Laves phase compounds evidences the presence of a contribution by conduction electrons to the crystal field.

  19. Selective oxidation of methylamine over zirconia supported Pt-Ru, Pt and Ru catalysts

    Institute of Scientific and Technical Information of China (English)

    Aiying Song; Gongxuan Lu

    2015-01-01

    Pt–Ru, Pt and Ru catalysts supported on zirconia were prepared by impregnation method and were tested in se-lective oxidation of methylamine (MA) in aqueous media. Among three catalysts, Ru/ZrO2 was more active than Pt/ZrO2 while Pt–Ru/ZrO2 demonstrated the best catalytic activity due to the fact that Pt addition efficiently pro-moted the dispersion of active species in bimetallic catalyst. Therefore, the~100%TOC conversion and N2 selec-tivity were achieved over Pt–Ru/ZrO2, Pt/ZrO2 and Ru/ZrO2 catalysts at 190, 220 and 250 °C, respectively.

  20. Carbon supported nanoparticles Pt Ru (Pt Ru/C electrocatalysts) prepared using electron beam irradiation; Preparacao de nanoparticulas de PtRu suportadas em carbono (eletrocatalisadores PtRu/C) utilizando feixe de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F. da; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Programa de Celulas a Combustivel], e-mail: espinace@ipen.br, e-mail: dfsilva@ipen.br

    2006-07-01

    Carbon-supported Pt Ru (electrocatalysts PtRu/C nanoparticles) were prepared submitting a water/ethylene glycol mixture containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The PtRu/C electrocatalysts were characterized by EDX, XRD and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C ETEK electrocatalyst at ambient temperature. (author)

  1. Carbon supported nanoparticles Pt Ru (Pt Ru/C electrocatalysts) prepared using electron beam irradiation; Preparacao de nanoparticulas de PtRu suportadas em carbono (eletrocatalisadores PtRu/C) utilizando feixe de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F. da; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Programa de Celulas a Combustivel], e-mail: espinace@ipen.br, e-mail: dfsilva@ipen.br

    2006-07-01

    Carbon-supported Pt Ru (electrocatalysts PtRu/C nanoparticles) were prepared submitting a water/ethylene glycol mixture containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The PtRu/C electrocatalysts were characterized by EDX, XRD and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C ETEK electrocatalyst at ambient temperature. (author)

  2. Pt Ru/C electrocatalysts prepared using electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio Furtunato da; Oliveira Neto, Almir; Pino, Eddy Segura; Brandalise, Michele; Linardi, Marcelo; Spinace, Estevam Vitorio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: espinace@ipen.br

    2007-10-15

    Pt Ru/C electrocatalysts (carbon-supported Pt Ru nanoparticles) were prepared submitting water/ethylene glycol mixtures containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The electrocatalysts were characterized by energy dispersive X ray analysis (EDX), X ray diffraction (XRD) and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained Pt Ru/C electrocatalysts showed superior performance for methanol electro-oxidation at room temperature compared to commercial Pt Ru/C electrocatalyst. (author)

  3. Adsorption of formaldehyde and formyl intermediates on Pt, PtRu-, and PtRuMo-alloy surfaces: A density functional study

    Science.gov (United States)

    Cahyanto, Wahyu Tri; Shukri, Ganes; Agusta, Mohammad Kemal; Kasai, Hideaki

    2013-02-01

    Stable binding configuration for formaldehyde (H2CO) and formyl (HCO) adsorption on Pt, PtRu, and PtRuMo are studied within the frame of density functional theory (DFT). We address this study to investigate the role of Ru and Mo on the binding characteristic of formaldehyde and formyl adsorption with respect to interaction strength and charge analysis. Several binding conformation on all possible surface adsorption sites are considered in determining the most stable adsorption geometry on three surfaces. Our results show that the presence of Ru in PtRu and Mo in PtRuMo stabilize the formaldehyde and formyl, which are indicated by stronger bond strength. Further electronic structure analysis shows that the addition of Ru in PtRu and Mo in PtRuMo modifies the electronic structure of Pt's surface significantly. The presence of both impurities shifted the derived anti-bonding state - which is originally located below the fermi level in pure Pt surface - to be above the fermi level in PtRu and PtRuMo systems. This fact explains the stronger adsorption found on PtRu & PtRuMo as compared to pure Pt surface.

  4. Pt Ru/C electrocatalysts prepared using electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F.; Oliveira Neto, Almir; Pino, Eddy S.; Brandalise, Michele; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: dfsilva@ipen.br; espinace@ipen.br

    2007-07-01

    Pt Ru/C electrocatalysts (carbon-supported Pt Ru nanoparticles) were prepared submitting water/ethylene glycol solutions containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The water/ethylene glycol ratio (v/v) was evaluated as synthesis parameters. The Pt Ru/C electrocatalysts were prepared with a nominal Pt:Ru atomic ratio of 50:50 and were characterized by energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) and tested for methanol electro-oxidation using cyclic voltammetry and chronoamperometry. The obtained Pt Ru/C electrocatalysts showed the typical fcc structure of platinum-ruthenium alloys and the electrocatalytic activity depends on the water/ethylene glycol ratio used in the preparation.

  5. Ternary rare-earth aluminium intermetallics RE10TAl3 (RE = Y, Ho, Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt) with an ordered anti-Co2Al5 structure.

    Science.gov (United States)

    Benndorf, Christopher; Eckert, Hellmut; Janka, Oliver

    2017-01-24

    Twenty new rare-earth metal rich intermetallic aluminium compounds, RE10TAl3 (RE = Y, Ho, Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt), were synthesized by arc melting the elements. The compounds crystallize, in analogy to e.g. the respective Cd representatives, with a ternary ordered structure as anti-type to the hexagonal Co2Al5 type, with the space group P63/mmc. The three crystallographically independent rare-earth metal sites occupy the aluminium positions of the aristotype, while the transition metal and aluminium atoms are ordered on the two cobalt sites. Like other rare-earth rich compounds the RE10TX3 members also exhibit transition-metal-centred T@RE6 trigonal prisms as striking structural building units. The prepared compounds have been investigated by susceptibility measurements and (27)Al solid-state MAS-NMR measurements conducted on the Pauli-paramagnetic Y and Lu compounds. Some compounds show a certain amount of disorder as seen from the single crystal structure analysis and from signal broadening in the NMR investigations. By separating Knight shifts from second-order quadrupolar shifts via field dependent measurements, monotonic trends can be discerned regarding the effect of the T atom valence electron concentration and period number, as well as the effect of the closed 4f shell contributed in the Lu compounds. The results confirm that a comparison of Knight shifts within a series of isotypic compounds can reveal important electronic structure information in intermetallic systems.

  6. Bifunctional electrocatalysis in pt-ru nanoparticle systems.

    Science.gov (United States)

    Roth, C; Benker, N; Theissmann, R; Nichols, R J; Schiffrin, D J

    2008-03-04

    Pt-Ru alloys are prominent electrocatalysts in fuel cell anodes as they feature a very high activity for the oxidation of reformate and methanol. The improved CO tolerance of these alloys has been discussed in relation to the so-called ligand and bifunctional mechanisms. Although these effects have been known for many years, they are still not completely understood. A new approach that bridges the gap between single crystals and practical catalysts is presented in this paper. Nanoparticulate model systems attached to an oxidized glassy carbon electrode were prepared by combining both ligand-stabilized and spontaneously deposited Pt and Ru nanoparticles. These electrodes showed very different voltammetric responses for CO and methanol oxidation. The cyclic voltammograms were deconvoluted into contributions attributed to Pt, Ru, and Pt-Ru contact regions to quantify the contribution of the latter to the bifunctional mechanism. Scanning transmission electron microscopy confirmed the proximity of Pt and Ru nanoparticles in the different samples.

  7. PtRu/C electrocatalysts prepared using {gamma}-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F.; Neto, Almir Oliveira; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP, Av. Professor Lineu Prestes, 2242, Cidade Universitaria, 05508-000 Sao Paulo, SP (Brazil)

    2007-07-10

    PtRu/C electrocatalysts (carbon-supported PtRu nanoparticles) were prepared submitting water/ethylene glycol solutions containing Pt(IV) and Ru(III) ions and the carbon support to {gamma}-irradiation. The water/ethylene glycol ratio (v/v) and the total dose (kGy) were evaluated as synthesis parameters. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C electrocatalyst at ambient temperature and the electrocatalytic activity depends on the water/ethylene glycol ratio used in the preparation. (author)

  8. London penetration depth measurements in Ba (Fe1-xTx)2As2(T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Ryan T. [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The London penetration depth has been measured in various doping levels of single crystals of Ba(Fe1-xTx)2As2 (T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors by utilizing a tunnel diode resonator (TDR) apparatus. All in-plane penetration depth measurements exhibit a power law temperature dependence of the form Δλab(T) = CTn, indicating the existence of low-temperature, normal state quasiparticles all the way down to the lowest measured temperature, which was typically 500 mK. Several different doping concentrations from the Ba(Fe1-xTx)2As2 (T=Co,Ni) systems have been measured and the doping dependence of the power law exponent, n, is compared to results from measurements of thermal conductivity and specific heat. In addition, a novel method has been developed to allow for the measurement of the zero temperature value of the in-plane penetration depth, λab(0), by using TDR frequency shifts. By using this technique, the doping dependence of λab(0) has been measured in the Ba(Fe1-xCox)2As2 series, which has allowed also for the construction of the doping-dependent superfluid phase stiffness, ρs(T) = [λ(0)/λ(T)]2. By studying the effects of disorder on these superconductors using heavy ion irradiation, it has been determined that the observed power law temperature dependence likely arises from pair-breaking impurity scattering contributions, which is consistent with the proposed s±-wave symmetry of the superconducting gap in the dirty scattering limit. This hypothesis is supported by the measurement of an exponential temperature dependence of the penetration depth in the intrinsically clean LiFeAs, indicative of a nodeless superconducting gap.

  9. X = Pt, Os, Ru, Ir, Rh

    African Journals Online (AJOL)

    Timothy Ademakinwa

    Department of Physics, Federal University of Technology, Akure. Nigeria. ... All structure relaxation and bulk modulus ... using the Sutton-Chen form of Embedded Atom ... In (1) - (3), c is a dimensionless quantity, r is the ij spacing ... to the large numbers of atoms involved, cubic ... in the theoretical prediction of hard materials.

  10. Enhancement of Solar Fuel Production Schemes by Using a Ru,Rh,Ru Supramolecular Photocatalyst Containing Hydroxide Labile Ligands.

    Science.gov (United States)

    Rogers, Hannah Mallalieu; Arachchige, Shamindri M; Brewer, Karen J

    2015-11-16

    Polyazine-bridged Ru(II)Rh(III)Ru(II) complexes with two halide ligands, Cl(-) or Br(-), bound to the catalytically active Rh center are efficient single-component photocatalysts for H2O reduction to H2 fuel, with the coordination environment on Rh impacting photocatalysis. Herein reported is a new, halide-free Ru(II)Rh(III)Ru(II) photocatalyst with OH(-) ligands bound to Rh, further enhancing the photocatalytic reactivity of the structural motif. H2 production experiments using the photocatalyst bearing OH(-) ligands at Rh relative to the analogues bearing halides at Rh in solvents of varying polarity (DMF, CH3CN, and H2O) suggest that ion pairing with halides deactivates photocatalyst function, representing an exciting phenomenon to exploit in the development of catalysts for solar H2 production schemes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Study of the Pt/Ru(0001) Interface

    DEFF Research Database (Denmark)

    Godowski, Jan P; Li, Zhe Shen; Bork, Jakob

    2007-01-01

    The growth process of platinum on Ru(0001) near room temperature was characterized using photoelectron spectroscopy of high resolution. The binding energy position and intensity of the Pt 4f7/2 and Ru 3d5/2 core levels as well as the shape and structure of the valence band spectra corresponding t...

  12. Mesoporous Pt and Pt/Ru alloy electrocatalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Planes, Gabriel A. [Departamento de Quimica, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3, 5800, Rio Cuarto (Argentina); Williams, Federico J. [Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina); Soler-Illia, Galo J.A.A. [Gerencia de Quimica, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Corti, Horacio R. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina)

    2011-02-15

    Mesoporous Pt and Pt/Ru catalysts with 2D-hexagonal mesostructure were synthesized using a triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (Pluronic F127 {sup registered}) template, on a gold support. Large electrochemical surface areas were observed for the catalysts prepared at high overpotentials. Compared to the Pt catalyst, the Pt/Ru alloy containing 3 at% of Ru exhibited lower onset potential and more than three times the limit mass activity for methanol oxidation. This behavior is assigned to the larger pore size of the mesoporous Pt and Pt/Ru catalysts obtained with this template that seems to improve the methanol accessibility to the active sites compared to those obtained using lyotropic liquid crystals. (author)

  13. 高温热电偶材料PtRh40/PtRh20合金性能研究%Prorerties of PtRh40/PtRh20 High-temperature Thermocouple Wires

    Institute of Scientific and Technical Information of China (English)

    吴保安; 刘庆宾; 陈德茂; 汪建胜; 唐会毅; 陈小军

    2013-01-01

    The long-term using temperature of PtRh40/PtRh20 high-temperature thermocouple wire is 1750℃. PtRh40/PtRh20 is belong to non-standard thermocouple, and mainly applies to measure the aircraft efflux plasma temperature. The influences of annealing temperature on the tensile strength and resistivity of PtRh40 and PtRh20 alloy wires, and the influences of the cold working on tensile strength and vickers hardness of the wires were studied. The results indicated that the tensile strengths increased with the increase of annealing temperature at first, then decreased sharply, finally it is stable forming a platform. The resistivities were increased with the annealing temperature, and the tensile strength and hardness were increased with the cold working. The errors of matching thermoelectric potential of PtRh40- PtRh20 relative to ASTM E1751-2000 standard thermoelectric power is 1℃ at 1200℃, 2℃ at 1500℃, and 1℃ at 1700℃.%  PtRh40/PtRh20高温热电偶长期使用温度为1750℃,主要用于飞机尾焰高温测量,属于非标热电偶,目前国内主要依靠进口。研究了 PtRh40、PtRh20退火温度与合金电阻率、抗拉强度及加工率与抗拉强度、硬度的关系,并测试了PtRh40/PtRh20热电偶热电性能。结果表明:抗拉强度随退火温度的升高先升高再急剧下降,最后稳定在一个平台,两者大约在900℃时抗拉强度降至最低;电阻率均随退火温度升高而升高;抗拉强度与硬度均随加工率的增加而提高;PtRh40/PtRh20配对热电势相对ASTM E1751-2000标准热电势测试结果为在1200℃时误差为1℃,在1500℃时误差2℃,在1700℃时误差1℃。

  14. Ternary Pt-Ru-Ni catalytic layers for methanol electrooxidation prepared by electrodeposition and galvanic replacement

    OpenAIRE

    Athanasios ePapaderakis; Nikolaos ePliatsikas; Chara eProchaska; Kalliopi M. Papazisi; Balomenou, Stella P.; Dimitrios eTsiplakides; Panagiotis ePatsalas; Sotiris eSotiropoulos

    2014-01-01

    Ternary Pt-Ru-Ni deposits on glassy carbon substrates, Pt-Ru(Ni)/GC, have been formed by initial electrodeposition of Ni layers onto glassy carbon electrodes, followed by their partial exchange for Pt and Ru, upon their immersion into equimolar solutions containing complex ions of the precious metals. The overall morphology and composition of the deposits has been studied by SEM microscopy and EDS spectroscopy. Continuous but nodular films have been confirmed, with a Pt ÷ Ru ÷ Ni % bulk atomi...

  15. Modeling the electro-oxidation of CO and H2/CO on Pt, Ru, PtRu and Pt3Sn

    DEFF Research Database (Denmark)

    Liu, Ping; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2003-01-01

    is developed to describe the electro-oxidation of CO and H-2 at conditions relevant to the anode of a PEM fuel cell. The model is very simple and allows us to express the kinetics of a promoted anode surface relative to the activity of pure Pt directly from the calculated adsorption energy differences...... geometry is the same. This ligand effect is ascribed to changes in the electronic structure of the surface atoms due to interactions with the surroundings, and the physical origin of the effect is discussed. The calculated adsorption energetics is used as input into a simple kinetic model, which....... In agreement with experiments, the model shows Ru, PtRu and Pt3Sn to start oxidizing CO at lower potentials than Pt. In addition, the model shows PtRu to have a considerably lower overpotential for H-2 oxidation in the presence of CO than Pt. Pt3Sn is even better than PtRu, while Ru is found to be considerably...

  16. Pt and PtRu catalyst bilayers increase efficiencies for ethanol oxidation in proton exchange membrane electrolysis and fuel cells

    Science.gov (United States)

    Altarawneh, Rakan M.; Pickup, Peter G.

    2017-10-01

    Polarization curves, product distributions, and reaction stoichiometries have been measured for the oxidation of ethanol at anodes consisting of Pt and PtRu bilayers and a homogeneous mixture of the two catalysts. These anode structures all show synergies between the two catalysts that can be attributed to the oxidation of acetaldehyde produced at the PtRu catalyst by the Pt catalyst. The use of a PtRu layer over a Pt layer produces the strongest effect, with higher currents than a Pt on PtRu bilayer, mixed layer, or either catalyst alone, except for Pt at high potentials. Reaction stoichiometries (average number of electrons transferred per ethanol molecule) were closer to the values for Pt alone for both of the bilayer configurations but much lower for PtRu and mixed anodes. Although Pt alone would provide the highest overall fuel cell efficiency at low power densities, the PtRu on Pt bilayer would provide higher power densities without a significant loss of efficiency. The origin of the synergy between the Pt and PtRu catalysts was elucidated by separation of the total current into the individual components for generation of carbon dioxide and the acetaldehyde and acetic acid byproducts.

  17. Methanol electro-oxidation on Pt-Ru-P/C and Pt-Ru-P/MWCNT in acidic medium

    CSIR Research Space (South Africa)

    Modibedi, M

    2009-06-01

    Full Text Available Pt-Ru-P was prepared by the chemical reduction method using sodium hypophoshite as a reducing agent on Vulcan XC 72 and multi-walled carbon nano-tubes (MWCNTs). Sodium citrate was added as the stabilizer during electro-catalyst preparation...

  18. Spontaneous deposition of Ru on Pt (100: morphological and electrochemical studies. Preliminary results of ethanol oxidation at Pt(100/Ru

    Directory of Open Access Journals (Sweden)

    Colle Vinicius D.

    2003-01-01

    Full Text Available In the present work ruthenium was deposited in submonolayer amounts on Pt(100 by spontaneous deposition at several deposition times. The Pt (100/Ru surfaces were analyzed using ex-situ STM to image the deposits characteristic of ruthenium on Pt (100. It was observed the formation of ruthenium islands with diameters between 1.0 and 4.5 nm with bi-atomic thickness in the center of the islands. A homogeneous distribution of the ruthenium islands on the platinum terraces was found, with no preferential deposition on steps or surface defect sites. The ruthenium coverage degree had been calculated by the decrease of charge of the hydrogen adsorption-desorption peaks in the cyclic voltammograms of the Pt(100/Ru electrodes. The Pt(100/Ru electrodes with a ruthenium coverage degree of ca. 0.3 showed a high activity for the ethanol electrooxidation. The electrochemical experimental results support strongly the bifunctional mechanism for the enhanced ethanol oxidation.

  19. 微波消解-双浊点萃取 ICP -MS 测定地球化学样品中的痕量铂钯钌铑%Determination of Pt,Pd,Ru,Rh in Geochemical Samples by ICP-MS with Microwave Digestion and Dual-cloud Point Extraction

    Institute of Scientific and Technical Information of China (English)

    沈宇; 张尼; 高小红; 李展; 李日升; 郑建斌

    2016-01-01

    Traditional cloud point extraction methods commonly enrich elements in the viscous surfactant. However,the viscosity of the solution will adversely affect the detection signal of the plasma.Harmful agents such as methanol are usually adopted as a thinner to reduce the viscosity of the organic phase,but the organic component affects the stability of the plasma,and organic absorption on the injection tube will enhance elemental memory effect.These disadvantages limit the widespread application of Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)in cloud point extraction.A method to determine Pt,Pd,Ru, Rh in geochemical samples by ICP-MS based dual-cloud point extraction has been established,and is reported in this paper.After the microwave digestion procedure,first cloud point extraction is performed on the sample solution using DDTP as the sequestrant and Triton X-114 as the surfactant.HNO3 is added into the organic phase,and second cloud point extraction is performed by heating so that Pt,Pd,Ru,Rh enter the water phase from the organic phase. Enrichment factors are 45,33,18,35,and detection limits are 0.05,0.02,0.10 and 0.03 μg/L for Pt,Pd,Ru and Rh,respectively.The proposed method succeeds in the simultaneous enrichment of trace platinum group elements in complex matrix geochemical samples,improving the stability of the ICP-MS measurement.%传统浊点萃取技术是将待测元素富集在黏稠的表面活性剂相中,溶液的黏度会对等离子体检测信号产生影响,通常使用甲醇作为稀释剂降低有机相黏度,有机成分也对等离子体的稳定性产生影响,同时有机物在进样管路上的吸附还会提高待测元素的记忆效应,因而限制了 ICP -MS 在浊点萃取中的应用。本文建立了双浊点萃取技术 ICP -MS 测定地球化学样品中铂钯钌铑的分析方法。样品用微波消解处理后,以DDTP 为螯合剂,Triton X -114为表面活性剂,对消解溶液第一次浊点萃取

  20. The Mechanism of Direct Formic Acid Fuel Cell Using Pd, Pt and Pt-Ru

    Science.gov (United States)

    Kamiya, Nobuyuki; Liu, Yan; Mitsushima, Shigenori; Ota, Ken-Ichiro; Tsutsumi, Yasuyuki; Ogawa, Naoya; Kon, Norihiro; Eguchi, Mika

    The electro-oxidation of formic acid, 2-propanol and methanol on Pd black, Pd/C, Pt-Ru/C and Pt/C has been investigated to clear the reaction mechanism. It was suggested that the formic acid is dehydrogenated on Pd surface and the hydrogen is occluded in the Pd lattice. Thus obtained hydrogen acts like pure hydrogen supplied from the outside and the cell performance of the direct formic acid fuel cell showed as high as that of a hydrogen-oxygen fuel cell. 2-propanol did not show such dehydrogenation reaction on Pd catalyst. Platinum and Pt-Ru accelerated the oxidation of C-OH of 2-propanol and methanol. Slow scan voltammogram (SSV) and chronoamperometry measurements showed that the activity of formic acid oxidation increased in the following order: Pd black > Pd 30wt.%/C > Pt50wt.%/C > 27wt.%Pt-13wt.%Ru/C. A large oxidation current for formic acid was found at a low overpotential on the palladium electrocatalysts. These results indicate that formic acid is mainly oxidized through a dehydrogenation reaction. For the oxidation of 2-propanol and methanol, palladium was not effective, and 27wt.%Pt-13wt.%Ru/C showed the best oxidation activity.

  1. Ternary Pt-Ru-Ni catalytic layers for methanol electrooxidation prepared by electrodeposition and galvanic replacement

    Directory of Open Access Journals (Sweden)

    Athanasios ePapaderakis

    2014-06-01

    Full Text Available Ternary Pt-Ru-Ni deposits on glassy carbon substrates, Pt-Ru(Ni/GC, have been formed by initial electrodeposition of Ni layers onto glassy carbon electrodes, followed by their partial exchange for Pt and Ru, upon their immersion into equimolar solutions containing complex ions of the precious metals. The overall morphology and composition of the deposits has been studied by SEM microscopy and EDS spectroscopy. Continuous but nodular films have been confirmed, with a Pt÷Ru÷Ni % bulk atomic composition ratio of 37÷12÷51 (and for binary Pt-Ni control systems of 47÷53. Fine topographical details as well as film thickness have been directly recorded using AFM microscopy. The composition of the outer layers as well as the interactions of the three metals present have been studied by XPS spectroscopy and a Pt÷Ru÷Ni % surface atomic composition ratio of 61÷12÷27 (and for binary Pt-Ni control systems of 85÷15 has been found, indicating the enrichment of the outer layers in Pt; a shift of the Pt binding energy peaks to higher values was only observed in the presence of Ru and points to an electronic effect of Ru on Pt. The surface electrochemistry of the thus prepared Pt-Ru(Ni/GC and Pt(Ni/GC electrodes in deaerated acid solutions (studied by cyclic voltammetry proves the existence of a shell consisting exclusively of Pt-Ru or Pt. The activity of the Pt-Ru(Ni deposits towards methanol oxidation (studied by slow potential sweep voltammetry is higher from that of the Pt(Ni deposit and of pure Pt; this enhancement is attributed both to the well-known Ru synergistic effect due to the presence of its oxides but also (based on the XPS findings to a modification effect of Pt electronic properties.

  2. Microwave sinthesys and characterization of Pt and Pt-Rh-Sn electrocatalysts for ethanol oxidation

    Directory of Open Access Journals (Sweden)

    Jovanović Vladislava M.

    2011-01-01

    Full Text Available Carbon supported Pt and Pt-Rh-Sn catalysts were synthesized by microwave-polyol method in ethylene glycol solution and investigated for the ethanol electro-oxidation reaction. The catalysts were characterized in terms of structure, morphology and composition by employing XRD, STM and EDX techniques. STM analysis indicated rather uniform particles and particle size of below 2 nm for both catalysts. XRD analysis of the Pt/C catalyst revealed two phases, one with the main characteristic peaks of face centered cubic crystal structure (fcc of platinum and another related to graphite like structure of carbon support Vulcan XC-72R. However, in XRD pattern of the Pt-Rh-Sn/C catalyst diffraction peaks for Pt, Rh or Sn cannot be resolved, indicating an extremely low crystallinity. The small particle sizes and homogeneous size distributions of both catalysts should be attributed to the advantages of microwave assisted modified polyol process in ethylene glycol solution. Pt-Rh- Sn/C catalyst is highly active for the ethanol oxidation with the onset potential shifted for more than 150 mV to negative values and with currents nearly 5 times higher in comparison to Pt/C catalyst. The stability tests of the catalysts, as studied by the chronoamperometric experiments, reveal that the Pt-Rh-Sn/C catalyst is evidently less poisoned then Pt/C catalyst. The increased activity of Pt-Rh-Sn/C in comparison to Pt/C catalyst is most probably promoted by bifunctional mechanism and the electronic effect of alloyed metals.

  3. Ethanol Oxidation Reaction on Tandem Pt/Rh/SnOx Catalyst

    Directory of Open Access Journals (Sweden)

    Phuong Tu Mai

    2017-08-01

    Full Text Available To elucidate the atomic arrangement of a Pt-Rh-Sn ternary catalyst with a high catalytic activity for ethanol oxidation reaction (EOR and high CO2 selectivity, we prepared a tandem Pt/Rh/SnOx, in which a Rh adlayer was deposited on a Pt substrate (Rh coverage: 0.28, followed by depositing several layers of SnOx only on the Rh surface (Sn coverage: 0.07. For reference, Sn was randomly deposited on the Rh-modified Pt (Pt/Rh electrode whose Rh and Sn coverages were 0.22 and 0.36 (random Pt/Rh/SnOx. X-ray photoelectron spectroscopy demonstrated that Pt and Rh were metallic, and Sn was largely oxidized. Both Pt/Rh/SnOx electrodes were less positive in onset potential of EOR current density and higher in EOR current density than Pt and Rh/Pt electrodes. In situ infrared reflection-absorption spectroscopy demonstrated that the tandem Pt/Rh/SnOx electrode did not produce acetic acid, but produced CO2 in contrast to the random Pt/Rh/SnOx, suggesting that a tandem arrangement of Pt, Rh and SnOx, in which the Pt and SnOx sites were separated by the Rh sites, was effective for selective CO2 production. In the electrostatic electrolysis at 0.5 V vs. RHE, the tandem Pt/Rh/SnOx electrode exhibited higher EOR current density than the Pt and Pt/Rh electrodes after 1.5 h.

  4. Metamagnetic domains in [Co/Pt]/Ru multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, N.S. [IFW Dresden (Germany); Donetsk Inst. for Physics and Technology (Russian Federation); Bran, C.; Wolff, U.; Schultz, L.; Bogdanov, A.N.; Neu, V.; Roessler, U.K. [IFW Dresden (Germany); Hellwig, O. [Hitachi GST, San Jose (United States)

    2009-07-01

    In antiferromagnetically coupled superlattices with perpendicular anisotropy, a magnetic field induces a cascade of reorientation transitions accompanied by metamagnetic multidomain states. For a micromagnetic model, we derive equilibrium sizes of stripe and bubble metamagnetic domains as functions of the antiferromagnetic exchange, magnetic field, and geometrical parameters of the multilayers. Magnetic phase diagrams display three different types of metamagnetic domains which separate the ferrimagnetic state from the antiferromagnetic and the saturated ferromagnetic state, and from ferrostripe phases. Experimental investigations have been carried out for an antiferromagnetically coupled [(Co/Pt){sub 8}Co/Ru]{sub 18} superlattice. Magnetic force microscopy (MFM) imaging in a magnetic fields reveals peculiarities of the nucleation and evolution of metamagnetic domains. Theoretical analysis of MFM data and the magnetization curves gives a consistent description of the magnetization processes in [Co/Pt]/Ru multilayers. Demagnetization processes starting from the multidomain metamagnetic states lead to specific remanents states, namely metamagnetic band and bubble topological defects.

  5. Contribution à la cristallochimie des isotypes de ThCr 2Si 2 et CaBe 2Ge 2. I. Les systèmes La T2- xT' xGe 2 ( T, T' = Ru, Rh, Pd, Ir, Pt) et La 1- xCa xCa xIr 2Ge 2: Distribution des éléments de transition dans le type CaBe 2Ge 2

    Science.gov (United States)

    Venturini, G.; Malaman, B.; Roques, B.

    1989-03-01

    There are several singularities in the systems investigated. Although the three germanides La T2Ge 2( T = Ru, Rh, Pd) are isostructural with ThCr 2Si 2, a complete solid solution occurs only between LaRu 2Ge 2 and LaRh 2Ge 2; in the system LaRh 2Ge 2LaPd 2Ge 2, there is a range of CaBe 2Ge 2-type solid solutions. The lattice constants of the ThCr 2Si 2-type compounds vary curiously according to the valence electron concentration (VEC). The CaBe 2Ge 2-type germanides are confined in a narrow range of VEC. The new compound CaIr 2Ge 2 is then of the ThCr 2Si 2-type while LaIr 2Ge 2 is of the CaBe 2Ge 2-type. In the latter structural type, the square pyramids of Ge atoms are favorite sites for Ir or Pt atoms. These results are discussed.

  6. Methanol Electro-Oxidation on Pt-Ru Alloy Nanoparticles Supported on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yangchuan Xing

    2009-09-01

    Full Text Available Carbon nanotubes (CNTs have been investigated in recent years as a catalyst support for proton exchange membrane fuel cells. Improved catalyst activities were observed and attributed to metal-support interactions. We report a study on the kinetics of methanol electro-oxidation on CNT supported Pt-Ru alloy nanoparticles. Alloy catalysts with different compositions, Pt53Ru47/CNT, Pt69Ru31/CNT and Pt77Ru23/CNT, were prepared and investigated in detail. Experiments were conducted at various temperatures, electrode potentials, and methanol concentrations. It was found that the reaction order of methanol electro-oxidation on the PtRu/CNT catalysts was consistent with what has been reported for PtRu alloys with a value of 0.5 in methanol concentrations. However, the electro-oxidation reaction on the PtRu/CNT catalysts displayed much lower activation energies than that on the Pt-Ru alloy catalysts unsupported or supported on carbon black (PtRu/CB. This study provides an overall kinetic evaluation of the PtRu/CNT catalysts and further demonstrates the beneficial role of CNTs.

  7. Ánodos de Pt-Ru y Pt-Ir para Celdas de Combustible Alimentadas con Metano y Propano Directo Pt-Ru and Pt-Ir Anodes for Direct Methane and Propane Proton Exchange Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Bibian A Hoyos

    2007-01-01

    Full Text Available En este trabajo se evalúa el efecto de la temperatura en el desempeño de celdas de combustible de membrana de intercambio protónico alimentadas con metano y propano, utilizando oxígeno como alimentación en el cátodo. Para la oxidación de los combustibles en los ánodos, se probaron cinco catalizadores soportados en carbón: Pt, Pt85Ru15, Pt50Ru50, Pt90Ir10 y Pt50Ir50. Como catalizador en el cátodo se usó platino puro soportado en carbón. El desempeño de las celdas de combustible fue evaluado mediante curvas de polarización obtenidas a partir de los datos corriente-potencial. Los resultados indican que la oxidación de metano se ve favorecida a altas temperaturas sobre los catalizadores Pt90/Ir10, Pt50/Ir50 y Pt50/Ru50. A bajas temperaturas los mejores catalizadores resultaron ser Pt y Pt85/Ru15. La mezcla bimetálica Pt85/Ru15 fue la que presentó mejor desempeño para llevar a cabo la oxidación de propano a 30 °C.In this paper, the effect of temperature in the performance of proton exchange membrane fuel cells feed with methane and propane, using oxygen as feed to the cathode, is presented. For the fuel oxidation in the anodes, five carbon supported catalysts were tested: Pt, Pt85/Ru15, Pt50/Ru50, Pt90/Ir10, and Pt50/Ir50. Carbon-supported pure platinum was used as catalysts in the cathode side. The performance of the fuel cells was evaluated by polarization curves obtained from the current-potential data. Results indicate that methane oxidation is favoured at high temperatures on the Pt90/Ir10, Pt50/Ir50 and Pt50/Ru50 catalysts. At low temperatures the best catalysts were Pt and Pt85/Ru15. The Pt85/Ru15 bimetallic mixture showed the best performance to carry out propane oxidation at 30 °C.

  8. Pt-Ru Catalysts Prepared by a Modified Polyol Process for Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junmin; ZHU Fangfang; ZHANG Kunhua; LIU Weiping; GUAN Weiming

    2012-01-01

    Supported PtRu/C catalysts used in direct methanol fuel cells (DMFCs) were prepared by a new modified polyol method.Transmission electron microscopy (TEM),X-ray diffraction (XRD) and cyclic voltammograms (CVs) were carried out to characterize the morphology,composition and the electrochemical properties of the PtRu/C catalyst.The results revealed that the PtRu nanoparticles with small average particle size (≈2.5 nm),and highly dispersed on the carbon support.The PtRu/C catalyst exhibited high catalytic activity and anti-poisoned performance than that of the JM PtRu/C.It is imply that the modified polyol method is efficient for PtRu/C catalyst preparation.

  9. Kinetic study of methanol oxidation on Pt2Ru3/C catalyst in the alkaline media

    Directory of Open Access Journals (Sweden)

    A. V. TRIPKOVIC

    2007-11-01

    Full Text Available The interaction of acridine orange (AO with double-stranded (ds The electrochemical oxidation of methanol in NaOH solution was examined on a thin film Pt2Ru3/C electrode. The XRD pattern revealed that the Pt2Ru3 alloy consisted of a solid solution of Ru in Pt and a small amount of Ru or a solid solution of Pt in Ru. It was shown that in alkaline solution, the difference in activity between Pt/C and Pt2Ru3/C is significantly smaller than in acid solution. It is proposed that the reaction follows a quasi bifunctional mechanism. The kinetic parameters indicated that the chemical reaction between adsorbed COad and OHad species could be the rate limiting step.

  10. The formation mechanism of bimetallic PtRu alloy nanoparticles in solvothermal synthesis.

    Science.gov (United States)

    Mi, Jian-Li; Nørby, Peter; Bremholm, Martin; Becker, Jacob; Iversen, Bo B

    2015-10-21

    An understanding of the nucleation and growth mechanism of bimetallic nanoparticles in solvothermal synthesis is important for further development of nanoparticles with tailored nanostructures and properties. Here the formation of PtRu alloy nanoparticles in a solvothermal synthesis using metal acetylacetonate salts as precursors and ethanol as both the solvent and reducing agent has been studied by in situ synchrotron radiation powder X-ray diffraction (SR-PXRD). Unlike the classical mechanism for the synthesis of monodisperse sols, the nucleation and growth processes of bimetallic PtRu nanoparticles occur simultaneously under solvothermal conditions. In the literature co-reduction of Pt and Ru is often assumed to be required to form PtRu bimetallic nanocrystals, but it is shown that monometallic Pt nanocrystals nucleate first and rapidly grow to an average size of 5 nm. Subsequently, the PtRu bimetallic alloy is formed in the second nucleation stage through a surface nucleation mechanism related to the reduction of Ru. The calculated average crystallite size of the resulting PtRu nanocrystals is smaller than that of the primary Pt nanocrystals due to the large disorder in the PtRu alloyed structure.

  11. PtRu colloid nanoparticles for CO oxidation in microfabricated reactors

    DEFF Research Database (Denmark)

    Klerke, Asbjørn; Saadi, Souheil; Toftegaard, Maja Bøg

    2006-01-01

    The catalytic activity of PtRu colloid nanoparticles for CO oxidation is investigated in microfabricated reactors. The measured catalytic performance describes a volcano curve as a function of the Pt/Ru ratio. The apparent activation energies for the different alloy catalysts are between 21 and 117...

  12. The electrocatalytic properties of carbon supported PtRu/C nanoalloys in oxidation of small organic molecules: Comparison with Pt/C catalyst

    Directory of Open Access Journals (Sweden)

    Lović Jelena D.

    2012-01-01

    Full Text Available The electrocatalytic activity of carbon supported PtRu/C catalysts, with different composition, toward the electrooxidation of methanol, CO and formic acid were examined in acid and alkaline solution at ambient temperature using thin-film rotating disk electrode (RDE method and compared with activity of Pt/C. The catalysts were characterized by XRD, AFM and STM techniques. XRD pattern revealed that PtRu-1/C catalyst is consisted of two structures e.g. Pt-Ru-fcc and Ru-hcp (the solid solution of Ru in Pt and the small amount of Ru or solid solution of Pt in Ru, as opposed to PtRu-2/C catalyst which is consisted of one structure mostly, Pt-Ru-fcc. According to STM images, PtRu as well as Pt, particles size were between 2 and 6 nm, which is in a good agreement with the mean particles size determined by XRD. To establish the activity and stability of the catalysts potentiodynamic and quasi steady-state measurements were performed. It was found that the activity of Pt and PtRu for CO and methanol oxidation is a strong function of pH of solution. The kinetics are much higher in alkaline than in acid solution and the difference between Pt/C and PtRu/C is much less pronounced in alkaline media. Results presented in this work indicate that activity of PtRu catalysts depends on catalyst composition, e.g. on Pt/Ru atomic ratio, as well as on alloying degree of catalysts. Comparison of CO, methanol and formic acid oxidation on PtRu-2/C, PtRu-1/C and Pt/C catalysts revealed that PtRu-2/C is the most active one. It was shown that the PtRu-2/C catalyst, due to fact that it is consisted of only one phase, with high alloying degree, through the bifunctional mechanism improved by electronic effect, achieve the activity two times higher related to PtRu-1/C in the oxidation of all organic molecules investigated, and about three times higher compared to Pt/C in the oxidation of methanol and CO, and five times higher in formic acid oxidation.

  13. First-principles study of phase equilibria in Cu-Pt-Rh disordered alloys.

    Science.gov (United States)

    Yuge, Koretaka

    2009-10-14

    Phase stability of Cu-Pt-Rh ternary disordered alloys is examined by a combination of cluster expansion techniques and Monte Carlo statistical simulation based on first-principles calculation. The sign of pseudo-binary ECIs indicates that neighboring Cu and Pt strongly prefer unlike-atom pairs, Pt and Rh weakly prefer unlike-atom pairs, and Cu and Rh atoms prefer like-atom pairs, indicating that the ternary alloy retains the ordering tendency of the constituent binary alloys. The formation energy of a random alloy at T = 1200 K exhibits a negative sign for a wide range of Pt-rich compositions, while at Pt-poor compositions of x≤0.25, the formation energy has a positive value. Calculated affinities for the random alloy show the variety of energetically favored bonds for the alloy: Cu-Pt bonds in both first-and second-nearest neighbor (1-NN and 2-NN) are energetically preferred for all the composition range, the Pt-Rh bond in 1-NN is preferred at Pt-rich compositions, the Pt-Rh in 2-NN and Rh-Cu in 1-NN bonds are unfavored for all compositions, and the Rh-Cu bond in 2-NN is unfavored for Pt-poor compositions. We elucidate that the ordering tendency of 1-NN and 2-NN Cu-Pt, 2-NN Pt-Rh and 1-NN Cu-Rh atoms in constituent binary alloys is retained for the whole composition range of Cu-Pt-Rh ternary alloys, while that of 1-NN Pt-Rh and 2-NN Cu-Rh atoms significantly depends on composition.

  14. Cyclic-Oxidation Behavior of Multilayered Pt/Ru-Modified Aluminide Coating

    Institute of Scientific and Technical Information of China (English)

    Yingxue Song; Hideyuki Murakami; Chungen Zhou

    2011-01-01

    Multilayered Pt/Ru modified aluminide coating for thermal barrier coating (TBC) systems has been investigated. 2 μm Pt+2μm Ru+2 μm Pt was first deposited on nickel-base superalloy DZ125 by electrodeposition, and then the coating was treated by annealing and a conventional pack-cementation aluminizing process. The cyclic oxidation tests were carried out at 1423 K in air. It was found that the thermal cyclic oxidation resistance of Pt/Ru-modified aluminide coating was comparable to that of Pt-modified aluminide coating, which was much better than simply aluminized DZ125. The addition of Ru to Pt-modified aluminide coating increased the resistance to rumpling. The microstructures and phase constitutions of the coating before and after oxidation were investigated.

  15. PtRu/C Electrocatalysts Prepared Using Gamma and Electron Beam Irradiation for Methanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Dionisio F. Silva

    2012-01-01

    Full Text Available PtRu/C electrocatalysts (carbon-supported PtRu nanoparticles were prepared in a single step submitting water/2-propanol mixtures containing Pt(IV and Ru(III ions and the carbon support to gamma and electron beam irradiation. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX, X-ray diffraction (XRD, transmission electron microscopy (TEM, and cyclic voltammetry and tested for methanol electrooxidation. PtRu/C electrocatalyst can be prepared in few minutes using high dose rate electron beam irradiation while using low dose rate gamma irradiation some hours were necessary to prepare it. The obtained materials showed the face-centered cubic (fcc structure of Pt and Pt alloys with average nanoparticle sizes of around 3 nm. The material prepared using electron beam irradiation was more active for methanol electrooxidation than the material prepared using gamma irradiation.

  16. Co-catalytic effect of Rh and Ru for the ethanol electro-oxidation in amorphous microparticulated alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Tamara C.; Pierna, Angel R.; Barroso, Javier [Dpto. de Ingenieria Quimica y del Medio Ambiente, Universidad del Pais Vasco, San Sebastian (Spain)

    2011-11-15

    The ethanol electro-oxidation on platinum catalyst in acid media leads to the formation of acetaldehyde and acetic acid as main products. Another problem is the poisoning of the electro-catalyst surface with CO formed during the fuel oxidation reaction. To increase the performance of Direct Ethanol Fuel Cells (DEFCs) it is necessary to develop new electrode materials or modification of the existing Pt catalysts. This work presents the electrochemical response to ethanol and CO oxidation of different compositional amorphous alloys obtained by ball milling technique, used as electrodes. Alloys with Ni{sub 59}Nb{sub 40}Pt{sub 0.6}Rh{sub 0.4} and Ni{sub 59}Nb{sub 40}Pt{sub 0.6}Rh{sub 0.2}Ru{sub 0.2} composi-tions were studied. The current density towards ethanol oxidation decreases with the presence of ruthenium; however, this electrode shows the best tolerance to CO, with lower surface coverage (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Theoretical investigation of water formation on Rh and Pt Surfaces

    Science.gov (United States)

    Wilke, Steffen; Natoli, Vincent; Cohen, Morrel H.

    2000-06-01

    Catalytic water formation from adsorbed H and O adatoms is a fundamental reaction step in a variety of technologically important reactions involving organic molecules. In particular, the water-formation rate determines the selectivity of the catalytic partial oxidation of methane to syngas. In this report we present a theoretical investigation of the potential-energy diagram for water formation from adsorbed O and H species on Rh(111) and Pt(111) surfaces. The study is based on accurate first-principles calculations applying density-functional theory. Our results are compared to the potential-energy diagram for this reaction inferred from experimental data by Hickman and Schmidt [AIChE. J. 39, 1164 (1993)]. The calculations essentially reproduce the scheme of Hickman and Schmidt for water formation on Rh(111) with the important difference that the OH molecule is significantly more stable than assumed by Hickman and Schmidt. On Pt(111) surfaces, however, the calculations predict a barrier to OH formation very similar to that found on Rh(111). In particular, the calculated barrier to OH formation of about 20 kcal/mol seems to contradict the small 2.5 kcal/mol barrier assumed in the Hickman-Schmidt scheme and the observed large rate of water formation on Pt. A possible explanation for the apparent discrepancy between the large calculated barrier for OH formation on Pt and the experimentally observed rapid formation of water even at low temperatures is that the active sites for water formation on Pt are at "defect" sites and not on the ideally flat terraces. A similar conclusion has been reached by Verheij and co-workers [Surf. Sci. 371, 100 (1997); Chem. Phys. Lett. 174, 449 (1990); Surf. Sci. 272, 276 (1991)], who did detailed experimental work on water formation on Pt surfaces. Analyzing our results, we develop an explicit picture of the interaction processes governing the formation of OH groups. This picture rationalizes the calculated weak dependence of OH

  18. Pt、Rh及Pt-Rh合金电极上氢的吸附%Hydrogen Adsorption on Pt, Rh and Pt-Rh Electrodes

    Institute of Scientific and Technical Information of China (English)

    贾梦秋; A.M.Meretskyi

    2005-01-01

    The hydrogen adsorption on Pt-Rh alloys in sulfuric acid aqueous solutions was studied by the method of cathode pulses. Hydrogen adsorption on the electrode with all ratio of alloy components (wRh = 0-100%) is well described by the Temkin logarithmic isotherm. The surface coverage by adsorbed hydrogen at the same potential is decreased with increasing content of rhodium in the system. A linear dependence of adsorption peak potential on the alloy compositions in the case of weakly bonded adsorbed hydrogen is established. Hydrogen adsorption heat as a function of surface coverage for Pt-Rh-electrodes was obtained. The shape of the current-potential curve and position of the weakly bonded hydrogen adsorption on the potential scale are all related to alloy compositions, thus can serve as the basis for the determination surface composition of alloys.

  19. A Synthetic Pseudo-Rh: NOx Reduction Activity and Electronic Structure of Pd–Ru Solid-solution Alloy Nanoparticles

    Science.gov (United States)

    Sato, Katsutoshi; Tomonaga, Hiroyuki; Yamamoto, Tomokazu; Matsumura, Syo; Zulkifli, Nor Diana Binti; Ishimoto, Takayoshi; Koyama, Michihisa; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Nagaoka, Katsutoshi

    2016-06-01

    Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd–Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions.

  20. A Synthetic Pseudo-Rh: NOx Reduction Activity and Electronic Structure of Pd-Ru Solid-solution Alloy Nanoparticles.

    Science.gov (United States)

    Sato, Katsutoshi; Tomonaga, Hiroyuki; Yamamoto, Tomokazu; Matsumura, Syo; Zulkifli, Nor Diana Binti; Ishimoto, Takayoshi; Koyama, Michihisa; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Nagaoka, Katsutoshi

    2016-06-24

    Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd-Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions.

  1. Ternary Pt9RhFex Nanoscale Alloys as Highly Efficient Catalysts with Enhanced Activity and Excellent CO-Poisoning Tolerance for Ethanol Oxidation.

    Science.gov (United States)

    Wang, Peng; Yin, Shibin; Wen, Ying; Tian, Zhiqun; Wang, Ningzhang; Key, Julian; Wang, Shuangbao; Shen, Pei Kang

    2017-03-22

    To address the problems of high cost and poor stability of anode catalysts in direct ethanol fuel cells (DEFCs), ternary nanoparticles Pt9RhFex (x = 1, 3, 5, 7, and 9) supported on carbon powders (XC-72R) have been synthesized via a facile method involving reduction by sodium borohydride followed by thermal annealing in N2 at ambient pressure. The catalysts are physically characterized by X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy, and their catalytic performance for the ethanol oxidation reaction (EOR) is evaluated by cyclic and linear scan voltammetry, CO-stripping voltammograms, and chronopotentiometry. All the Pt9RhFex/C catalysts of different atomic ratios produce high EOR catalytic activity. The catalyst of atomic ratio composition 9:1:3 (Pt/Rh/Fe) has the highest activity and excellent CO-poisoning tolerance. Moreover, the enhanced EOR catalytic activity on Pt9RhFe3/C when compared to Pt9Rh/C, Pt3Fe/C, and Pt/C clearly demonstrates the presence of Fe improves catalytic performance. Notably, the onset potential for CO oxidation on Pt9RhFe3/C (0.271 V) is ∼55, 75, and 191 mV more negative than on Pt9Rh/C (0.326 V), Pt3Fe/C (0.346 V), and Pt/C (0.462 V), respectively, which implies the presence of Fe atoms dramatically improves CO-poisoning tolerance. Meanwhile, compared to the commercial PtRu/C catalyst, the peak potential on Pt9RhFe3/C for CO oxidation was just slightly changed after several thousand cycles, which shows high stability against the potential cycling. The possible mechanism by which Fe and Rh atoms facilitate the observed enhanced performance is also considered herein, and we conclude Pt9RhFe3/C offers a promising anode catalyst for direct ethanol fuel cells.

  2. EXAFS Peaks and TPR Characterizing Bimetallic Interactions: Effects of Impregnation Methods on the Structure of Pt-Ru/C Catalysts

    Directory of Open Access Journals (Sweden)

    Nan-Yu Chen

    2014-01-01

    Full Text Available To investigate bimetallic interactions, Pt-Ru/C catalysts were prepared by coimpregnation (Pt-Ruco/C and successive impregnation (Ru-Ptse/C, while Pt/C, Ru/C, and reduced Pt-Rublack were used as reference. Those samples were characterized by XAS and TPR. When Pt(absorber-Ru(backscatter phase-and-amplitude correction is applied to Fourier transformed (FT EXAFS of Pt-Rublack at Pt edge, the characteristic peak of Pt-Ru interactions appears at 2.70 Å´, whereas, when Pt-Pt correction is applied, the peak appears at about 2.5 Å´. Detailed EXAFS analysis for Pt-Ruco/C and Pt-Ruse/C confirms the nature of the characteristic peak and further indicates that the interactions can semiquantitatively be determined by the relative intensity between Pt-Ru and Pt-Pt characteristic peaks. This simple method in determining bimetallic interaction can be extended to characterize Pt-Pd/γ-Al2O3. However, for Pt-Re/γ-Al2O3, Pt-Re interactions cannot be determined by the method because of the overlap of Pt-Pt and Pt-Re characteristic peaks due to similar phase functions.

  3. Synthesis of nanostructured lean-NO x catalysts by direct laser deposition of monometallic Pt-, Rh- and bimetallic PtRh-nanoparticles on SiO2 support

    Science.gov (United States)

    Savastenko, N.; Volpp, H.-R.; Gerlach, O.; Strehlau, W.

    2008-02-01

    Monometallic Pt and Rh and bimetallic PtRh catalysts with a highly dispersed noble metal weight loading of ca. 1 wt% were produced via the direct deposition of nanoparticles on different SiO2 supports by means of pulsed ultra-violet (248 nm) excimer laser ablation of Pt, Rh bulk metal and PtRh alloy targets. Backscattered electron microscopy (BSE), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were employed to characterize the deposited nanoparticles, which were found to exhibit narrow size distribution centred around 2.5 nm. The catalytic activities for lean NO x reduction of the monometallic and bimetallic catalyst samples were investigated in a flow reactor setup in the temperature range 100-400°C using a test gas mixture representative of oxygen rich diesel engine exhaust gas. For comparison a Rh/SiO2 reference catalyst prepared by a conventional impregnation method was also tested. Further experiments were performed in which PtRh nanoparticles were deposited on a Rh/SiO2 reference catalyst sample to study the possibility for controlled modification of its activity. The catalytic activity measurements revealed that among the samples solely prepared by laser deposition the PtRh-SiO2 nanoparticle catalyst showed the highest activity for NO x reduction at low temperatures 100-300°C. In addition, it could be demonstrated that the initially low NO x reduction activity and the N2 selectivity of the Rh/SiO2 reference catalyst sample for temperatures below 250°C can be enhanced by post laser deposition of PtRh nanoparticles.

  4. Electrochemical activation of nanostructured carbon-supported PtRuMo electrocatalyst for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Huerta, M.V., E-mail: mmartinez@icp.csic.e [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Tsiouvaras, N.; Pena, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Rodriguez, J.L.; Pastor, E. [Departamento de Quimica Fisica, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, 38071 Tenerife (Spain)

    2010-11-01

    The factors controlling the behavior and the stability of electrocatalysts based on Pt, Ru and Mo nanoparticles during exhaustive electrochemical treatment are examined. Along this treatment, it has been observed that in the case of ternary catalysts there are pronounced changes in the structure of their surface resulting in electrode activation for methanol and CO electrooxidation, whereas the activity of binary PtRu/C and PtMo/C catalysts decreases. Therefore, the role of both Ru and Mo is crucial for the electrochemical activation of the catalyst, though metal losses do occur during electrochemical process. For the first time a detailed study of this phenomenon is presented, including characterization by HRTEM, TXRF, XRD, electrochemical measurements and in situ Fourier transform infrared spectroscopy (FTIR). In order to get a deeper insight into the surface structure, chemical state, and stability of the electrocatalyst under reaction conditions, a combination of cyclic voltammetry, chronoamperometry and X-ray photoelectron spectroscopy (XPS) has been used. By comparing bulk and surface composition, our results point out to the key role of the geometric effect enhanced by previous reduction of the nanoparticles. At the end of the electrochemical treatment, Mo-PtRu/C catalysts surface was restructured with substantial enrichment in Pt and a less pronounced Mo surface enrichment, while Ru is incorporated into the Pt-Mo overlayer. These results underline the possibility of further optimization of the surface structure and composition producing PtRuMo nanoparticles with high methanol and CO oxidation activity.

  5. Decay of the neutron-rich isotope {sup 113}Ru to {sup 113}Rh

    Energy Technology Data Exchange (ETDEWEB)

    Kurpeta, J.; Plochocki, A. [Institute of Experimental Physics, Warsaw University (Poland); Lhersonneau, G.; Wang, J.C.; Dendooven, P.; Honkanen, A.; Huhta, M.; Oinonen, M.; Penttilae, H.; Peraejaervi, K.; Persson, J.R. [Department of Physics, University of Jyvaeskylae (Finland); Aeystoe, J. [Department of Physics, University of Jyvaeskylae (Finland); EP-ISOLDE, CERN, Geneva (Switzerland)

    2002-04-01

    The decay of neutron-rich isotope {sup 113}Ru obtained as on-line mass separated product of proton-induced fission has been investigated by {gamma}{gamma} coincidence and spectrum multiscaling measurements. Decay schemes for both low- and high-spin isomers of {sup 113}Ru have been constructed. The level scheme of {sup 113}Rh is considerably extended. Systematics of the lowest-lying rhodium levels is smooth. The picture of shape coexistence established for neutron-rich Rh isotopes near-neutron midshell is confirmed with the observation of a K=1/2 deformed band, with its 3/2{sup +} state at 600 keV being the lowest-lying level and of probable 7/2{sup +} and 5/2{sup +} band members. A large fraction of {beta} feeding is found to populate high-lying levels in {sup 113}Rh. The GT strength in {sup 113}Ru{sup m} decay is significantly larger than for the decay of {sup 113}Ru{sub g} and of lighter rhodium isotopes. (orig.)

  6. The role of surface Pt on the coadsorption of hydrogen and CO on Pt monolayer film modified Ru(0001) surfaces

    Science.gov (United States)

    Diemant, T.; Hartmann, H.; Bansmann, J.; Behm, R. J.

    2016-10-01

    We have investigated the impact and role of the Pt surface modification on the coadsorption of hydrogen and CO on structurally well defined bimetallic Pt monolayer island/film modified Ru(0001) surfaces with Pt contents up to a complete Pt layer, employing temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRRAS). Kinetic limitations in the surface diffusion are shown to play an important role for adsorption at 90 K, and lead to profound effects of the dosing sequence on the adsorption and desorption characteristics. Furthermore, they are responsible for spill-over effects during the TPD measurements, where COad becomes mobile and can spill-over from weakly bonding Pt monolayer areas to strongly bonding Pt-free Ru(0001) areas, which displaces Dad from these surface areas. The present findings are discussed in comparison with previous results on related metallic and bimetallic adsorption and coadsorption systems.

  7. Evaluation of nanostructured Pt-Ru catalyst for application in DMFC

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo, A.L.; Gamboa, S.A. [Centro de Investigacion en Energia-UNAM, Morelos (Mexico); Sebastien, P.J. [Centro de Investigacion en Energia-UNAM, Morelos (Mexico)]|[Chiapas Politecnica Univ., Chiapas (Mexico); Morgado, J.; Montoya, J.A. [IMP, Eje Central Lazaro Cardenas, (Mexico); Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratoire d' electrochimie et de materiaux energetiques

    2006-07-01

    Slow methanol oxidation kinetics and the poisoning of the anode catalyst are the major factors that limit the performance of the direct methanol fuel cell (DMFC). Catalysts with higher catalytic activity are needed in order to overcome these challenges. Although platinum (Pt) is a good catalyst for methanol oxidation, it can be highly affected by carbon monoxide (CO) reaction intermediates. Superior catalytic activity occurs in Pt based alloys, such as platinum ruthenium (Pt-Ru), platinum molybdenum (Pt-Mo), platinum tin (Pt-Sn), and platinum osmium (Pt-Os). This is due to the bifunctional mechanism and/or by the electronic effect, which indicates a promotional effect of the alloyed metal on Pt. The most studied binary system is the Pt-Ru (ruthenium), which has shown the best catalytic activity. There are many factors that influence the physical properties and the electrochemical performance of the Pt-Ru catalyst. These include the preparation method; the atomic ratio between platinum and ruthenium; the nature of the catalyst support; and, an optional heat treatment. Other important factors such as the particle size, the morphology, the electrochemically active area, and the crystalline phase influence the physical properties. In this study, nanostructured Pt-Ru catalysts were fabricated and evaluated physicochemically and electrochemically for its use in direct methanol fuel cell (DMFC). The catalysts were synthesized from the carbonyl compounds of Pt and Ru via a pyrolysis-condensation reaction. The high resolution results showed a homogenous distribution of the nanostructured catalysts on Vulcan support. The catalyst was evaluated by XRD, HRTEM, electrochemical impedance spectroscopy and the methanol oxidation on the catalyst was studied using volt-amperometry. The performance of the catalyst was found to be similar or better than the commercial one. It was concluded that it is possible to synthesize Pt-Ru/C with good morphological characteristics and improve it

  8. Technical Note: Monte Carlo study of (106) Ru/(106) Rh ophthalmic plaques including the (106) Rh gamma spectrum.

    Science.gov (United States)

    Hermida-López, Marcelino; Brualla, Lorenzo

    2017-06-01

    To assess the influence of the (106) Rh gamma spectrum on the Monte Carlo simulation of (106) Ru/(106) Rh ophthalmic plaques, which has been neglected without a quantitative estimation in all previous publications. Simulations were run with the penelope 2014 Monte Carlo code for radiation transport. Depth-dose distributions in water were simulated for the plaque models CCA, CCC, CCX and CIA. In addition to the (106) Rh beta spectrum, all gamma components from the (106) Rh gamma spectrum were included in the simulations. Depth-dose curves were compared with those obtained without considering the (106) Rh gamma spectrum. Moreover, half-value (HVL) and tenth-value layers (TVL) were estimated for the (106) Rh gamma spectrum in water, PMMA, stainless steel and lead. Some practical radiation protection applications were discussed. Parallel computing was implemented to reduce computing time. The contribution of the (106) Rh gamma spectrum on the depth-dose curves is negligible at depths of clinical interest. The HVL and TVL of the (106) Rh gamma spectrum were found to be similar to those of (137) Cs. The air-kerma rate at 1 m for a CCA plaque in typical clinical conditions was about 0.4μGym2h-1, resulting in equivalent doses at that point elow 0.05 mSv during a treatment. The air-kerma rate would be underestimated by a factor of 5 if the (106) Rh gamma spectrum were not considered. Also, a freely available software tool was developed to ease parallelization of penelope 2014 simulations that use penmain as steering main program. The influence of the (106) Rh gamma spectrum is not relevant for clinical purposes, thus validating the common assumption from the literature. However, for simulations at large distances from the plaques, such as for radiation shielding assessment and estimation of dose to personnel, the gamma spectrum from (106) Rh must be taken into account to obtain accurate results. © 2017 American Association of Physicists in Medicine.

  9. H2-splitting on Pt/Ru alloys supported on sputtered HOPG

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Dahl, Søren; Chorkendorff, Ib

    2011-01-01

    that alloying Pt with Ru improves significantly the resistance toward CO poisoning with respect to pure Pt, and the resistance increases with an increasing amount of Ru in the bulk alloys. The faster hydrogen exchange rate with respect to the pure metals and the higher CO tolerance of the alloys are attributed......, and it is attributed to geometrical ensemble effects. © 2011 American Chemical Society....

  10. Synthesis and Electrocatalytic Performance of Multi-Component Nanoporous PtRuCuW Alloy for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Xiaoting Chen

    2015-06-01

    Full Text Available We have prepared a multi-component nanoporous PtRuCuW (np-PtRuCuW electrocatalyst via a combined chemical dealloying and mechanical alloying process. The X-ray diffraction (XRD, transmission electron microscopy (TEM and electrochemical measurements have been applied to characterize the microstructure and electrocatalytic activities of the np-PtRuCuW. The np-PtRuCuW catalyst has a unique three-dimensional bi-continuous ligament structure and the length scale is 2.0 ± 0.3 nm. The np-PtRuCuW catalyst shows a relatively high level of activity normalized to mass (467.1 mA mgPt−1 and electrochemically active surface area (1.8 mA cm−2 compared to the state-of-the-art commercial PtC and PtRu catalyst at anode. Although the CO stripping peak of np-PtRuCuW 0.47 V (vs. saturated calomel electrode, SCE is more positive than PtRu, there is a 200 mV negative shift compared to PtC (0.67 V vs. SCE. In addition, the half-wave potential and specific activity towards oxygen reduction of np-PtRuCuW are 0.877 V (vs. reversible hydrogen electrode, RHE and 0.26 mA cm−2, indicating a great enhancement towards oxygen reduction than the commercial PtC.

  11. Co oxidation on spontaneous Pt-Ru deposits on composite polymeric electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Bavio, M.A.; Kessler, T. [Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad Nacional del Centro de la Provincia de Buenos Aires, Av. del Valle 5737, B7400JWI, Olavarria (Argentina); Castro Luna, A.M. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas, INIFTA, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Diagonal 113 y 64, 1900, La Plata (Argentina)

    2010-06-15

    Composite polyaniline electrodes containing carbon nanotubes incorporated in the film and spontaneous Pt-Ru deposits as catalytic material for CO oxidation are reported. PANI films were electrosynthesized from a monomer acid solution with the addition of carbon nanotubes. Then, Pt-Ru deposits were obtained by immersing the polymeric film in H{sub 2}PtCl{sub 6} and/or RuCl{sub 3} in HCl. Three series of deposits were prepared by either immersion in a solution containing both metallic ions during a fixed time or successive immersion in different solutions containing only one of the metallic ions during half of the established time and varying the sequence as follows: (i) first in H{sub 2}PtCl{sub 6} and then in RuCl{sub 3} or (ii) first in RuCl{sub 3} and then in H{sub 2}PtCl{sub 6}. Adsorbed CO oxidation was studied by cyclic voltammetry in H{sub 2}SO{sub 4} solution. The electrodes were characterized through SEM and EDX. The different ways to obtain spontaneous Pt-Ru deposits are analyzed and their influence on CO oxidation is discussed. (author)

  12. Structure of Pt/C and PtRu/C catalytic layers prepared by plasma sputtering and electric performance in direct methanol fuel cells (DMFC)

    Energy Technology Data Exchange (ETDEWEB)

    Caillard, A.; Brault, P.; Mathias, J. [Groupe de Recherche sur l' Energetique des Milieux Ionises, UMR6606 Universite d' Orleans, CNRS, Polytech' Orleans BP6744, F-45067 Orleans Cedex 2 (France); Coutanceau, C.; Leger, J.-M. [Laboratoire de Catalyse en Chimie Organique, UMR6503 Universite de Poitiers, CNRS, F-86022 Poitiers (France)

    2006-11-08

    Plasma sputtering process was used to deposit Pt and PtRu on conductive carbon diffusion layer. Low metal loading catalysts for methanol electrooxidation were prepared and characterized by TEM and XRD. The main result is that codeposition of Pt and Ru leads to alloy phase, whereas multi-layers deposition leads to no-alloyed structure. The electrochemical performance of sputtered Pt/C electrodes was compared with that of standard electrodes, and was found lower. However, the specific activity was much higher, indicating that the catalyst utilization efficiency was higher than that obtained with a standard electrode. Then, different bimetallic PtRu/C electrodes were prepared by plasma sputtering, leading to different catalyst structures (Pt and Ru multilayer deposition or simultaneous deposition of Pt and Ru) and composition (from 100:0 to 50:50 Pt/Ru atomic ratios). At last, the different PtRu electrodes were compared in term of DMFC electrical performance. The best efficiency of the DMFC was reached when both metals Pt and Ru are simultaneously deposited (alloyed) with a ruthenium atomic ratio of 30% or 40 % Ru depending of the working potentials of the cell. (author)

  13. Strong interlayer exchange coupling and high post-annealing stability in perpendicularly magnetized [Pt/Co]/Ru/[Co/Pt] structures

    Directory of Open Access Journals (Sweden)

    Seok Jin Yun

    2016-02-01

    Full Text Available Strong interlayer exchange coupling (IEC and high post-annealing stability are demonstrated for perpendicular synthetic ferrimagnets (p-SyFs with [Pt/Co]6/Ru/[Co/Pt]3 structures. The observed IEC strength was 2.55 ergs/cm2 for a Ru thickness of 0.35 nm, representing the highest value achieved up to date for similar structures. The IEC remained strong even after annealing at 450oC, for the practically important Ru layer thickness of 0.85 nm. The biquadratic IEC, a parameter quantifying the pinhole effects in SyFs, was confirmed by analyzing the experimental results by using the total energy functional, and its strength increased with decreasing the temperature and Ru layer thickness.

  14. pH dependence of the electroreduction of nitrate on Rh and Pt polycrystalline electrodes.

    Science.gov (United States)

    Yang, Jian; Sebastian, Paula; Duca, Matteo; Hoogenboom, Thijs; Koper, Marc T M

    2014-02-28

    From a study of the electrocatalytic reduction of nitrate on Pt and Rh electrodes over a wide pH range, HNO3 is suggested as the only reducible species in nitrate reduction on Pt, whereas both HNO3 and the nitrate anion are reducible on Rh. Rh is the more active catalyst of the two because it can activate nitrate even if no protons are available in solution. This is an important insight into the development of more effective nitrate reduction catalysts.

  15. Comparative Assessment of DFT Performances in Ru- and Rh-Promoted σ-Bond Activations.

    Science.gov (United States)

    Sun, Yuanyuan; Hu, Lianrui; Chen, Hui

    2015-04-14

    In this work, the performances of 19 density functional theory (DFT) methods are calibrated comparatively on Ru- and Rh-promoted σ-bond (C-H, O-H, and H-H) activations. DFT calibration reference is generated from explicitly correlated coupled cluster CCSD(T)-F12 calculations, and the 4s4p core-valence correlation effect of the two 4d platinum group transition metals is also included. Generally, the errors of DFT methods for calculating energetics of Ru-/Rh-mediated reactions appear to correlate more with the magnitude of energetics itself than other factors such as metal identity. For activation energy calculations, the best performing functionals for both Ru and Rh systems are MN12SX DFT empirical dispersion correction on the performance of the DFT methods is beneficial for most density functionals tested in this work, reducing their MUDs to different extents. After including empirical dispersion correction, ωB97XD, B3LYP-D3, and CAM-B3LYP-D3 (PBE0-D3, B3LYP-D3, and ωB97XD) are the three best performing DFs for activation energy (reaction energy) calculations, from which B3LYP-D3 and ωB97XD can notably be recommended uniformly for both the reaction energy and reaction barrier calculations. The good performance of B3LYP-D3 in quantitative description of the energetic trends further adds value to B3LYP-D3 and singles this functional out as a reasonable choice in the Ru/Rh-promoted σ-bond activation processes.

  16. Electrooxidation of ethanol on Pt and PtRu surfaces investigated by ATR surface-enhanced infrared absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcio F.; Camara, Giuseppe A., E-mail: giuseppe.silva@ufms.br [Departamento de Quimica, Universidade Federal do Mato Grosso do Sul, Campo Grande-MS (Brazil); Batista, Bruno C.; Boscheto, Emerson [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos-SP, (Brazil); Varela, Hamilton, E-mail: varela@iqsc.usp.br [Ertl Center for Electrochemistry and Catalysis, Gwangju Institute of Science and Technology (GIST), Gwangju (Korea, Republic of)

    2012-05-15

    Herein, it was investigated for the first time the electro-oxidation of ethanol on Pt and PtRu electrodeposits in acidic media by using in situ surface enhanced infrared absorption spectroscopy with attenuated total reflection (ATR-SEIRAS). The experimental setup circumvents the weak absorbance signals related to adsorbed species, usually observed for rough, electrodeposited surfaces, and allows a full description of the CO coverage with the potential for both catalysts. The dynamics of adsorption-oxidation of CO was accessed by ATR-SEIRAS experiments (involving four ethanol concentrations) and correlated with expressions derived from a simple kinetic model. Kinetic analysis suggests that the growing of the CO adsorbed layer is nor influenced by the presence of Ru neither by the concentration of ethanol. The results suggest that the C-C scission is not related to the presence of Ru and probably happens at Pt sites. (author)

  17. Large perpendicular magnetic anisotropy of ultrathin Ru and Rh films on a NiAl(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongyoo; Yang, JeongHwa; Hong, Jisang [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2010-10-27

    Using the full potential linearized augmented plane wave (FLAPW) method, the magnetic properties of two-dimensional Ru and Rh monolayers (MLs) on a NiAl(001) surface have been investigated. It has been found that free standing one monolayer Ru and Rh films have ferromagnetic ground state with magnetic moments of 2.21 and 1.48 {mu}{sub B}, respectively. The ferromagnetism is still observed even on a Ni terminated NiAl(001) surface, while no magnetic state is found on an Al terminated surface. The calculated magnetic moments of Ru and Rh atoms are 1.56 and 0.88 {mu}{sub B}, respectively. In addition, an induced magnetic moment in surface Ni is observed. It has been found that the free standing Ru film has perpendicular magnetization to the film surface with a magnetocrystalline anisotropy (MCA) energy of 0.66 meV/atom, while an in-plane MCA energy of 0.37 meV/atom is achieved in Rh film. Very interestingly, we find that both Ru/NiAl(001) and Rh/NiAl(001) films have perpendicular magnetic anisotropy and the calculated MCA energies are 0.66 and 1.11 meV in Ru/NiAl(001) and Rh/NiAl(001), respectively. Along with the magnetic anisotropy, we have presented theoretically calculated x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) results.

  18. Large perpendicular magnetic anisotropy of ultrathin Ru and Rh films on a NiAl(001) surface.

    Science.gov (United States)

    Kim, DongYoo; Yang, JeongHwa; Hong, Jisang

    2010-10-27

    Using the full potential linearized augmented plane wave (FLAPW) method, the magnetic properties of two-dimensional Ru and Rh monolayers (MLs) on a NiAl(001) surface have been investigated. It has been found that free standing one monolayer Ru and Rh films have ferromagnetic ground state with magnetic moments of 2.21 and 1.48 μ(B), respectively. The ferromagnetism is still observed even on a Ni terminated NiAl(001) surface, while no magnetic state is found on an Al terminated surface. The calculated magnetic moments of Ru and Rh atoms are 1.56 and 0.88 μ(B), respectively. In addition, an induced magnetic moment in surface Ni is observed. It has been found that the free standing Ru film has perpendicular magnetization to the film surface with a magnetocrystalline anisotropy (MCA) energy of 0.66 meV/atom, while an in-plane MCA energy of 0.37 meV/atom is achieved in Rh film. Very interestingly, we find that both Ru/NiAl(001) and Rh/NiAl(001) films have perpendicular magnetic anisotropy and the calculated MCA energies are 0.66 and 1.11 meV in Ru/NiAl(001) and Rh/NiAl(001), respectively. Along with the magnetic anisotropy, we have presented theoretically calculated x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) results.

  19. Synthesis of PtRu nanoparticles from the hydrosilylation reaction and application as catalyst for direct methanol fuel cell.

    Science.gov (United States)

    Huang, Junchao; Liu, Zhaolin; He, Chaobin; Gan, Leong Ming

    2005-09-08

    Nanosized Pt, PtRu, and Ru particles were prepared by a novel process, the hydrosilylation reaction. The hydrosilylation reaction is an effective method of preparation not only for Pt particles but also for other metal colloids, such as Ru. Vulcan XC-72 was selected as catalyst support for Pt, PtRu, and Ru colloids, and TEM investigations showed nanoscale particles and narrow size distribution for both supported and unsupported metals. All Pt and Pt-rich catalysts showed the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Ru and Ru-rich alloys were more typical of a hexagonal close-packed (hcp) structure. As evidenced by XPS, most Pt and Ru atoms in the nanoparticles were zerovalent, except a trace of oxidation-state metals. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results concluded that some alloy catalysts showed higher catalytic activities and better CO tolerance than the Pt-only catalyst; Pt56Ru44/C have displayed the best electrocatalytic performance among all carbon-supported catalysts.

  20. The microstructure and magnetic properties of electrodeposited Co-Pt thin films on Ru buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, G.H. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)], E-mail: skk94@skku.edu; Lee, C.H.; Jang, J.H. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, N.J. [Department of Materials Science and Engineering, Kumoh National University of Technology, Kumi 730-701 (Korea, Republic of); Suh, S.J. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Advanced Materials and Process Research Center for IT, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2008-11-15

    For high-density magnetic recording media, this study examined the crystal structure and the texture of electrodeposited cobalt-platinum (Co-Pt) films on Ru buffer layer. A 15-nm-thick Co-Pt film exhibited very high out-of-plane coercivity and squareness, which were 6248 Oe and 0.89, respectively. The coercivity, H{sub c}, of Co-Pt films grown on Ru buffer layer decreased significantly with increasing thickness, possibly due to the lattice misfit of 5.4% between Co-Pt and Ru, leading to the decrease of perpendicular magnetic anisotropy (PMA) of Co-Pt films as indicated by the observed hexagonal-closed-packed (HCP) (1 1-bar 0 1) plane of Co-Pt films. According to nano beam diffraction pattern (NBDP), however, Co-Pt film grown on Ru layer of HCP exhibited mixed HCP and FCC phases. Also, cross-sectional TEM image suggests that the high PMA may result from the columnar structure of physically isolated Co-Pt grains with the c-axis perpendicular to the film plane.

  1. Supported PtRu on mesoporous carbons for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Arbizzani, Catia; Beninati, Sabina; Soavi, Francesca; Varzi, Alberto; Mastragostino, Marina [University of Bologna, Department of Metal Science, Electrochemistry and Chemical Techniques, via San Donato 15, 40127 Bologna (Italy)

    2008-12-01

    We prepared and characterized several cryogel mesoporous carbons of different pore size distribution and report the catalytic activity of PtRu supported on mesoporous carbons of pore size >15 nm in passive and in active direct methanol fuel cells (DMFCs). At room temperature (RT), the specific maximum power of the passive DMFCs with mesoporous carbon/PtRu systems as anode was in the range 3-5 W g{sup -1}. Passive DMFC assembly and RT tests limit the performance of the electrocatalytic systems and the anodes were thus tested in active DMFCs at 30, 60 and 80 C. Their responses were also compared to those of commercial Vulcan carbon/PtRu. At 80 C, the specific maximum power of the active DMFC with C656/PtRu was 37 W g{sup -1} and the required amount of Pt per kW estimated at 0.4 V cell voltage was 31 g kW{sup -1}, a value less than half that of Vulcan carbon/PtRu. (author)

  2. Study on hydrogen evolution performance of the carbon supported PtRu alloy film electrodes

    Institute of Scientific and Technical Information of China (English)

    YANG; Bin; LI; Yang; ZAN; Lin-han

    2005-01-01

    The carbon supported PtRu alloy film electrodes having Pt about 0.10 mg/cm2 or even less were prepared by ion beam sputtering method (IBSM). It was valued on the hydrogen analyse performance, the temperature influence factor and the stability by electroanalysis hydrogen analyse method. It was found that the carbon supported PtRu alloy film electrodes had higher hydrogen evolution performance and stability, such as the hydrogen evolution exchange current density (j0) was increase as the temperature (T) rised, and it overrun 150 mA/cm2 as the trough voltage in about 0.68V, and it only had about 2.8% decline in 500 h electrolytic process. The results demonstrated that the carbon supported PtRu alloy film electrodes kept highly catalytic activity and stability, and it were successfully used in pilot plant for producing H2 on electrolysis of H2S.

  3. Soft Landing of Bare PtRu Nanoparticles for Electrochemical Reduction of Oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Colby, Robert J.; Engelhard, Mark H.; Moon, DaeWon; Laskin, Julia

    2015-08-07

    Magnetron sputtering of two independent Pt and Ru targets coupled with inert gas aggregation in a modified commercial source has been combined with soft landing of mass-selected ions to prepare bare 4.5 nm diameter PtRu alloy nanoparticles on glassy carbon electrodes with controlled size and morphology for electrochemical reduction of oxygen in solution. Employing atomic force microscopy (AFM) it is shown that the nanoparticles bind randomly to the glassy carbon electrode at a relatively low coverage of 7 x 104 ions µm-2 and that their average height is centered at 4 nm. Scanning transmission electron microscopy images obtained in the high-angle annular dark field mode (STEM-HAADF) further confirm that the soft-landed PtRu alloy nanoparticles are uniform in size and have a Ru core decorated with small regions of Pt on the surface. Wide-area scans of the electrodes using X-ray photoelectron spectroscopy (XPS) reveal the presence of both Pt and Ru in relative atomic concentrations of ~9% and ~33%, respectively. Deconvolution of the high energy resolution XPS spectra in the Pt4f and Ru3d regions indicates the presence of both oxidized Pt and Ru. The substantially higher loading of Ru compared to Pt and enrichment of Pt at the surface of the alloy nanoparticles is confirmed by wide-area analysis of the electrodes using time-of-flight medium energy ion scattering (TOF-MEIS) employing both 80 keV He+ and O+ ions. The activity of electrodes containing 7 x 104 ions µm-2 of bare 4.5 nm PtRu nanoparticles toward the electrochemical reduction of oxygen was evaluated employing cyclic voltammetry (CV) in 0.1 M HClO4 and 0.5 M H2SO4 solutions. In both electrolytes a pronounced reduction peak was observed during O2 purging of the solution that was not evident during purging with Ar. Repeated electrochemical cycling of the electrodes revealed little evolution in the shape or position of the voltammograms indicating high stability of the alloy nanoparticles supported on glassy

  4. Microwave-assisted synthesis and characterization of bimetallic PtRu alloy nanoparticles supported on carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rahsepar, Mansour, E-mail: rahsepar@shirazu.ac.ir [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Boulevard, Shiraz, 7134851154 (Iran, Islamic Republic of); Kim, Hasuck, E-mail: hasuckim@snu.ac.kr [Department of Chemistry, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-747 (Korea, Republic of); Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science & Technology, Daegu, 711-873 (Korea, Republic of)

    2015-11-15

    Multiwalled carbon nanotube (MWCNT) supported PtRu nanoparticles were synthesized by using a microwave-assisted improved impregnation technique. X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy were used to characterize the prepared PtRu/MWCNT nanoparticles. The PtRu nanoparticles with a satisfactory dispersion were formed on the external surface of MWCNTs. The CO stripping experiment was performed to evaluate the poisoning resistance of the prepared PtRu/MWCNT nanoparticles. Results of electrochemical measurements indicate that the prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning. The results of characterization revealed that microwave-assisted improved impregnation technique have a high yield of alloy phase formation and could be effectively used as a simple, quick and efficient technique for preparation of bimetallic PtRu/MWCNT nanoparticles. - Highlights: • Highly dispersed PtRu/MWCNTs were formed without use of any stabilizing agent. • Microwave irradiation enhances the uniform dispersion of the PtRu nanoparticles. • Microwave-assisted improved impregnation have a high yield of alloy phase formation. • The prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning.

  5. Mechanistic Investigation of the Reduction of NOx over Pt- and Rh-Based LNT Catalysts

    Directory of Open Access Journals (Sweden)

    Lukasz Kubiak

    2016-03-01

    Full Text Available The influence of the noble metals (Pt vs. Rh on the NOx storage reduction performances of lean NOx trap catalysts is here investigated by transient micro-reactor flow experiments. The study indicates a different behavior during the storage in that the Rh-based catalyst showed higher storage capacity at high temperature as compared to the Pt-containing sample, while the opposite is seen at low temperatures. It is suggested that the higher storage capacity of the Rh-containing sample at high temperature is related to the higher dispersion of Rh as compared to Pt, while the lower storage capacity of Rh-Ba/Al2O3 at low temperature is related to its poor oxidizing properties. The noble metals also affect the catalyst behavior upon reduction of the stored NOx, by decreasing the threshold temperature for the reduction of the stored NOx. The Pt-based catalyst promotes the reduction of the adsorbed NOx at lower temperatures if compared to the Rh-containing sample, due to its superior reducibility. However, Rh-based material shows higher reactivity in the NH3 decomposition significantly enhancing N2 selectivity. Moreover, formation of small amounts of N2O is observed on both Pt- and Rh-based catalyst samples only during the reduction of highly reactive NOx stored at 150 °C, where NOx is likely in the form of nitrites.

  6. Kinetic limitations in surface alloy formation: PtCu/Ru(0001)

    Science.gov (United States)

    Engstfeld, A. K.; Jung, C. K.; Behm, R. J.

    2016-01-01

    We have systematically investigated the structure and structure formation of two-dimensional PtCu monolayer surface alloys on Ru(0001) as model systems for bimetallic PtCu catalysts and surfaces by scanning tunneling microscopy (STM). The surface alloys were prepared by deposition of Pt and Cu on Ru(0001) and thermal intermixing; different procedures were developed and tested to produce bimetallic surfaces with homogeneous structure, including also a homogeneous distribution of the different surface species, while at the same time intermixing with the Ru(0001) substrate should be inhibited. STM imaging revealed that for Pt concentrations below 65% surface alloys with homogeneous distribution could be formed, while at higher concentrations in the mixed phase, up to 82%, pure Pt or Pt-rich surface areas were formed as well. At Pt contents of 0.20 0.65 line structures were observed, but of different nature. The distribution of surface atoms in the mixed phase was evaluated from STM images with chemical contrast, the related short-range order parameters were determined. The resulting structures and their energetics, the influence of different deposition and annealing procedures and the suitability of these surfaces as model systems for studies of the surface chemistry of bimetallic PtCu surfaces are discussed.

  7. Mixed phase Pt-Ru catalyst for direct methanol fuel cell anode by flame aerosol synthesis

    DEFF Research Database (Denmark)

    Chakraborty, Debasish; Bischoff, H.; Chorkendorff, Ib

    2005-01-01

    A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst......Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy. (c) 2005 The Electrochemical Society....

  8. The Effect of PtRuIr Nanoparticle Crystallinity in Electrocatalytic Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Vladimir Linkov

    2013-04-01

    Full Text Available Two structural forms of a ternary alloy PtRuIr/C catalyst, one amorphous and one highly crystalline, were synthesized and compared to determine the effect of their respective structures on their activity and stability as anodic catalysts in methanol oxidation. Characterization techniques included TEM, XRD, and EDX. Electrochemical analysis using a glassy carbon disk electrode for cyclic voltammogram and chronoamperometry were tested in a solution of 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4. Amorphous PtRuIr/C catalyst was found to have a larger electrochemical surface area, while the crystalline PtRuIr/C catalyst had both a higher activity in methanol oxidation and increased CO poisoning rate. Crystallinity of the active alloy nanoparticles has a big impact on both methanol oxidation activity and in the CO poisoning rate.

  9. Stability and ordering properties of fcc alloys based on Rh, Ir, Pd, and Pt

    Science.gov (United States)

    Turchi, P. E. A.; Drchal, V.; Kudrnovský, J.

    2006-08-01

    Stability properties and ordering trends for the six face-centered cubic binary combinations of the four transition metals Rh, Ir, Pd, and Pt are examined in the context of electronic structure calculations. The method is based on a Green’s function description of the electronic structure of random alloys. Configurational order is treated within the generalized perturbation method. On one hand, the three alloys Pd-Rh, Pd-Ir, and Pt-Ir that have been studied experimentally are confirmed to behave like phase-separating systems. On the other hand, the other three mixtures Pd-Pt, Rh-Ir, and Pt-Rh, for which phase-separating trends have been inferred from experiments, are found to display chemical order with ordering of the (1 0 0) and (11/20) family types and a mixture of both, respectively. The origin of these results is discussed in terms of electronic structure properties.

  10. Next generation nanolithography based on Ru/Be and Rh/Sr multilayer optics

    Directory of Open Access Journals (Sweden)

    N. I. Chkhalo

    2013-08-01

    Full Text Available A prospective move to 10.5 and 11.2 nm wavelengths, as an alternative to 6.7 and 13.5 nm, for next generation nanolithography is discussed. Ten-mirror optical systems based on Ru/Be, Mo/Be, Rh/Sr, Mo/Si, and La/B multilayers were compared for efficiency at their working wavelengths. It is shown that a transition to 10.5 nm and 11.2 nm may be a solution to the problem of increasing performance and resolution of a projection system.

  11. Derivation of the liquidus surface projection for the Al-Pt-Ru system from as-cast samples

    CSIR Research Space (South Africa)

    Prins, SN

    2005-11-10

    Full Text Available .% platinum. Most of the other phases showed more limited solubilities for the ternary element: similar to RuAl2, similar to Pt2Al3 and similar to PtAl contained only about 2at.% of the third component similar to Ru 4Al13 has less than 1at.% solubility...

  12. High pressure organic colloid method for the preparation of high performance carbon nanotube-supported Pt and PtRu catalysts for fuel cell applications

    Institute of Scientific and Technical Information of China (English)

    WANG; KateNing; Viola; BIRSS

    2010-01-01

    Highly dispersed,high performance Pt and PtRu catalysts,supported on multiwalled carbon nanotubes(CNTs),were prepared by a high pressure organic colloid method.The particle sizes of the active components were as small as 1.2 nm for Pt and 1.1 nm for PtRu,and the active Pt surface areas were 295 and 395 m2/g,respectively.The catalysts showed very high activities toward the anodic oxidation of methanol,evaluated by cyclic voltammetry,being up to 4 times higher than that of commercial Johnson Matthey Hispec 2000 Pt/XC-72R and 5 times better than Hispec 5000 PtRu/XC-72R catalysts.In a full air/hydrogen fuel cell,a membrane-electrode assembly prepared using our Pt/CNT and PtRu/CNT catalysts showed 50% and 100% higher performances than those prepared with commercial Johnson Matthey Pt/XC-72R and PtRu/XC-72R catalysts for the same Pt loading and operating conditions.

  13. Carbon Nanotubes Supported Pt-Ru-Ni as Methanol Electro-Oxidation Catalyst for Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    Fei Ye; Shengzhou Chen; Xinfa Dong; Weiming Lin

    2007-01-01

    Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure.The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.

  14. Insight into the Reaction Mechanisms of Methanol on PtRu/Pt(111): A Density Functional Study

    Science.gov (United States)

    Ding, Qiuyue; Xu, Wenbin; Sang, Pengpeng; Xu, Jing; Zhao, Lianming; He, Xiaoli; Guo, Wenyue

    2016-04-01

    Periodic DFT calculations have been performed to systematically investigate the mechanisms of methanol decomposition and oxidation on the PtRu/Pt(111) surface. Geometries and energies for the primary species involved are analyzed and the reaction network has been mapped out. The calculation shows that among three initial Csbnd H, Osbnd H, and Csbnd O bond scissions of methanol, the Osbnd H bond scission is found to be the most favorable and bears a lower energy barrier than the desorption of methanol. The decomposition of CH3O occurs via the path CH3O → CH2O → CHO → CO with the limiting step of the first dehydrogenation. Although the oxidation of CO is hindered by a high barrier, the CHO oxidation to CHOOH could occur facilely. Further decomposition of formic acid to CO2 and/or CO could occur via four possible pathways, that is, initial Csbnd H, Osbnd H, and Csbnd O bond activations as well as simultaneous activation of Csbnd H and Csbnd O bonds, where the first pathway, HCOOH → COOH → CO2, is the most favorable from a kinetic point of view. Compared to that on Pt(111), methanol on PtRu/Pt(111) prefers to decomposition rather than desorption and then oxidation via the favorable non-CO path with a lower rate-determining energy barrier of CH3O → CH2O for the whole reaction, which indicates that PtRu alloy can improved tolerance toward CO poisoning compared with pure Pt.

  15. Synthesis of carbon-supported PtRh random alloy nanoparticles using electron beam irradiation reduction method

    Science.gov (United States)

    Matsuura, Yoshiyuki; Seino, Satoshi; Okazaki, Tomohisa; Akita, Tomoki; Nakagawa, Takashi; Yamamoto, Takao A.

    2016-05-01

    Bimetallic nanoparticle catalysts of PtRh supported on carbon were synthesized using an electron beam irradiation reduction method. The PtRh nanoparticle catalysts were composed of particles 2-3 nm in size, which were well dispersed on the surface of the carbon support nanoparticles. Analyses of X-ray diffraction and scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy revealed that the PtRh nanoparticles have a randomly alloyed structure. The lattice constant of the PtRh nanoparticles showed good correlation with Vegard's law. These results are explained by the radiochemical formation process of the PtRh nanoparticles. Catalytic activities of PtRh/C nanoparticles for ethanol oxidation reaction were found to be higher than those obtained with Pt/C.

  16. Preparation of PtRu/C and PtSn/C electrocatalysts using electron beam irradiation for direct and ethanol fuel cell; Preparacao de eletrocatalisadores PtRu/C e PtSn/C utilizando feixe de eletrons para aplicacao como anodo na oxidacao direta de metanol e etanol em celulas a combustivel de baixa temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio Furtunato da

    2009-07-01

    PtRu/C and PtSn/C electrocatalysts were prepared using electron beam irradiation. The metal ions were dissolved in water/2-propanol and water/ethylene glycol solutions and the carbon support was added. The resulting mixtures were irradiated under stirring. The effect of water/ethylene glycol and water/2-propanol (v/v) ratio, Pt:Ru and Pt:Sn atomic ratios, the irradiation time and dose rate were studied. The obtained materials were characterized by Energy dispersive analysis of X-rays (EDX), X-ray diffraction (XRD), cyclic voltammetry (CV) and Moessbauer spectroscopy. The electro-oxidation of methanol and ethanol were studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were also tested on the Direct Methanol and Ethanol Fuel Cells. PtRu/C electrocatalysts prepared in water/ethylene glycol showed Pt:Ru atomic ratios different from the nominal ones. The results suggested that part of the Ru(III) ions were not reduced. The obtained materials showed the face-centered cubic (fcc) structure of Pt and Pt alloys with crystallite sizes of 2-3 nm. PtRu/C electrocatalysts prepared in water/2-propanol showed Pt:Ru atomic ratios similar to the nominal ones. The obtained materials also showed the fcc structure of platinum and platinum alloys with crystallite sizes of 3-4 nm. PtSn/C electrocatalysts prepared in water/ethylene glycol and water/2-propanol showed Pt:Sn atomic ratios similar to the nominal ones. The obtained materials showed the platinum (fcc) phase with crystallite sizes in the range of 2 - 4 nm and a SnO{sub 2} (cassiterite) phase. The obtained PtRu/C and PtSn/C electrocatalysts showed similar or superior performance for methanol and ethanol electro-oxidation compared to commercial PtRu/C (E-TEK) and PtSn/C (BASF) electrocatalysts. (author)

  17. Pt promotion and spill-over processes during deposition and desorption of upd-H(ad) and OH(ad) on Pt(x)Ru(1-x)/Ru(0001) surface alloys.

    Science.gov (United States)

    Hoster, Harry E; Janik, Michael J; Neurock, Matthew; Behm, R Jürgen

    2010-09-21

    The electrochemical adsorption of underpotential deposited hydrogen (upd-H(ad)) and OH(ad) on structurally well-defined Pt(x)Ru(1-x)/Ru(0001) surface alloys was investigated by cyclic voltammetry and density functional theory (DFT) calculations. The adsorption energies of both upd-H(ad) and OH(ad) decrease with increasing Pt content in the adsorption ensemble, shifting the onset of upd-H(ad) and OH(ad) formation to increasingly cathodic and anodic potentials, respectively. For bare Ru(0001) and for Ru(3) sites in the surface alloy, the stability regions of these two species overlap or almost overlap, respectively. Similar to previous findings for upd-H(ad) adsorption/desorption on partly Pt monolayer island covered Ru(0001) surfaces (J. Phys. Chem. B 2004, 108, 14780), we find a sharp peak at approximately 100 mV vs. RHE in each scan direction, which is attributed to a Pt catalyzed OH(ad) upd-H(ad) replacement on Ru(3) sites, via adsorption on Pt rich sites and spill-over to Ru(3) sites. The decrease of the integrated charge in these peaks with the third power of the Ru surface concentration, which for a random distribution of surface atoms reflects the availability of Ru(3) sites, supports the above assignment.

  18. Metal-metal bonding and aromaticity in [M2(NHCHNH)3]2 (μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh).

    Science.gov (United States)

    Yan, Xiuli; Meng, Lingpeng; Sun, Zheng; Li, Xiaoyan

    2016-02-01

    The nature of M-M bonding and aromaticity of [M2(NHCHNH)3]2(μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh) was investigated using atoms in molecules (AIM) theory, electron localization function (ELF), natural bond orbital (NBO) and molecular orbital analysis. These analyses led to the following main conclusions: in [M2(NHCHNH)3]2(μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh), the Nb-Nb, Ru-Ru, and Rh-Rh bonds belong to "metallic" bonds, whereas Mo-Mo and Tc-Tc drifted toward the "dative" side; all these bonds are partially covalent in character. The Nb-Nb, Mo-Mo, and Tc-Tc bonds are stronger than Ru-Ru and Rh-Rh bonds. The M-M bonds in [M2(NHCHNH)3]2(μ-S)2 are stronger than those in [M2(NHCHNH)3]2(μ-O)2 for M = Nb, Mo, Tc, and Ru. The NICS(1)ZZ values show that all of the studied molecules, except [Ru2(NHCHNH)3]2(μ-O)2, are aromaticity molecules. O-bridged compounds have more aromaticity than S-bridged compounds. Graphical Abstract Left Molecular graph, and right electron localization function (ELF) isosurface of [M2(NHCHNH)3]2(μ-E)2(E = O, S; M = Nb, Mo, Tc, Ru, Rh).

  19. High-activity PtRuPd/C catalyst for direct dimethyl ether fuel cells.

    Science.gov (United States)

    Li, Qing; Wen, Xiaodong; Wu, Gang; Chung, Hoon T; Gao, Rui; Zelenay, Piotr

    2015-06-22

    Dimethyl ether (DME) has been considered as a promising alternative fuel for direct-feed fuel cells but lack of an efficient DME oxidation electrocatalyst has remained the challenge for the commercialization of the direct DME fuel cell. The commonly studied binary PtRu catalyst shows much lower activity in DME than methanol oxidation. In this work, guided by density functional theory (DFT) calculation, a ternary carbon-supported PtRuPd catalyst was designed and synthesized for DME electrooxidation. DFT calculations indicated that Pd in the ternary PtRuPd catalyst is capable of significantly decreasing the activation energy of the CO and CH bond scission during the oxidation process. As evidenced by both electrochemical measurements in an aqueous electrolyte and polymer-electrolyte fuel cell testing, the ternary catalyst shows much higher activity (two-fold enhancement at 0.5 V in fuel cells) than the state-of-the-art binary Pt50 Ru50 /C catalyst (HiSPEC 12100).

  20. Solvent effects on Pt-Ru/C catalyst for methanol electro-oxidation

    Institute of Scientific and Technical Information of China (English)

    Jinwei Chen; Chunping Jiang; Hui Lu; Lan Feng; Xin Yang; Liangqiong Li; Ruilin Wang

    2009-01-01

    Alloying degree,particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance,which lead to a great positive impact on its properties. In this work,three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H_2O or binary solvents of H_2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems,Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity,lower onset and peak potentials,compared with the above catalysts. Moreover,the catalyst prepared in ternary solvents of isopropanol,water and tetrahydrofuran had the smallest particle size,and the high alloying degree and the dispersion kept unchanged. Therefore,this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.

  1. Electrochemical Oxidation of the Carbon Support to Synthesize Pt(Cu and Pt-Ru(Cu Core-Shell Electrocatalysts for Low-Temperature Fuel Cells

    Directory of Open Access Journals (Sweden)

    Griselda Caballero-Manrique

    2015-04-01

    Full Text Available The synthesis of core-shell Pt(Cu and Pt-Ru(Cu electrocatalysts allows for a reduction in the amount of precious metal and, as was previously shown, a better CO oxidation performance can be achieved when compared to the nanoparticulated Pt and Pt-Ru ones. In this paper, the carbon black used as the support was previously submitted to electrochemical oxidation and characterized by XPS. The new catalysts thus prepared were characterized by HRTEM, FFT, EDX, and electrochemical techniques. Cu nanoparticles were generated by electrodeposition and were further transformed into Pt(Cu and Pt-Ru(Cu core-shell nanoparticles by successive galvanic exchange with Pt and spontaneous deposition of Ru species, the smallest ones being 3.3 nm in mean size. The onset potential for CO oxidation was as good as that obtained for the untreated carbon, with CO stripping peak potentials about 0.1 and 0.2 V more negative than those corresponding to Pt/C and Ru-decorated Pt/C, respectively. Carbon oxidation yielded an additional improvement in the catalyst performance, because the ECSA values for hydrogen adsorption/desorption were much higher than those obtained for the non-oxidized carbon. This suggested a higher accessibility of the Pt sites in spite of having the same nanoparticle structure and mean size.

  2. Characterization and evaluation of Pt-Ru catalyst supported on multi-walled carbon nanotubes by electrochemical impedance

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo, A.L.; Miranda-Hernandez, M.; Sebastian, P.J. [Centro de Investigacion en Energia-UNAM, Temixco, 62580 Morelos (Mexico); Morgado, J.; Montoya, J.A. [IMP, Eje Central Lazaro Cardenas 152, 07730 D.F. Mexico (Mexico)

    2006-10-06

    In this work the authors present the results of a systematic characterization and evaluation of the carbon nanotube supported Pt-Ru (Pt-Ru/CNT) for its use as methanol oxidation catalyst. Its activity was compared with that of Pt and Pt-Ru catalysts supported on Vulcan and synthesized from carbonyl precursors, and another commercial Pt-Ru catalyst. The cyclic voltammetry, CO stripping and electrochemical impedance techniques were employed to determine the electrocatalytic activity of the catalysts. The electrochemical studies were performed in 0.5M H{sub 2}SO{sub 4} containing different concentrations of methanol (0.05-1M). The results showed a noticeable influence of the catalyst support (CNT) on the performance of the catalyst for CO oxidation. The electrochemical impedance studies allowed us to separate the different steps in the methanol oxidation reaction and to control these steps or reactions by varying the applied potential and the methanol concentration. At low methanol concentration and potentials the de-hydrogenation of methanol predominated. But, at high potential and methanol concentrations, the CO oxidation predominated. These results allowed us to clearly describe at what potential and concentration ranges the bi-functional effect of Ru becomes evident. Our results indicated that the CO oxidation occurs both on Pt and Ru. Compared to other catalysts, Pt-Ru supported on carbon nanotubes showed superior catalytic activity for CO and methanol oxidation. (author)

  3. Emission Spectroscopy as a Probe into Photoinduced Intramolecular Electron Transfer in Polyazine Bridged Ru(II,Rh(III Supramolecular Complexes

    Directory of Open Access Journals (Sweden)

    Karen J. Brewer

    2010-08-01

    Full Text Available Steady-state and time-resolved emission spectroscopy are valuable tools to probe photochemical processes of metal-ligand, coordination complexes. Ru(II polyazine light absorbers are efficient light harvesters absorbing in the UV and visible with emissive 3MLCT excited states known to undergo excited state energy and electron transfer. Changes in emission intensity, energy or band-shape, as well as excited state lifetime, provide insight into excited state dynamics. Photophysical processes such as intramolecular electron transfer between electron donor and electron acceptor sub-units may be investigated using these methods. This review investigates the use of steady-state and time-resolved emission spectroscopy to measure excited state intramolecular electron transfer in polyazine bridged Ru(II,Rh(III supramolecular complexes. Intramolecular electron transfer in these systems provides for conversion of the emissive 3MLCT (metal-to-ligand charge transfer excited state to a non-emissive, but potentially photoreactive, 3MMCT (metal-to-metal charge transfer excited state. The details of the photophysics of Ru(II,Rh(III and Ru(II,Rh(III,Ru(II systems as probed by steady-state and time-resolved emission spectroscopy will be highlighted.

  4. On the antitumor properties of novel cyclometalated benzimidazole Ru(II), Ir(III) and Rh(III) complexes.

    Science.gov (United States)

    Yellol, Gorakh S; Donaire, Antonio; Yellol, Jyoti G; Vasylyeva, Vera; Janiak, Christoph; Ruiz, José

    2013-12-21

    Smart design and efficient synthesis of benzimidazole Ru, Ir and Rh cyclometalated complexes are reported with promising cytotoxic activity against HT29, T47D, A2780 and A2780cisR cancer cell lines. Their apoptosis, accumulation, cell cycle arrest, protein binding and DNA binding effects are also discussed.

  5. Atomic structure solution of the complex quasicrystal approximant Al77Rh15Ru8 from electron diffraction data.

    Science.gov (United States)

    Samuha, Shmuel; Mugnaioli, Enrico; Grushko, Benjamin; Kolb, Ute; Meshi, Louisa

    2014-12-01

    The crystal structure of the novel Al77Rh15Ru8 phase (which is an approximant of decagonal quasicrystals) was determined using modern direct methods (MDM) applied to automated electron diffraction tomography (ADT) data. The Al77Rh15Ru8 E-phase is orthorhombic [Pbma, a = 23.40 (5), b = 16.20 (4) and c = 20.00 (5) Å] and has one of the most complicated intermetallic structures solved solely by electron diffraction methods. Its structural model consists of 78 unique atomic positions in the unit cell (19 Rh/Ru and 59 Al). Precession electron diffraction (PED) patterns and high-resolution electron microscopy (HRTEM) images were used for the validation of the proposed atomic model. The structure of the E-phase is described using hierarchical packing of polyhedra and a single type of tiling in the form of a parallelogram. Based on this description, the structure of the E-phase is compared with that of the ε6-phase formed in Al-Rh-Ru at close compositions.

  6. Ligand Effects on the Hydrogenation of Biomass-Inspired Substrates with Bifunctional Ru, Ir, and Rh Complexes

    NARCIS (Netherlands)

    Jansen, E.; Jongbloed, L.S.; Tromp, D.S.; Lutz, M.; de Bruin, B.; Elsevier, C.J.

    2013-01-01

    We herein report on the application and structural investigation of a new set of complexes that contain bidentate N-heterocyclic carbenes (NHCs) and primary amine moieties of the type [M(arene)Cl(L)] [M=Ru, Ir, or Rh; arene=p-cymene or pentamethylcyclopentadienyl; L=1-(2-aminophenyl)-3-(n-alkyl)imid

  7. Ni2P Makes Application of the PtRu Catalyst Much Stronger in Direct Methanol Fuel Cells.

    Science.gov (United States)

    Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei

    2015-10-12

    PtRu is regarded as the best catalyst for direct methanol fuel cells, but the performance decay resulting from the loss of Ru seriously hinders commercial applications. Herein, we demonstrated that the presence of Ni2 P largely reduces Ru loss, which thus makes the application of PtRu much stronger in direct methanol fuel cells. Outstanding catalytic activity and stability were observed by cyclic voltammetry. Upon integrating the catalyst material into a practical direct methanol fuel cell, the highest maximum power density was achieved on the PtRu-Ni2P/C catalyst among the reference catalysts at different temperatures. A maximum power density of 69.9 mW cm(-2) at 30 °C was obtained on PtRu-Ni2P/C, which is even higher than the power density of the state-of-the-art commercial PtRu catalyst at 70 °C (63.1 mW cm(-2)). Moreover, decay in the performance resulting from Ru loss was greatly reduced owing to the presence of Ni2 P, which is indicative of very promising applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Preparation of Pt Ru/C + rare earths by the method of reduction by alcohol for the electro-oxidation of ethanol; Preparacao de eletrocatalisadores PtRu/C + terras raras pelo metodo da reducao por alcool para a eletro-oxidacao do etanol

    Energy Technology Data Exchange (ETDEWEB)

    Tusi, M.M.; Rodrigues, R.M.S.; Spinace, E.V.; Oliveira Neto, A., E-mail: aolivei@ipen.b, E-mail: espinace@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    PtRu/C electrocatalyst was prepared in a single step, while that PtRu/85%C-15%Ce, PtRu/85%C-15%La, PtRu/85%C-15%Nd and PtRu/85%C-15%Er electrocatalyst were prepared in a two step. In the first step a Carbon Vulcan XC72 + rare earth supports were prepared. In the second step PtRu electrocatalyst were prepared by an alcohol-reduction process using ethylene glycol as solvent and reducing agent and supported on Vulcan XC72 + earth rare. The obtained electrocatalysts were characterized by EDAX, XRD and chronoamperometry. The electro-oxidation of ethanol was studied by chronoamperometry at room temperature. PtRu/85%C- 15%Ce electrocatalyst showed a significant increase of performance for ethanol oxidation compared to PtRu/C electrocatalyst. (author)

  9. Structural, electronic, elastic and superconducting properties of noble metal nitrides MN{sub 2} (M = Ru, Rh, Pd)

    Energy Technology Data Exchange (ETDEWEB)

    Puvaneswari, S. [Department of Physics, E.M.G. Yadava Women' s College, Madurai, Tamilnadu 625 014 (India); Rajeswarapalanichamy, R., E-mail: rrpcaspd2003@gmail.com [Department of Physics, N.M.S.S. Vellaichamy Nadar College, Madurai, Tamilnadu 625019 (India); Sudha Priyanga, G. [Department of Physics, N.M.S.S. Vellaichamy Nadar College, Madurai, Tamilnadu 625019 (India)

    2015-02-01

    The structural stability, electronic structure, elastic and superconducting properties of noble metal nitrides MN{sub 2} (M = Ru, Rh, Pd) are investigated in tetragonal (P4/mbm), fluorite (Fm3m), orthorhombic (Pnnm), pyrite (Pa-3) and hexagonal (P6/mmm) phases using first principles calculations. The calculated lattice parameters are in good agreement with other theoretical results. Among the considered structures, RhN{sub 2} and PdN{sub 2} are found to be most stable in tetragonal structure, whereas RuN{sub 2} is stable in fluorite structure. A sequence of structural phase transition is predicted under high pressure in these metal nitrides. The electronic structure reveals that these nitrides are metallic. These metal nitrides are found to be covalent, ionic and metallic in the stable phase. The observations show that these metal nitrides are mechanically stable at ambient condition. The superconducting transition temperatures for RuN{sub 2}, RhN{sub 2} and PdN{sub 2} are found to be 1.65 K, 5.01 K and 8.7 K respectively. - Highlights: • Electronic, structural and elastic properties of RuN{sub 2}, RhN{sub 2} and PdN{sub 2} are studied. • A pressure induced structural phase transition is predicted. • Electronic structure reveals that these materials exhibit metallic behavior. • High bulk modulus indicates that RuN{sub 2}, RhN{sub 2} and PdN{sub 2} are superhard materials. • Superconducting temperature values are reported.

  10. Low Pt content direct methanol fuel cell anode catalyst: nanophase PtRuNiZr

    Science.gov (United States)

    Narayanan, Sekharipuram R. (Inventor); Whitacre, Jay F. (Inventor)

    2010-01-01

    A method for the preparation of a metallic material having catalytic activity that includes synthesizing a material composition comprising a metal content with a lower Pt content than a binary alloy containing Pt but that displays at least a comparable catalytic activity on a per mole Pt basis as the binary alloy containing Pt; and evaluating a representative sample of the material composition to ensure that the material composition displays a property of at least a comparable catalytic activity on a per mole Pt basis as a representative binary alloy containing Pt. Furthermore, metallic compositions are disclosed that possess substantial resistance to corrosive acids.

  11. On the differences in the reaction mechanism for CO and CO/H{sub 2} electrooxidation on PtRu and PtSn alloy electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Gasteiger, H.A. [Univ. Ulm (Germany). Abteilung Oberflaechenchemie und Katalyse; Markovic, N.M.; Ross, P.N. Jr. [Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Electrooxidation kinetics of mixtures of carbon monoxide and hydrogen were studied on well-characterized surfaces of Pt and alloys of PtRu and PtSn in 0.5 M H{sub 2}SO{sub 4} at room temperature and 60 C. The alloy electrode surfaces were prepared in UHV by sputter/anneal cycles and their surface compositions were determined via low energy ion scattering. Subsequently, the electrodes were transferred contamination-free from UHV into a rotating disk electrode (RDE) configuration in a conventional electrochemical cell and their activity was measured both by CO stripping voltammetry and under the continuous flow of CO and CO/H{sub 2} gas mixtures in RDE-experiments. The overpotential for the continuous oxidation of pure CO on PtSn electrodes with a Sn surface composition of x{sub Sn,s} {approximately} 0.2 is significantly smaller than on PtRu alloys (x{sub Ru,s} {approximately} 0.5) and on pure Pt. The reaction order with respect to solution phase CO is negative on PtRu alloys due to the competition between OH{sub ads} nucleation and CO adsorption on Ru surface atoms. Owing to the lack of CO adsorption on OH{sub ads}-providing Sn surface atoms, the reaction order with respect to CO is positive on PtSn electrodes. Therefore, the activity enhancement of PtSn electrodes versus PtRu and Pt electrodes is most pronounced in pure CO and decreases with the CO concentration in CO/N{sub 2} and CO/H{sub 2} mixtures.

  12. Pt-Rh/g Al2O3 Benzene Hydrogenation Reaction as a Characterization Technique

    Directory of Open Access Journals (Sweden)

    Fonseca N.M. da

    1998-01-01

    Full Text Available Pt-Rh/Al2O3 catalysts prepared by successive incipient impregnations and coimpregnation were characterized by H2 chemisorption, temperature programmed reduction and benzene hydrogenation reaction in the vapor phase. The results showed that Rh plays the role of Pt reducting agent, which is very different from the effects of metal-metal interaction which appear mainly in solids with the highest metal contents. The most important parameter that results in bimetallic particles in the catalyst prepared by successive impregnation is the sequence of metal addition.

  13. Electronic Structure of the fcc Transition Metals Ir, Rh, Pt, and Pd

    DEFF Research Database (Denmark)

    Andersen, O. Krogh

    1970-01-01

    /atom)/Ry, respectively. Spin-orbit coupling is important for all four metals and the coupling parameter varies by 30% over the d bandwidth. Detailed comparisons with de Haas—van Alphen Fermi-surface dimensions have previously been presented and the agreement was very good. Comparison with measured electronic specific......We give a complete description of a relativistic augmented-plane-wave calculation of the band structures of the paramagnetic fcc transition metals Ir, Rh, Pt, and Pd. The width and position of the d band decrease in the sequence Ir, Pt, Rh, Pd; and N(EF)=13.8,23.2,18.7, and 32.7 (states...

  14. Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films.

    Science.gov (United States)

    Liu, Mingfeng; Jin, Tianli; Hao, Liang; Cao, Jiangwei; Wang, Ying; Wu, Dongping; Bai, Jianmin; Wei, Fulin

    2015-01-01

    The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

  15. Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films

    Science.gov (United States)

    Liu, Mingfeng; Jin, Tianli; Hao, Liang; Cao, Jiangwei; Wang, Ying; Wu, Dongping; Bai, Jianmin; Wei, Fulin

    2015-04-01

    The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

  16. Ethylene glycol oxidation on Pt and Pt-Ru nanoparticle decorated polythiophene/multiwalled carbon nanotube composites for fuel cell applications.

    Science.gov (United States)

    Selvaraj, Vaithilingam; Alagar, Muthukaruppan

    2008-01-30

    A novel supporting material containing polythiophene (PTh) and multiwalled carbon nanotubes (MWCNTs) (PTh-CNTs) is prepared by in situ polymerization of thiophene on carbon nanotubes using FeCl(3) as oxidizing agent under sonication. The prepared polythiophene/CNT composites are further decorated with Pt and Pt-Ru nanoparticles by chemical reduction of the corresponding metal salts using HCHO as reducing agent at pH = 11 (Pt/PTh-CNT and Pt-Ru/PTh-CNT). The fabricated composite films decorated with nanoparticles were investigated towards the electrochemical oxidation of ethylene glycol (EG). The presence of carbon nanotubes in conjugation with a conducting polymer produces a good catalytic effect, which might be due to the higher electrochemically accessible surface areas, electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces, which allows higher dispersion of Pt and Pt-Ru nanoparticles. Such nanoparticle modified PTh-CNT electrodes exhibit better catalytic behavior towards ethylene glycol oxidation. Results show that Pt/PTh-CNT and Pt-Ru/PTh-CNT modified electrodes show enhanced electrocatalytic activity and stability towards the electro-oxidation of ethylene glycol than the Pt/PTh electrodes, which shows that the composite film is more promising for applications in fuel cells.

  17. Ethylene glycol oxidation on Pt and Pt-Ru nanoparticle decorated polythiophene/multiwalled carbon nanotube composites for fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Selvaraj, Vaithilingam; Alagar, Muthukaruppan [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)

    2008-01-30

    A novel supporting material containing polythiophene (PTh) and multiwalled carbon nanotubes (MWCNTs) (PTh-CNTs) is prepared by in situ polymerization of thiophene on carbon nanotubes using FeCl{sub 3} as oxidizing agent under sonication. The prepared polythiophene/CNT composites are further decorated with Pt and Pt-Ru nanoparticles by chemical reduction of the corresponding metal salts using HCHO as reducing agent at pH = 11 (Pt/PTh-CNT and Pt-Ru/PTh-CNT). The fabricated composite films decorated with nanoparticles were investigated towards the electrochemical oxidation of ethylene glycol (EG). The presence of carbon nanotubes in conjugation with a conducting polymer produces a good catalytic effect, which might be due to the higher electrochemically accessible surface areas, electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces, which allows higher dispersion of Pt and Pt-Ru nanoparticles. Such nanoparticle modified PTh-CNT electrodes exhibit better catalytic behavior towards ethylene glycol oxidation. Results show that Pt/PTh-CNT and Pt-Ru/PTh-CNT modified electrodes show enhanced electrocatalytic activity and stability towards the electro-oxidation of ethylene glycol than the Pt/PTh electrodes, which shows that the composite film is more promising for applications in fuel cells.

  18. Development of a database for the prediction of phases in Pt-based Superalloys: Cr-Pt-Ru

    Institute of Scientific and Technical Information of China (English)

    A. Watson; L.A. Cornish; R. Süss

    2006-01-01

    Work has been ongoing in building a thermodynamic database for the prediction of phase equilibria in Pt-based superalloys. The alloys are being developed for high temperature applications in aggressive environments. The database will aid the design of alloys by enabling the calculation of the composition and proportions of phases present in alloys of differ ent compositions. In order to extend this database, a preliminary assessment of the Cr-Pt-Ru system has been undertaken,using a combination of Pandat and MTDATA software. As a first step, it was necessary to provide thermodynamic models for the three associated binary systems. Owing to a lack of thermodynamic information for these systems, the binary assessments were based on phase diagrams available in the literature. Using recent experimental phase equilibria data for the ternary system, a preliminary assessment of the Cr-Pt-Ru system has been produced. In this preliminary assessment, simplified models were employed for the L12 and sigma phases with a view to extending the descriptions as new experimental information becomes available.

  19. Highly (110)- and (111)-oriented BiFeO3 films on BaPbO3 electrode with Ru or Pt /Ru barrier layers

    Science.gov (United States)

    Lee, Chia-Ching; Wu, Jenn-Ming; Hsiung, Chang-Po

    2007-04-01

    Highly (110)- and (111)-oriented BiFeO3 (BFO) films were fabricated with BaPbO3 (BPO )/Ru and BPO /Pt/Ru as electrode/barrier on Si substrates by rf-magnetron sputtering. The BPO /Ru and BPO /Pt/Ru stacks both induce oriented BFO films and act as diffusion barriers. The (110)- and (111)-oriented BFO films possess excellent ferroelectric properties with only minor leakage. The values of remnant polarization are almost the same, about 42μC/cm2, for (110)- and (111)-oriented BFO films. However, polarization measured under varying pulse widths demonstrates that the switching polarization in (111)-oriented BFO films is higher than in (110)-oriented films. Additionally, (111)-oriented BFO films exhibit better retention properties than (110)-oriented films.

  20. Sol-Gel Process for Making Pt-Ru Fuel-Cell Catalysts

    Science.gov (United States)

    Narayanan, Sekharipuram; Valdez, Thomas; Kumta, Prashant; Kim, Y.

    2005-01-01

    A sol-gel process has been developed as a superior alternative to a prior process for making platinum-ruthenium alloy catalysts for electro-oxidation of methanol in fuel cells. The starting materials in the prior process are chloride salts of platinum and ruthenium. The process involves multiple steps, is time-consuming, and yields a Pt-Ru product that has relatively low specific surface area and contains some chloride residue. Low specific surface area translates to incomplete utilization of the catalytic activity that might otherwise be available, while chloride residue further reduces catalytic activity ("poisons" the catalyst). In contrast, the sol-gel process involves fewer steps and less time, does not leave chloride residue, and yields a product of greater specific area and, hence, greater catalytic activity. In this sol-gel process (see figure), the starting materials are platinum(II) acetylacetonate [Pt(C5H7O2)2, also denoted Pt-acac] and ruthenium(III) acetylacetonate [Ru(C5H7O2)3, also denoted Ru-acac]. First, Pt-acac and Ru-acac are dissolved in acetone at the desired concentrations (typically, 0.00338 moles of each salt per 100 mL of acetone) at a temperature of 50 C. A solution of 25 percent tetramethylammonium hydroxide [(CH3)4NOH, also denoted TMAH] in methanol is added to the Pt-acac/Ruacac/ acetone solution to act as a high-molecular-weight hydrolyzing agent. The addition of the TMAH counteracts the undesired tendency of Pt-acac and Ru-acac to precipitate as separate phases during the subsequent evaporation of the solvent, thereby helping to yield a desired homogeneous amorphous gel. The solution is stirred for 10 minutes, then the solvent is evaporated until the solution becomes viscous, eventually transforming into a gel. The viscous gel is dried in air at a temperature of 170 C for about 10 hours. The dried gel is crushed to make a powder that is the immediate precursor of the final catalytic product. The precursor powder is converted to the

  1. Decoupling between Field-instabilities of Antiferromagnetism and Pseudo-metamagnetism in Rh-doped CeRu2Si2 Kondo Lattice

    OpenAIRE

    Aoki, Dai; Paulsen, Carley; Kotegawa, Hisashi; Hardy, Frederic; Meingast, Christoph; Haen, Pierre; Boukahil, Mounir; Knafo, William; Ressouche, Eric; Raymond, Stephane; Flouquet, Jacques

    2012-01-01

    Doping Kondo lattice system CeRu2Si2 with Rh-8% (Ce(Ru0.92Rh0.08)2Si2) leads to drastic consequences due to the mismatch of the lattice parameters between CeRu2Si2 and CeRh2Si2. A large variety of experiments clarifies the unusual properties of the ground state induced by the magnetic field from longitudinal antiferromagnetic (AF) mode at H = 0 to polarized paramagnetic phase in very high magnetic field. The separation between AF phase, paramagnetic phase and polarized paramagnetic phase vary...

  2. Carbon-Supported PtRuMo Electrocatalysts for Direct Alcohol Fuel Cells

    Directory of Open Access Journals (Sweden)

    José L.G. Fierro

    2013-10-01

    Full Text Available The review article discusses the current status and recent findings of our investigations on the synthesis and characterization of carbon-supported PtRuMo electrocatalysts for direct alcohol fuel cells. In particular, the effect of the carbon support and the composition on the structure, stability and the activity of the PtRuMo nanoparticles for the electrooxidation of CO, methanol and ethanol have been studied. Different physicochemical techniques have been employed for the analysis of the catalysts structures: X-ray analytical methods (XRD, XPS, TXRF, thermogravimetry (TGA and transmission electron microscopy (TEM, as well as a number of electrochemical techniques like CO adsorption studies, current-time curves and cyclic voltammetry measurements. Furthermore, spectroscopic methods adapted to the electrochemical systems for in situ studies, such as Fourier transform infrared spectroscopy (FTIRS and differential electrochemical mass spectrometry (DEMS, have been used to evaluate the oxidation process of CO, methanol and ethanol over the carbon-supported PtRuMo electrocatalysts.

  3. Extended Pi-Sigma tilde orbital model for CO adsorption on Pt and Ru

    Science.gov (United States)

    Mion, Thomas; Dimakis, Nicholas; Alamgir, Faisal; Jaye, Cherno; Fischer, Daniel; McGinn, Paul; Cooper, James; Greenbaum, Steve; Smotkin, Eugene

    2011-03-01

    Several discrepencies between the predicted Blyholder-type adsobtion models and experimental, as well as DFT calculated infared spectra have been addressed for atop CO on Pt in contrast to Ru. This model correlates increased Near Edge X-Ray Absorbtion Fine Structure intensity as the result of a sub-eV downshift from CO on Ru compared to CO on Pt thereby forming a weaker C-O bond. The model accounts for the hybrid orbitals electron transfer between the CO - metal bonds while taking in to consideration the orbital polarization within the CO itself. The charge redistribution of the s-tilde orbitals and reduced charge donation from CO to the surface results in a weaker internal CO bond upon Ru relative to Pt. The extended Pi-Sigma model explains why atop C-O stretching frequencies do not correlate with carbon p-type vacancies. Calculations done on the High Performance Computing Cluster at UT-Pan American. NEXAFS was done on U7A NIST/DOW beamline at Brookheaven National Synchrotron Light Source with funding from the Army Research Office.

  4. Electro-oxidation of carbon monoxide and methanol on bare and Pt-modified Ru(1010) electrodes.

    Science.gov (United States)

    Pinheiro, A L N; Zei, M S; Ertl, G

    2005-03-21

    The activity towards CO and methanol electrooxidation of bare and platinum-modified Ru(1010) surfaces has been investigated. The structure/morphology and composition of the modified surfaces were characterized using electron diffraction techniques (LEED, RHEED) and Auger spectroscopy. The bare Ru(1010) surface exhibits a higher catalytic activity towards CO electrooxidation than the Ru(0001) surface due to the lower oxidation potential of the former surface. The early stages of surface oxidation lead to disordering of the surface and further enhancing of the electrocatalytic activity. Electrodeposition of Pt on Ru(1010) leads to epitaxial growth via a Volmer-Weber growth mode. The Pt clusters grow preferentially with the (311) plane parallel to the substrate surface with (011) rows in the layers in contact with the substrate compressed by about 3% with respect to bulk Pt, in order to match with the (1210) rows of the Ru(1010) surface. This compression leads to enhanced catalytic activity towards CO oxidation for thin Pt deposits whereas for large deposited Pt particles the dominating factor for the catalytic enhancement is the higher concentration of surface defects. On the other hand, in the case of methanol oxidation, the dominant factor in determining the catalytic activity is the concentration of adjacent Pt-Ru sites, although surface defects play an important role in the methanol dehydrogenation steps.

  5. Electrochemical characterization of SnO{sub 2} electrodes doped with Ru and Pt

    Energy Technology Data Exchange (ETDEWEB)

    Berenguer, R. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Quijada, C. [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, 1, E-03801 Alcoy (Alicante) (Spain); Morallon, E. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: morallon@ua.es

    2009-09-01

    Antimony-platinum doped tin dioxide electrodes supported on titanium have been prepared by thermal decomposition. The effect of the progressive replacement of Sb with Ru (x = 0.00; 3.25; 6.50; 13.00 at.%) on their electrochemical response in acid medium has been analysed by cyclic voltammetry. The morphology of the coatings was observed by scanning electron microscopy. Ti/SnO{sub 2}-Sb-Pt electrodes without Ru presented a cracked-mud structure, typical of oxide electrodes prepared by thermal decomposition. The introduction of Ru in the oxide layer modified the coating morphology. The roughness increased and passed through a maximum with the increase of Ru content. A relation between the surface morphology, the roughness factor, voltammetric charge and the electrochemical activity has been established. The mechanism and electrocatalytic activity towards the oxygen evolution reaction has been studied from Tafel measurements. The progressive introduction of Ru in the electrodes increased their electrocatalytic activity for the oxygen evolution reaction with a change on the mechanism from non-active to active electrodes. The electrocatalytic activity mainly depends on electronic factors.

  6. Relating Composition and Thermoelectric Stability of Pt-Rh Alloy Thermocouples

    Science.gov (United States)

    Pearce, J. V.; Greenen, A. D.; Smith, A.; Elliott, C. J.

    2017-02-01

    A simple model is presented which relates the electromotive force drift rate of Pt-Rh thermoelements to dS/dc, the sensitivity of the Seebeck coefficient, S, to rhodium mass fraction, c. The model has been tested by repeated measurements of a Pt-Rh thermocouple assembly consisting of five thermoelements, using a Co-C high-temperature fixed point (1324°C) for a total duration of 500 h. By considering various thermocouples from the assembly, it is demonstrated that in this case, remarkably, there is a linear relationship between the measured drift rate and the combined dS/dc, where the combination is determined by addition of the individual values for each wire. Particular emphasis is placed on evaluation of the uncertainties associated with the calculations. This result supports previous findings that the thermoelectric stability of Pt-Rh thermoelements improves as the rhodium mass fraction increases. Within this paradigm, it is shown that for a selected Pt-Rh thermoelement of any given composition, there exists a second thermoelement having a composition that yields a minimum drift when combined with the first to form a thermocouple.

  7. Partition coefficients for Ni, Cu, Pd, Pt, Rh, and Ir between monosulfide solid solution and sulfide liquid and the formation of compositionally zoned Ni-Cu sulfide bodies by fractional crystallization of sulfide liquid

    DEFF Research Database (Denmark)

    Barnes, S.J.; Makovicky, E.; Makovicky, M.

    1996-01-01

    Many nickel–copper sulfide orebodies contain Cu- and Fe-rich portions. The Fe-rich ore is generally richer in Os, Ir, Ru, and Rh and poorer in Pt, Pd, and Au than the Cu-rich ore. In komatiite-hosted ores Ni tends to be concentrated in the Cu-rich ore, whereas in tholeiitic ores it tends to be co...

  8. 溶剂萃取法分离Pt、Pd、Rh%Separating Pt, Pd and Rh by Solvent Extracition

    Institute of Scientific and Technical Information of China (English)

    荆小旦

    2001-01-01

    @@ 铂族金属的再生资源经常是含有两种或两种以上铂族金属的物料,如硝酸工业报废的铂钯铑合金催化网,失效的三元汽车尾气净化催化剂(其活性组分为Pt、Pd、Rh),测温热电偶丝(Pt,Rh-Pt热电偶),玻纤工业产生的废漏板托砖等.这些物料的浸出液通常要进行一系列复杂的分离精炼作业,才能获得符合一定质量标准的单个铂族金属产品.

  9. Estimates of relative doses of {sup 106}Ru/{sup 106}Rh of spherical applicators used in ophthalmic brachytherapy; Estimativas de doses relativas de aplicadores esfericos de {sup 106}Ru/{sup 106}Rh usados em braquiterapia oftalmologica

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Eduardo de, E-mail: edup2112@gmail.com, E-mail: epaiva@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Fisica Medica

    2016-11-01

    Spherical ophthalmic applicators containing the beta emitter {sup 106}Ru / {sup 106}Rh are much used in brachytherapy for the treatment of various eye diseases. However, there is great difficulty in dosimetry these sources because of its geometric shape, the short range of the beta particles and the large dose gradient, and because of that calculation methods of dose distributions around these sources take on a great importance. In this work an analytical / numerical method is used to estimate the dose rates for a function of depth for spherical sources containing {sup 106}Ru / {sup 106}Rh. The results of the doses on along the central axis for applicators models CXS, CCX, CCY, CCZ, CCD and CGD and CCC are compared with published values calculated by Monte Carlo simulation and measurement results.

  10. Electrochemical promotion of catalytic reactions with Pt/C (or Pt/Ru/C)//PBI catalysts

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Bandur, Viktor;

    2007-01-01

    The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 degrees C and Fischer-Tropsch synthesis (FTS) at 170 degrees C in the [CH4/O-2(or NO/H-2 or CO/H-2)/Ar//Pt(or Pt...

  11. Antileishmanial action of organometallic complexes of Pt(II and Rh(I

    Directory of Open Access Journals (Sweden)

    CM Mesa-Valle

    1996-10-01

    Full Text Available The three organometallic complexes [(Cis-PtII (DDH (2,5-Dihidroxibenzensulfonic2, RhI (CO2 Cl(2-Aminobenzothiazole and RhI (CO2 Cl(5-Cl-2-Methilbenzothiazole] used in this study had been previously found to have a high in vitro activity against promastigote and amastigote like forms of Leishmania donovani. Here, the cytotoxic effect of these new organometallic complexes on the J-774 macrophages were studied. Only the RhI(CO2 Cl (2-Aminobenzothiazole complex induced substantial toxicity in the cells. Also, we assayed the effect of this complex on the parasite's biosynthesis of macromolecules. The RhI(CO2Cl (5-Cl-2-Methylbenzothiazole complex inhibited DNA, RNA, and protein synthesis. On the other hand, the two other compounds tested did not inhibit the incorporation of radioactive precursors. Finally important ultrastructural alterations in the parasites treated with the two non-cytotoxic complexes were observed.

  12. Achieving Remarkable Activity and Durability toward Oxygen Reduction Reaction Based on Ultrathin Rh-Doped Pt Nanowires.

    Science.gov (United States)

    Huang, Hongwen; Li, Kan; Chen, Zhao; Luo, Laihao; Gu, Yuqian; Zhang, Dongyan; Ma, Chao; Si, Rui; Yang, Jinlong; Peng, Zhenmeng; Zeng, Jie

    2017-06-21

    The research of active and sustainable electrocatalysts toward oxygen reduction reaction (ORR) is of great importance for industrial application of fuel cells. Here, we report a remarkable ORR catalyst with both excellent mass activity and durability based on sub 2 nm thick Rh-doped Pt nanowires, which combine the merits of high utilization efficiency of Pt atoms, anisotropic one-dimensional nanostructure, and doping of Rh atoms. Compared with commercial Pt/C catalyst, the Rh-doped Pt nanowires/C catalyst shows a 7.8 and 5.4-fold enhancement in mass activity and specific activity, respectively. The combination of extended X-ray absorption fine structure analysis and density functional theory calculations reveals that the compressive strain and ligand effect in Rh-doped Pt nanowires optimize the adsorption energy of hydroxyl and in turn enhance the specific activity. Moreover, even after 10000 cycles of accelerated durability test in O2 condition, the Rh-doped Pt nanowires/C catalyst exhibits a drop of 9.2% in mass activity, against a big decrease of 72.3% for commercial Pt/C. The improved durability can be rationalized by the increased vacancy formation energy of Pt atoms for Rh-doped Pt nanowires.

  13. Pt-Ni and Pt-M-Ni (M = Ru, Sn Anode Catalysts for Low-Temperature Acidic Direct Alcohol Fuel Cells: A Review

    Directory of Open Access Journals (Sweden)

    Ermete Antolini

    2017-01-01

    Full Text Available In view of a possible use as anode materials in acidic direct alcohol fuel cells, the electro-catalytic activity of Pt-Ni and Pt-M-Ni (M = Ru, Sn catalysts for methanol and ethanol oxidation has been widely investigated. An overview of literature data regarding the effect of the addition of Ni to Pt and Pt-M on the methanol and ethanol oxidation activity in acid environment of the resulting binary and ternary Ni-containing Pt-based catalysts is presented, highlighting the effect of alloyed and non-alloyed nickel on the catalytic activity of these materials.

  14. Epitaxial growth of unusual 4H hexagonal Ir, Rh, Os, Ru and Cu nanostructures on 4H Au nanoribbons

    KAUST Repository

    Fan, Zhanxi

    2016-09-12

    Metal nanomaterials normally adopt the same crystal structure as their bulk counterparts. Herein, for the first time, the unusual 4H hexagonal Ir, Rh, Os, Ru and Cu nanostructures have been synthesized on 4H Au nanoribbons (NRBs) via solution-phase epitaxial growth under ambient conditions. Interestingly, the 4H Au NRBs undergo partial phase transformation from 4H to face-centered cubic (fcc) structures after the metal coating. As a result, a series of polytypic 4H/fcc bimetallic Au@M (M = Ir, Rh, Os, Ru and Cu) core-shell NRBs has been obtained. We believe that the rational crystal structure-controlled synthesis of metal nanomaterials will bring new opportunities for exploring their phase-dependent physicochemical properties and promising applications.

  15. Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon

    Energy Technology Data Exchange (ETDEWEB)

    Wu Gang [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: wugang@lanl.gov; Swaidan, Raja [Department of Chemical Engineering, Cooper Union, New York, NY 10003 (United States); Li Deyu; Li Ning [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

    2008-11-01

    A typical heteroatom (nitrogen)-doped carbon materials were successfully synthesized through the carbonization of a hybrid containing traditional carbon black covered by in situ polymerized polyaniline. The nitrogen content onto carbon can be adjusted up to 5.1 at.% by changing the coverage of polyaniline. The effects of nitrogen doping on the surface physical and electrochemical properties of carbon were studied using XPS, XRD and HRTEM, as well as CV and EIS techniques. With increasing nitrogen doping, the carbon structure became more compact, showing curvatures and dislocations in the graphene stacking. The nitrogen-doped carbon also exhibited a higher accessible surface area in electrochemical reactions, and a lower charge transfer resistance at the carbon/electrolyte interface. Moreover, to investigate the influence of nitrogen doping on the electrocatalytic activity of the PtRu/C catalyst, comparisons in CO stripping and methanol oxidation were carried out on PtRu catalysts supported by non-doped and nitrogen-doped carbon. Since the promotional roles of nitrogen doping, including the high electrochemically accessible surface area, the richness of the disordered nanostructures and defects, and the high electron density on N-doped carbon supports, contribute to the synthesis of well-dispersed PtRu particles with high Pt utilization and stronger metal-support interactions, an enhanced catalytic activity for methanol oxidation was obtained in the case of the PtRu/N-C catalyst in comparison with the traditional PtRu/C catalyst.

  16. Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Gang; Li, Deyu; Li, Ning [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Swaidan, Raja [Department of Chemical Engineering, Cooper Union, New York, NY 10003 (United States)

    2008-11-01

    A typical heteroatom (nitrogen)-doped carbon materials were successfully synthesized through the carbonization of a hybrid containing traditional carbon black covered by in situ polymerized polyaniline. The nitrogen content onto carbon can be adjusted up to 5.1 at.% by changing the coverage of polyaniline. The effects of nitrogen doping on the surface physical and electrochemical properties of carbon were studied using XPS, XRD and HRTEM, as well as CV and EIS techniques. With increasing nitrogen doping, the carbon structure became more compact, showing curvatures and dislocations in the graphene stacking. The nitrogen-doped carbon also exhibited a higher accessible surface area in electrochemical reactions, and a lower charge transfer resistance at the carbon/electrolyte interface. Moreover, to investigate the influence of nitrogen doping on the electrocatalytic activity of the PtRu/C catalyst, comparisons in CO stripping and methanol oxidation were carried out on PtRu catalysts supported by non-doped and nitrogen-doped carbon. Since the promotional roles of nitrogen doping, including the high electrochemically accessible surface area, the richness of the disordered nanostructures and defects, and the high electron density on N-doped carbon supports, contribute to the synthesis of well-dispersed PtRu particles with high Pt utilization and stronger metal-support interactions, an enhanced catalytic activity for methanol oxidation was obtained in the case of the PtRu/N-C catalyst in comparison with the traditional PtRu/C catalyst. (author)

  17. Preparation of ternary Pt/Rh/SnO2 anode catalysts for use in direct ethanol fuel cells and their electrocatalytic activity for ethanol oxidation reaction

    Science.gov (United States)

    Higuchi, Eiji; Takase, Tomonori; Chiku, Masanobu; Inoue, Hiroshi

    2014-10-01

    Pt, Rh and SnO2 nanoparticle-loaded carbon black (Pt/Rh/SnO2/CB) catalysts with different contents of Pt and Rh were prepared by the modified Bönnemann method. The mean size and size distribution of Pt, Rh and SnO2 for Pt-71/Rh-4/SnO2/CB (Pt : Rh : Sn = 71 at.%: 4 at.%: 25 at.%) were 3.8 ± 0.7, 3.2 ± 0.7 and 2.6 ± 0.5 nm, respectively, indicating that Pt, Rh and SnO2 were all nanoparticles. The onset potential of ethanol oxidation current for the Pt-65/Rh-10/SnO2/CB and Pt-56/Rh-19/SnO2/CB electrodes was ca. 0.2 V vs. RHE which was ca. 0.2 V less positive than that for the Pt/CB electrode. The oxidation current at 0.6 V for the Pt/Rh/SnO2/CB electrode (ca. 2% h-1) decayed more slowly than that at the Pt/SnO2/CB electrode (ca. 5% h-1), indicating that the former was superior in durability to the latter. The main product of EOR in potentiostatic electrolysis at 0.6 V for the Pt-71/Rh-4/SnO2/CB electrode was acetic acid.

  18. Preparation of high dispersion and high performance PtRu/CNTs catalyst by an organic colloid method

    Institute of Scientific and Technical Information of China (English)

    王宁卡特; 刘军民; 廖世军; V.Birss

    2006-01-01

    A high dispersion and high performance PtRu catalyst supported on carbon nanotubes was prepared by an organic colloid method. The particle size of the active components could be as small as 1.0 nm,the active surface area was about 466 m2/g(Pt). The catalytic activity toward anodic oxidation of methanol was about 3 ~ 4 times higher than that of Johnson Matthey PtRu/XC-72R catalyst. The single testing showed that the performance of the prepared catalyst was higher than that of the commercial one.

  19. Magnetic properties and microstructure of FePt/MoC/CrRu films

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Jai-Lin, E-mail: tsaijl@dragon.nchu.edu.tw; Luo, Qi-Shao; Chen, Po-Ran; Tseng, Yun-Ting

    2015-05-15

    The FePt films with thickness of 4−10 nm were deposited on MoC/CrRu/glass at substrate temperature ranged from 260 to 410 °C by using magnetron sputtering and strong (001) textured FePt films were obtained at 380 °C and 410 °C. The multi-functional MoC conductive intermediate layer was used to resist the Cr diffusion and promote the epitaxial growth of the (001) textured FePt film which shows perpendicular magnetization and a linear-like in-plane magnetic loop. The out-of plane coercivity and shape of demagnetization curve were dominated by the ordering degree and perpendicular magnetic anisotropy which were increased with deposited temperature. The FePt film deposited at 290 °C shows continuous morphology and change to interconnected structure at 350 °C and finally form the island like structure at 380 °C and 410 °C. Each island contains many FePt grains and the smaller grains size was 12.2 nm which obtained at 5 nm thick FePt film. Perpendicular anisotropy of 1.1×10{sup 7} erg/cm{sup 3} and coercivity of 8.2 kOe have been demonstrated in 7 nm thick FePt film. - Highlights: • The MoC conductive intermediate layer was resisted the Cr diffusion. • The MoC layer promote the epitaxial growth of (001) textured FePt film. • The FePt film shows perpendicular magnetization on MoC layer.

  20. Heat flux measurements of Tb3M series (M=Co, Rh and Ru): Specific heat and magnetocaloric properties

    Science.gov (United States)

    Monteiro, J. C. B.; Lombardi, G. A.; dos Reis, R. D.; Freitas, H. E.; Cardoso, L. P.; Mansanares, A. M.; Gandra, F. G.

    2016-12-01

    We report on the magnetic properties and magnetocaloric effect (MCE) for the Tb3M series, with M=Co, Rh and Ru, obtained using a heat flux technique. The specific heat of Tb3Co and Tb3Rh are very similar, with a first order type transition occurring around 6 K below the magnetic ordering temperature without any corresponding feature on the magnetization. The slightly enhanced electronic specific heat, the Debye temperature around 150 K and the presence of the magnetic specific heat well above the ordering temperature are also characteristic of many other compounds of the R3M family (R=Rare Earth). The specific heat for Tb3Ru, however, presents two peaks at 37 K and 74 K. The magnetization shows that below the first peak the system presents an antiferromagnetic behavior and is paramagnetic above 74 K. We obtained a magnetocaloric effect for M=Co and Rh, -∆S=12 J/kg K, but for Tb3Ru it is less than 3 J/kg K (μ0∆H=5 T). We believe that the experimental results show that the MCE is directly related with the process of hybridization of the (R)5d-(M)d electrons that occurs in the R3M materials.

  1. Visual outcome, local tumour control, and eye preservation after {sup 106}Ru/Rh brachytherapy for choroidal melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Isager, Peter; Ehlers, Niels; Urbak, Steen F. [Aarhus Univ. Hospital (Denmark). Dept. of Ophthalmology; Overgaard, Jens [Aarhus Univ. Hospital (Denmark). Dept. of Experimental Clinical Oncology

    2005-05-15

    To study the visual outcome, local tumour control, and eye preservation 5 years after ruthenium/rhodium 106 brachytherapy for choroidal melanoma. The study included 55 consecutive patients treated by {sup 106}Ru/Rh brachytherapy for a choroidal melanoma during the period 1988-2000 and followed through 2004. The 5-year probability for not losing at least 5 Snellen lines was 59% (n=45), for retaining a visual acuity of 0.33 or better was 28% (n=34), and for retaining better than 0.1 was 40% (n=45). The 5-year probability for no local recurrence was 73% and for eye preservation 72% (n=55). {sup 106}Ru/Rh brachytherapy for choroidal melanoma resulted in a clinically significant vision loss, no local recurrence, and eye preservation in most patients after 5 years. {sup 106}Ru/Rh brachytherapy can be regarded as a good treatment option for small and medium-sized tumours but not for large tumours.

  2. Adsorption of precious and coinage metals on Rh (111), Ru (0001) and W (110) surfaces

    Science.gov (United States)

    Zhu, Quanxi; Wang, Shao-qing

    2017-07-01

    Bimetallic surface alloys have been considered as an effective strategy to achieve better catalytic performance and to modify the work function of the substrate toward metal-gate electrode application. We perform a systematical investigation of Group 10 and Group 11 transition metals adsorption on Rh (111), Ru (0001) and W (110) surfaces with various coverages using first-principles method. Through comparing the Bader charge results and the plots of work function shift, it is found that the polarization effect plays an important role in modification of the bimetallic surface work functions rather than the charge transfer effect especially at low coverages. The coverage-dependent work function behavior gives a general feature: as it has a large negative shift at 0.25ML coverage, then increases almost linearly with the coverage and followed by a saturation value which is controlled by the lattice strain. It is also found that the metal over-layer growth modes are correlated with the specific features of the coverage-dependent metal-substrate adhesion energy. All these findings may give some guidelines for the bimetallic catalysts design in terms of growth, stability and activity.

  3. Functional separation of oxidation–reduction reactions and electron transport in PtRu/ND and conductive additive hybrid electrocatalysts during methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Wang, Yanhui [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Bian, Linyan [College of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, Henan 454000 (China); Lu, Rui [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Zang, Jianbing, E-mail: jbzang@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-02-28

    Graphical abstract: - Highlights: • Functional separation of reactions and electron transport in PtRu/ND + AB (or CNT). • A conductive network was formed after the addition of AB or CNT. • PtRu/ND + AB (or CNT) exhibited enhanced activity and stability than PtRu/ND. - Abstract: Undoped nanodiamond (ND) supported PtRu (PtRu/ND) electrocatalyst for methanol oxidation reactions (MOR) in direct methanol fuel cells was prepared by a microwave-assisted polyol reduction method. Sp{sup 3}-bonded ND possesses high electrochemical stability but low conductivity, while sp{sup 2}-bonded carbon nanomaterials with high conductivity are prone to oxidation. Therefore, the functions of the supporting material were separated in this study. ND (sp{sup 3}), as a support, and AB or CNTs (sp{sup 2}), as a conductive additive, were combined to form the hybrid electrocatalysts PtRu/ND + AB and PtRu/ND + CNT for MOR. The morphology of the electrocatalysts was characterized by scanning electron microscopy and electrochemical measurements were performed using an electrochemical workstation. The results indicated that the electrocatalytic activity of PtRu/ND for MOR was improved with the addition of AB or CNTs as a conductive additive. Moreover, adding CNTs to PtRu/ND as a conductive additive showed better electrocatalytic activities than adding AB, which can be ascribed to the better electron-transfer ability of CNTs.

  4. New Synthesis of Pt-Ru Nanoparticles on Surface Modified Carbon Vulcane XC-72 as an Effective Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Ahmad; Nozad; Golikand; Sajjad; Sadaghat; Sharehjini; Mohammad; Yari

    2007-01-01

    1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...

  5. Comparing Pt/SrTiO3 to Rh/SrTiO3 for hydrogen photocatalytic production from ethanol

    KAUST Repository

    Wahab, A. K.

    2013-08-13

    Photocatalytic hydrogen production from ethanol as an example of biofuel is studied over 0.5 wt% Rh/SrTiO3 and 0.5 wt% Pt/SrTiO3 perovskite materials. The rate of hydrogen production, rH2, over Pt/SrTiO3 is found to be far higher than that observed over Rh/SrTiO3 (4 × 10−6 mol of H2 g catal. −1 min−1 (1.1 × 10−6 mol of H2 m catal. −2 min−1) compared to 0.7 × 10−6 mol of H2 g catal. −1 min−1 (5.5 × 10−8 mol of H2 m catal. −2 min−1), respectively, under UV excitation with a flux equivalent to that from the sun light (ca. 1 mW cm−2). Analyses of the XPS Rh3d and XPS Pt4f indicate that Rh is mainly present in its ionic form (Rh3+) while Pt is mainly present in its metallic form (Pt0). A fraction of the non-metallic state of Rh in the catalyst persisted even after argon ion sputtering. The tendency of Rh to be oxidized compared to Pt might be the reason behind the lower activity of the former compared to the later. On the contrary, a larger amount of methane are formed on the Rh containing catalyst compared to that observed on the Pt containing catalyst due to the capacity of Rh to break the carbon–carbon bond of the organic compound.

  6. Incorporation of metals (Pt-Ni-Ru) in the zeolite ZSM-5 through ion exchange competitive: synthesis and characterization; Incorporacao de metais (Pt-Ni-Ru) na zeolita ZSM-5 atraves da troca ionica competitiva: sintese e caracterizacao

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, A.S.; Rodrigues, M.G.F., E-mail: antusiasb@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia Quimica; Grau, J.M. [Instituto de Investigaciones en Catalisis y Petroquimica (INCAPE/FIQ/UNL-CONICET), Santa Fe (Argentina)

    2012-07-01

    Zeolites are very important materials due to their high specific surface area. Moreover, they are suitable for use as catalyst support. Noble metals supported on zeolites have been widely used as catalysts in the petrochemical industry. This paper was prepared and characterized, a powder aiming its use in heterogeneous catalysis. Support was used as ZSM-5 and the method of incorporation of the metals (Ru-PtNi) was competitive ion exchange. The materials (ZSM-5 and Pt-Ni-Ru/ZSM-5) were characterized by spectrophotometry Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD) and nitrogen physisorption (BET method). Based on the results of X-ray diffraction, it is possible to demonstrate the preservation of the structure of zeolite ZSM-5 after the competitive ion Exchange with metals (Ru-Pt-Ni) and calcination. The dispersion of metals on ZSM-5 did not change the textural characteristics of the zeolite. (author)

  7. The pilot test of Pt-Pd and Pt-Rh feeds extracted and separated with a new sulfoxide extractant

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Platinum, palladium and rhodium of the raw feeds extracted and separated with a new sulfoxide extractant (MSO)were studied in the paper. The pilot test results showed that the percentage extractions are more than 99% for platinum and palladium in Pt-Pd feed, and the percentage strippings are 100% and 99.2% with HCl and ammonia, respectively. The ratio of palladium to platinum is 0.0016 in stripping platinum solution, and the ratio of platinum to palladium is 0.0020 in stripping palladium solution. The percentage extraction of platinum is 99% in Pt-Rh feed, and the percentage stripping is 100%.The ratio of rhodium to platinum is 0.0002 in stripping platinum solution. Therefore, platinum, palladium, and rhodium feeds are separated effectively with MSO.

  8. A comprehensive study on the effect of Ru addition to Pt electrodes for direct ethanol fuel cell

    Indian Academy of Sciences (India)

    J Datta; S Singh; S Das; N R Bandyopadhyay

    2009-12-01

    The electro-oxidation of ethanol was studied over nanosized Pt and different compositions of PtRu catalysts synthesized by the borohydride reduction method. Physicochemical characterizations of the catalyst material were made by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDX analysis and transmission electron microscopy (TEM). XRD patterns showed that Ru induces a contraction of the Pt lattice. EDX provided the composition of binary catalysts while TEM images indicated uniform distribution of discrete nanoparticle of the catalysts with narrow range. The electro-catalytic activities of the materials towards ethanol oxidation were investigated through electrochemical techniques, viz. cyclic voltammetry (CV), potentiodynamic polarization, chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature. The onset potential of ethanol electro-oxidation is lowered on bimetallic PtRu catalysts compared to that on Pt alone. Of the investigated catalyst compositions the one with the highest electrocatalytic activity was found to be Pt82Ru18. This enhancement towards ethanol oxidation is explained on the basis of a structural effect and modified bi-functional mechanism.

  9. Nonlinear behavior during NO2 hydrogenation on a nanosized Pt-Rh catalyst sample

    Science.gov (United States)

    Barroo, Cédric; De Decker, Yannick; Jacobs, Luc; de Bocarmé, Thierry Visart

    2017-08-01

    Automotive pollution control crucially relies on the reactivity of metal alloy catalysts. Understanding how the chemistry of an alloy compares with that of pure metals forms a decisive step towards the rational development of applied formulations of such catalysts. In this context, we studied the hydrogenation of NO2 on Pt-Rh catalysts at the nanoscale with field emission microscopy (FEM). Previous studies have shown the presence of complex reaction kinetics at the surface of Pt for this reaction, including periodic oscillations at 390 K. As we briefly show here, similar kinetics can also be observed on Rh at higher temperatures. The alloy samples (Pt-17.4 at.%Rh) show signs of important reactivity and associated nonlinear dynamics in an intermediate temperature range. In particular, at 425 K isothermal oscillations are observed on this specific alloy catalyst. The role of the alloy composition on the window of reactivity is explained with a simple theoretical model for the kinetics of the reaction.

  10. On the role of reactant transport and (surface) alloy formation for the CO tolerance of carbon supported PtRu polymer electrolyte fuel cell catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, J.; Colmenares, L.; Jusys, Z.; Behm, R.J. [Abt. Oberflaechenchemie und Katalyse, Universitaet Ulm (Germany); Moertel, R.; Boennemann, H. [Max-Planck-Institut fuer Kohlenforschung, Muelheim a.d. Ruhr (Germany); Koehl, G.; Modrow, H.; Hormes, J. [Physikalisches Institut, Universitaet Bonn (Germany)

    2006-07-15

    The role of atomic scale intermixing for the electrocatalytic activity of bimetallic PtRu anode catalysts in reformate operated polymer electrolyte fuel cells (PEFC) was investigated, exploiting the specific properties of colloid based catalyst synthesis for the selective preparation of alloyed and non-alloyed bimetallic catalysts. Three different carbon supported PtRu catalysts with different degrees of Pt and Ru intermixing, consisting of (i) carbon supported PtRu alloy particles (PtRu/C), (ii) Pt and Ru particles co-deposited on the same carbon support (Pt+Ru/C), and (iii) a mixture of carbon supported Pt and carbon supported Ru (Pt/C+Ru/C) as well as the respective monometallic Pt/C and Ru/C catalysts were prepared and characterized by electron microscopy (TEM), X-ray absorption spectroscopy, and CO stripping. Their performance as PEFC anode catalysts was evaluated by oxidation of a H{sub 2}/2%CO gas mixture (simulated reformate) under fuel cell relevant conditions (elevated temperature, continuous reaction and controlled reactant transport) in a rotating disk electrode (RDE) set-up. The CO tolerance and H{sub 2} oxidation activity of the three catalysts is comparable and distinctly different from that of the monometallic catalysts. The results indicate significant transport of the reactants, CO{sub ad} and/or OH{sub ad}, between Pt and Ru surface areas and particles for all three catalysts, with only subtle differences from the alloy catalyst to the physical mixture. The high activity and CO tolerance of the bimetallic catalysts, through the formation of bimetallic surfaces, is explained, e.g., by contact formation in nanoparticle agglomerates or by material transport and subsequent surface decoration/surface alloy formation during catalyst preparation, conditioning, and operation. The instability and mobility of the catalysts under these conditions closely resembles concepts in gas phase catalysis. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  11. Ultrasonically treated multi-walled carbon nanotubes (MWCNTs) as PtRu catalyst supports for methanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunwei; Hu, Xinguo; Wang, Dianlong; Dai, Changsong [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhang, Liang; Jin, Haibo [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Agathopoulos, Simeon [Department of Materials Science and Engineering, University of Ioannina, GR-451 10 Ioannina (Greece)

    2006-09-29

    In the quest of fabricating supported catalysts, experimental results of transmission electron microscopy, Raman and infrared spectroscopy indicate that ultrasonic treatment effectively functionalizes multi-walled carbon nanotubes (MWCNTs), endowing them with groups that can act as nucleation sites which can favor well-dispersed depositions of PtRu clusters on their surface. Ultrasonic treatment seems to be superior than functionalization via regular refluxing. This is confirmed by the determination of the electrochemistry active surface area (ECA) and the CO-tolerance performance of the PtRu catalysts, measured by adsorbed CO-stripping voltammetry in 0.5M sulfuric acid solution, and the real surface area of the PtRu catalysts, evaluated by Brunauer-Emmett-Teller (BET) measurements. Finally, the effectiveness for methanol oxidation is assessed by cyclic voltammetry (CV) in a sulfuric acid and methanol electrolyte. (author)

  12. Decoupling between Field-Instabilities of Antiferromagnetism and Pseudo-Metamagnetism in Rh-Doped CeRu2Si2 Kondo Lattice

    Science.gov (United States)

    Aoki, Dai; Paulsen, Carley; Kotegawa, Hisashi; Hardy, Frédéric; Meingast, Christoph; Haen, Pierre; Boukahil, Mounir; Knafo, William; Ressouche, Eric; Raymond, Stephane; Flouquet, Jacques

    2012-03-01

    Doping Kondo lattice system CeRu2Si2 with Rh-8% (Ce(Ru0.92Rh0.08)2Si2) leads to drastic consequences due to the mismatch of the lattice parameters between CeRu2Si2 and CeRh2Si2. A large variety of experiments clarifies the unusual properties of the ground state induced by the magnetic field from longitudinal antiferromagnetic (AF) mode at H=0 to polarized paramagnetic phase in very high magnetic field. The separation between AF phase, paramagnetic phase and polarized paramagnetic phase varying with temperature, magnetic field and pressure is discussed on the basis of the experiments down to very low temperature. Similarities and differences between Rh and La substituted alloys are discussed with emphasis on the competition between transverse and longitudinal AF modes, and ferromagnetic fluctuations.

  13. Interactions between interfacial water and CO adsorbed on Pt and Pt-Ru alloy surfaces under electrochemical conditions: Density-functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Juan A. [Department of Chemistry, University of Puerto Rico, San Juan, PR 00931-3346 (Puerto Rico); Ishikawa, Yasuyuki, E-mail: yishikawa@uprrp.ed [Department of Chemistry, University of Puerto Rico, San Juan, PR 00931-3346 (Puerto Rico)

    2010-12-30

    The structural and electronic properties of interfacial water and adsorbed CO on platinum and platinum/ruthenium alloy have been studied via density-functional theory calculations to gain insight into the water-adsorbate interaction under electrochemical conditions. The computational simulations reveal a new interpretation for the interaction of adsorbed CO and water at the electrochemical interfaces. The new interaction model rationalizes the observed quantitative relationship between infrared intensities for adsorbed bridging CO and water molecules that impart a high-frequency O-H stretch, ca. 3630-3660 cm{sup -1} on pure Pt and 3600-3620 cm{sup -1} on PtRu alloy. The theoretical modeling indicates that the observed feature common to both pure Pt and PtRu alloy surfaces is due to interfacial water molecules firmly hydrogen-bonded to bridging CO.

  14. Preparation of L11-CoPt/MgO/L11-CoPt tri-layer film on Ru(0001 underlayer

    Directory of Open Access Journals (Sweden)

    Mitsuru Ohtake

    2016-05-01

    Full Text Available A CoPt/MgO/CoPt tri-layer film is prepared on an Ru(0001 single-crystal underlayer at 300 °C by ultra-high vacuum magnetron sputtering. The growth behavior and the crystallographic properties are investigated by reflection high-energy electron diffraction, x-ray diffraction, and cross-sectional transmission electron microscopy. A fully epitaxial CoPt/MgO/CoPt film is formed on the Ru underlayer. The lower CoPt, the MgO, and the upper CoPt layers consist of two (111 variants whose atomic stacking sequences of close-packed plane along the perpendicular direction are ABCABC... and ACBACB... The lower and the upper CoPt layers involve metastable L11 structure, whereas the crystal structure of MgO layer is B1. Flat and atomically sharp interfaces are formed between the layers. The tri-layer film shows a strong perpendicular magnetic anisotropy reflecting the magnetocrystalline anisotropy of L11 crystal. The present study shows that an epitaxial L11-CoPt/MgO/L11-CoPt tri-layer film with perpendicular magnetic anisotropy can be formed by using a low substrate temperature of 300 °C.

  15. CATALYTIC AND ELECTROCATALYTIC ACTIVITY OF Pt-Ru/C ELECTRODE FOR HYDROGEN OXIDATION IN ALKALINE

    Directory of Open Access Journals (Sweden)

    D. LABOU

    2008-07-01

    Full Text Available The kinetics of the oxidation of H2 on PtRu/C gas-diffusion electrode was studied by interfacing the electrode with aqueous electrolytes at different pH values. The conducting electrolytes were KOH and HClO4 aqueous solutions with different concentrations. It is shown that the nature of the aqueous electrolyte plays the role of an active catalyst support for the PtRu/C electrode which drastically affects its catalytic properties. During the aforementioned interaction, termed electrochemical metal support interaction (EMSI, the electrochemical potential of the electrons at the catalyst Fermi level is equalised with the electrochemical potential of the solvated electron in the aqueous electrolyte. The electrochemical experiments carried out at various pH values showed that the electrochemical promotion catalysis (EPOC is more intense when the catalyst-electrode is interfaced with electrolytes with high pH values where the OH– ionic conduction prevails. It was concluded that similar to the solid state electrochemical systems EPOC proceeds through the formation of a polar adsorbed promoting layer of , electrochemically supplied by the OH- species, at the three phase boundaries of the gas exposed gas diffusion catalyst-electrode surface.

  16. In situ spectroscopic ellipsometry during atomic layer deposition of Pt, Ru and Pd

    Science.gov (United States)

    Leick, N.; Weber, J. W.; Mackus, A. J. M.; Weber, M. J.; van de Sanden, M. C. M.; Kessels, W. M. M.

    2016-03-01

    The preparation of ultra-thin platinum-group metal films, such as Pt, Ru and Pd, by atomic layer deposition (ALD) was monitored in situ using spectroscopic ellipsometry in the photon energy range of 0.75-5 eV. The metals’ dielectric function was parametrized using a ‘flexible’ Kramers-Kronig consistent dielectric function because it was able to provide accurate curve shape control over the optical response of the metals. From this dielectric function, it was possible to extract the film thickness values during the ALD process. The important ALD process parameters, such as the nucleation period and growth per cycle of Pt, Ru and Pd could be determined from the thickness evolution. In addition to process parameters, the film resistivity in particular could be extracted from the modeled dielectric function. Spectroscopic ellipsometry thereby revealed itself as a feasible and valuable technique to be used in research and development applications, as well as for process monitoring during ALD.

  17. Improved voltammetric method for simultaneous determination of Pt and Rh using second derivative signal transformation - application to environmental samples.

    Science.gov (United States)

    Monteiro, Carlos E; Cobelo-Garcia, Antonio; Caetano, Miguel; Correia Dos Santos, Margarida M

    2017-12-01

    The determination of Platinum-group elements (PGE) in relevant environmental matrices is a challenging task. Sensitive and accurate analytical procedures for simultaneous determination of Pt and Rh are still needed. In this study, we report for the first time on the use of second derivative signal transformation to the ultra-trace simultaneous determination of Pt and Rh by Adsorptive Cathodic Stripping Voltammetry (AdCSV). With that step, the ill-defined peaks typically observed in the original voltammograms are transformed into well-shaped peaks, resulting in accurate detection. The experimental conditions were investigated and optimised: a suitable electrolyte for both elements, with less reagents consumption, (0.25M H2SO4, 0.05M HCl, 0.01M FA and 0.5mM HZ), deposition time (td) and deposition potential (Ed). For td = 120s and Ed = -0.75V, linear relationships r > 0.999 were obtained in the concentration range up to 5.8ngL(-1) (27 pM) for Pt and up to 3.4ngL(-1) (34 pM) for Rh. Limits of detection were 0.2ngL(-1) for Pt and 0.08ngL(-1) for Rh. Lower values can be achieved by increasing the deposition time. Limits of quantification, LOQ, calculated as 3 times LOD, were 0.5ngL(-1) for Pt and 0.2ngL(-1) for Rh. The sensitivity of Pt was affected by elevated Zn concentrations, whereas a minor effect was observed for Rh. However, Pt and Rh determinations were not influenced using the standard addition method. Precision as intermediate precision and expressed as relative standard deviation, based on Pt and Rh spiked solutions and digested road dust CRM BCR-723 was 17% and 20% for Pt and Rh, respectively. Recoveries of CRM were around 90% for both elements. The method was successfully applied in the simultaneous determination of Pt and Rh in sediments from Tagus estuary and, for the first time, dissolved Rh was determined in water samples of a waste water treatment plant. Application of this technique in a multidisciplinary approach will be a relevant contribution to

  18. Impact of IrRu oxygen evolution reaction catalysts on Pt nanostructured thin films under start-up/shutdown cycling

    Science.gov (United States)

    Cullen, David A.; More, Karren L.; Atanasoska, Ljiljana L.; Atanasoski, Radoslav T.

    2014-12-01

    Electron microscopy and X-ray photoelectron spectroscopy (XPS) were utilized to study the role of oxygen evolution reaction (OER) catalysts in mitigating degradation arising from start-up/shutdown events. Pt nanostructured thin films (NSTF) were coated with a Ru0.1Ir0.9 OER catalyst at loadings ranging from 1 to 10 μg cm-2 and submitted to 5000 potential cycles within a membrane electrode assembly. Analysis of the as-deposited catalyst showed that the Ir and Ru coating is primarily metallic, and further evidence is provided to support the previously reported interaction between Ru and the perylene-red support. Aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy were used to observe the impact of the OER catalysts on Pt dissolution and migration into the membrane. Elemental mapping showed a high percentage of the Ir catalyst was maintained on the NSTF whisker surfaces following testing. The presence of the OER catalysts greatly reduced the smoothing of the Pt NSTF whiskers, which has been correlated with Pt dissolution and losses in electrochemically active surface area. The dissolution of both Ir and Pt led to the formation of IrPt nanoparticle clusters in the membrane close to the cathode, as well as the formation of a Pt band deeper in the membrane.

  19. Ru-decorated Pt nanoparticles on N-doped multi-walled carbon nanotubes by atomic layer deposition for direct methanol fuel cells

    DEFF Research Database (Denmark)

    Johansson, Anne-Charlotte Elisabeth Birgitta; Yang, R.B.; Haugshøj, K.B.

    2013-01-01

    (methylcyclopentadienyl)platinum MeCpPtMe3, bis(ethylcyclopentadienyl)ruthenium Ru(EtCp)2 and O2 as the precursors. Catalysts with 5, 10 and 20 ALD Ru cycles grown onto the CNT-supported ALD Pt nanoparticles (150 cycles) were prepared and tested towards the electro-oxidation of CO and methanol, using cyclic voltammetry...

  20. Radiolytic Synthesis of Pt-Ru Catalysts Based on Functional Polymer-Grafted MWNT and Their Catalytic Efficiency for CO and MeOH

    Directory of Open Access Journals (Sweden)

    Dae-Soo Yang

    2011-01-01

    Full Text Available Pt-Ru catalysts based on functional polymer-grafted MWNT (Pt-Ru@FP-MWNT were prepared by radiolytic deposition of Pt-Ru nanoparticles on functional polymer-grafted multiwalled carbon nanotube (FP-MWNT. Three different types of functional polymers, poly(acrylic acid (PAAc, poly(methacrylic acid (PMAc, and poly(vinylphenyl boronic acid (PVPBAc, were grafted on the MWNT surface by radiation-induced graft polymerization (RIGP. Then, Pt-Ru nanoparticles were deposited onto the FP-MWNT supports by the reduction of metal ions using γ-irradiation to obtain Pt-Ru@FP-MWNT catalysts. The Pt-Ru@FP-MWNT catalysts were then characterized by XRD, XPS, TEM ,and elemental analysis. The catalytic efficiency of Pt-Ru@FP-MWNT catalyst was examined for CO stripping and MeOH oxidation for use in a direct methanol fuel cell (DMFC. The Pt-Ru@PVPBAc-MWNT catalyst shows enhanced activity for electro-oxidation of CO and MeOH oxidation over that of the commercial E-TEK catalyst.

  1. Structure of carbon-supported Pt-Ru nanoparticles and their electrocatalytic behavior for hydrogen oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez, Amado; Centellas, Francesc; Garrido, Jose Antonio; Arias, Conchita; Rodriguez, Rosa Maria; Brillas, Enric; Cabot, Pere-Lluis [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-02-01

    The electrochemical activity towards hydrogen oxidation reaction (HOR) of a high performance carbon-supported Pt-Ru electrocatalyst (HP 20 wt.% 1:1 Pt-Ru alloy on Vulcan XC-72 carbon black) has been studied using the thin-film rotating disk electrode (RDE) technique. The physical properties of the Pt-Ru nanoparticles in the electrocatalyst were previously determined by transmission electron microscopy (TEM), high resolution TEM, fast Fourier transform (FFT), electron diffraction and X-ray diffraction (XRD). The corresponding compositional and size-shape analyses indicated that nanoparticles generally presented a 3D cubo-octahedral morphology with about 26 at.% Ru in the lattice positions of the face-centred cubic structure of Pt. The kinetics for HOR was studied in a hydrogen-saturated 0.5 M H{sub 2}SO{sub 4} solution using thin-film electrodes prepared by depositing an ink of the electrocatalyst with different Nafion contents in a one-step process on a glassy carbon electrode. A maximum electrochemically active surface area (ECSA) of 119 m{sup 2} g Pt{sup -1} was found for an optimum Nafion composition of the film of about 35 wt.%. The kinetic current density in the absence of mass transfer effects was 21 mA cm{sup -2}. A Tafel slope of 26 mV dec{sup -1}, independent of the rotation rate and Nafion content, was always obtained, evidencing that HOR behaves reversibly. The exchange current density referred to the ECSA of the Pt-Ru nanoparticles was 0.17 mA cm{sup -2}, a similar value to that previously found for analogous inks containing pure Pt nanoparticles. (author)

  2. CO tolerant PtRu-MoO{sub x} nanoparticles supported on carbon nanofibers for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsiouvaras, N.; Pena, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Martinez-Huerta, M.V. [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Facultad de Quimicas, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, 38071, La Laguna, Tenerife (Spain); Moliner, R.; Lazaro, M.J. [Instituto de Carboquimica, CSIC, Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Rodriguez, J.L.; Pastor, E. [Facultad de Quimicas, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, 38071, La Laguna, Tenerife (Spain)

    2009-01-15

    Novel nanostructured catalysts based on PtRu-MoO{sub x} nanoparticles supported on carbon nanofibers have been investigated for CO and methanol electrooxidation. Carbon nanofibers are prepared by thermocatalytic decomposition of methane (NF), and functionalized with HNO{sub 3} (NF.F). Electrocatalysts are obtained using a two-step procedure: (1) Pt and Ru are incorporated on the carbon substrates (Vulcan XC 72R, NF and NF.F), and (2) Mo is loaded on the PtRu/C samples. Differential electrochemical mass spectrometry (DEMS) analyses establish that the incorporation of Mo increases significantly the CO tolerance than respective binary counterparts. The nature of the carbon support affects considerably the stabilization of MoO{sub x} nanoparticles and also the performance in methanol electrooxidation. Accordingly, a significant increase of methanol oxidation is obtained in PtRu-MoO{sub x} nanoparticles supported on non-functionalized carbon nanofiber, in parallel with a large reduction of the Pt amount in comparison with binary counterparts and commercial catalyst. (author)

  3. Solid solution alloy nanoparticles of immiscible Pd and Ru elements neighboring on Rh: changeover of the thermodynamic behavior for hydrogen storage and enhanced CO-oxidizing ability.

    Science.gov (United States)

    Kusada, Kohei; Kobayashi, Hirokazu; Ikeda, Ryuichi; Kubota, Yoshiki; Takata, Masaki; Toh, Shoichi; Yamamoto, Tomokazu; Matsumura, Syo; Sumi, Naoya; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kitagawa, Hiroshi

    2014-02-05

    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 the atomic level in the bulk state. From the XRD measurement, it was found that the dominant structure of Pd(x)Ru(1-x) changes from fcc to hcp with increasing Ru content. The structures of Pd(x)Ru(1-x) nanoparticles in the Pd composition range of 30-70% consisted of both solid solution fcc and hcp structures, and both phases coexist in a single particle. In addition, the reaction of hydrogen with the Pd(x)Ru(1-x) nanoparticles changed from exothermic to endothermic as the Ru content increased. Furthermore, the prepared Pd(x)Ru(1-x) nanoparticles demonstrated enhanced CO-oxidizing catalytic activity; Pd0.5Ru0.5 nanoparticles exhibit the highest catalytic activity. This activity is much higher than that of the practically used CO-oxidizing catalyst Ru and that of the neighboring Rh, between Ru and Pd.

  4. In situ time-resolved FTIR investigation on the reaction mechanism of partial oxidation of methane to syngas over supported Rh and Ru catalysts

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In situ time-resolved FTIR spectroscopy was used to study the reaction mechanism of partial oxidation of methane (POM) to synthesis gas and the reaction of CH4/O2/He (2/1/45, molar ratio) gas mixture with adsorbed CO species over Rh/SiO2, Ru/γ-Al2O3 and Ru/SiO2 catalysts at 500-600℃. It was found that CO is the primary product of POM reaction over reduced and working state Rh/SiO2 catalysts. Direct oxidation of CH4 is the main pathway of synthesis gas formation over Rh/SiO2 catalyst. CO2 is the primary product of POM over Ru/γ-Al2O3 and Ru/SiO2 catalysts. The dominant reaction pathway for synthesis gas formation over Ru/γ-Al2O3 catalyst is via the reforming reactions of CH4 with CO2 and H2O. For the POM reaction over Rh/SiO2 and Ru/γ-Al2O3 catalysts, consecutive oxidation of surface CO species is an important pathway of CO2 formation.

  5. Simultaneous leaching of Pt, Pd and Rh from automotive catalytic converters in chloride-containing solutions

    Science.gov (United States)

    Hasani, M.; Khodadadi, A.; Koleini, S. M. J.; Saeedi, A. H.; Meléndez, A. M.

    2017-01-01

    Dissolution of platinum group metals (PGM; herein Pt, Pd and Rh) in different chloride-based leaching systems from spent auto catalysts was performed. Response surface methodology and a five-level-five-factor central composite design were used to evaluate the effects of 1) temperature, 2) liquid-to-solid ratio, 3) stirring speed, 4) acid concentration and 5) particle size on extraction yield of PGM by aqua regia. Analysis of variance was used to determine the optimum conditions and most significant factors affecting the overall metal extraction. In the optimum conditions, leaching of Pt, Pd and Rh was 91.58%, 93.49% and 60.15%, respectively. The effect of different oxidizing agents on the PGM dissolution in chloride medium was studied comparatively in the following leaching systems: a) aqua regia/sulfuric acid mixture, b) hydrogen peroxide in sulfuric acid (piranha solution), c) sodium hypochlorite and d) copper(II). Dissolution of Rh is increased in both aqua regia and hydrogen peroxide/hydrochloric acid solutions by adding sulfuric acid.

  6. Preparation of PtRu/C anode electrocatalysts using gamma radiation for methanol electro-oxidation; Preparacao de eletrocatalisadores PtRu/C utilizando radiacao gama para aplicacao como anodo na oxidacao direta de metanol

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio Fortunato da

    2006-07-01

    Pt Ru/C (carbon-supported Pt Ru nanoparticles) anode electrocatalysts were prepared using radiolytic process (gamma radiation) and tested for methanol electro-oxidation. In this process, water/2-propanol and water/ethylene glycol solutions containing the metallic ions and the carbon support were submitted to gamma radiation under stirring. The water/alcohol ratio (v/v) and the total dose (kGy) were studied. A nominal Pt Ru atomic ratio of 50:50 were used in all experiments. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry (CV). The electro-oxidation of methanol was studied by cyclic voltammetry using the thin porous coating technique. The electrocatalysts prepared in water/2-propanol showed crystallite size in the range of 3-5 nm and Pt Ru atomic ratio of 50:50. The electrocatalysts prepared in water/ethylene glycol showed crystallite size (2-3 nm) smaller than the ones obtained in water/2-propanol, however, the Pt Ru atomic ratios obtained were approximately 80:20, showing that only part of ruthenium ions were reduced. For methanol oxidation the electrocatalytic activity depends on the water/2-propanol and water/ethylene glycol ratio used in the reaction medium. The electrocatalysts prepared in water/2-propanol showed inferior performance to the ones prepared in water/ethylene glycol, which showed similar or superior performances (amperes per gram of platinum) to the commercial electrocatalyst from E-TEK. (author)

  7. Dispersal and accumulation of Pt, Pd and Rh derived from a roundabout in Sheffield (UK): From stream to tidal estuary.

    Science.gov (United States)

    Prichard, H M; Jackson, M T; Sampson, J

    2008-08-15

    The Coisley Hill roundabout, a typical urban source for PGE in stream sediments, has anomalously high values of up to 408 ppb Pt, 444 ppb Pd and 113 ppb Rh in road dust, up to 416 ppb Pt and 278 ppb Pd in gulley sediment and up to 606 ppb Pt and 1050 ppb Pd in verge soil. For samples collected at the same time, the road dust values are much higher than in sediments in the Shire Brook stream, that drains the roundabout, with values of 3-64 ppb Pt, 4-57 ppb Pd and up to 7 ppb Rh. Downstream sediments from rivers Rother and Don have lower values of 2-35 ppb Pt, 2-14 ppb Pd and up to 3 ppb Rh. The Humber estuary values are low with 6-8 ppb Pt, 5-8 ppb Pd and 1-2 ppb Rh. Pt/Pd increases down catchment with Coisley Hill 0.8, Shire Brook 1.0, Trent and Don 1.5 and the Humber estuary 2.0. Pt/Rh and Pd/Rh also increase downstream. Precious metals are generally dispersed away from their vehicle catalytic source and Pd is dispersed more than Pt and Rh but Pt and Pd are re-concentrated in acid mine drainage in the Shire Brook, with concentrations varying with stream flow. Pt and Pd values are slightly elevated at the tidal limit and in mud deposited when the river is in spate. On Coisley Hill, values of 133 ppb Pt and 230 ppb Pd occur in dust from a new road surface (two weeks old when sampled). These are similar to those on much older road surfaces suggesting that Pt and Pd collect and disperse rapidly from roads. Au is low in road dust and higher values in conurbations suggest the presence of more Au sources in urban rather than in rural areas. Au values are not diluted downstream as much as PGE suggesting different processes of dispersion and sedimentation.

  8. Influence of alcohol additives in the preparation of electrodeposited Pt-Ru catalysts on oxidized graphite cloths

    Energy Technology Data Exchange (ETDEWEB)

    Sieben, Juan Manuel, E-mail: jmsieben@uns.edu.ar [Instituto de Ingenieria Electroquimica y Corrosion, Universidad Nacional del Sur, B8000CPB Bahia Blanca (Argentina); Duarte, Marta M.E.; Mayer, Carlos E. [Instituto de Ingenieria Electroquimica y Corrosion, Universidad Nacional del Sur, B8000CPB Bahia Blanca (Argentina)

    2011-03-03

    Research highlights: > Pt-Ru catalysts were prepared by potential pulse electrodeposition from solutions containing EtOH or EG at pH 2 and 5. > The catalyst particle size, loading and dispersion were influenced by solution pH and alcohol addition. > The deposits prepared at pH 2 exhibited large irregular agglomerates while those prepared at pH 5 presented smaller globular particles. > Pt-Ru system prepared using EG at pH 5 exhibited the best performance for CH{sub 3}OH oxidation. - Abstract: Carbon supported Pt-Ru catalysts were prepared by multiple cycles of potentiostatic pulses from aqueous diluted chloroplatinic acid and ruthenium chloride solutions in the presence of ethanol or ethylene glycol at pH 2 and 5. SEM images showed that the metallic deposit prepared at pH 2 consisted of large irregular agglomerates, whereas smaller globular particles were obtained at pH 5. In addition, the average particle size was considerably decreased in the presence of the stabilizers. The supported Pt-Ru alloys were tested as catalysts for methanol electro-oxidation in acid media. Electrocatalytic activity measurements indicated that the most active electrode was obtained with ethylene glycol as additive at pH 5.

  9. Pulse electrodeposition of Pt and Pt–Ru methanol-oxidation nanocatalysts onto carbon nanotubes in citric acid aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Huei-Yu [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Hsieh, Chien-Kuo [Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan, ROC (China); Tsai, Ming-Chi; Wei, Yu-Hsuan; Yeh, Tsung-Kuang [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Tsai, Chuen-Horng, E-mail: tsai@aec.gov.tw [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China)

    2015-06-01

    In this study, platinum nanoparticle/carbon nanotube (Pt NP/CNT) and platinum–ruthenium nanoparticle (Pt–Ru NP/CNT) hybrid nanocatalysts were prepared by the pulse-electrodeposition method in different aqueous solutions containing citric acid (CA) or sulfuric acid (SA). The electrocatalytic properties of the Pt NP/CNT and Pt–Ru NP/CNT electrodes prepared using different aqueous solutions were investigated for methanol oxidation. The results show that the electrochemical mass activities of these hybrid nanocatalysts prepared in the CA aqueous solution were increased by factors of 1.46 and 2.77 for Pt NPs and Pt–Ru NPs, respectively, compared with those prepared in SA aqueous solutions using the same procedure. These increased mass activities are attributed to the CA playing dual roles as both a stabilizing agent and a particle size reducing agent in the aqueous solutions. The approach developed in this work enables further reductions in the particle sizes of noble-metal nanocatalysts. - Highlights: • Pulse-electrodeposition of Pt or Pt–Ru nanoparticles on carbon nanotubes • Carbon nanotubes used as a catalyst-supporting material • Citric acid used as reducing agent in the aqueous electrodeposition solutions • Electrochemical activity for methanol oxidation improved by a factor of 1.46 to 2.77.

  10. Effect of the structure of Pt-Ru/C particles on CO{sub ad} monolayer vibrational properties and electrooxidation kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Maillard, Frederic; Chatenet, Marian [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces, UMR 5631, CNRS/INPG/UJF, 1130 rue de la Piscine, BP75, 38402 Saint Martin d' Heres (France); Bonnefont, Antoine [Laboratoire d' Electrochimie et de Chimie Physique du Corps Solide, Institut de chimie, UMR 7177, CNRS/Universite Louis Pasteur, 4 rue Blaise Pascal, 67000 Strasbourg (France); Guetaz, Laure [Grenoble Electron Microscopy at Minatec, LITEN/DTH/LCPEM, CEA-Grenoble, 38054 Grenoble Cedex 9 (France); Doisneau-Cottignies, Beatrice [Science et Ingenierie Materiaux Procedes, 1130 rue de la Piscine, BP75, 38402 Saint Martin d' Heres (France); Roussel, Herve [Laboratoire des Materiaux et du Genie Physique, Institut National Polytechnique de Grenoble, Minatec, 3 parvis Louis Neel, BP 257, 38016 Grenoble Cedex 1 (France); Stimming, Ulrich [Physik Department E19, Technische Universitaet, Muenchen, D-85748 Garching bei Muenchen (Germany)

    2007-12-01

    In this paper, we combined FTIR spectroscopy and CO{sub ad} stripping voltammetry to investigate CO{sub ad} adsorption and electrooxidation on Pt-Ru/C nanoparticles. The Pt:Ru elemental composition and the metal loading were determined by ICP-AES. The X-ray diffraction patterns of the Pt-Ru/C indicated formation of a Pt-Ru (fcc) alloy. HREM images revealed an increase in the fraction of agglomerated Pt-Ru/C particles with increasing the metal loading and showed that agglomerated Pt-Ru/C nanoparticles present structural defects such as twins or grain boundaries. In addition, isolated Pt-Ru/C nanoparticles have similar mean particle size (ca. 2.5 nm) and particle size distributions whatever the metal loading. Therefore, we could determine precisely the effect of particle agglomeration on the CO{sub ad} vibrational properties and electrooxidation kinetics. FTIR measurements revealed a main CO{sub ad} stretching band at ca. {sub anti} {sub {nu}}{sub CO{sub L}}=2030 cm{sup -1}, which we ascribed to a-top CO{sub ad} on Pt domains electronically modified by the presence of Ru. As the metal loading increased, the position of this band was blue shifted by ca. 5 cm{sup -1} and a shoulder around 2005 cm{sup -1} developed, which was ascribed to a-top CO{sub ad} on Ru domains. The reason for this was suggested to be the increasing size of Ru domains on agglomerated Pt-Ru/C particles, which lifts dipole-dipole coupling and allows two vibrational features to be observed (CO{sub ad}/Ru, CO{sub ad}/Pt). This is evidence that FTIR spectroscopy can be used to probe small chemical fluctuations of the Pt-Ru/C surface. Finally, we comment on the CO{sub ad} electrooxidation kinetics. We observed that CO{sub ad} was converted more easily into CO{sub 2} as the metal loading, i.e. the fraction of agglomerated Pt-Ru/C nanoparticles, increased. (author)

  11. Synthetic, structural and antifungal studies of coordination compounds of Ru(III, Rh(III and Ir(III with tetradentate Schiff bases

    Directory of Open Access Journals (Sweden)

    ANKITA SRIVASTAVA

    2006-09-01

    Full Text Available A series of octahedral Ru(III, Rh(III and Ir(III complexes have been prepared with tetradentate Schiff bases derived by condensing isatin with 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,2-diaminobenzene and 1,3-diaminobenzene. The obtained complexes were characterized on the basis of their elemental analyses, magnetic moment, conductance, IR, electronic, 1HNMR and FAB mass spectra, as well as thermal analyses. The Ru(III complexes are low spin paramagnetic, while Rh(III and Ir(III behave as diamagnetic complexes. The IR spectral data revealed that all the Schiff bases behave as tetradentate and are coordinated to Ru(III, Rh(III and Ir(III via nitrogen and oxygen. Antifungal studies of the ligands as well as their complexes were carried out by the agar plate method.

  12. Electroactivity of high performance unsupported Pt-Ru nanoparticles in the presence of hydrogen and carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez-Palenzuela, Amado; Cabot, Pere-Lluis; Centellas, Francesc; Garrido, Jose Antonio; Arias, Conchita; Rodriguez, Rosa Maria; Brillas, Enric [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-10-15

    The electrochemical activity of high performance unsupported (1:1) Pt-Ru electrocatalyst in the presence of hydrogen and carbon monoxide has been studied using the thin-film rotating disk electrode (RDE) technique. The kinetic parameters of these reactions were determined in H{sub 2}- and CO-saturated 0.5 M H{sub 2}SO{sub 4} solutions by means of cyclic voltammetry, including CO stripping, and RDE voltammetry. Pt-Ru/Nafion inks were prepared in one step with different Nafion mass fractions, allowing determining the ionomer influence in electrocatalytic response and obtaining the kinetic current density in absence of mass-transfer effects, being 41 and 12 mA cm{sup 2} (geometrical area), for H{sub 2} and CO oxidation, respectively. These values correspond to mass activities of 1.37 and 0.40 A mg{sub Pt}{sup 1} and to specific activities of 1.52 and 0.44 mA cm{sub Pt}{sup 2}. The Tafel analysis confirmed that hydrogen oxidation was a two-electron reversible reaction, while CO oxidation exhibited an irreversible behavior with a charge-transfer coefficient of 0.42. The kinetic results for CO oxidation are in agreement with the bifunctional theory, in which the reaction between Pt-CO and Ru-OH is the rate-determining step. The exchange current density for hydrogen reaction was 0.28 mA cm{sup 2} (active surface area), thus showing similar kinetics to those found for carbon-supported Pt and Pt-Ru electrocatalyst nanoparticles. (author)

  13. Assessment of ocular beta radiation dose distribution due to 106Ru/106Rh brachytherapy applicators using MCNPX Monte Carlo code

    Directory of Open Access Journals (Sweden)

    Nilseia Aparecida Barbosa

    2014-08-01

    Full Text Available Purpose: Melanoma at the choroid region is the most common primary cancer that affects the eye in adult patients. Concave ophthalmic applicators with 106Ru/106Rh beta sources are the more used for treatment of these eye lesions, mainly lesions with small and medium dimensions. The available treatment planning system for 106Ru applicators is based on dose distributions on a homogeneous water sphere eye model, resulting in a lack of data in the literature of dose distributions in the eye radiosensitive structures, information that may be crucial to improve the treatment planning process, aiming the maintenance of visual acuity. Methods: The Monte Carlo code MCNPX was used to calculate the dose distribution in a complete mathematical model of the human eye containing a choroid melanoma; considering the eye actual dimensions and its various component structures, due to an ophthalmic brachytherapy treatment, using 106Ru/106Rh beta-ray sources. Two possibilities were analyzed; a simple water eye and a heterogeneous eye considering all its structures. Two concave applicators, CCA and CCB manufactured by BEBIG and a complete mathematical model of the human eye were modeled using the MCNPX code. Results and Conclusion: For both eye models, namely water model and heterogeneous model, mean dose values simulated for the same eye regions are, in general, very similar, excepting for regions very distant from the applicator, where mean dose values are very low, uncertainties are higher and relative differences may reach 20.4%. For the tumor base and the eye structures closest to the applicator, such as sclera, choroid and retina, the maximum difference observed was 4%, presenting the heterogeneous model higher mean dose values. For the other eye regions, the higher doses were obtained when the homogeneous water eye model is taken into consideration. Mean dose distributions determined for the homogeneous water eye model are similar to those obtained for the

  14. A general approach for the synthesis of bimetallic M–Sn (M = Ru, Rh and Ir) catalysts for efficient hydrogenolysis of ester

    KAUST Repository

    Samal, Akshaya K.

    2016-11-24

    A versatile synthetic method was applied for the preparation of Sn containing bimetallic catalysts. The synthesis was performed by simply mixing the super hydride [LiB(C2H5)(3)H], with a metal (Ru, Rh or Ir) salt and an organotin complex in tetrahydrofuran solvent without using any surfactant. This leads to the formation of monodispersed M-Sn (M = Ru, Rh or Ir) bimetallic nanoparticles (NPs). These bimetallic catalysts show high performances in the hydrogenolysis of ester to the corresponding alcohol.

  15. σ-Aromaticity in polyhydride complexes of Ru, Ir, Os, and Pt.

    Science.gov (United States)

    Jimenez-Izal, Elisa; Alexandrova, Anastassia N

    2016-04-28

    Transition-metal hydrides represent a unique class of compounds, which are essential for catalysis, organic synthesis, and hydrogen storage. In this work we study IrH5(PPh3)2, (RuH5(P(i)Pr3)2)(-), (OsH5(P(i)Pr3)2)(-), and OsH4(PPhMe2)3 polyhydride complexes, inspired by the recent discovery of the σ-aromatic PtZnH5(-) cluster anion. The distinctive feature of these molecules is that, like in the PtZnH5(-) cluster, the metal is five-fold coordinated in-plane, and holds additional ligands at the axial positions. This work shows that the unusual coordination in these compounds indeed can be explained by σ-aromaticity in the pentagonal arrangement, stabilized by the atomic orbitals on the metal. Based on this newly elucidated bonding principle, we additionally propose a new family of polyhydrides that display a uniquely high coordination. We also report the first indications of how aromaticity may impact the reactivity of these molecules.

  16. Pt, Au, Pd and Ru Partitioning Between Mineral and Silicate Melts: The Role of Metal Nanonuggets

    Science.gov (United States)

    Malavergne, V.; Charon, E.; Jones, J.; Agranier, A.; Campbell, A.

    2012-01-01

    The partition coefficients of Pt and other Pt Group Elements (PGE) between metal and silicate D(sub Metal-Silicate) and also between silicate minerals and silicate melts D(sub Metal-Silicate) are among the most challenging coefficients to obtain precisely. The PGE are highly siderophile elements (HSE) with D(sub Metal-Silicate) >10(exp 3) due to the fact that their concentrations in silicates are very low (ppb to ppt range). Therefore, the analytical difficulty is increased by the possible presence of HSE-rich-nuggets in reduced silicate melts during experiments). These tiny HSE nuggets complicate the interpretation of measured HSE concentrations. If the HSE micro-nuggets are just sample artifacts, then their contributions should be removed before calculations of the final concentration. On the other hand, if they are produced during the quench, then they should be included in the analysis. We still don't understand the mechanism of nugget formation well. Are they formed during the quench by precipitation from precursor species dissolved homogeneously in the melts, or are they precipitated in situ at high temperature due to oversaturation? As these elements are important tracers of early planetary processes such as core formation, it is important to take up this analytical and experimental challenge. In the case of the Earth for example, chondritic relative abundances of the HSE in some mantle xenoliths have led to the concept of the "late veneer" as a source of volatiles (such as water) and siderophiles in the silicate Earth. Silicate crystal/liquid fractionation is responsible for most, if not all, the HSE variation in the martian meteorite suites (SNC) and Pt is the element least affected by these fractionations. Therefore, in terms of reconstructing mantle HSE abundances for Mars, Pt becomes a very important player. In the present study, we have performed high temperature experiments under various redox conditions in order to determine the abundances of Pt, Au

  17. Anthropogenic platinum group element (Pt, Pd, Rh) concentrations in PM10 and PM2.5 from Kolkata, India.

    Science.gov (United States)

    Diong, Huey Ting; Das, Reshmi; Khezri, Bahareh; Srivastava, Bijayen; Wang, Xianfeng; Sikdar, Pradip K; Webster, Richard D

    2016-01-01

    This study investigates platinum group elements (PGEs) in the breathable (PM10) and respirable (PM2.5) fractions of air particulates from a heavily polluted Indian metro city. The samples were collected from traffic junctions at the heart of the city and industrial sites in the suburbs during winter and monsoon seasons of 2013-2014. PGE concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The PGE concentrations in the samples from traffic junctions are within the range of 2.7-111 ng/m(3) for Pd, 0.86-12.3 ng/m(3) for Pt and 0.09-3.13 ng/m(3) for Rh, and from industrial sites are within the range of 3.12-32.3 ng/m(3) for Pd, 0.73-7.39 ng/m(3) for Pt and 0.1-0.69 ng/m(3) for Rh. Pt concentrations were lower in the monsoon compared to winter while Pd concentrations increased during monsoon and Rh stayed relatively unaffected across seasons. For all seasons and locations, concentrations of Pd > Pt > Rh, indicating dominance of Pd-containing exhaust converters. Most of the PGEs were concentrated in the PM2.5 fraction. A strong correlation (R ≥ 0.62) between the PGEs from traffic junction indicates a common emission source viz. catalytic converters, whereas a moderate to weak correlation (R ≤ 0.5) from the industrial sites indicate mixing of different sources like coal, raw materials used in the factories and automobile. A wider range of Pt/Pd, Pt/Rh and Pd/Rh ratios measured in the traffic junction possibly hint towards varying proportions of PGEs used for catalyst productions in numerous rising and established car brands.

  18. In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2015-01-01

    Full Text Available PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI- functionalized multiwalled carbon nanotubes (MWCNTs via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray powder diffraction (XRD, and energy dispersive X-ray spectroscopy (EDX, respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC.

  19. Responses of different dosemeters in beta dosimetry of {sup 106}Ru/{sup 106}Rh ophthalmic applicators;Respostas de diferentes dosimetros termoluminescentes na dosimetria beta de aplicadores oftalmicos de {sup 106}Ru/{sup 106}Rh

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, D.F.P.; Daros, K.A.C.; Segreto, R.A.; Medeiros, R.B. [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil)

    2009-07-01

    This work presents the TL response of three kinds of dosimeters from different manufacturing characteristics under irradiation of 106 Ru / 106 Rh sealed sources used in ophthalmic brachytherapy. They are: Ca SO{sub 4}:Dy + teflon (D- Ca SO{sub 4}:Dy -0,4), LiF:Mg, Ti (TLD-100) and Ca SO{sub 4}:Dy (TLD-900). Some of reports accepted by scientific community (NCS report 14 e ICRU report 72) as reference in the quality control of beta applicators dosimetry recommend that the absorbed dose standard uncertainties can be kept below 20%. The TLD Ca SO{sub 4}:Dy + teflon presented proper sensibility and high precision comparing with the others. Considering the similar dimensions of ophthalmic tumors and aside critical structures it is relevant to reduce undesirable effects due to the irradiation of these structures. Therefore, the quality control in the beta dosimetry using this kind of source is a constant challenge. (author)

  20. [Determination of ru, rh and Pd in 30% trialkyl phosphine oxide (TRPO)-kerosene by inductively coupled plasma-atomic emission spectrum (ICP-AES)].

    Science.gov (United States)

    Wang, Jian-Chen; Zhang, Lin

    2013-07-01

    The determination method of Ru, Rh and Pd in 30% TRPO-kerosene ICP-AES was studied by using aqueous calibration reference solution and choosing ethanol as diluent. The effects of the contents of 30% TRPO-kerosene and aqueous solution and the concentration of HNO3 in 30% TRPO-kerosene on the intensities of Ru, Rh and Pd were described. The optimized condition for preparing samples and calibration solutions was chosen as follows: The contents of 30% TRPO-kerosene and aqueous phase were 10% (V/V) and 5% (V/V) respectively and the concentration of HNO3 30% TRPO-kerosene was 0.20 mol x L(-1). The determination method of Au, Ru and Pd was set up according to the above condition. The detection limit, precision and recovery ratio of Ru, Rh and Pd are well. The method is not only used in determination of Au, Ru and Pd in 30% TRPO-kerosene, but also used in other organic phases.

  1. Tetrapropylammonium ion influence on the synthesis of Pt Ru/carbon hybrids by hydrothermal carbonization; Influencia do ion tetrapropilamonio na sintese de hibridos PtRu/carbono por carbonizacao hidrotermica

    Energy Technology Data Exchange (ETDEWEB)

    Tusi, M.M.; Polanco, N.S.O.; Brandalise, M.; Correa, O.V.; Silva, A.C.; Oliveira Neto, A.; Linardi, M.; Spinace, E.V., E-mail: espinace@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    PtRu/Carbon hybrid materials were prepared by hydrothermal carbonization using starch as carbon source and reducing agent and H{sub 2}PtCl{sub 6}.6H{sub 2}O e RuCl{sub 3}.xH{sub 2}O as metals source and catalyst of the carbonization process. The materials were prepared in the following conditions: without pH adjustment, in the absence and in the presence of tetrapropylammonium chloride (TPACl), and adjusting the pH using potassium hydroxide (KOH) or tetrapropylammonium hydroxide (TPAOH). The obtained materials were treated under argon atmosphere at 900 deg C and characterized by SEM/EDX, BET isotherm, XRD and TEM. The electro-oxidation of methanol was studied by chronoamperometry. The material prepared using TPAOH showed the best performance for methanol electro-oxidation. (author)

  2. First measurement of the Ru-96(p,gamma)Rh-97 cross section for the p process with a storage ring

    NARCIS (Netherlands)

    Mei, Bo; Aumann, Thomas; Bishop, Shawn; Blaum, Klaus; Boretzky, Konstanze; Bosch, Fritz; Brandau, Carsten; Braeuning, Harald; Davinson, Thomas; Dillmann, Iris; Dimopoulou, Christina; Ershova, Olga; Fueloep, Zsolt; Geissel, Hans; Glorius, Jan; Gyuerky, Gyoergy; Heil, Michael; Kaeppeler, Franz; Kelic-Heil, Aleksandra; Kozhuharov, Christophor; Langer, Christoph; Le Bleis, Tudi; Litvinov, Yuri; Lotay, Gavin; Marganiec, Justyna; Muenzenberg, Gottfried; Nolden, Fritz; Petridis, Nikolaos; Plag, Ralf; Popp, Ulrich; Rastrepina, Ganna; Reifarth, Rene; Riese, Bjoern; Rigollet, Catherine; Scheidenberger, Christoph; Simon, Haik; Sonnabend, Kerstin; Steck, Markus; Stoehlker, Thomas; Szuecs, Tamas; Suemmerer, Klaus; Weber, Guenter; Weick, Helmut; Winters, Danyal; Winters, Natalya; Woods, Philip; Zhong, Qiping

    2015-01-01

    This work presents a direct measurement of the Ru-96(p,gamma)Rh-97 cross section via a novel technique using a storage ring, which opens opportunities for reaction measurements on unstable nuclei. A proof-of-principle experiment was performed at the storage ring ESR at GSI in Darmstadt, where circul

  3. Preparation and characterization of nano-sized Pt-Ru/C catalysts and their superior catalytic activities for methanol and ethanol oxidation.

    Science.gov (United States)

    Şen, Selda; Şen, Fatih; Gökağaç, Gülsün

    2011-04-21

    Carbon-supported PtRu nanoparticles (Ru/Pt: 0.25) were prepared by three different methods; simultaneous reduction of PtCl(4) and RuCl(3) (catalyst I) and changing the reduction order of PtCl(4) and RuCl(3) (catalysts II and III) to enhance the performance of the anodic catalysts for methanol and ethanol oxidation. Structure, microstructure and surface characterizations of all the catalysts were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the XRD analysis showed that all catalysts had a face-centered cubic (fcc) structure with different and smaller lattice parameters than that of pure platinum, showing that the Ru incorporates into the Pt fcc structure by different ratios in all the catalysts. The typical particle sizes of all catalysts were in the range of 2-3 nm. The most active and stable catalyst for methanol and ethanol oxidation is catalyst III, in which a large amount (more than 90%) of PtRu alloy formation was observed. It has been found that this catalyst is about 8.0 and 33.4 times more active at ∼0.60 V towards the methanol and ethanol oxidation reactions, respectively, compared to the commercial Pt catalyst.

  4. Quantum Criticality and Lifshitz Transition in the Ising System CeRu2Si2: Comparison with YbRh2Si2

    Science.gov (United States)

    Pourret, Alexandre; Aoki, Dai; Boukahil, Mounir; Brison, Jean-Pascal; Knafo, William; Knebel, Georg; Raymond, Stephane; Taupin, Mathieu; Ōnuki, Yoshichika; Flouquet, Jacques

    2014-06-01

    New thermoelectric power (TEP) measurements on prototype heavy-fermion compounds close to magnetic quantum criticality are presented. The highly sensitive technique of TEP is an unique tool to reveal Fermi surface instabilities, referred here as Lifshitz transitions. The first focus is on the Ising CeRu2Si2 series. Doping CeRu2Si2 with Rh produces a decoupling between the first order metamagnetic transition and the pseudo-metamagnetism observed in the pure compound. Comparison is made with the case of YbRh2Si2 which is often considered as the archetype of local quantum criticality by contrast to CeRu2Si2, taken as an example of spin-density wave criticality. Up to now for ferromagnetic materials showing ferromagnetic wings, no simple case appears where the Fermi surface is preserved between the ferromagnetic and paramagnetic phases. An open issue is the consequence of Lifshitz transitions on superconductivity in these multiband systems.

  5. Synthesis of higher alcohols from CO2 hydrogenation over a PtRu/Fe2O3 catalyst under supercritical condition.

    Science.gov (United States)

    He, Zhenhong; Qian, Qingli; Zhang, Zhaofu; Meng, Qinglei; Zhou, Huacong; Jiang, Zhiwei; Han, Buxing

    2015-12-28

    Hydrogenation of CO(2) to alcohols is of great importance, especially when producing higher alcohols. In this work, we synthesized heterogeneous PtRu/Fe(2)O(3), in which the Pt and Ru bimetallic catalysts were supported on Fe(2)O(3). The catalyst was used to catalyse CO(2) hydrogenation to alcohols. It was demonstrated that the activity and selectivity could be tuned by the bimetallic composition, and the catalyst with a Pt to Ru molar ratio of 1:2 (Pt(1)Ru(2)/Fe(2)O(3)) had high activity and selectivity at 200°C, which is very low for heterogeneous hydrogenation of CO(2) to produce higher alcohols. The conversion and the selectivity increased with increasing pressures of CO(2) and/or H(2). The catalyst could be reused at least five times without any obvious change in activity or selectivity.

  6. Dynamics of electrocatalytic oxidation of ethylene glycol, methanol and formic acid at MWCNT platform electrochemically modified with Pt/Ru nanoparticles

    CSIR Research Space (South Africa)

    Maxakato, NW

    2010-03-01

    Full Text Available Comparative electrocatalytic behavior of functionalized multiwalled carbon nanotubes (fMWCNTs) electrodecorated with Pt/Ru nanoparticles towards the oxidation of methanol (MeOH), ethylene glycol (EG) and formic acid (FA) has been investigated...

  7. Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid media

    Institute of Scientific and Technical Information of China (English)

    Shengzhou Chen; Fei Ye; Weiming Lin

    2009-01-01

    Carbon nanotubes-Nafion (CNTs-Nafion) composites were prepared by impregnated CNTs with Nafion in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nafion incorporation in CNTs-Nafion composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Nafion showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.

  8. Enhanced Stability of PtRu Supported on N-Doped Carbon for the Anode of a DMFC

    Science.gov (United States)

    2012-09-18

    Stability of PtRu Supported on N-Dop Block 13: Supplementary Note © 2012 . Published in Journal of the Electrochemical Society , Vol. Ed. 0 159, (11...sign up http://jes.ecsdl.org/subscriptions go to: Journal of The Electrochemical SocietyTo subscribe to © 2012 The Electrochemical Society F768...Journal of The Electrochemical Society , 159 (11) F768-F778 (2012) 0013-4651/2012/159(11)/F768/11/$28.00 © The Electrochemical Society Enhanced

  9. Effect of BaO on Catalytic Activity of Pt-Rh TWC

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effects of BaO doping on the three-way catalytic activity of Pt-Rh catalyst and on water-gas shift were investigated. The results show that the light-off temperatures of hydrocarbon and carbon monoxide and nitrogen oxides of the fresh catalysts slightly differ from those of the aged catalysts, and the catalysts containing CeO2-ZrO2-BaO have lower lightoff temperature and better catalytic activity than these containing BaO and CeO2-ZrO2 after hydrothermal aging for 5 h at 1000 C. The catalysts were characterized by means of the temperature-programmed reduction (TPR) in hydrogen and the temperature-programmed desorption (TPD) in oxygen. It is confirmed that the suggested route of CeO2-ZrO2-BaO by coprecipitation can improve the catalytic activity of catalysts.

  10. Fast preparation of PtRu catalysts supported on carbon nanofibers by the microwave-polyol method and their application to fuel cells.

    Science.gov (United States)

    Tsuji, Masaharu; Kubokawa, Masatoshi; Yano, Ryuto; Miyamae, Nobuhiro; Tsuji, Takeshi; Jun, Mun-Suk; Hong, Seonghwa; Lim, Seongyop; Yoon, Seong-Ho; Mochida, Isao

    2007-01-16

    PtRu alloy nanoparticles (24 +/- 1 wt %, Ru/Pt atomic ratios = 0.91-0.97) supported on carbon nanofibers (CNFs) were prepared within a few minutes by using a microwave-polyol method. Three types of CNFs with very different surface structures, such as platelet, herringbone, and tubular ones, were used as new carbon supports. The dependence of particles sizes and electrochemical properties on the structures of CNFs was examined. It was found that the methanol fuel cell activities of PtRu/CNF catalysts were in the order of platelet > tubular > herringbone. The methanol fuel cell activities of PtRu/CNFs measured at 60 degrees C were 1.7-3.0 times higher than that of a standard PtRu (29 wt %, Ru/Pt atomic ratio = 0.92) catalyst loaded on carbon black (Vulcan XC72R) support. The best electrocatalytic activity was obtained for the platelet CNF, which is characterized by its edge surface and high graphitization degree.

  11. Effects of the Electrodeposition Time in the Synthesis of Carbon-Supported Pt(Cu and Pt-Ru(Cu Core-Shell Electrocatalysts for Polymer Electrolye Fuel Cells

    Directory of Open Access Journals (Sweden)

    Griselda Caballero-Manrique

    2016-08-01

    Full Text Available Pt(Cu/C and Pt-Ru(Cu/C electrocatalysts with core-shell structure supported on Vulcan Carbon XC72R have been synthesized by potentiostatic deposition of Cu nanoparticles on the support, galvanic exchange with Pt and spontaneous deposition of Ru species. The duration of the electrodeposition time of the different species has been modified and the obtained electrocatalysts have been characterized using electrochemical and structural techniques. The High Resolution Transmission Electron Microscopy (HRTEM, Fast Fourier Transform (FFT and Energy Dispersive X-ray (EDX microanalyses allowed the determining of the effects of the electrodeposition time on the nanoparticle size and composition. The best conditions identified from Cyclic Voltammetry (CV corresponded to onset potentials for CO and methanol oxidation on Pt-Ru(Cu/C of 0.41 and 0.32 V vs. the Reversible Hydrogen Electrode (RHE, respectively, which were smaller by about 0.05 V than those determined for Ru-decorated commercial Pt/C. The CO oxidation peak potentials were about 0.1 V smaller when compared to commercial Pt/C and Pt-Ru/C. The positive effect of Cu was related to its electronic effect on the Pt shells and also to the generation of new active sites for CO oxidation. The synthesis conditions to obtain the best performance for CO and methanol oxidation on the core-shell Pt-Ru(Cu/C electrocatalysts were identified. When compared to previous results in literature for methanol, ethanol and formic acid oxidation on Pt(Cu/C catalysts, the present results suggest an additional positive effect of the deposited Ru species due to the introduction of the bifunctional mechanism for CO oxidation.

  12. Reforming of Ethanol to Produce Hydrogen over PtRuMg/ZrO2 Catalyst

    Directory of Open Access Journals (Sweden)

    Josh Y. Z. Chiou

    2012-01-01

    Full Text Available A modified PtRu/ZrO2 catalyst with Mg is evaluated for the oxidative steam reforming of ethanol (OSRE and the steam reforming of ethanol (SRE. In order to understand the variation in the reaction mechanism on OSRE and SRE, further analysis of both fresh and used catalyst is concentrated on for TEM, TG, Raman, and TPR characterization. The results show that the OSRE reaction requires a higher temperature (∼390°C to achieve 100% ethanol conversion than the SRE reaction (∼2500°C. The distribution of CO is minor for both reactions (< 5% for OSRE, < 1% for SRE. This demonstrates that the water gas shift (WGS reaction is an important side-reaction in the reforming of ethanol to produce H2 and CO2. A comparison of the temperature of WGS (WGS shows it is lower for the SRE reaction (WGS∼250°C for SRE, ~340°C for OSRE.

  13. Microwave synthesis of polymer-embedded Pt-Ru catalyst for direct methanol fuel cell.

    Science.gov (United States)

    Bensebaa, Farid; Farah, Abdiaziz A; Wang, Dashan; Bock, Christina; Du, Xiaomei; Kung, Judy; Le Page, Yvon

    2005-08-18

    Platinum-ruthenium nanoparticles stabilized within a conductive polymer matrix are prepared using microwave heating. Polypyrrole di(2-ethylhexyl) sulfosuccinate, or PPyDEHS, has been chosen for its known electrical conductivity, thermal stability, and solubility in polar organic solvents. A scalable and quick two-step process is proposed to fabricate alloyed nanoparticles dispersed in PPyDEHS. First a mixture of PPyDEHS and metallic precursors is heated in a microwave under reflux conditions. Then the nanoparticles are extracted by centrifugation. Physical characterization by TEM shows that crystalline and monodisperse alloyed nanoparticles with an average size of 2.8 nm are obtained. Diffraction data show that crystallite size is around 2.0 nm. Methanol electro-oxidation data allow us to propose these novel materials as potential candidates for direct methanol fuel cells (DMFC) application. The observed decrease in sulfur content in the polymer upon incorporation of PtRu nanoparticles may have adversely affected the measured catalytic activity by decreasing the conductivity of PPyDEHS. Higher concentration of polymer leads to lower catalyst activity. Design and synthesis of novel conductive polymers is needed at this point to enhance the catalytic properties of these hybrid materials.

  14. Electrochemical oxidation of ammonia-containing wastewater using Ti/RuO2-Pt electrode

    Directory of Open Access Journals (Sweden)

    Wei-wu HU

    2009-12-01

    Full Text Available The electrochemical oxidation degradation processes for artificial and actual wastewater containing ammonia were carried out with a Ti/RuO2-Pt anode and a Ti plate cathode. We studied the effects of different current densities, space sizes between the two electrodes, and amounts of added NaCl on ammonia-containing wastewater treatment. It was shown that, after a 30-min treatment under the optimal conditions, which were a current density of 20 mA/cm2, a space size between the two electrodes of 1 cm, and an added amount of 0.5 g/L of NaCl, the COD concentration in municipal wastewater was 40 mg/L, a removal rate of 90%; and the NH3-N concentration was 7 mg/L, a removal rate of 88.3%. The effluent of municipal wastewater qualified for Class A of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002.

  15. Pt-Rh/g Al2O3 Influence of Catalyst Preparation Methods on Metallic Particle Dispersion and Size Distribution

    Directory of Open Access Journals (Sweden)

    N.M. da Fonseca

    1998-06-01

    Full Text Available - Pt-Rh/Al2O3 catalysts were prepared by successive incipient impregnations or coimpregnation. Characterization was achieved by H2 chemisorption and transmission electron microscopy. It was verified that method of preparation, ratio of metal weights and sequence of deposition are factors that result in very distinct catalysts.

  16. Chemical Tuning of Magnetic Properties through Ru/Rh Substitution in Th7Fe3-type FeRh6-nRunB3 (n = 1-5) Series.

    Science.gov (United States)

    Shankhari, Pritam; Misse, Patrick R N; Mbarki, Mohammed; Park, Hyounmyung; Fokwa, Boniface P T

    2017-01-03

    The new quaternary boride series FeRh6-nRunB3 (n = 1-5) was synthesized by arc melting and characterized by powder and single-crystal X-ray diffraction (XRD), energy-dispersive X-ray analysis, and superconducting quantum interference device magnetometry. Single-crystal structure refinement showed the distribution of the iron atoms in two of three possible crystallographic 4d metal sites in the structure (Th7Fe3-type, space group P63mc). Rietveld refinements of the powder XRD data indicated single-phase synthesis of all the members. A linear decrease of the lattice parameters and the unit cell volume with increasing Ru content was found, indicating Vegard's behavior. Susceptibility measurements show decreasing Curie temperature and magnetic moment (μa(5T)) recorded at 5 T with increasing Ru content from TC = 295 K and μa(5T) = 3.35 μB (FeRh5RuB3) to TC = 205 K and μa(5T) = 0.70 μB (FeRhRu5B3). The measured coercivities lie between 1.0 and 2.2 kA/m indicating soft to semihard magnetic materials.

  17. Electrochemical characterization of IrO{sub 2}-Pt and RuO{sub 2}-Pt mixtures as bifunctional electrodes for unitized regenerative fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Escalante-Garcia, I.L.; Duron-Torres, S.M. [Univ. Autonoma de Zacatecas, Zacatecas (Mexico). Unidad Academica de Ciencias Quimicas; Cruz, J.C.; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo (Mexico)

    2010-07-15

    A unitized regenerative fuel cell (URFC) is a single electrochemical cell that has the potential to meet the required features of an idealized energy cycle whereby hydrogen can be produced from renewable energy sources. A URFC is a system which can operate as a polymer electrolyte water electrolyzer (PEMWE) or as a polymer electrolyte fuel cell (PEMFC). In the PEMWE mode, water is converted into hydrogen and oxygen by using electricity from solar or wind energy. In the PEMFC mode, the stored hydrogen and oxygen are supplied to generate electricity and water. Combining PEMWEs and PEMFCs remains a great challenge because several practical and structural features must be considered. The limiting reaction steps at the oxygen electrode for PEMFC or PEMWE are the oxygen reduction reaction (ORR) and the water oxidation reaction (OER), respectively. The high-efficiency therefore depends on the type of electrocatalysts and the capability of the oxygen electrode to operate under PEMFC or PEMWE conditions. As such, much research has gone into the development of a new oxygen electrode design for URFCs. Several bifunctional electrodes for OER and ORR were designed in this study using platinum (Pt) and iridium oxide (IrO{sub 2}) electrocatalysts or Pt and ruthenium oxide (RuO{sub 2}) supported electrocatalysts on Ebonex{sup R}. According to electrochemical characterization by CV, LV and EIS in aqueous 0.5 M H{sub 2}SO{sub 4}, IrO{sub 2}-Pt and RuO{sub 2}-Pt supported on Ebonex have high electrocatalytic properties for ORR and OER, indicating potential use in URFCs. IrO{sub 2} based electrodes were more stable than RuO{sub 2} based electrodes. 31 refs., 2 tabs., 6 figs.

  18. First Measurement of the $^{96}$Ru(p,$\\gamma$)$^{97}$Rh Cross Section for the p-Process with a Storage Ring

    CERN Document Server

    Mei, Bo; Bishop, Shawn; Blaum, Klaus; Boretzky, Konstanze; Bosch, Fritz; Brandau, Carsten; Bräuning, Harald; Davinson, Thomas; Dillmann, Iris; Dimopoulou, Christina; Ershova, Olga; Fülöp, Zsolt; Geissel, Hans; Glorius, Jan; Gyürky, György; Heil, Michael; Käppeler, Franz; Kelic-Heil, Aleksandra; Kozhuharov, Christophor; Langer, Christoph; Bleis, Tudi Le; Litvinov, Yuri; Lotay, Gavin; Marganiec, Justyna; Münzenberg, Gottfried; Nolden, Fritz; Petridis, Nikolaos; Plag, Ralf; Popp, Ulrich; Rastrepina, Ganna; Reifarth, René; Riese, Björn; Rigollet, Catherine; Scheidenberger, Christoph; Simon, Haik; Sonnabend, Kerstin; Steck, Markus; Stöhlke, Thomas; Szücs, Tamás; Sümmerer, Klaus; Weber, Günter; Weick, Helmut; Winters, Danyal; Winters, Natalya; Woods, Philip; Zhong, Qiping

    2015-01-01

    This work presents a direct measurement of the $^{96}$Ru($p, \\gamma$)$^{97}$Rh cross section via a novel technique using a storage ring, which opens opportunities for reaction measurements on unstable nuclei. A proof-of-principle experiment was performed at the storage ring ESR at GSI in Darmstadt, where circulating $^{96}$Ru ions interacted repeatedly with a hydrogen target. The $^{96}$Ru($p, \\gamma$)$^{97}$Rh cross section between 9 and 11 MeV has been determined using two independent normalization methods. As key ingredients in Hauser-Feshbach calculations, the $\\gamma$-ray strength function as well as the level density model can be pinned down with the measured ($p, \\gamma$) cross section. Furthermore, the proton optical potential can be optimized after the uncertainties from the $\\gamma$-ray strength function and the level density have been removed. As a result, a constrained $^{96}$Ru($p, \\gamma$)$^{97}$Rh reaction rate over a wide temperature range is recommended for $p$-process network calculations.

  19. Standardization of (106)Ru/Rh by live-timed anticoincidence counting and gamma emission determination.

    Science.gov (United States)

    da Silva, C J; Rezende, E A; Poledna, R; Tauhata, L; Iwahara, A; Lopes, R T

    2017-04-01

    The absolute activity standardization measurement system of radionuclide by live-timed anticoincidence counting was implemented at LNMRI in 2008 to reduce the effects of some correction factors on the determination of activity with coincidence counting technique used for decades in the laboratory, for example, the corrections of dead time and resolution. With the live-timed anticoincidence system, the variety of radionuclides that can be calibrated by LNMRI was increased in relation to the type of decay. The objective of this study was to standardize the (106)Ru activity, determine gamma emission probabilities by spectrometric method for some energies, and estimate measurement uncertainties.

  20. Quantum criticality and Lifshitz transition in the Ising system CeRu2Si2: Comparison with YbRh2Si2

    OpenAIRE

    Pourret, A.; Aoki, D.; Boukahil, M.; Brison, J. -P.; Knafo, W.; Knebel, G.; Raymond, S.; Taupin, M.; Onuki, Y.; Flouquet, J.

    2013-01-01

    New thermoelectric power (TEP) measurements on prototype heavy-fermion compounds close to magnetic quantum criticality are presented. The highly sensitive technique of TEP is an unique tool to reveal Fermi surface instabilities, referred here as Lifshitz transitions. The first focus is on the Ising CeRu2Si2 series. Doping CeRu2Si2 with Rh produces a decoupling between the first order metamagnetic transition and the pseudo-metamagnetism observed in the pure compound. Comparison is made with th...

  1. Core-shell Rh-Pt nanocubes: A model for studying compressive strain effects in bimetallic nanocatalysts

    Science.gov (United States)

    Harak, Ethan William

    Shape-controlled bimetallic nanocatalysts often have increased activities and stabilities over their monometallic counterparts due to surface strain effects and electron transfer between the two metals. Here, we demonstrate that the degree of surface strain can be manipulated in shape-controlled nanocrystals through a bimetallic core shell architecture. This ability is achieved in a model core shell Rh Pt nanocube system through control of shell thickness. An increase in the Pt shell thickness leads to more compressive strain, which can increase the Pt 4f7/2 binding energy by as much as 0.13 eV. This change in electronic structure is correlated with a weakening of surface-adsorbate interactions, which we exploit to reduce catalyst poisoning by CO during formic acid electrooxidation. In fact, by precisely controlling the Pt shell thickness, the maximum current density achieved with Rh Pt nanocubes was 3.5 times greater than that achieved with similarly sized Pt nanocubes, with decreased CO generation as well. This system serves as a model for how bimetallic architectures can be used to manipulate the electronic structure of nanoparticle surfaces for efficient catalysis. The strategy employed here should enable the performance of bimetallic nanomaterials comprised of more cost-effective metals to be enhanced as well.

  2. Genetic Pd, Pt, Au, Ag, and Rh mineralogy in Noril'sk sulfide ores

    Science.gov (United States)

    Spiridonov, E. M.; Kulagov, E. A.; Serova, A. A.; Kulikova, I. M.; Korotaeva, N. N.; Sereda, E. V.; Tushentsova, I. N.; Belyakov, S. N.; Zhukov, N. N.

    2015-09-01

    The undeformed ore-bearing intrusions of the Noril'sk ore field (NOF) cut through volcanic rocks of the Late Permian-Early Triassic trap association folded in brachysynclines. Due to the nonuniform load on the roof of intrusive bodies, most sulfide melts were squeezed, up to the tops of ore-bearing intrusions; readily fusible Ni-Fe-Cu sulfide melts were almost completely squeezed. In our opinion, not only one but two stages of mineralization developed at the Noril'sk deposits: (i) syntrap magmatic and (ii) epigenetic post-trap metamorphic-hydrothermal. All platinum-group minerals (PGM) and minerals of gold are metasomatic in the Noril'sk ores. They replaced sulfide solid solutions and exsolution structures. All types of PGM and Au minerals occur in the ores, varying in composition from pyrrhotite to chalcopyrite, talnakhite, mooihoekite, and rich in galena; they are localized in the inner and outer contact zones and differ only in the quantitative proportions of ore minerals. The aureoles of PGM and Au-Ag minerals are wider than the contours of sulfide bodies and coincide with halos of fluid impact on orebodies and adjacent host rocks. The pneumatolytic PGM and Au-Ag minerals are correlated in abundance with the dimensions of sulfide bodies. Their amounts are maximal in veins of late fusible ore composed of eutectic PbS ss and iss intergrowths, as well as at their contacts. The Pd and Pt contents in eutectic sulfide ores of NOF are the world's highest. In the process of noble-metal mineral formation, the fluids supply Pd, Pt, Au, As, Sb, Sn, Bi, and a part of Te, whereas Fe, Ni, Cu, Pb, Ag, Rh, a part of Te and Pd are leached from the replaced sulfide minerals. The pneumatolytic PGM of the early stage comprises Pd and Pt intermetallic compounds enriched in Au along with Pd-Pt-Fe-Ni-Cu-Sn-Pb(As) and (Pd,Pt,Au)(Sn,Sb,Bi,Te,As) solid solutions. Pneumatolytic PGM and Au minerals of the middle stage are products of solid-phase transformation and recrystallization of

  3. The High Temperature Creep Behavior of Dispersion Strengthened Pt5Rh Composite%Pt5Rh ODS复合材料的高温蠕变性能研究

    Institute of Scientific and Technical Information of China (English)

    张吉明; 耿永红; 陈松; 管伟明; 张昆华

    2011-01-01

    采用大塑性变形法制备氧化物弥散强化铂铑(Pt5Rh ODS)复合材料,对材料进行了高温蠕变试验.结果表明,复合材料在高温低应力条件下,表现出的名义应力指数随温度变化较小,名义激活能高于纯Pt和Pt10Rh合金,而且比常规合金材料具有更好的高温蠕变性能.复合材料的高温蠕变性能用晶界反应控制来解释,说明复合材料的蠕变受到扩散蠕变机制控制.复合材料的蠕变断裂行为符合连续蠕变损伤中的内截面损伤模型,蠕变断裂特征为沿晶断裂.%Adopting a large plastic deformation process,the dispersion strengthened PtSRh composite was prepared.The microstructure of the composite was analyzed by SEM,and the high temperature creep tests were carried out by a self-made high temperature creep test facility.The experimem results show that at high temperature and under low load the stress exponent of the dispersion strengthened Pt5Rh alloy does not change obviously with increasing of the temperature,and its apparent activation energy is much higher than those of pure platinum and Pt10Rh alloy.The high temperature creep properties of the dispersion strengthened Pt5Rh are better than those of conventional alloys.The creep mechanism of the dispersion strengthened Pt5Rh belongs to the proliferation creep mechanism; the creep fracture at high temperatures presents the brittle fracture.

  4. Novel method for the synthesis of hydrophobic Pt-Ru nanoparticles and its application to preparing a Nafion-free anode for the direct methanol fuel cell.

    Science.gov (United States)

    Tu, Hung-Chi; Wang, Wen-Lin; Wan, Chi-Chao; Wang, Yung-Yun

    2006-08-17

    Pt-Ru alloy is a bimetallic catalyst most commonly used in the direct methanol fuel cell (DMFC). In this paper, a new process to synthesize an unsupported Pt-Ru colloid has been introduced. The characteristics of synthesized nanoparticles were identified by XRD, TEM/EDX, and SEM, and it shows that Ru atoms are incorporated into the Pt fcc structure and the well-dispersed particles (diameter approximately 4 nm) possess a Pt-rich feature. This catalyst shows a hydrophobic characteristic which can adsorb very well on the hydrophobic-treated carbon paper or carbon cloth without the need of Nafion. Accordingly, this method can avoid particle agglomeration, and the synthesized catalyst demonstrates strong adsorption with carbon paper. In addition, this colloid-type Nafion-free catalyst was measured via linear sweep voltammetry (LSV) and exhibited electrochemical activity for methanol oxidation comparable to the commercial one with Nafion binding.

  5. Catalytic activity and mechanistic approach of NO reduction by CO over M0.05Co2.95O4 (M = Rh, Pd & Ru) spinel system

    Science.gov (United States)

    Salker, A. V.; Desai, M. S. Fal

    2016-12-01

    Pd, Rh and Ru doped cobalt oxide spinels have been prepared by citric acid assisted sol-gel method to yield nano-catalysts. Compositions have been characterized by XRD, FTIR, TG/DTA, BET, SEM, TEM, TPD and XPS techniques. Simultaneous catalytic detoxification of nitric oxide and carbon monoxide is investigated over the doped and pristine catalysts. Metal doping is found to enhance the activity of the catalysts due to their better adsorption capacity. Moisture and oxygen tolerance is investigated for Rh and Pd substituted catalysts. A probable reaction mechanism on the catalyst surface has been proposed.

  6. Surface enhanced vibrational spectroscopy and first-principles study of L-cysteine adsorption on noble trimetallic Au/Pt@Rh clusters.

    Science.gov (United States)

    Loganathan, B; Chandraboss, V L; Senthilvelan, S; Karthikeyan, B

    2015-09-07

    The Rh shell of the Au/Pt/Rh trimetallic nanoparticles induces a wide variety of interesting surface reactions by allowing the adsorption of amino acids like L-cysteine (L-Cys). We present a snapshot of theoretical and experimental investigation of L-Cys adsorption on the surface of noble trimetallic Au/Pt@Rh colloidal nanocomposites. Density functional theoretical (DFT) investigations of L-Cys interaction with the Rhodium (Rh) shell of a trimetallic Au/Pt@Rh cluster in terms of geometry, binding energy (E(B)), binding site, energy gap (E(g)), electronic and spectral properties have been performed. L-Cys establishes a strong interaction with the Rh shell. It binds to Rh by the S1-site, which makes a stable L-Cys-Rh surface complex. DFT can be taken as a valuable tool to assign the vibrational spectra of the adsorption of L-Cys on trimetallic Au/Pt@Rh colloidal nanocomposites and mono-metallic Rh nanoparticles. Surface-enhanced infrared spectroscopy (SEIRS) with L-Cys on a Rh6 cluster surface has been simulated for the first time. Experimental information on the L-Cys-Rh surface complex is included to examine the interaction. The experimental spectral observations are in good agreement with the simulated DFT results. Characterization of the synthesized trimetallic Au/Pt@Rh colloidal nanocomposites has been done by high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern, energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS) measurements, zeta potential, zeta deviation analysis and UV-visible (UV-Vis) spectroscopic studies.

  7. Energy deposition by a {sup 106}Ru/{sup 106}Rh eye applicator simulated using LEPTS, a low-energy particle track simulation

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, M.C. [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Munoz, A.; Oller, J.C. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avenida Complutense 22, 28040 Madrid (Spain); Blanco, F. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Avenida Complutense, 28040 Madrid (Spain); Williart, A. [Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey 9, 28040 Madrid (Spain); Limao-Vieira, P. [Laboratorio de Colisoes Atomicas e Moleculares, Departamento de Fisica, CEFITEC, FCT-Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica (Portugal); Borge, M.J.G.; Tengblad, O. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Huerga, C.; Tellez, M. [Hospital Universitario La Paz, Paseo de la Castellana 261, 28046 Madrid (Spain); Garcia, G., E-mail: g.garcia@iff.csic.es [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey 9, 28040 Madrid (Spain)

    2011-09-15

    The present study introduces LEPTS, an event-by-event Monte Carlo programme, for simulating an ophthalmic {sup 106}Ru/{sup 106}Rh applicator relevant in brachytherapy of ocular tumours. The distinctive characteristics of this code are the underlying radiation-matter interaction models that distinguish elastic and several kinds of inelastic collisions, as well as the use of mostly experimental input data. Special emphasis is placed on the treatment of low-energy electrons for generally being responsible for the deposition of a large portion of the total energy imparted to matter. - Highlights: > We present the Monte Carlo code LEPTS, a low-energy particle track simulation. > Carefully selected input data from 10 keV to 1 eV. > Application to an electron emitting Ru-106/Rh-106 plaque used in brachytherapy.

  8. Methanol oxidation on carbon supported Pt-Ru catalysts prepared by electrodeposition - Evaluation of Nafion {sup registered} 117 film effect

    Energy Technology Data Exchange (ETDEWEB)

    Sieben, J.M. [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Universidad Nacional del Sur, Av. Alem 1253 (B8000CPB) Bahia Blanca, Buenos Aires (Argentina); Duarte, M.M.E.; Mayer, C.E. [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Universidad Nacional del Sur, Av. Alem 1253 (B8000CPB) Bahia Blanca, Buenos Aires (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC) (Argentina)

    2010-03-15

    Diverse electrochemical techniques were performed in order to obtain meaningful information about the methanol oxidation reaction on nanostructured planar carbon supported Pt-Ru electrodes prepared by electrodeposition, on which a layer of Nafion ionomer was incorporated. A metallic deposit consisting of dendritic agglomerates (between 50 and 200 nm) constituted by smaller particles (6 nm) was obtained. The average bulk Ru content obtained by EDX analysis was between 23 and 25 at. %. A decrease of the activity in the electrodes for methanol oxidation was determined when the thickness of the Nafion 117 film was increased. These results may be associated with the partial blocking of the surface active sites by hydrophobic domains of the polymer, and the presence of CO{sub 2} molecules retained within the Nafion hydrophilic microchannels. EIS results indicated that methanol electro-oxidation mechanism does not change with Nafion presence. (author)

  9. The effect of methanol on the stability of Pt/C and Pt-RuO{sub x}/C catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rufino, Elen C.G.; Olivi, Paulo [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, CEP 14040-901, Ribeirao Preto, SP (Brazil)

    2010-12-15

    The behavior of Pt/C and Pt-RuO{sub x}/C electrodes subjected to a larger number of potential scans and constant potential for prolonged time periods was investigated in the absence and presence of methanol. The structural changes were analyzed on the basis of the modifications observed in the X-ray diffraction pattern of the catalysts. Carbon monoxide stripping experiments were performed before and after the potential scans, thus enabling analysis of the behavior of the electrochemically active surface area. The resulting solutions were examined by inductively coupled plasma mass spectrometry (ICP-MS). There was reduction in the electrochemically active surface area, as well as increase in crystallite size and dissolution of catalyst components after the potential scan tests. Catalyst degradation was more pronounced in the presence of methanol, and cyclic potential conditions accelerate the degradation mechanisms. (author)

  10. Microstructures and magnetic properties of meta-stable Co{sub 50−X}M{sub X}Pt{sub 50} (M = Cu or Ru) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, An-Cheng, E-mail: acsun@saturn.yzu.edu.tw; Huang, Chuan-Fa; Chen, Sheng-Fu; Chen, Yu-Shen

    2014-11-03

    Co{sub 50−X}M{sub X}Pt{sub 50} (M = Cu or Ru) films were magnetron sputtered on textured Pt(111) underlayer on glass substrate at 350 °C. The results show that perpendicular magnetic anisotropy of superlattice L1{sub 1} phase can be maintained well with doping Cu element into CoPt film. Out-of-plane coercivity (H{sub c⊥}) was also increased with the increase of Cu content. However, disordered A1(111) structure and lower H{sub c⊥} were obtained with the addition of Ru element in CoPt film. The magnetic force microscopy images indicated that doping Cu diminished the domain size. Oppositely, doping Ru made the domain reversed incompletely. Surface morphology of Co{sub 24}Cu{sub 26}Pt{sub 50} thin film was much smoother than that of Co{sub 23}Ru{sub 27}Pt{sub 50} thin film, indicative of maintenance of the epitaxial growth of L1{sub 1}(111) from flat Pt(111) underlayer. The transmission electron microscopy (TEM) images show that the Cu element could be incorporated in L1{sub 1} CoPt grains; however, the RuPt alloy was segregated at CoPt grain boundary. The cross section TEM pictures showed that the columnar structures starting from Pt(111) underlayer and extending into magnetic CoCuPt(111) layer confirmed that epitaxy existed at CoCuPt/Pt interface. Our research demonstrates that replacing Co with Cu = 23–26 at.% effectively increases the perpendicular magnetic properties of L1{sub 1} CoPt phase, which largely increase the potential of L1{sub 1} films for the application of perpendicular magnetic media and advance spintronic device. - Highlights: • Strengthen superstructural CoPt phase with perpendicular magnetic anisotropy • Enhanced coercivity in L1{sub 1} CoPt thin films with doping 3rd elements • Impedances of domain wall motion adjusted the coercivity.

  11. Relationship between element-selective electronic states and hydrogen absorption properties of Pd-M (M =Ru ,Rh,Ag, and Au) alloys

    Science.gov (United States)

    Fujii, Kanako; Ishimatsu, Naoki; Maruyama, Hiroshi; Shishidou, Tatsuya; Hayakawa, Shinjiro; Kawamura, Naomi

    2017-01-01

    To understand how the constituent atoms participate in the hydrogenation of Pd-based alloys at ˜0.1 MPa of hydrogen pressure (PH2),we investigated the electronic states in Pd-M (M =Ru,Rh,Ag, and Au) alloys and their hydrides element-selectively by using x-ray absorption spectroscopy at the L2 ,3 edges. Spectral changes near the absorption edge demonstrate that both Pd and M atoms form bonds with H atoms in the Pd-M (M =Ru and Rh) alloys even at PH 2˜0.1 MPa. This is a striking result because high pressures of more than 1 GPa are required for the hydrogenation of Rh and Ru pure metals. In contrast, only Pd atoms bond with H atoms and the M -H bond is absent in the case of Pd-M (M =Ag and Au) alloys. Therefore, the hydrogen-induced changes in the electronic states differ between M s with fully occupied d shells and M s with partially occupied d shells. This study reveals that the thermodynamic hydrogenation properties of Pd-M alloys can be determined by a combination of the formation of the M -H bond and lattice expansion or compression by alloying Pd metal with M .

  12. Oxygen Storage Capacity of Pt-, Pd-, Rh/CeO2-Based Oxide Catalyst

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CZO (CeO2-ZrO2) and CZYO (CeO2-ZrO2-Y2O3) series of mixed oxides were prepared by coprecipitaion, and a part of these oxides were loaded with precious metals (PM). XRD, BET, and oxygen storage capacity (OSC) investigations were performed on samples aged at 750, 900, and 1050 ℃. It was observed that BET surface area and OSC showed a marked decrease in CeO2 aged at high temperature, and the crystallite size showed an obvious increase. The CZO samples consist of cubic- and tetragonal crystal phases, and their crystallite size increase rapidly when aged at high temperature. The CZYO samples consist of single crystal phase when the content of Y exceeds 0.15 mol, and their crystallite size increases slowly during high-temperature aging. It is concluded that additive Y can stabilize the performance of CZYO oxides. In the aged CZO and CZYO mixed-oxide systems, addition of a small amount of precious metals (Pt, Pd, Rh) increased the rate of reduction and led to an obvious improvement in OSC. OSC of CZO and CZYO with precious metals are related to their composition and the type of precious metal.

  13. Comparison of measured and calculated spatial dose distributions for a bench-mark 106Ru/106Rh hot particle source.

    Science.gov (United States)

    Aydarous, A Sh; Charles, M W; Darley, P J

    2008-01-01

    This study is a part of a programme of research to provide validated dose measurement and calculation techniques for beta emitting hot particles by the construction of well-defined model hot particle sources. This enables parallel measurements and calculations to be critically compared. This particular study concentrates on the high-energy beta emitter, (106)Ru/(106)Rh (Emax = 3.54 MeV). This source is a common constituent of failed nuclear fuel, particularly in accident situations. The depth dose distributions were measured using radiochromic dye film (RDF); an imaging photon detector coupled to an LiF thermoluminescent dosemeter (LiF-IPD) and an extrapolation ionisation chamber (ECH). Dose calculations were performed using the Monte Carlo radiation transport code MCNP4C. Doses were measured and calculated as average values over various areas and depths. Of particular interest are the doses at depths of 7 and 30-50 mg cm(-2), and averaged over an area of 1 cm2, as recommended by the International Commission on Radiological Protection for use in routine and accidental over-exposures of the skin. In this case, the average ratios (MCNP/measurement) for RDF, ECH and LiF-IPD were 1.07 +/- 0.02, 1.02 +/- 0.01 and 0.83 +/- 0.16, respectively. There are significantly greater discrepancies between the ECH and LiF-IPD measurement techniques and calculations-particularly for shallow depths and small averaging areas.

  14. Ab Initio evaluation of electron transport properties of Pt, Rh, Ir, and Pd nanowires for advanced interconnect applications

    Science.gov (United States)

    Lanzillo, Nicholas A.

    2017-05-01

    The electronic and structural properties of nanowires composed of either Pt, Ir, Rh, or Pd are calculated using density functional theory and a non-equilibrium Green's function scattering approach. The results for these nanowires are compared with Cu nanowires of comparable dimensions and evaluated for potential use in interconnect technology applications. The cohesive energies of the Pt, Rh and Ir nanowires are found to be stronger than the corresponding value for bulk Cu, indicating superior structural integrity and resistance to electromigration relative to Cu. Several of the nanowires considered are found to exhibit larger values of ballistic conductance relative to Cu, with maximum conductance occurring along the [110] crystallographic direction. Electron scattering at some representative twin grain boundaries is evaluated and an empirical resistivity model is used to quantitatively estimate the impact of grain size on total resistivity.

  15. Electrocatalytic performance of Pt/Ru/Sn/W fullerene electrode for methanol oxidation in direct methanol fuel cell

    Institute of Scientific and Technical Information of China (English)

    Mohammad Karimi; Forouzan Aboufazeli; Hamid Reza Lotfi Zadeh Zhad; Omid Sadeghi; Ezzatollah Najafi

    2013-01-01

    In this work,fullerene was modified by platinum,ruthenium,tin and tungsten nanoparticles.The material was characterized by XRD,ICP-OES and TEM micrograph.The average nanoparticle size on fullerene was 5 ~ 8 nm.The application of this material was investigated as a catalyst for methanol oxidation in direct methanol fuel cell.A glassy carbon electrode was modified by Pt/Ru/Sn/W fullerene and electrocatalytic activity of the electrode toward methanol oxidation in basic medium has been demonstrated and investigated using cyclic voltammetry.The catalyst showed good reactivity for methanol oxidation.

  16. Ultra-small Tetrametallic Pt-Pd-Rh-Ag Nanoframes with Tunable Behavior for Direct Formic Acid/Methanol Oxidation.

    Science.gov (United States)

    Saleem, Faisal; Ni, Bing; Yong, Yang; Gu, Lin; Wang, Xun

    2016-10-01

    Reversible tuning of ultra-small multimetallic Pt-Pd-Rh-Ag nanoframes is achieved. These nanoframes showed tunable and reversible modes for the oxidation of small organic molecules by simply inducing segregation with adsorbates, such as SO4(2-) and OH(-) . This is the first example of reversible segregation under electrocatalytic conditions in atomic-sized electrocatalysts. These nanoframes also showed a controllable activity and good stability for the oxidation of small organic molecules.

  17. Effect of counterpart metals in carbon-supported Pt-based catalysts prepared using radiation chemical method

    Science.gov (United States)

    Okazaki, Tomohisa; Seino, Satoshi; Matsuura, Yoshiyuki; Otake, Hiroaki; Kugai, Junichiro; Ohkubo, Yuji; Nitani, Hiroaki; Nakagawa, Takashi; Yamamoto, Takao A.

    2017-04-01

    The process of nanoparticle formation by radiation chemical synthesis in a heterogeneous system has been investigated. Carbon-supported Pt-based bimetallic nanoparticles were synthesized using a high-energy electron beam. Rh, Cu, Ru, and Sn were used as counterpart metals. The nanoparticles were characterized by inductively coupled plasma atomic emission spectrometry, transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. PtRh formed a uniform random alloy nanoparticle, while Cu partially formed an alloy with Pt and the remaining Cu existed as CuO. PtRu formed an alloy structure with a composition distribution of a Pt-rich core and Ru-rich shell. No alloying was observed in PtSn, which had a Pt-SnO2 structure. The alloy and oxide formation mechanisms are discussed considering the redox potentials, the standard enthalpy of oxide formation, and the solid solubilities of Pt and the counterpart metals.

  18. Modification of the hydrogenation properties of LaNi{sub 5} upon Ni substitution by Rh, Ir, Pt or Au

    Energy Technology Data Exchange (ETDEWEB)

    Prigent, J. [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux Paris-Est, CNRS, Universite Paris-Est, 2-8 rue H. Dunant, 94320 Thiais Cedex (France); Laboratoire de Thermodynamique et Physico-Chimie des Hydrures et Oxydes, Universite Paris-Sud Orsay, Bat 410, 91405 Orsay (France); Joubert, J.-M., E-mail: jean-marc.joubert@icmpe.cnrs.fr [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux Paris-Est, CNRS, Universite Paris-Est, 2-8 rue H. Dunant, 94320 Thiais Cedex (France); Gupta, M. [Laboratoire de Thermodynamique et Physico-Chimie des Hydrures et Oxydes, Universite Paris-Sud Orsay, Bat 410, 91405 Orsay (France)

    2012-01-15

    Highlights: > Hydrogen absorption properties of LaNi{sub 5-x}M{sub x} intermetallic compounds (M = Rh, Ir, Au). > Stability of LaNi{sub 5-x}M{sub x} (M = Rh, Pt) intermetallics and hydrides using ab initio calculations. > Influence of the substituting elements (geometric, thermodynamic and electronic) on the hydride stability. - Abstract: The hydrogenation properties of the LaNi{sub 5-x}M{sub x} (M = Rh, Ir, Au) compounds have been studied. The Ni substitution has several consequences: pressure plateau splitting and increase of plateau pressure. This latter observation disagrees with the general rule that a cell volume increase of the alloy should result in a plateau pressure lowering. In order to elucidate the origin of this anomalous behaviour, DFT calculations have been performed on both LaNi{sub 5-x}Rh{sub x} and LaNi{sub 5-x}Pt{sub x} intermetallic compounds, which, according to the present and previous experimental work, present a similar anomaly. We discuss our results in light of the models proposed in the literature. We conclude that, in the case of a Ni substitution by 4d or 5d elements, the size effect alone fails in predicting the hydrogen absorption properties while the rule of reverse stability is obeyed.

  19. The acanthocephalan Paratenuisentis ambiguus as a sensitive indicator of the precious metals Pt and Rh from automobile catalytic converters

    Energy Technology Data Exchange (ETDEWEB)

    Sures, B.; Zimmermann, S.; Sonntag, C.; Stueben, D.; Taraschewski, H

    2003-04-01

    The eel parasite, Paratenuisentis ambiguus, takes up and accumulates catalytic metals. - Recent studies revealed that intestinal acanthocephalans of fish can accumulate heavy metals to concentrations orders of magnitude higher than those in the host tissues or the aquatic environment. This significant heavy metal accumulation by acanthocephalans, even surpassing that of established free living accumulation bioindicators, encouraged us to study the bioavailability of the platinum-group-metals (PGM) Pt and Rh for parasites. These precious metals are used in catalytic converters of cars for exhaust gas purification in Europe since the early 1980s. In addition to the beneficial effect in reducing the emission of CH{sub x}, CO and NO{sub x} of cars there is an increasing emission of these metals. However, it still remains unclear if these elements become accumulated in the biosphere and whether they affect the health of organisms. The present study reveals that in European eels (Anguilla anguilla) naturally infected with the eoacanthocephalan parasite Paratenuisentis ambiguus and experimentally exposed to ground catalytic converter material, the parasites take up and accumulate the catalytic active metals Pt and Rh whereas in the examined host tissues we found no metal uptake. Compared with the PGM concentrations in the water the worms contained 1600 times higher Rh and 50 times higher Pt concentrations. Thus, the parasites can be used as sentinel organisms reflecting even very low levels of precious metals.

  20. The structure and reactivity of adsorbates on stepped Rh and Pt surfaces investigated by LEED, HREELS, TPD, XPS and STM

    Energy Technology Data Exchange (ETDEWEB)

    Batteas, J.D. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Materials Science Div.

    1995-06-01

    Defects on surfaces such as steps play an important role in surface chemistry. In order to obtain an understanding of the influence of steps in surface chemical reactions, the structure and reactivity of small molecules (O{sub 2}, CO, H{sub 2}S, and C{sub 2}H{sub 4}) on atomically stepped surfaces of RH and Pt have been investigated. The detailed structures of CO and oxygen bonded to the Rh(110) surface were determined. The CO molecules bond near the short bridge sites with the CO molecular axis tilted approximately 24{degree} from the surface normal. Oxygen atoms are bound asymmetrically in the 3-fold fcc hollow-sites to the (111) facets of the steps. The interactions of CO and oxygen on the Rh(311) surface were examined. The reaction of CO with the ordered phases of O shows two distinct reaction channels, a low temperature reaction limited channel (200 K) and a high temperature diffusion limited channel (350 K). Models of the reaction geometry and dynamics are proposed. The thermal decomposition of ethylene was examined on the Rh(311) surface. The stable decomposition species (C{sub 2}H, CH and C{sub 2}) are formed near 300 K, approximately 100 K lower on the stepped Rh(311) than on the flatter Rh(111) surface. The formation of these species at lower temperatures is attributed to the stepped nature of the surface. Finally, in situ STM was used to examine surface structural changes of a stepped Pt(111) crystal under coadsorption of sulfur and CO. This is the first direct evidence for a new mechanism by which a surface covered with an unreactive, strongly chemisorbed overlayer can form new sites, for bonding and reactions to occur, by massive surface restructuring at the step edges. This new surface phenomenon answers some of the puzzles of metal surface catalysis and its implications are described. 278 refs.

  1. Synthesis, Characterization, and Catalytic Hydrogenation Activity of New N-Acyl-Benzotriazole Rh(I and Ru(III Complexes in [bmim][BF4

    Directory of Open Access Journals (Sweden)

    Hakan Ünver

    2016-09-01

    Full Text Available The hydrogenation activity of new N-acyl-benzotriazole Rh(I and Ru(III complexes in ionic liquid media is reported in this study. Both complexes were completely soluble in 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4], and they were able to catalyze the hydrogenation of styrene and 1-octene. While ethylbenzene conversion in styrene hydrogenation reached 84% when the Ru complex was used, 100% conversion was obtained with the Rh complex at 393 K in 6 h. Additionally, total conversion in 1-octene hydrogenation reached 100% with the Rh complex in [bmim][BF4] media. The hydrogenation of styrene and 1-octene in dimethyl sulfoxide (DMSO and toluene was also studied to compare the solvent effect on catalytic system. The effect of some catalytic parameters such as temperature, H2 (g pressure, and catalyst amount on the conversion was examined, and it was found that the conversion increased parallel to the increasing temperature and H2 pressure. The recyclability of catalysts was also investigated, and it was revealed that the Rh complex in particular maintained the activity for at least 10 cycles.

  2. On new ternary equiatomic scandium transition metal aluminum compounds ScTAl with T = Cr, Ru, Ag, Re, Pt, and Au

    Energy Technology Data Exchange (ETDEWEB)

    Radzieowski, Mathis; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Haverkamp, Sandra [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; University of Sao Paulo, Sao Carlos, SP (Brazil). Inst. of Physics

    2016-08-01

    The new equiatomic scandium transition metal aluminides ScTAl for T = Cr, Ru, Ag, Re, Pt, and Au were obtained by arc-melting of the elements followed by subsequent annealing for crystal growth. The samples were studied by powder and single crystal X-ray diffraction. The structures of three compounds were refined from single crystal X-ray diffractometer data: ScCrAl, MgZn{sub 2} type, P6{sub 3}/mmc, a = 525.77(3), c = 858.68(5) pm, R{sub 1} = 0.0188, wR{sub 2} = 0.0485, 204 F{sup 2} values, 13 variables, ScPtAl, TiNiSi type, Pnma, a = 642.83(4), b = 428.96(2), c = 754.54(5) pm, R{sub 1} = 0.0326, wR{sub 2} = 0.0458, 448 F{sup 2} values, 20 variables and ScAuAl, HfRhSn type, P anti 62c, a = 722.88(4), c = 724.15(4) pm, R{sub 1} = 0.0316, wR{sub 2} = 0.0653, 512 F{sup 2} values, 18 variables. Phase pure samples of all compounds were furthermore investigated by magnetic susceptibility measurements, and Pauli-paramagnetism but no superconductivity was observed down to 2.1 K for all of them. The local structural features and disordering phenomena have been characterized by {sup 27}Al and {sup 45}Sc magic angle spinning (MAS) and static NMR spectroscopic investigations.

  3. Low-energy magnetic fluctuations in U(Ru{sub 1-x}Rh{sub x}){sub 2}Si{sub 2}(x=<0.02)

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, M. [Faculty of Science, Ibaraki University, Mito 310-8512 (Japan)]. E-mail: makotti@mx.ibaraki.ac.jp; Matsuda, K. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Amitsuka, H. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Tenya, K. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Aso, N. [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, Tokai 319-1106 (Japan); Yoshizawa, H. [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, Tokai 319-1106 (Japan)

    2007-03-15

    Inelastic neutron scattering experiments were performed on U(Ru{sub 1-x}Rh{sub x}){sub 2}Si{sub 2} with x=0 and 0.02 in order to investigate the variations of the antiferromagnetic (AF) fluctuations with doping Rh. We have found that the energy of the magnetic excitation observed at Q=(1,0,0) in the hidden order (HO) phase markedly decreases from {approx}2.6meV(x=0) to {approx}0(x=0.02) with increasing x. In addition, the staggered susceptibility {chi}{sub Q} estimated from the inelastic peak develops in the HO phase at x=0.02, while it is suppressed at x=0. These results indicate that the AF fluctuation in the HO phase is significantly enhanced with doping Rh.

  4. Preparation of Pt-Ru@ polypyrrole-MWNT catalysts by gamma-irradiation and chemical reduction and their adsorption capacity for CO.

    Science.gov (United States)

    Bae, Hyoung-Bong; Oh, Sang-Hyub; Woo, Jin-Chun; Choi, Seong-Ho

    2010-10-01

    With the objective to prepare electrocatalysts with high efficiency, the Pt-Ru@PPy-MWNT catalysts were prepared by different approaches. First, the polypyrrole (PPy) as anchoring materials was coated on the surface of multi walled carbon nanotubes (MWNT) by in situ polymerization. Subsequently, Pt-Ru nanoparticles were deposited onto PPy-MWNT composite by different methods like the reduction of metal ions by gamma-irradiation and chemical reduction using formaldehyde as reducing agent assisted with stirring of magnetic bar, and assisted with microwave irradiation, and assisted with ultrasonic irradiation, in order to prepare electrocatalyst for fuel cell. The catalytic efficiency of Pt-Ru@PPy-MWNT catalyst was examined for CO stripping.

  5. Electrooxidation of H{sub 2}/CO on carbon-supported PtRuMo nanoparticles for polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsiouvaras, N.; Pena, M.A.; Fierro, J.L.G.; Martinez-Huerta, M.V. [CSIC, Madrid (Spain). Inst. de Catalisis y Petroleoquimica; Alcaide, F.; Alvarez, G. [CIDETEC-IK4, Donostia, San Sebastian (Spain)

    2010-07-01

    Ternary anodic PtRuMo catalysts have been prepared following a two step procedure. All catalysts prepared present PtRu metal loading of 30%wt and a Mo load of 0, 1, 2.5 and 5%wt supported on Vulcan XC 72R. Different physicochemical techniques have been employed for the analysis of the catalysts as well as electrochemical techniques in combination with FTIR for in situ studies. The fuel cell performance was evaluated at 80 C in a PEMFC fed with H{sub 2}/CO (10 ppm). Catalysts obtained exhibit good dispersion and small particle size (2.6 nm). FTIR results obtained in CO saturated confirm that lower amounts of CO are adsorbed on ternary catalysts compared with binary catalyst, whichever Mo composition was used. However, polarization curves of the catalysts show that the activity strongly depend on the composition, where PtRu-Mo(1%wt)/C displays the highest CO tolerance. (orig.)

  6. Synthesis of Highly Active Sub-Nanometer Pt@Rh Core-Shell Nanocatalyst via a Photochemical Route: Porous Titania Nanoplates as a Superior Photoactive Support.

    Science.gov (United States)

    Zhan, Wen-Wen; Zhu, Qi-Long; Dang, Song; Liu, Zheng; Kitta, Mitsunori; Suenaga, Kazutomo; Zheng, Lan-Sun; Xu, Qiang

    2017-02-02

    Sub-nanometer Pt@Rh nanoparticles highly dispersed on MIL-125-derived porous TiO2 nanoplates are successfully prepared for the first time by a photochemical route, where the porous TiO2 nanoplates with a relatively high specific surface area play a dual role as both effective photoreductant and catalyst support. The resulting Pt@Rh/p-TiO2 can be utilized as a highly active catalyst.

  7. First-principle investigation of the interactions between Pt{sub x}Ru{sub 55−x} (x = 0, 13, 42, 55) nanoparticles and [BMIM][PF{sub 6}] ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Ping; Liu, Chuan; Yang, Yongpeng; Huang, Shiping, E-mail: huangsp@mail.buct.edu.cn

    2015-05-01

    Highlights: • Interaction between PtRu nanoparticle and [BMIM][PF{sub 6}] is performed by DFT calculations. • The structure of Pt{sub 13}Ru{sub 42} nanoparticle is distorted induced by [BMIM][PF{sub 6}]. • The d-band center show that catalytic activities of Pt{sub 13}Ru{sub 42} and Ru{sub 55} are enhanced. • Two C atoms of [BMIM][PF{sub 6}] form the bond with Pt{sub 13}Ru{sub 42} nanoparticles. - Abstract: Density functional theory calculations have been performed to characterize the interactions between [BMIM][PF{sub 6}] ionic liquid and icosahedral Pt{sub x}Ru{sub 55−x} (x = 0, 13, 42, 55) nanoparticles. In Ru{sub 13}Pt{sub 42}–[BMIM][PF{sub 6}], only one F atom of the anion form the bond with nanoparticle, resulting in the smallest interaction energy (−0.56 eV). While in Pt{sub 13}Ru{sub 42}–[BMIM][PF{sub 6}], two F atoms of the anion together with two C atoms of cation form the bonds with nanoparticle, resulting in the biggest interaction energy (−10.65 eV). The interaction between [BMIM][PF{sub 6}] and Pt{sub 13}Ru{sub 42} is so strong that it induces a significant distortion in the original core–shell structure of Pt{sub 13}Ru{sub 42}. Moreover, after interacting with [BMIM][PF{sub 6}], the Pt{sub 55}, Pt{sub 13}Ru{sub 42} and Ru{sub 55} nanoparticles become more stable based on the negative relaxation energy. The d-band centers of Pt{sub 13}Ru{sub 42} and Ru{sub 55} shift from −1.90, −1.78 eV up to −1.78, −1.56 eV, suggesting that the catalytic activities of Pt{sub 13}Ru{sub 42} and Ru{sub 55} are enhanced.

  8. Effect of an Sb-Doped SnO2 Support on the CO-Tolerance of Pt2Ru3 Nanocatalysts for Residential Fuel Cells

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Ogihara

    2016-09-01

    Full Text Available We prepared monodisperse Pt2Ru3 nanoparticles supported on carbon black and Sb-doped SnO2 (denoted as Pt2Ru3/CB and Pt2Ru3/Sb-SnO2 with identical alloy composition and particle size distribution by the nanocapsule method. The activities for the hydrogen oxidation reaction (HOR of these anode catalysts were examined in H2-saturated 0.1 M HClO4 solution in both the presence and absence of carbon monoxide by use of a channel flow electrode at 70 °C. It was found that the CO-tolerant HOR mass activity at 0.02 V versus a reversible hydrogen electrode (RHE on the Pt2Ru3/Sb-SnO2 electrode was higher than that at the Pt2Ru3/CB electrode in 0.1 M HClO4 solution saturated with 1000 ppm CO (H2-balance. The CO tolerance mechanism of these catalysts was investigated by in situ attenuated total reflection Fourier transform infrared reflection-adsorption spectroscopy (ATR-FTIRAS in 1% CO/H2-saturated 0.1 M HClO4 solution at 60 °C. It was found, for the Pt2Ru3/Sb-SnO2 catalyst, that the band intensity of CO linearly adsorbed (COL at step/edge sites was suppressed, together with a blueshift of the COL peak at terrace sites. On this surface, the HOR active sites were concluded to be more available than those on the CB-supported catalyst surface. The observed changes in the adsorption states of CO can be ascribed to an electronic modification effect by the Sb-SnO2 support.

  9. Comparative study of steam reforming of methane, ethane and ethylene on Pt, Rh and Pd supported on yttrium-stabilized zirconia.

    NARCIS (Netherlands)

    Graf, P.O.; Mojet, Barbara; van Ommen, J.G.; Lefferts, Leonardus

    2007-01-01

    In the present paper steam reforming of methane, ethane and ethylene was compared on Pt, Rh and Pd supported on yttrium-stabilized zirconia (YSZ). Both reactivity and product distribution changed with the use of different catalysts. The order of activity for the hydrocarbons on Rh was C2H6 > C2H4 >

  10. Bifunctional electrodes with ir and Ru oxide mixtures and pt for unified regenerative cells; Electrodos bifuncionales basados en mezclas de oxidos de Ir y Ru con Pt para celdas regenerativas unificadas

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Escalante-Garcia, I.L. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico); Cruz, J. C.; Arriaga-Hurtado; L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)]. E-mail: duronsm@prodigy.net.mx

    2009-09-15

    Unified regenerative fuel cells (URFC) represent an attractive option to obtain hydrogen and generate energy using a compact device. Nevertheless, the fusion of a fuel cell (PEMFC) and a water electrolyzer continue to be a challenge because of the wide range of conditions to which this type of device is subject. Because of its kinetic characteristics, oxygen reduction reaction (ORR) in PEMFC and oxygen evolution reaction (OER) in PEMWE are the limiting stages of the URFC depending on the mode of operation. The primary focus of research related to URFC is the obtainment of bifunctional electrocatalysts that satisfactorily perform in both oxygen reactions and support the different working conditions found in a fuel cell and an electrolyzer. The present work contributes to the research on bifunctional electrocatalysts and shows some preliminary results from the electrochemical study of different Pt gcc, IrO{sub 2} and RuO{sub 2} mixtures supported in Ebonex® as oxygen electrodes. The electrochemical characterization with cyclic voltamperometry (CV), linear voltamperometry (LV) and electrochemical impedance spectroscopy (EIS) in H{sub 2}SO{sub 4} 0.5 M, in the absence and present of oxygen shows that Ebonex®-supported bifunctional electrodes IrO{sub 2}-Pt and RuO{sub 2}-Pt present reasonable electrocatalytic properties for oxygen evolution and reduction reactions and present the possibility of their use in an URFC. The Ir- based oxide electrodes show greater stability than ruthenium-oxide electrodes. [Spanish] Las celdas de combustible regenerativas unificadas (URFC) representan una atractiva opcion para la obtencion de hidrogeno y generacion de energia en un dispositivo compacto. Sin embargo, la fusion de una celda de combustible (PEMFC) y un electrolizador de agua (PEMWE) sigue siendo un reto por la amplia gama de condiciones a que se sujeta un dispositivo de este tipo. Por sus caracteristicas cineticas, la reaccion de reduccion de oxigeno (ORR) en la PEMFC y la

  11. Surface noble metal modified PdM/C (M = Ru, Pt, Au) as anode catalysts for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Han; Huang, Tao, E-mail: huangt@fudan.edu.cn; Yu, Aishui, E-mail: asyu@fudan.edu.cn

    2016-08-15

    In this article, we studied the surface noble metal modification on Pd nanoparticles, other than the homogeneous or core-shell structure. The surface modification will lead to the uneven constitution within the nanoparticles and thus more obvious optimization effect toward the catalyst brought by the lattice deformation. The surface of the as-prepared Pd nanoparticles was modified with Ru, Pt or Au by a moderate and green approach, respectively. XPS results confirm the interactive electron effects between Pd and the modified noble metal. Electrochemical measurements show that the surface noble metal modified catalysts not only show higher catalytic activity, but also better stability and durability. The PdM/C catalysts all exhibit good dispersion and very little agglomeration after long-term potential cycles toward ethanol oxidation. With only 10% metallic atomic ratio of Au, PdAu/C catalyst shows extraordinary catalytic activity and stability, the peak current reaches 1700 mA mg{sup −1} Pd, about 2.5 times that of Pd/C. Moreover, the PdAu/C maintains 40% of the catalytic activity after 4500 potential cycles. - Highlights: • Pd-based catalysts with complicated exposed facets. • Much enhanced electrocatalytic activity and stability with about 10% noble metal M (M = Ru, Pt, Au) on Pd nanoparticles. • The outstanding electrocatalytic performance of PdAu/C towards ethanol oxidation after the Au modification.

  12. Investigation of the behavior of Pt-Ru mixtures with nafion in the oxygen reduction reaction; Investigacion del comportamiento de mezclas de Pt-Ru con nafion en la reaccion de reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez M, O

    2005-07-01

    In this work the electrochemical study for the reduction reaction of oxygen (RRO) of ruthenium, platinum and two mixtures of Pt-Ru (10:90) and Pt-Ru (50:50); to this last its were determined the kinetic and electrochemical parameters. The platinum used was analytical platinum and the ruthenium it was obtained of the decarboxylation of 200 mg of ruthenium dode carbonyl with 200 ml of 1-2 dichlorobenzene under a reflux system by 20 hours with agitation. Decanted and centrifuged by 30 minutes, the obtained ruthenium was washed with ether and it was evaporated for it later use. The material was characterized by means of X-ray diffraction, elementary analysis, scanning electron microscopy and infrared spectroscopy. To determine the optimum quantity of nafion to be deposited on the catalytic material, they were carried out tests with different quantities deposited on the electrodes with 1, 2, 4 and 8 {mu}L, giving better result 2 {mu}L for that it was opted for to work with this proportion in the mixtures. The electrochemical performance of 2 ruthenium relationships and platinum 0.05 mg - 0.45 mg and 0.25 mg - 0.25 mg respectively were studied with a potentiostat galvanostat EG and G Princeton Applied Research model 273a; it was found that the electrode with the mixture of 0.25 mg of platinum with 0.25 mg of ruthenium has a bigger response of current intensity after to deposit the nafion in the surface. The electro active area was determined carrying out recurrent voltametry to different scanning velocities (5, 10, 20, 30, 40, 50, 60, 70 and 80 mV/s) in the non faraday region with a value of 0.2082 cm{sup 2}. The mixture Pt-Ru (50:50) it presents a first order kinetics for the RRO and it is carried out via 4 electrons; the study of current density in function of the temperature presents values of 0.47 {+-} 0.3 for the charge transfer coefficient, of 118 mV/decade for the Tafel slope and it has an activation energy of 0.39 eV. (Author)

  13. Electronic properties of a heavy-fermion U (Ru0.92Rh0.08 )2Si2 single crystal

    Science.gov (United States)

    Prokeš, K.; Huang, Y.-K.; Reehuis, M.; Klemke, B.; Hoffmann, J.-U.; Sokolowski, A.; de Visser, A.; Mydosh, J. A.

    2017-01-01

    We report the crystal structure and highly anisotropic magnetic, transport, and thermal properties of an exceptionally good single crystal of U (Ru0.92Rh0.08)2Si2 , prepared using a modified Czochralski method. Our study, that also includes neutron diffraction results, shows all the heavy-fermion signatures of pristine URu2Si2 ; however, the superconductivity, hidden order, and remnant weak antiferromagnetic orders are absent. Instead, the ground state of the doped system can be classified as a spin liquid that preserves the heavy-fermion character. U (Ru0.92Rh0.08)2Si2 exhibits a short-range magnetic order distinguished by reflections of a Lorentzian profile at qIII=(1/2 1/2 1/2 ) positions that disappear above ˜15 K. The short-range order seems to be a precursor of a long-range magnetic order that occurs with higher Rh concentration. We indicate that these short-range fluctuations involve, at least partially, inelastic scattering processes.

  14. Structure analysis of CoPt alloy film with metastable ordered phases of L11 and Bh formed on Ru(0001 underlayer

    Directory of Open Access Journals (Sweden)

    Ohtake Mitsuru

    2014-07-01

    Full Text Available CoPt alloy films of 40 nm thickness are prepared on MgO(111 substrates with and without Ru(0001 underlayer at 300 °C by radio-frequency magnetron sputtering. CoPt films with the close-packed plane parallel to the substrate surface grow epitaxially on the Ru underlayer as well as on the MgO substrate. Flat surfaces with the arithmetical mean roughness value of 0.2 nm are realized for both films. The crystal structure is determined by considering the atomic stacking sequence of close-packed plane and the order degree. The film formed on MgO substrate consists of an fcc-based L11 ordered crystal, whereas the film grown on Ru underlayer involves an hcp-based Bh ordered crystal in addition to the L11 ordered crystal. The order degrees of films formed on MgO substrate and Ru underlayer are 0.30 and 0.34, respectively. The L11 crystal consists of two variants whose stacking sequences of close-packed plane are ABCABC… and ACBACB…, while the Bh crystal is a single-crystal with the stacking sequence of ABAB… Formation of Bh crystal is promoted on the Ru underlayer. The film formed on Ru underlayer shows a strong perpendicular magnetic anisotropy reflecting the magnetocrystalline anisotropies of L11 and Bh crystals.

  15. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts.

    Science.gov (United States)

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-05-07

    An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the

  16. Ni/Carbon Hybrid Prepared by Hydrothermal Carbonization and Thermal Treatment as Support for PtRu Nanoparticles for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Marcelo Marques Tusi; Michele Brandalise; Nataly Soares de Oliveira Polanco; Olandir Vercino Correa; Antonio Carlos da Silva; Juan Carlo Villalba; Fauze Jaco Anaissi

    2013-01-01

    Ni/Carbon was prepared in two steps:initially cellulose as carbon source and NiCl2.6H20 as catalyst of the carbonization process were submitted to hydrothermal treatment at 200 ℃ and further to thermal treatment at 900 ℃ under argon atmosphere.The obtained material contains Ni nanoparticles with face-centered cubic (fcc) structure dispersed on amorphous carbon with graphitic domains.PtRu/C electrocatalysts (carbonsupported PtRu nanoparticles) were prepared by an alcohol-reduction process using Ni/Carbon as support.The materials were characterized by thermogravimetric analysis,energy-dispersive X-ray spectroscopy,Fourier transform infrared spectroscopy,X-ray diffraction,transmission electron microscopy and tested as anodes in single direct methanol fuel cell (DMFC).The performances of PtRu/C electrocatalysts using Ni/Carbon as support were superior to those obtained for PtRu/C using commercial carbon black Vulcan XC72 as support.

  17. XPS investigations of Pt and Rh supported on γ-Al 2O 3 and TiO 2

    Science.gov (United States)

    Huizinga, T.; van'T Blik, H. F. J.; Vis, J. C.; Prins, R.

    1983-12-01

    An XPS investigation of Pt and Rh supported on γ-Al 2O 3 and TiO 2 was performed in order to establish the differences in metal-support interactions. The binding energies of the core levels of the supported metal particles were found to vary as a function of the dispersion of the supported metal, with the highest binding energy for the highest dispersion. This binding energy variation is caused by differences in the extra-atomic relaxation of metal particles of different sizes. In small particles there is a less effective screening of the core holes created during photoemission. For Pt/TiO 2 catalysts prereduced below 1015 K, slightly higher binding energies were found than for Pt/Al 2O 3 catalysts after comparable pretreatments. No differences in binding energies could be observed between Rh/TiO 2 and Rh/Al 2O 3 over a wide range of dispersions. In situ reduction of M/TiO 2 at 523 or 823 K led to essentially the same biding energy. These results show that there is no significant electron transfer from Ti 3+ to metallic platinum or rhodium. Consequently the strongly reduced chemisorption properties of metals on TiO 2, observed after high temperature reduction (SMSI), cannot be due to negatively charged metal atoms. For M/TiO 2 samples prereduced above 1015 K, an increase in binding energy of the metal core levels is found in combination with a decrease in dispersion of the metal. This behaviour is explained by encapsulation and spalling of the metal particles during an observed anatase-to-rutile phase transformation.

  18. Irreversible dynamics of the phase boundary in U(Ru0.96Rh0.04)2Si2 and implications for ordering.

    Science.gov (United States)

    Silhanek, A V; Jaime, M; Harrison, N; Fanelli, V R; Batista, C D; Amitsuka, H; Nakatsuji, S; Balicas, L; Kim, K H; Fisk, Z; Sarrao, J L; Civale, L; Mydosh, J A

    2006-04-07

    We report measurements and analysis of the specific heat and magnetocaloric effect-induced temperature changes at the phase boundary into the single magnetic field-induced phase (phase II) of U(Ru0.96Rh0.04)2Si2, which yield irreversible properties similar to those at the valence transition of Yb(1-x)Y(x)InCu4. To explain these similarities, we propose a bootstrap mechanism by which lattice parameter changes caused by an electric quadrupolar order parameter within phase II become coupled to the 5f-electron hybridization, giving rise to a valence change at the transition.

  19. Magnetic properties of U(Ru sub 1 minus x Rh sub x ) sub 2 Si sub 2 single crystals (0 le x le 1)

    Energy Technology Data Exchange (ETDEWEB)

    Miyako, Y.; Kawarazaki, S. (Department of Physics, Faculty of Science, Osaka University, Toyonaka 560, Osaka (Japan)); Amitsuka, H.; Paulsen, C.C. (Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060 (Japan)); Hasselbach, K. (Centre de Recherches sur les Tres Basses Temperatures, C.N.R.S., BP166X, 38042, Grenoble Cedex (France))

    1991-11-15

    The temperature dependence of the nonlinear susceptibility of URu{sub 2}Si{sub 2} has been studied in order to understand the properties of the phase transition at 17.5 K. We have also studied the various magnetic phases of U(Ru{sub 1{minus}{ital x}}Rh{sub {ital x}}){sub 2}Si{sub 2} as a function of {ital x} by means of specific heat, susceptibility, and neutron scattering experiments. Special attention has been paid to {ital x}=0.3 where two successive phase transitions occur.

  20. Photoemission study of 5f localization in UPd/sub 3-//sub x/(Pt,Rh)/sub x/

    Energy Technology Data Exchange (ETDEWEB)

    Arko, A.J.; Koelling, D.D.; Dunlap, B.D.; Mitchell, A.W.; Capasso, C.; del Giudice, M.

    1988-04-15

    Photoemission measurements in the two systems UPd/sub 3-//sub x/(Pt,Rh)/sub x/ show that the 5f spectra are consistent with localized 5f electrons (peak in spectral weight is below E/sub F/ for all x within the double hexagonal DO/sub 24/ phase) while at both phase transitions the 5f peaks lock in at E/sub F/ consistent with intinerancy. A satellite 5f peak which we attribute to d screening is observed in both localized and itinerant systems.

  1. Photoemission study of 5f localization in UPd/sub 3-x/(Pt,Rh)/sub x/

    Energy Technology Data Exchange (ETDEWEB)

    Arko, A.J.; Koelling, D.D.; Dunlap, B.D.; Mitchell, A.W.

    1987-10-01

    Photoemission measurements in the two systems UPd/sub 3-x/(Pt,Rh)/sub x/ show that the 5f spectra are consistent with localized 5f electrons (peak in spectral weight is below E/sub F/ for all x within the double hexagonal DO/sub 24/ phase) while at both phase transitions the 5f peaks lock in at E/sub F/ consistent with intinerancy. A satellite 5f peak representative of d-screening is observed in both localized and itinerant systems. 17 refs., 3 figs.

  2. Influence of method of preparation of Pt Ru/C electrocatalysts on the catalytic activity for the ethanol oxidation reaction in acidic medium; Influencia do metodo de preparacao de eletrocatalisadores PtRu/C sobre a atividade catalitica frente a reacao de oxidacao de etanol em meio acido

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Walber dos Santos; Silva, Uriel Lean Valente; Souza, Jose Pio Iudice de, E-mail: jpio@ufpa.br [Universidade Federal do Para, (UFPA), Belem, PA (Brazil). Instituto de Ciencias Exatas e Naturais. Faculdade de Quimica

    2013-09-01

    In this work the influence of variations in the borohydrate reduction method on the properties of Pt Ru/C electrocatalysts was investigated. The electrocatalysts were prepared using 1:1 ; 2:1; 5:1; 50:1 and 250:1 molar ratios of NaBH{sub 4} to metals. The reduction was also performed by dripping or by fast addition of the solution. The results showed that Pt Ru nanoparticles obtained by fast addition had the smallest crystallite sizes. It was also noted that the catalytic activity increased as the borohydrate:metal molar ratio increased. The Pt Ru/C electrocatalysts (50:1) obtained by fast addition presented the best catalytic activity for ethanol electro-oxidation. (author)

  3. Tuning the Curie temperature of L1{sub 0} ordered FePt thin films through site-specific substitution of Rh

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Dongbin, E-mail: dongbin.xu@seagate.com [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg; Heald, Steve M. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chen, Jing-Sheng; Chow, Gan Moog, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg [Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhou, Tie-Jun [Data Storage Institute, Agency for Science, Technology and Research (A-STAR), Singapore 117608 (Singapore); Bergman, Anders; Sanyal, Biplab [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden)

    2014-10-14

    In structurally ordered magnetic thin films, the Curie temperature (T{sub C}) of ferromagnetic films depends on the exchange integral of the short range ordered neighboring atoms. The exchange integral may be adjusted by controlling the elemental substitutional concentration at the lattice site of interest. We show how to control the T{sub C} in high anisotropy L1{sub 0} Fe{sub 50}Pt{sub 50} magnetic thin films by substituting Rh into the Pt site. Rh substitution in L1{sub 0} FePt modified the local atomic environment and the corresponding electronic properties, while retaining the ordered L1{sub 0} phase. The analysis of extended x-ray Absorption Fine Structure spectra shows that Rh uniformly substitutes for Pt in L1{sub 0} FePt. A model of antiferromagnetic defects caused by controlled Rh substitution of the Pt site, reducing the T{sub C,} is proposed to interpret this phenomenon and its validity is further examined by ab initio density functional calculations.

  4. Photocatalytic hydrogen evolution from CdS-ZnO-CdO systems under visible light irradiation: Effect of thermal treatment and presence of Pt and Ru cocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, R.M.; del Valle, F.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Cantoblanco, 28049 Madrid (Spain)

    2008-08-15

    A CdS-CdO-ZnO mixture annealed at different temperatures and loaded with Ru or Pt cocatalysts has been investigated in the production of hydrogen from aqueous solutions containing SO{sub 3}{sup 2-}+S{sup 2-} as sacrificial reagents under visible light. The physicochemical characterization of the CdS-CdO-ZnO catalyst revealed significant changes in the crystalline structure and visible light absorption capacity as a result of thermal treatments. Catalytic activity was found to be strongly dependent on physicochemical changes associated with thermal annealing. Hydrogen evolution over the CdS-CdO-ZnO catalyst was enhanced in the sample annealed at 773 K by the better contact between the CdS and CdO-ZnO phases, which improved physical charge separation. CdS-CdO-ZnO catalyst activity was significantly improved by the addition of Pt or Ru cocatalysts. Among the noble metals studied, activity promotion was higher for the sample loaded with Ru. The enhancement of activity associated with Ru loading is linked to a good interaction between Ru oxide particles and CdS, which reduces the possibility of electron-hole recombination, thus resulting in more efficient water splitting. (author)

  5. Cytotoxic Pt(IV and Ru(II complexes containing a biologically relevant edda-type ligand: A comparative study of their thermal properties

    Directory of Open Access Journals (Sweden)

    Mihajlović-Lalić Ljiljana E.

    2016-01-01

    Full Text Available The thermal behaviour of a Pt(IV and a Ru(II complex coordinated to O,O'-di-n-butyl-(S,S-ethylenediamine-N,N'-di-2-(3-cyclohexylpropanoate has been investigated using thermogravimetry (TG and differential scanning calorimetry (DSC. The study included investigation of the thermal decomposition of these complexes in the temperature range of 30 to 590°C and evaluation of activation energy for the first decomposition steps. For both metal complexes, broad DSC peaks indicated complex thermal transformation processes. The two-step decomposition of the Pt(IV complex started at 175 and ended at about 418°C, leaving elemental platinum as a final residue. On the other hand, the Ru(II analogue decomposed in three stages. Thermal degradation was evident beginning at 144°C and suggested the decomposition of a coordinated ligand as dominant process. For this complex, the proposed final residue was RuO2. Kinetic parameters for the first decomposition step were obtained by means of multi-heating rates method, in this case the Kissinger-Akahira-Sunose (KAS method. The mean activation energy calculated for 0.2 < α < 0.8 were 122.0 kJ mol−1 for the Pt(IV and 118.9 kJ mol−1 for the Ru(II complex and decreased constantly, characteristic of a multi-step process. [Projekat Ministarstva nauke Republike Srbije, br. 172035, 172055 i br. 172018

  6. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts

    Science.gov (United States)

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-04-01

    An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the

  7. Preparation of Pt Ru/C electrocatalysts using gamma radiation for application as anode in direct methanol fuel cell; Preparacao de eletrocatalisadores PtRu/C utilizando radiacao {gamma} para aplicacao como anodo na oxidacao direta de metanol em celulas a combustivel

    Energy Technology Data Exchange (ETDEWEB)

    Spinace, Estevam V.; Silva, Dionisio F. da; Cruz, Victor A. da; Oliveira Neto, Almir; Machado, Luci D.B.; Pino, Eddy S.; Linardi, Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: espinace@ipen.br

    2005-07-01

    PtRu nanoparticles supported on carbon (PtRu/C electrocatalysts) were prepared submitting a water/2-propanol mixture containing the metal ions and the carbon support to gamma radiation. The water/2-propanol (v/v) and the total dose (kGy) were studied. The electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The methanol electro-oxidation was studied by cyclic voltammetry using the thin porous coating. In the studied conditions, the electrocatalytic activity of the prepared electrocatalysts depend on the water/2-propanol ratio used in the reaction medium. (author)

  8. Electrooxidation Mechanism of Methanol at Pt-Ru Catalyst Modified GC Electrode in Electrolytes with Different pH Using Electrochemical and SERS Techniques

    Institute of Scientific and Technical Information of China (English)

    DING Yue Min; LIU Yao-Long; RAO Gui-Shi; WANG Guo-Fu; ZHONG Qi-Ling; REN Bin; TIAN Zhong-Qun

    2007-01-01

    The electrochemical and in-situ surface-enhanced Raman spectroscopy (SERS) techniques were used to investigate the electrooxidation behavior of methanol in acidic, neutral and alkaline media at a Pt-Ru nanoparticle modified glassy carbon (Pt-Ru/GC) electrode. The results showed that methanol could be dissociated spontaneously at the Pt-Ru/GC electrode to produce a strongly adsorbed intermediate, CO. It was found that CO could be oxidized more easily in the alkaline medium than in the acidic and neutral media. The peak potential of methanol oxidation was shifted from 0.663 and 0.708 V in the acidic and neutral media to -0.030 V in the alkaline medium, which is due to that the adsorption strength of CO on the Pt surface in the alkaline medium is weaker than that in the acidic and neutral media. The final product of the methanol oxidation is CO2. However, in the alkaline medium, CO2 produced would form CO32- and HCO3- resulting in the decrease in the alkaline concentration and then in the decrease in the performance of DMFC. Therefore, the performance of the alkaline DMFC is not Stable.

  9. Quaternary Pt{sub 2}Ru{sub 1}Fe{sub 1}M{sub 1}/C (M=Ni, Mo, or W) catalysts for methanol electro-oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Min Ku; Lee, Ki Rak; Kang, Kweon Ho; Park, Geun Il [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Jeon, Hyung Joon [Kyoto University, Kyoto (Japan); McGinn, Paul J. [University of Notre Dame, Indiana (United States)

    2015-02-15

    Quaternary Pt{sub 2}Ru{sub 1}Fe{sub 1}M{sub 1}/C (M=Ni, Mo, or W) catalysts were investigated for the methanol electro-oxidation reaction (MOR). Electrocatalytic activities of the quaternary catalysts for CO electro-oxidation were studied via CO stripping experiments, and the Pt{sub 2}Ru{sub 1}Fe{sub 1}Ni{sub 1}/C and Pt{sub 2}Ru{sub 1}Fe{sub 1}W{sub 1}/C catalysts exhibited lowered on-set potential compared to that of a commercial PtRu/C catalyst. MOR activities of the quaternary catalysts were determined by linear sweep voltammetry (LSV) experiments, and the Pt{sub 2}Ru{sub 1}Fe{sub 1}W{sub 1}/C catalyst outperformed the commercial PtRu/C catalyst by 170 and 150% for the mass and specific activities, respectively. X-ray photoelectron spectroscopy (XPS) was employed to analyze surface oxidation states of constituent atoms, and it was identified that the structure of the synthesized catalysts are close to a nano-composite of Pt and constituent metal hydroxides and oxides. In addition, the XPS results suggested that the bi-functional mechanism accounts for the improved performance of the Pt{sub 2}Ru{sub 1}Fe{sub 1}Ni{sub 1}/C and Pt{sub 2}Ru{sub 1} Fe{sub 1}W{sub 1}/C catalysts.

  10. Predictions of the Pt(8)Ti phase in unexpected systems.

    Science.gov (United States)

    Taylor, Richard H; Curtarolo, Stefano; Hart, Gus L W

    2010-05-19

    The binary A(8)B phase (prototype Pt(8)Ti) has been experimentally observed in 11 systems. A high-throughput search over all the binary transition intermetallics, however, reveals 59 occurrences of the A(8)B phase: Au(8)Zn(dagger), Cd(8)Sc(dagger), Cu(8)Ni(dagger), Cu(8)Zn(dagger), Hg(8)La, Ir(8)Os(dagger), Ir(8)Re, Ir(8)Ru(dagger), Ir(8)Tc, Ir(8)W(dagger), Nb(8)Os(dagger), Nb(8)Rh(dagger), Nb(8)Ru(dagger), Nb(8)Ta(dagger), Ni(8)Fe, Ni(8)Mo(dagger)*, Ni(8)Nb(dagger)*, Ni(8)Ta*, Ni(8)V*, Ni(8)W, Pd(8)Al(dagger), Pd(8)Fe, Pd(8)Hf, Pd(8)Mn, Pd(8)Mo*, Pd(8)Nb, Pd(8)Sc, Pd(8)Ta, Pd(8)Ti, Pd(8)V*, Pd(8)W*, Pd(8)Zn, Pd(8)Zr, Pt(8)Al(dagger), Pt(8)Cr*, Pt(8)Hf, Pt(8)Mn, Pt(8)Mo, Pt(8)Nb, Pt(8)Rh(dagger), Pt(8)Sc, Pt(8)Ta, Pt(8)Ti*, Pt(8)V*, Pt(8)W, Pt(8)Zr*, Rh(8)Mo, Rh(8)W, Ta(8)Pd, Ta(8)Pt, Ta(8)Rh, V(8)Cr(dagger), V(8)Fe(dagger), V(8)Ir(dagger), V(8)Ni(dagger), V(8)Pd, V(8)Pt, V(8)Rh, and V(8)Ru(dagger) ((dagger) = metastable, * = experimentally observed). This is surprising for the wealth of new occurrences that are predicted, especially in well-characterized systems (e.g., Cu-Zn). By verifying all experimental results while offering additional predictions, our study serves as a striking demonstration of the power of the high-throughput approach. The practicality of the method is demonstrated in the Rh-W system. A cluster-expansion-based Monte Carlo model reveals a relatively high order-disorder transition temperature.

  11. Adsorption of NO on the Rh-13, Pd-13, Ir-13, and Pt-13 Clusters: A Density Functional Theory Investigation

    DEFF Research Database (Denmark)

    Piotrowski, Mauricio J.; Piquini, Paulo; Zeng, Zhenhua

    2012-01-01

    of real catalyst devices. In this study, we report a density functional theory study of the adsorption properties of NO on the TM13 (TM = Rh, Pd, Ir, Pt) clusters employing the projected augmented wave method. We found that the interaction of NO with TM13 is much more complex than that for NO/TM(111...... of the binding energy of NO to the TM13 clusters compared with the TM(111) surfaces, as the antibonding NO states are not occupied for NO/TM13, and the general relationship based on the d-band model between adsorption energy and the center of gravity of the occupied d-states does not hold for the studied TM13...

  12. Fabrication of Nonenzymatic Glucose Sensors Based on Multiwalled Carbon Nanotubes with Bimetallic Pt-M (M = Ru and Sn Catalysts by Radiolytic Deposition

    Directory of Open Access Journals (Sweden)

    Sun-Young Kwon

    2012-01-01

    Full Text Available Nonenzymatic glucose sensors employing multiwalled carbon nanotubes (MWNTs with highly dispersed Pt-M (M = Ru and Sn nanoparticles (Pt-M@PVP-MWNTs were fabricated by radiolytic deposition. The Pt-M nanoparticles on the MWNTs were characterized by transmittance electron microscopy, elemental analysis, and X-ray diffraction. They were found to be well dispersed and to exhibit alloy properties on the MWNT support. Electrochemical testing showed that these nonenzymatic sensors had larger currents (mA than that of a bare glassy carbon (GC electrode and one modified with MWNTs. The sensitivity (A mM−1, linear range (mM, and detection limit (mM (S/N = 3 of the glucose sensor with the Pt-Ru catalyst in NaOH electrolyte were determined as 18.0, 1.0–2.5, 0.7, respectively. The corresponding data of the sensor with Pt-Sn catalyst were 889.0, 1.00–3.00, and 0.3, respectively. In addition, these non-enzymatic sensors can effectively avoid interference arising from the oxidation of the common interfering species ascorbic acid and uric acid in NaOH electrolyte. The experimental results show that such sensors can be applied in the detection of glucose in commercial red wine samples.

  13. A novel Pt/Cr/Ru/C cathode catalyst for direct methanol fuel cells (DMFC) with simultaneous methanol tolerance and oxygen promotion

    Energy Technology Data Exchange (ETDEWEB)

    Perez, G.; Zinola, C.F. [Laboratorio de Electroquimica Fundamental, Facultad de Ciencias, Universidad de la Republica, Igua 4225, C.P. 11400, Montevideo (Uruguay); Pastor, E. [Departamento de Quimica Fisica, Facultad de Quimica, Universidad de La Laguna, Astrofisico F. Sanchez s/n, 38071 La Laguna, Tenerife (Spain)

    2009-12-15

    New carbon supported electrocatalysts Pt/Cr/Ru with distinct compositions and preparation methods were studied with the help of different electrochemical and spectroscopic techniques. The purposes of obtaining these catalysts lie on their possibilities towards methanol/oxygen fuel cells. In this sense, the oxygen reduction reaction and methanol oxidation reaction were analyzed using stationary and fluid dynamic methodologies. Pt{sub 7.8}/Ru{sub 1.3}/Cr{sub 0.5} and Pt{sub 8.0}/Ru{sub 2.0}/Cr{sub 0.1} were the most interesting prepared substrates, on which the first one shows the best catalytic properties towards methanol oxidation and the second the finest performance towards oxygen reduction reaction. Reaction orders with respect to oxygen for the oxygen reduction reaction were obtained being equal to 1/2 at potentials lower than 0.80 V for both catalysts. Polarization curves run for this reaction depicted two Tafel slopes, i.e. 0.09 V dec{sup -1} above 0.8 V and 0.20 V dec{sup -1} below 0.8 V for both catalysts. An analysis of the most likely mechanism for the oxygen reduction was proposed on the base of those reaction orders and Tafel slopes. (author)

  14. Structural and chelation behaviors of new Ru(II), Pt(IV) and Ir(III) gatifloxacin drug complexes: Spectroscopic characterizations

    Science.gov (United States)

    Alghamdi, Mohammed T.; Alsibaai, A. A.; El-Shahawi, M. S.; Refat, Moamen S.

    2017-02-01

    The interaction between gatifloxacin drug (GAT) with some transition metals (Ru(III), Pt(IV) and Ir(III)) yield the complexes of formulas [Ru(GAT-NH4)(Cl)3(H2O)2], [Pt(GAT-NH4)2(Cl)4]·3H2O and [Ir(GAT-NH4)2(Cl)2(H2O)2]·Cl·2H2O at pH = 7-8. The composition of the GAT complexes was confirmed by elemental data. The IR frequencies reveal the coordination of the GAT with metal ions and the coordination mode of the sbnd N atom of 3-methylpiperazinyl moiety to metal. XRD pattern show isomorphism among the complexes with similar chelation behavior. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to identify the particle size of GAT complexes. The thermal data reveals that various steps of decomposition of the complexes to form their metal oxide as final product. The electronic spectra and the magnetic susceptibility values reveal that the coordination and geometry of Ru3+, Pt4+ and Ir3+ complexes possess distorted octahedral geometry with six number of coordination. Thermodynamic parameters (E*, ΔS*, ΔH* and ΔG*) were calculated from TG curves dependent on Coats-Redfern and Horowitz-Metzeger non-isothermal methods.

  15. Spectroscopic Study of the Thermal Degradation of PVP-capped Rh and Pt Nanoparticles in H2 and O2 Environments

    Energy Technology Data Exchange (ETDEWEB)

    Borodko, Yuri; Lee, Hyun Sook; Joo, Sang Hoon; Zhang, Yawen; Somorjai, Gabor A.

    2009-09-15

    Poly(N-vinylpyrrolidone) (PVP) capped platinum and rhodium nanoparticles (7-12 nm) have been studied with UV-VIS, FTIR and Raman spectroscopy. The absorption bands in the region 190-900 nm are shown to be sensitive to the electronic structure of surface Rh and Pt atoms as well as to the aggregation of the nanoparticles. In-situ FTIR-DRIFT spectroscopy of the thermal decay of PVP stabilized Rh and Pt nanoparticles in H{sub 2} and O{sub 2} atmospheres in temperatures ranging from 30 C-350 C reveal that decomposition of PVP above 200 C, PVP transforms into a 'polyamidpolyene' - like material that is in turn converted into a thin layer of amorphous carbon above 300 C. Adsorbed carbon monoxide was used as a probing molecule to monitor changes of electronic structure of surface Rh and Pt atoms and accessible surface area. The behavior of surface Rh and Pt atoms with ligated CO and amide groups of pyrrolidones resemble that of surface coordination compounds.

  16. The effect of Rhδ+ dopant in SrTiO3 on the active oxidation state of co-catalytic Pt nanoparticles in overall water splitting

    NARCIS (Netherlands)

    Zoontjes, M.G.C.; Han, K.; Huijben, M.; Wiel, van der W.G.; Mul, G.

    2016-01-01

    We report on the oxidation state of Pt nanoparticles when deposited on SrTiO3 or Rh-doped SrTiO3 under realistic solar water-splitting conditions. The oxidation state was investigated using state-of-the-art analysis of the reaction in a continuously stirred tank reactor (CSTR) connected to a micro g

  17. High-quality graphene grown on polycrystalline PtRh{sub 20} alloy foils by low pressure chemical vapor deposition and its electrical transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, He; Shen, Chengmin, E-mail: cmshen@iphy.ac.cn; Tian, Yuan; Bao, Lihong; Chen, Peng; Yang, Rong; Yang, Tianzhong; Li, Junjie; Gu, Changzhi; Gao, Hong-Jun [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-02-08

    High-quality continuous uniform monolayer graphene was grown on polycrystalline PtRh{sub 20} alloy foils by low pressure chemical vapor deposition. The morphology of graphene was investigated by Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. Analysis results confirm that high quality single-layer graphene was fabricated on PtRh{sub 20} foil at 1050 °C using a lower flux of methane under low pressure. Graphene films were transferred onto the SiO{sub 2}/Si substrate by the bubbling transfer method. The mobility of a test field effect transistor made of the graphene grown on PtRh{sub 20} was measured and reckoned at room temperature, showing that the carrier mobility was about 4000 cm{sup 2} V{sup −1} s{sup −1}. The results indicate that desired quality of single-layer graphene grown on PtRh{sub 20} foils can be obtained by tuning reaction conditions.

  18. Influence of hydrogen on the thermoelectric power of palladium alloyed with neighbouring elements: I. Pd/Ru/H and Pd/Rh/H alloys

    CERN Document Server

    Szafranski, A W

    2003-01-01

    Pd/Ru and Pd/Rh alloys have been loaded with hydrogen in high-pressure conditions. The resulting hydrogen contents were close to the stoichiometric composition, H/(Pd + Me) = 1. Lower hydrogen contents have been obtained by successive partial desorptions. The thermoelectric power and electrical resistance of one- and two-phase alloys have been measured simultaneously in the temperature range between 80 and 300 K. A Nordheim-Gorter type correlation of the two quantities has been observed in many cases and the partial thermopowers corresponding to electron-phonon scattering and lattice disorder could be determined. The observed anomalous behaviour of the total and partial thermopowers is attributed to virtual bound states of ruthenium or rhodium.

  19. Magnetic excitations in U(Ru{sub 1-x}Rh{sub x}){sub 2}Si{sub 2}(x=<0.03)

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, M. [Faculty of Science, Ibaraki University, Mito 310-8512 (Japan); Amitsuka, H. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Itoh, S. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Kawasaki, I. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Tenya, K. [Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)]. E-mail: tenya@phys.sci.hokudai.ac.jp; Yoshizawa, H. [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, Tokai 319-1106 (Japan)

    2005-04-30

    We have investigated magnetic excitations for a mixed phase of hidden order (HO) and the antiferromagnetic (AF) order in U(Ru{sub 1-x}Rh{sub x}){sub 2}Si{sub 2}(x=<0.03) by means of inelastic neutron scattering. The inelastic peaks observed at Q=(1,0,0) and (1,0.4,0) in the HO phase for x=0 and 0.015 at 1.4K are found to be strongly reduced in the AF dominant compositions of x=0.02 and 0.03. Similar behavior is observed as the HO is replaced by the AF order upon cooling for x=0.02. The x-T region in which the strong reduction of inelastic peaks is observed corresponds to the AF-rich region, indicating that the magnetic excitations typical for the HO-phase vanish in the AF phase.

  20. AB-INITIO STUDY OF BULK MODULUS AND CHARGE DENSITY OF CUBIC SrMO3 PEROVSKITES (M = Ti, Zr, Mo, Rh, Ru

    Directory of Open Access Journals (Sweden)

    AVINASH DAGA

    2012-03-01

    Full Text Available Bulk modulus & charge density of cubic SrMO3 perovskites (M = Ti, Zr, Mo, Rh & Ru have been investigated systematically using the first principle density functional calculations. Local density approximation (LDAmethod has been used to compute the two quantities for five perovskites. It is found that the calculated bulk modulus for all the transition metal oxides are in good agreement with the available experimental data and with other theoretical results previously reported in the literature. ABINIT computer code is used to carry out all the calculations. Charge density plots for all the five cubic SrMO3 perovskites have been drawn using MATLAB. The maximum and minimum values of charge density along with the corresponding reduced coordinates are reported for all the perovskites.

  1. Polyhedral metallaheteroborane chemistry. Synthesis, spectroscopy, structure and dynamics of eleven-vertex {RhNB(9)} and {PtCB(9)} metallaheteroboranes.

    Science.gov (United States)

    Macías, Ramón; Bould, Jonathan; Holub, Josef; Kennedy, John D; Stíbr, Bohumil; Thornton-Pett, Mark

    2007-07-21

    Reaction between [RhCl(PPh(3))(3)] and the [nido-6-NB(9)H(11)](-) anion in CH(2)Cl(2) yields orange eleven-vertex [8,8-(PPh(3))(2)-nido-8,7-RhNB(9)H(11)]. Reaction of the [nido-6-CB(9)H(12)](-) anion with [cis-PtCl(2)(PMe(2)Ph)(2)] in methanol affords yellow eleven-vertex [9-(OMe)-8,8-(PMe(2)Ph)(2)-nido-8,7-PtCB(9)H(10)], which is also formed from the reaction of MeOH with [8,8-(PPh(3))(2)-nido-8,7-PtCB(9)H(10)]. Both compounds have been characterised by single-crystal X-ray diffraction analysis and examined by NMR spectroscopy and have structures based on eleven-vertex nido-type geometries, with the metal centre and the heteroatoms in the adjacent (8)- and (7)-positions on the pentagonal open face. The metal-to-heteroborane bonding sphere of is fluxional, with a DeltaG(double dagger) value of 48.4 kJ mol(-1). DFT calculations on the model compounds [8,8-(PH(3))(2)-nido-8,7-RhNB(9)H(11)] and [8,8-(PH(3))(2)-nido-8,7-RhSB(9)H(10)] have been carried out to define the fluxional process and the intermediates involved.

  2. Rh(III) and Ru(II)-catalyzed site-selective C-H alkynylation of quinolones.

    Science.gov (United States)

    Kang, Dahye; Hong, Sungwoo

    2015-04-17

    C2- and C5-alkynylated quinolone scaffolds are core structures of numerous biologically active molecules. Utilizing TIPS-EBX as an alkynylating agent, we have developed an efficient and site-selective C5 alkynylation of 4-quinolones that is directed by the weakly coordinating carbonyl group. In addition, Ru(II) catalyzed C2-selective alkynylation was successfully realized via N-pyrimidyl group-directed cross-couplings to access valuable C2-alkynylated 4-quinolones. This strategy provides direct access to the C2 or C5 alkynylated 4-quinolones. Furthermore, the reaction was applied to isoquinolones for C3-selective alkynylation.

  3. A computational mechanistic investigation of hydrogen production in water using the [Rh(III)(dmbpy)2Cl2](+)/[Ru(II)(bpy)3](2+)/ascorbic acid photocatalytic system.

    Science.gov (United States)

    Kayanuma, Megumi; Stoll, Thibaut; Daniel, Chantal; Odobel, Fabrice; Fortage, Jérôme; Deronzier, Alain; Collomb, Marie-Noëlle

    2015-04-28

    We recently reported an efficient molecular homogeneous photocatalytic system for hydrogen (H2) production in water combining [Rh(III)(dmbpy)2Cl2](+) (dmbpy = 4,4'-dimethyl-2,2'-bipyridine) as a H2 evolving catalyst, [Ru(II)(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and ascorbic acid as a sacrificial electron donor (Chem. - Eur. J., 2013, 19, 781). Herein, the possible rhodium intermediates and mechanistic pathways for H2 production with this system were investigated at DFT/B3LYP level of theory and the most probable reaction pathways were proposed. The calculations confirmed that the initial step of the mechanism is a reductive quenching of the excited state of the Ru photosensitizer by ascorbate, affording the reduced [Ru(II)(bpy)2(bpy˙(-))](+) form, which is capable, in turn, of reducing the Rh(III) catalyst to the distorted square planar [Rh(I)(dmbpy)2](+) species. This two-electron reduction by [Ru(II)(bpy)2(bpy˙(-))](+) is sequential and occurs according to an ECEC mechanism which involves the release of one chloride after each one-electron reduction step of the Rh catalyst. The mechanism of disproportionation of the intermediate Rh(II) species, much less thermodynamically favoured, cannot be barely ruled out since it could also be favoured from a kinetic point of view. The Rh(I) catalyst reacts with H3O(+) to generate the hexa-coordinated hydride [Rh(III)(H)(dmbpy)2(X)](n+) (X = Cl(-) or H2O), as the key intermediate for H2 release. The DFT study also revealed that the real source of protons for the hydride formation as well as the subsequent step of H2 evolution is H3O(+) rather than ascorbic acid, even if the latter does govern the pH of the aqueous solution. Besides, the calculations have shown that H2 is preferentially released through an heterolytic mechanism by reaction of the Rh(III)(H) hydride and H3O(+); the homolytic pathway, involving the reaction of two Rh(III)(H) hydrides, being clearly less favoured. In parallel to this

  4. Search for unconventional superconductors among the YTE2Si2 compounds (TE = Cr, Co, Ni, Rh, Pd, Pt).

    Science.gov (United States)

    Pikul, Adam P; Samsel-Czekala, Malgorzata; Chajewski, Grzegorz; Romanova, Tetiana; Hackemer, Alicja; Gorzelniak, Roman; Wiśniewski, Piotr; Kaczorowski, Dariusz

    2017-03-21

    Motivated by the recent discovery of exotic superconductivity in YFe2Ge2 we undertook reinvestigation of formation and physical properties of yttrium-based 1:2:2 silicides. Here we report on syntheses and crystal structures of the YTE2Si2 compounds with TE = Cr, Co, Ni, Rh, Pd, and Pt, and their low-temperature physical properties measurements, supplemented by results of fully relativistic FPLO band structure calculations. We confirm that most of the members of that family crystallize in a tetragonal ThCr2Si2-type structure (space group I4/mmm) and have three-dimensional Fermi surface, while only one of them (YPt2Si2) forms with a closely-related primitive CaBe2Ge2-type unit cell (space group P4/nmm) and possess quasi-two-dimensional Fermi surface sheets. Physical measurements indicated that BCS-like superconductivity is observed only in YPt2Si2 (Tc = 1.54 K) and YPd2Si2 (Tc = 0.43 K), while no superconducting phase transition was found in other systems at least down to 0.35 K. Thermal analysis showed no polymorphism in both superconducting phases. No clear relation between the superconductivity and the crystal structure (and dimensionality of the Fermi surface) was observed.

  5. Kinetic and Performance Studies of the Regeneration Phase of Model Pt/Ba/Rh NOx Traps for Design and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Michael Harold; Vemuri Balakotaiah

    2010-05-31

    In this project a combined experimental and theoretical approach was taken to advance our understanding of lean NOx trap (LNT) technology. Fundamental kinetics studies were carried out of model LNT catalysts containing variable loadings of precious metals (Pt, Rh), and storage components (BaO, CeO{sub 2}). The Temporal Analysis of Products (TAP) reactor provided transient data under well-characterized conditions for both powder and monolith catalysts, enabling the identification of key reaction pathways and estimation of the corresponding kinetic parameters. The performance of model NOx storage and reduction (NSR) monolith catalysts were evaluated in a bench scale NOx trap using synthetic exhaust, with attention placed on the effect of the pulse timing and composition on the instantaneous and cycle-averaged product distributions. From these experiments we formulated a global model that predicts the main spatio-temporal features of the LNT and a mechanistic-based microkinetic models that incorporates a detailed understanding of the chemistry and predicts more detailed selectivity features of the LNT. The NOx trap models were used to determine its ability to simulate bench-scale data and ultimately to evaluate alternative LNT designs and operating strategies. The four-year project led to the training of several doctoral students and the dissemination of the findings as 47 presentations in conferences, catalysis societies, and academic departments as well 23 manuscripts in peer-reviewed journals. A condensed review of NOx storage and reduction was published in an encyclopedia of technology.

  6. The intelligent catalyst having the self-regenerative function of Pd, Rh and Pt for automotive emissions control

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hirohisa; Uenishi, Mari; Taniguchi, Masashi; Tan, Isao [Materials Research and Development Division, Daihatsu Motor Co. Ltd., Ikeda, Osaka 563-8651 (Japan); Narita, Keiichi; Kimura, Mareo [Research and Development Division, Cataler Corporation, Kakegawa, Shizuoka 437-1492 (Japan); Kaneko, Kimiyoshi [Fine Chemical Research Laboratories, Hokko Chemical Industry Co. Ltd., Atsugi, Kanagawa 243-0023 (Japan); Nishihata, Yasuo; Mizuki, Jun' ichiro [Kansai Photon Science Institute, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148 (Japan)

    2006-09-30

    The self-regenerative function of precious metals in the intelligent catalyst is an epoch-making technology in the history of automotive catalysts after the 1970's. The mechanism of the self-regenerative function is studied by X-ray absorption fine-structure (XAFS) analyses. The function was realized through a cyclic movement of Pd between the outside (as Pd nanoparticles) and the inside (as Pd cations in the lattice) of the perovskite crystal in synchronization with the inherent fluctuations between reductive and oxidative (redox) atmospheres that occur in real automotive exhaust gases. As the result, the growth of Pd particles can be suppressed during the entire lifetime of the vehicle. Moreover, the speed of this function was measured at the time resolution of a 10ms by in situ energy dispersive XAFS, and it is proved that the self-regenerative function occurs at an extremely high speed. Furthermore, the new perovskite catalysts which have the self-regenerative function of Rh and Pt, as well as Pd, are discussed here. This self-regenerative function provides a new and useful tool for designing the future catalyst technology. (author)

  7. Barrier characteristics of Pt/Ru Schottky contacts on -type GaN based on –– and –– measurements

    Indian Academy of Sciences (India)

    N Nanda Kumar Reddy; V Rajagopal Reddy

    2012-02-01

    We have investigated the current–voltage (–) and capacitance–voltage (–) characteristics of Ru/Pt/-GaN Schottky diodes in the temperature range 100–420 K. The calculated values of barrier height and ideality factor for the Ru/Pt/-GaN Schottky diode are 0.73 eV and 1.4 at 420 K, 0.18 eV and 4.2 at 100 K, respectively. The zero-bias barrier height ($\\Phi_{\\text{b}0}$) calculated from – characteristics is found to be increased and the ideality factor () decreased with increasing temperature. Such a behaviour of $\\Phi_{\\text{b}0}$ and n is attributed to Schottky barrier (SB) inhomogeneities by assuming a Gaussian distribution (GD) of barrier heights (BHs) at themetal/semiconductor interface. The current–voltage–temperature (––) characteristics of the Ru/Pt/-GaN Schottky diode have shown a double Gaussian distribution having mean barrier heights ($\\bar{\\Phi}_{\\text{b}0}$) of 1.001 eV and 0.4701 eV and standard deviations ($\\sigma_{0}$) of 0.1491 V and 0.0708 V, respectively. The modified ln($J_{0}/T^{2}$) − ($q^{2}\\sigma^{2}_{0}/2k^{2}T^{2}$) vs 10$^{3}/T$ plot gives $\\bar{\\Phi}_{\\text{b}0}$ and Richardson constant values as 0.99 eV and 0.47 eV, and 27.83 and 10.29 A/cm2K2, respectively without using the temperature coefficient of the barrier height. The difference between the apparent barrier heights (BHs) evaluated from the – and – methods has been attributed to the existence of Schottky barrier height inhomogeneities.

  8. Hydrogen Production by Steam Reforming of Ethanol on Rh-Pt Catalysts: Influence of CeO2, ZrO2, and La2O3 as Supports

    Directory of Open Access Journals (Sweden)

    Bernay Cifuentes

    2015-11-01

    Full Text Available CeO2-, ZrO2-, and La2O3-supported Rh-Pt catalysts were tested to assess their ability to catalyze the steam reforming of ethanol (SRE for H2 production. SRE activity tests were performed using EtOH:H2O:N2 (molar ratio 1:3:51 at a gaseous space velocity of 70,600 h−1 between 400 and 700 °C at atmospheric pressure. The SRE stability of the catalysts was tested at 700 °C for 27 h time on stream under the same conditions. RhPt/CeO2, which showed the best performance in the stability test, also produced the highest H2 yield above 600 °C, followed by RhPt/La2O3 and RhPt/ZrO2. The fresh and aged catalysts were characterized by TEM, XPS, and TGA. The higher H2 selectivity of RhPt/CeO2 was ascribed to the formation of small (~5 nm and stable particles probably consistent of Rh-Pt alloys with a Pt surface enrichment. Both metals were oxidized and acted as an almost constant active phase during the stability test owing to strong metal-support interactions, as well as the superior oxygen mobility of the support. The TGA results confirmed the absence of carbonaceous residues in all the aged catalysts.

  9. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

    Energy Technology Data Exchange (ETDEWEB)

    Porobova, Svetlana, E-mail: porobova.sveta@yandex.ru; Loskutov, Oleg, E-mail: lom58@mail.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); Markova, Tat’jana, E-mail: patriot-rf@mail.ru [Siberian State Industrial University. 42 Kirov St., Novokuznetsk, 654007 (Russian Federation); Klopotov, Vladimir, E-mail: vdklopotov@mail.ru [Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation); Klopotov, Anatoliy, E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36, Lenin Ave., Tomsk, 634050 (Russian Federation); Vlasov, Viktor, E-mail: vik@tsuab.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen’s law.

  10. Study of Pt-Rh/CeO2-ZrO2-MxOy (M = Y, La)/Al2O3 three-way catalysts

    Science.gov (United States)

    Jiaxiu, Guo; Zhonghua, Shi; Dongdong, Wu; Huaqiang, Yin; Maochu, Gong; Yaoqiang, Chen

    2013-05-01

    CeO2-ZrO2-MxOy (M = Y; La) mixed oxides, prepared by co-precipitation method and characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman spectra (RM) and oxygen pulse reaction, were comparatively investigated to elucidate the combinational effects of Y and/or La oxide promoters on the catalytic activity and anti-aging performance of monolithic cordierite honeycomb catalysts with low Pt and Rh content. The catalytic activities, water-gas shift (WGS) and steam reforming reaction (SR) were studied under a simulated gas mixture. The catalysts were also characterized by H2-temperature-programmed reduction (H2-TPR) and O2-temperature-programmed desorption (O2-TPD). The results showed that the prepared CeO2-ZrO2-MxOy oxides have a face-centered cubic fluorite structure and are nanosize. La3+ ions can significantly improve thermal stability and efficiently retard CeO2-ZrO2 crystal sintering and growth. Doped CeO2-ZrO2 with Y3+ and La3+ has 105 and 60 m2/g surface area and 460 and 390 μmol/g OSC before and after aging. The T50 of fresh Pt-Rh/CZYL/LA is 170 °C for CO, 222 °C for C3H8 and 189 °C for NO, and shift to 205, 262 and 228 °C after hydrothermal aging, which are better than those of Pt-Rh/CZY/LA or Pt-Rh/CZL/LA. WGS and SR are relate to the OSC of oxygen storage materials and absorbed oxygen species on the catalyst surface and affect the three-way catalytic activities of catalysts. The reductive property of noble metals and the dissociatively adsorbed O2 on the surface of catalysts are closely related to the catalytic activities.

  11. Mono- and bimetallic Rh and Pt NSR-catalysts prepared by controlled deposition of noble metals on support or storage component.

    Science.gov (United States)

    Büchel, Robert; Pratsinis, Sotiris E; Baiker, Alfons

    2012-02-22

    Mono- and bimetallic Rh and Pt based NOx storage-reduction (NSR) catalysts, where the noble metals were deposited on the Al2O3 support or BaCO3 storage component, have been prepared using a twin flame spray pyrolysis setup. The catalysts were characterized by nitrogen adsorption, CO chemisorption combined with diffuse reflectance infrared Fourier transform spectroscopy, X-ray diffraction, and scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy. The NSR performance of the catalysts was investigated by fuel lean/rich cycling in the absence and presence of SO2 (25 ppm) as well as after H2 desulfation at 750 °C. The performance increased when Rh was located on BaCO3 enabling good catalyst regeneration during the fuel rich phase. Best performance was observed for bimetallic catalysts where the noble metals were separated, with Pt on Al2O3 and Rh on BaCO3. The Rh-containing catalysts generally showed much higher tolerance to SO2 during fuel rich conditions and lost only little activity during thermal aging at 750 °C.

  12. Dendrimer Templated Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole Hydrogenation.

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wenyu; Kuhn, John N.; Tsung, Chia-Kuang; Zhang, Yawen; Habas, Susan E.; Yang, Peidong; Somorjai, Gabor A.

    2008-05-09

    Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as {approx}1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H{sub 2} after reduction (76 torr of H{sub 2} mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.

  13. Investigation of Nuclear Phase Transition by Solvababe supersymmetric algebraic model and its application in Ru-Rh and Zn-Cu Isotopes

    CERN Document Server

    Jafarizadeh, M A; Fouladi, N; Ranjbar, Z; Sadighzadeh, A

    2016-01-01

    Solvable supersymmetric algebraic model for descriptions of the spherical to gama unstable shape- phase transition in even and odd mass nuclei is proposed. This model is based on dual algebraic structure and Richardson - Gaudin method, where the duality relations between the unitary and quasispin algebraic structures for the boson and fermion systems are extended to mixed boson- fermion system. The structure of two type of nuclear supersymmetry schemes, based on the U(6/2) and U(6/4) supergroups, is discussed. We investigate the change in level structure induced by the phase transition by doing a quantal analysis. By using the generalized quasispin algebra, it is shown that the nuclear supersymmetry concept can be also used for transitional regions in addition to dynamical symmetry limits. Experimental evidence for the U(5)-O(6) transition in Ru-Rh and Zn- Cu supermultiplets is presented. The low-states energy spectra and B(E2)values for these nuclei have been calculated and compared with the experimental dat...

  14. Electronic and magnetic properties of infinite 1D chains of paddlewheel carboxylates M2(COOR)4 (M = Mo, W, Ru, Rh, Ir, Cu)

    KAUST Repository

    Peskov, Maxim

    2013-03-14

    Dinuclear complexes of transition metals bridged by four carboxylate-groups are examples of stable atomic configurations serving as fundamental building blocks of catalysts and prototypical molecular electronic devices. The electronic structure and magnetic properties of many molecular tetracarboxylate complexes were meticulously studied; however, the properties of the one-dimensional (1D) polymeric chain of associated tetracarboxylates have so far evaded much attention. Using periodic density-functional theory calculations, we analyze the electronic structure of condensed tetracarboxylates Mo(II), W(II), Ru(II), Rh(II), Ir(II), and Cu(II). The relationship between crystal structure of the polymerized tetracarboxylates and the electronic properties of the metal-metal bond in the M24+ core is studied. The electronic effects emanating from the association of dinuclear transition metal tetracarboxylates are important for designing molecular electronic devices. In this study, its influence on both direct and indirect metal-metal interactions, and the electronic structure, in particular transport properties, is discussed. © 2013 American Chemical Society.

  15. Distribution of Precious Metals (Ag, Au, Pd, Pt, and Rh) Between Copper Matte and Iron Silicate Slag

    Science.gov (United States)

    Avarmaa, Katri; Johto, Hannu; Taskinen, Pekka

    2016-02-01

    The distributions of precious metals (Ag, Au, Pd, Pt, and Rh) between copper matte and silica-saturated iron silicate slag were determined at 1523 K to 1623 K (1250 °C to 1350 °C), in controlled CO-CO2-SO2-Ar gas mixtures. The experiments were done in silica crucibles and a fixed partial pressure of sulfur dioxide for matte grades of 55, 65, and 75 wt pct Cu. High-temperature equilibration/quenching/electron probe X-ray microanalysis technique was used to obtain compositions of the equilibrated matte and slag. The technique was applied for the first time to the distributions of precious metals in simulated flash smelting conditions. The resolution of electron probe microanalysis became critical as the detection limits were insufficient to measure reliably the precious metals concentrations (except silver) in the slag. The distribution coefficient of silver, L m/s[Ag] = [wt pctAg in matte]/(wt pctAg in slag), was found to be between 200 and 300, which agrees well with the latest studies in the literature. For other precious metals, the minimum values of distribution coefficients were determined according to the detection limits in the slag. The values obtained were for gold and platinum >250, for palladium >1000, and for rhodium >900. The distribution coefficients of palladium, although locating above distribution coefficient of the detection limit, formed a clear dependency with a good repeatability as a function of the matte grade. It increased along with matte grade and was approximately 1000 at 50 pct Cu and 2000 to 3000 at 70 pct Cu. The precious metals replace metal in the matte structure and they are present as sulfides in the copper matte.

  16. Use of Dendrimers during the Synthesis of Pt-Ru Electrocatalysts for PEM Fuel Cells: Effects on the Physical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    J. C. Calderón

    2011-01-01

    Full Text Available In this work, Pt-Ru catalysts were synthesized by a novel methodology which includes the use as encapsulating molecules of dendrimers of different generation: zero (DN-0, one (DN-1, two (DN-2, and three (DN-3. Synthesized catalysts were heat-treated at 350°C, and the effects of this treatment was established from the physical (X-ray dispersive energy (XDE and X-ray diffraction (XRD and electrochemical characterization (cyclic voltammetry and chronoamperometry. Results showed that the heat-treatment benefits the catalytic properties of synthesized materials in terms of CO and methanol electrochemical oxidation. The curves for CO stripping were more defined for heat-treated catalysts, and methanol oxidation current densities were higher for these materials. These changes are principally explained from the removal of organic residues remaining on the surface of the Pt-Ru nanoparticles after the synthesis procedure. After the activation of the catalysts by heating at 350°C, the real importance of the use of these encapsulating molecules and the effect of the generation of the dendrimer become visible. From these results, it can be concluded that synthesized catalysts are good catalytic anodes for direct methanol fuel cells (DMFCs.

  17. 不饱和有机酸在Pt-Rh合金电极上的吸附动力学%ADSORPTION KINETICS OF SOME UNSATURATED ALIPHATIC ACIDS ON Pt-Rh ALLOY ELECTRODES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    On Pt-Rh alloy electrodes, the effect of some operational parameters on the adsorption process of several unsaturated aliphatic acids was respectively examined by fast cathodically potentiodynamic polarization. As the experimental results shown, the adsorption rates of acrylic acid , crotonic acid, and maleic acid, obey Rogynski-Zilidowicz equation always in the middle coverage .Comparatively, the maximal values are determined on the pure Pt-electrode, and as the electrode binary composition is varied successively from the pure Pt to Rh , the adsorption rates for these acids are generally decreased, even by 20~30 times. Among the three unsaturated aliphatic acids, acrylic acid is most advantageously adsorbed on the electrode surfaces. The adsorption activity order is acrylic acid >crotonic acid>maleic acid.%采用快速动电位扫描方法,系统地研究了吸附时间、溶液浓度、温度、吸附电位等因素对在不同组成的Pt-Rh电极上不饱和有机酸吸附过程的影响. 研究结果表明,在中等表面覆盖率下,所研究的不饱和有机酸在Pt-Rh合金电极上吸附速率都遵循Rogynski-Zilidowicz方程,Pt电极上吸附速率最大,从Pt电极向Rh电极过渡中,吸附速率下降20~30倍. 温度升高吸附速率加快. 丙烯酸在Pt-Rh电极表面的吸附速率比其他不饱和有机酸高,并按丙烯酸>丁烯酸>顺丁烯二酸顺序递减.

  18. Selectivity of Chemisorbed Oxygen in C–H Bond Activation and CO Oxidation and Kinetic Consequences for CH₄–O₂ Catalysis on Pt and Rh Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Ya-Huei; Buda, Corneliu; Neurock, Matthew; Iglesia, Enrique

    2011-10-06

    Rate measurements, density functional theory (DFT) within the framework of transition state theory, and ensemble-averaging methods are used to probe oxygen selectivities, defined as the reaction probability ratios for O* reactions with CO and CH₄, during CH₄–O₂ catalysis on Pt and Rh clusters. CO₂ and H₂O are the predominant products, but small amounts of CO form as chemisorbed oxygen atoms (O*) are depleted from cluster surfaces. Oxygen selectivities, measured using ¹²CO–¹³CH₄–O₂ reactants, increase with O₂/ CO ratio and O* coverage and are much larger than unity at all conditions on Pt clusters. These results suggest that O* reacts much faster with CO than with CH₄, causing any CO that forms and desorbs from metal cluster surfaces to react along the reactor bed with other O* to produce CO₂ at any residence time required for detectable extents of CH₄ conversion. O* selectivities were also calculated by averaging DFTderived activation barriers for CO and CH₄ oxidation reactions over all distinct surface sites on cubo-octahedral Pt clusters (1.8 nm diameter, 201 Pt atoms) at low O* coverages, which are prevalent at low O₂ pressures during catalysis. CO oxidation involves non-activated molecular CO adsorption as the kinetically relevant step on exposed Pt atoms vicinal of chemisorbed O* atoms (on *–O* site pairs). CH₄ oxidation occurs via kinetically relevant C–H bond activation on *–* site pairs involving oxidative insertion of a Pt atom into one of the C–H bonds in CH₄, forming a three-centered HC₃–Pt–H transition state. C–H bond activation barriers reflect the strength of Pt–CH₃ and Pt–H interactions at the transition state, which correlates, in turn, with the Pt coordination and with CH₃ * binding energies. Ensemble-averaged O* selectivities increase linearly with O₂/CO ratios, which define the O* coverages, via a proportionality constant. The proportionality constant is given by the ratio of rate

  19. The influence of methanol on the chemical state of PtRu anodes in a high-temperature direct methanol fuel cell studied in situ by synchrotron-based near-ambient pressure x-ray photoelectron spectroscopy

    Science.gov (United States)

    Saveleva, Viktoriia A.; Daletou, Maria K.; Savinova, Elena R.

    2017-01-01

    Synchrotron radiation-based near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) has recently become a powerful tool for the investigation of interfacial phenomena in electrochemical power sources such as batteries and fuel cells. Here we present an in situ NAP-XPS study of the anode of a high-temperature direct methanol fuel cell with a phosphoric acid-doped hydrocarbon membrane, which reveals an enhanced flooding of the Pt3Ru anode with phosphoric acid in the presence of methanol. An analysis of the electrode surface composition depending on the cell voltage and on the presence of methanol reveals the strong influence of the latter on the extent of Pt oxidation and on the transformation of Ru into Ru (IV) hydroxide.

  20. DFT study of the formate formation on Ni(111) surface doped by transition metals [Ni(111)-M; M=Cu, Pd, Pt, Rh

    Science.gov (United States)

    Nugraha; Saputro, A. G.; Agusta, M. K.; Rusydi, F.; Maezono, R.; Dipojono, H. K.

    2016-08-01

    We report on a theoretical study of the formation of formate (HCOO) from the reaction of CO2 gas and a pre- adsorbed H atom (CO2 (g) + *H → *HCOO) on Ni(111) surface doped by transition-metals [Ni(111)-M; M= Cu, Pd, Pt, Rh] by means of density functional theory (DFT) calculations. This *HCOO formation reaction is one of the most important rate- limiting steps in the methanol synthesis process. We find that the presence of transition metal doping on the first-layer of Ni(111) surface could reduce the activation barrier of this reaction [up to ~38.4%, compared to clean Ni(111) surface].

  1. Distribution of platinum group elements (Pt, Pd, Rh) in environmental and clinical matrices: Composition, analytical techniques and scientific outlook: Status report.

    Science.gov (United States)

    Hees, T; Wenclawiak, B; Lustig, S; Schramel, P; Schwarzer, M; Schuster, M; Verstraete, D; Dams, R; Helmers, E

    1998-01-01

    Trace concentrations of the platinum group elements (PGE; here: Pt, Pd and Rh) play an important role in environmental analysis and assessment. Their importance is based on 1. their increasing use as active compartments in automobile exhaust catalysts, 2. their use as cancer anti-tumor agents in medicine. Due to their allergenic and cytotoxic potential, it is necessary to improve selectivity and sensitivity during analytical investigation of matrices like soil, grass, urine or blood. This paper summarizes the present knowledge of PGE in the fields of analytical chemistry, automobile emission rates, bioavailability, toxicology and medicine.

  2. Steam reforming of methane over Pt/Rh based wire mesh catalyst in single channel reformer for small scale syngas production

    DEFF Research Database (Denmark)

    Sigurdsson, Haftor Örn; Kær, Søren Knudsen

    2012-01-01

    of a catalytic parallel plate type heat exchanger (CPHE) reformer stack, where coated Pt/Rh based wire mesh is used as a catalyst. Heat is supplied to the endothermic reaction with infrared electric heaters. All the experiments were performed under atmospheric pressure and at stable operating conditions....... The following parameters are considered in the experiment: catalyst temperature, gas hourly space velocity (GHSV) and steam to carbon ratio (S/C). The catalyst was tested at temperatures between 600 and 900°C, S/C ratios between 2 and 5 and GHSV between 319 and 2201 1/h. The experimental results are used...

  3. Experimental investigation of air relative humidity (RH) cycling tests on MEA/cell aging in PEMFC. Pt. II. Study of low RH cycling test with air RH at 62%/0%

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B.T.; Chatillon, Y.; Bonnet, C.; Lapicque, F. [Laboratoire Reactions et Genie des Procedes, CNRS-Nancy University, Nancy (France); Leclerc, S. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, CNRS-Nancy University, Vandoeuvre-les-Nancy (France); Hinaje, M.; Rael, S. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, Nancy University, Vandoeuvre-les-Nancy (France)

    2012-06-15

    The effect of low relative humidity (RH) cycling (RH{sub C} 62%/0%) on the degradation mechanisms of a single proton exchange membrane fuel cell (5 x 5 cm{sup 2}) was investigated and compared to a cell operated at constant humidification (RH{sub C} = 62%). The overall cell performance loss was near 33 {mu}V h{sup -1}, which is greater than the voltage decay under constant RH condition near 3 {mu}V h{sup -1}. The electroactive surface was reduced but to an acceptable level. Impedance spectroscopy revealed that the ohmic and charge transfer resistances were reduced by the likely improved hydration of the ionomeric layer at the catalyst due to hydrogen crossover. This was so important that H{sub 2} starvation was finally responsible for the collapse of the cell after 650 h. Transmission electron microscopy showed occurrence of various phenomena, e.g., bubbles and pinholes formation in the membrane due to local overheat from hydrogen combustion at the cathode, and thickness reduction of catalytic layers. The water up take obtained by {sup 1}H NMR within the membrane electrode assembly (MEA) after low RH cycling reduced by 24% compared to a fresh MEA. Observations are also compared to those obtained at high RH cycling (RH{sub C} 62%/100%) presented in Part I of this study [1]. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Experimental investigation of air relative humidity (RH) cycling tests on MEA/cell aging in PEMFC. Pt. I. Study of high RH cycling test with air RH at 62%/100%

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B.T.; Chatillon, Y.; Bonnet, C.; Lapicque, F. [Laboratoire Reactions et Genie des Procedes, CNRS-Nancy University, Nancy (France); Leclerc, S. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, CNRS-Nancy University, Vandoeuvre-les-Nancy (France); Hinaje, M.; Rael, S. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, CNRS-Nancy University, Vandoeuvre-les-Nancy (France)

    2012-06-15

    The effect of high air relative humidity (RH) cycling (RH{sub C} 62%/100%) on the degradation mechanisms of a single (5 x 5 cm{sup 2}) proton exchange membrane fuel cells was investigated. The cell performance was compared to a cell operated at constant humidification (RH{sub C} = 62%). Runs were conducted over approximately 1,500 h at 0.3 A cm{sup -2}. The overall loss in cell performance for the high RH cycling test was 12 {mu}V h{sup -1} whereas it was at 3 {mu}V h{sup -1} under constant humidification. Impedance spectroscopy reveals that the ohmic and charge transfer resistances were little modified in both runs. H{sub 2} crossover measurement indicated that both high RH cycling and constant RH test did not promote serious effect on gas permeability. The electroactive surface loss for anode and cathode during high air RH cycling was more significant than at constant RH operation. The water uptake determined by {sup 1}H nuclear magnetic resonance within the membrane electrode assembly (MEA) after high RH cycling was reduced by 12% in comparison with a fresh MEA. Transmission electron microscopy showed bubbles and pinholes formation in the membrane, catalyst particles agglomeration (also observed by X-ray diffraction), catalyst particles migration in the membrane and thickness reduction of the catalytic layers. Scanning electron microscopy was conducted to observe the changes in morphology of gas diffusion layers after the runs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Determination of traces of Pt and Rh in soil and quartz samples contaminated by automobile exhaust after an ion-exchange matrix separation.

    Science.gov (United States)

    Kowalska, Joanna; Kińska, Katarzyna; Pałdyna, Joanna; Czyżewska, Monika; Boder, Kamila; Krasnodębska-Ostręga, Beata

    2014-09-01

    Monitoring of PGEs content in the natural samples is a crucial point in the environment science since catalytic car converters have been introduced. In the presented paper application of a very sensitive voltammetric method for determination of traces of Pt and Rh in the environmental samples contaminated by automobile exhausts is discussed. Voltammetric measurements were carried out in the supporting electrolyte containing formaldehyde and semicarbazide. PGEs were separated from the digested solutions of soils or quartz samples, collected from monitoring plots-by applying an ion-exchange resin Cellex-T. Pt was very effectively separated from the matrix approaching nearly 100% recovery after its elution by hydrochloric acid. Moreover the conditions of soil and quartz samples digestion were discussed. To validate the obtained result an independent analytical method-ICP MS was applied and analysis of certified reference material road dust 723-was completed.

  6. Pt{sub X}Ru{sub Y}Ir{sub Z} as a bifunctional electrocatalyst for oxygen reduction reaction in a PEM fuel cell; Pt{sub X}Ru{sub Y}Ir{sub Z} como electrocatalizador bifuncional para la reaccion redox del oxigeno en una celda tipo PEM

    Energy Technology Data Exchange (ETDEWEB)

    Morales, L.; Fernandez, A.M. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico)]. E-mail: limos@cie.unam.mx; Cano, U. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2009-09-15

    This work presents the synthesis and characterization of the ternary material Pt{sub X}Ru{sub Y}Ir{sub Z}, obtained by chemical reduction with NaBH{sub 4}. Two different atomic compositions were developed (sample A and B) in order to observe the kinetic effect, as suggested by the combinatorial libraries. The main objective of this synthesis is to study the oxygen reduction reaction (ORR and OER) and its potential use in the construction of a bifunctional catalyst. In addition, each of the metals are synthesized separately using the same technique in order to make the corresponding comparison. The compounds obtained were characterized by sweep electron microscopy, x-ray diffraction and composition using fluorescence and energy-dispersive x-ray spectroscopy. The results showed a displacement of the x-ray diffraction peaks for Ir and Pt in sample A, and displacement in sample B for Ru and Ir peaks. These changes suggest the possible formation of a solid solution substitution. Separate cyclic and linear voltamperometry studies were performed for the oxygen reduction and release reactions. The electrochemical analysis showed improved kinetic behavior when combining the three metals according to the composition of sample B. [Spanish] En este trabajo se presenta la sintesis y caracterizacion del material ternario Pt{sub X}Ru{sub Y}Ir{sub Z}, elaborado por la tecnica de Reduccion Quimica utilizando al NaBH{sub 4}. Se elaboraron dos composiciones atomicas diferentes (Muestra A y B) con el fin de observar el efecto cinetico, como lo sugieren las librerias combinatorias. El objetivo principal de esta sintesis es para el estudio de la Reaccion Redox del Oxigeno (RRO y REO) y su potencial uso para la construccion de un catalizador bifuncional. Asi mismo, se realiza la sintesis de cada uno de los metales por separado empleando la misma tecnica, con el proposito de realizar la comparacion correspondiente. Los compuestos obtenidos se caracterizaron por Microscopia Electronica de

  7. Estudo do efeito de tratamentos térmicos em catalisadores de PtRu/C frente à reação de oxidação de hidrogênio na presença de CO Study of the effect of thermal treatments of PtRu/C catalysts on the hydrogen oxidation reaction in the presence of CO

    Directory of Open Access Journals (Sweden)

    Pietro Papa Lopes

    2007-10-01

    Full Text Available In this work the effects of time and temperature of thermal treatments under reducing atmosphere (H2 on PtRu/C catalysts for the hydrogen oxidation reaction (HOR in the presence of CO on a proton exchange membrane fuel cell (PEMFC single cells have been studied. It can be seen that the increase of the treatment temperature leads to an increasing sintering of the catalyst particles with reduction of the active area, although the catalyst treated at 550 ºC presents more CO tolerance for the HOR.

  8. Synthesis, characterization of α-amino acid Schiff base derived Ru/Pt complexes: Induces cytotoxicity in HepG2 cell via protein binding and ROS generation

    Science.gov (United States)

    Alsalme, Ali; Laeeq, Sameen; Dwivedi, Sourabh; Khan, Mohd. Shahnawaz; Al Farhan, Khalid; Musarrat, Javed; Khan, Rais Ahmad

    2016-06-01

    We have synthesized two new complexes of platinum (1) and ruthenium (2) with α-amino acid, L-alanine, and 2,3-dihydroxybenzaldehyde derived Schiff base (L). The ligand and both complexes were characterized by using elemental analysis and several other spectroscopic techniques viz; IR, 1H, 13C NMR, EPR, and ESI-MS. Furthermore, the protein-binding ability of synthesized complexes was monitored by UV-visible, fluorescence and circular dichroism techniques with a model protein, human serum albumin (HSA). Both the PtL2 and RuL2 complexes displayed significant binding towards HSA. Also, in vitro cytotoxicity assay for both complexes was carried out on human hepatocellular carcinoma cancer (HepG2) cell line. The results showed concentration-dependent inhibition of cell viability. Moreover, the generation of reactive oxygen species was also evaluated, and results exhibited substantial role in cytotoxicity.

  9. Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) with Th{sub 7}Fe{sub 3}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Misse, Patrick R.N.; Mbarki, Mohammed [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany); Fokwa, Boniface P.T., E-mail: boniface.fokwa@ac.rwth-aachen.de [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany)

    2012-08-15

    Powder samples and single crystals of the new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. - Graphical abstract: The new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) has been synthesized by arc melting the elements under purified argon atmosphere. Beside the 3d/4d site preference within the whole solid solution, an unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. Highlights: Black-Right-Pointing-Pointer Synthesis of a new boride series fulfilling Vegard Acute-Accent s rule. Black-Right-Pointing-Pointer 3d/4d site preference. Black-Right-Pointing-Pointer Unexpected Ru/Rh site preference. Black-Right-Pointing-Pointer Rh-rich region is Pauli paramagnetic. Black-Right-Pointing-Pointer Ru-rich region is Pauli and temperature-dependent paramagnetic.

  10. Reactivity of [M2 (μ-Cl)2 (cod)2 ] (M=Ir, Rh) and [Ru(Cl)2 (cod)(CH3 CN)2 ] with Na[H2 B(bt)2 ]: Formation of Agostic versus Borate Complexes.

    Science.gov (United States)

    Bakthavachalam, K; Yuvaraj, K; Zafar, Mohammad; Ghosh, Sundargopal

    2016-11-21

    Treatment of [M2 (μ-Cl)2 (cod)2 ] (M=Ir and Rh) with Na[H2 B(bt)2 ] (cod=1,5-cyclooctadiene and bt=2-mercaptobenzothiazolyl) at low temperature led to the formation of dimetallaheterocycles [(Mcod)2 (bt)2 ], 1 and 2 (1: M=Ir and 2: M=Rh) and a borate complex [Rh(cod){κ(2) -S,S'-H2 B(bt)2 }], 3. Compounds 1 and 2 are structurally characterized metal analogues of 1,5-cyclooctadiene. Metal-metal bond distances of 3.6195(9) Å in 1 and 3.6749(9) Å in 2 are too long to consider as bonding. In an attempt to generate the Ru analogue of 1 and 2, that is [(Rucod)2 (bt)2 ], we have carried out the reaction of [Ru(Cl)2 (cod)(CH3 CN)2 ] with Na[H2 B(bt)2 ]. Interestingly, the reaction yielded agostic complexes [Ru(cod)L{κ(3) -H,S,S'-H2 B(bt)2 }], 4 and 5 (4: L=Cl; 5: L=C7 H4 NS2 ). One of the key differences between 4 and 5 is the presence of different ancillary ligands at the metal center. The natural bond orbital (NBO) analysis of 1 and 2 shows that there is four lone pairs of electrons on each metal center with a significant amount of d character. Furthermore, the electronic structures and the bonding of these complexes have been established on the ground of quantum-chemical calculations. All of the new compounds were characterized by IR, (1) H, (11) B, (13) C NMR spectroscopy, and X-ray crystallographic analysis.

  11. Atomic site preferences and its effect on magnetic structure in the intermetallic borides M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir)

    Energy Technology Data Exchange (ETDEWEB)

    Brgoch, Jakoah, E-mail: jrbrgoc@gmail.com [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Mahmoud, Yassir A. [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Miller, Gordon J., E-mail: gmiller@iastate.edu [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States)

    2012-12-15

    The site preference for a class of intermetallic borides following the general formula M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir), has been explored using ab initio and semi-empirical electronic structure calculations. This intermetallic boride series contains two potential sites, the Wyckoff 2c and 8j sites, for Rh or Ir to replace Ru atoms. Since the 8j site is a nearest neighbor to the magnetically active Fe atom, whereas the 2c site is a next nearest neighbor, the substitution pattern should play an important role in the magnetic structure of these compounds. The substitution preference is analyzed based on the site energy and bond energy terms, both of which arise from a tight-binding evaluation of the electronic band energy, and are known to influence the locations of atoms in extended solids. According to these calculations, the valence electron-rich Rh and Ir atoms prefer to occupy the 8j site, a result also corroborated by experimental evidence. Additionally, substitution of Rh or Ir at the 8j site results in a modification of the magnetic structure that ultimately results in larger local magnetic moment on the Fe atoms. - Graphical abstract: The site preference for electron rich atoms to occupy the 8j (gray) site is identified in these intermetallic borides, while the magnetic structure is modified as a function of the substituted atoms band center. Highlights: Black-Right-Pointing-Pointer We identify the energetics dictating the site preference in a series of intermetallic borides. Black-Right-Pointing-Pointer Establish substitution rules for use in future directed synthetic preparations. Black-Right-Pointing-Pointer Identified changes in magnetic structure that accompany the site preference.

  12. Synthesis, crystal structure and physical properties of EuTGe{sub 3} (T = Co, Ni, Rh, Pd, Ir, Pt) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bednarchuk, Oleksandr; Gągor, Anna; Kaczorowski, Dariusz, E-mail: D.Kaczorowski@int.pan.wroc.pl

    2015-02-15

    Highlights: • Single crystals of EuTGe{sub 3} (T = Co, Ni, Rh, Pd, Ir, Pt) compounds were prepared. • The crystal structures were refined from single-crystal X-ray diffraction data. • The physical properties of oriented single crystals were determined. • For each compound, an antiferromagnetic ordering was found at low temperatures. - Abstract: Single crystals of six EuTGe{sub 3} compounds with T = Co, Ni, Rh, Pd, Ir and Pt were prepared by high-temperature solution growth method. Their crystal structures of the BaNiSn{sub 3}-type were refined from single-crystal X-ray diffraction data. The physical properties of oriented single-crystalline specimens were studied by means of magnetic susceptibility, heat capacity and electrical resistivity measurements. For each compound, an antiferromagnetic ordering was found to set in at low temperatures due to localized magnetic moments carried on divalent Eu ions. Despite the same crystal structure, the EuTGe{sub 3} compounds exhibit diverse magnetic structures with different directions of the ordered magnetic moments and a variety of dissimilar mutual arrangements of adjacent spins.

  13. Exposure of Pt(5 5 3) and Rh(1 1 1) to atomic and molecular oxygen: do defects enhance subsurface oxygen formation?

    Science.gov (United States)

    Farber, Rachael G; Turano, Marie E; Oskorep, Eleanor C N; Wands, Noelle T; Juurlink, Ludo B F; Killelea, Daniel R

    2017-04-26

    Subsurface oxygen is known to form in transition metals, and is thought to be an important aspect of their ability to catalyze chemical reactions. The formation of subsurface oxygen is not, however, equivalent across all catalytically relevant metals. As a result, it is difficult to predict the stability and ease of the formation of subsurface oxygen in metals, as well as how the absorbed oxygen affects the chemical and physical properties of the metal. In comparing how a stepped platinum surface, Pt(5 5 3), responds to exposure to gas-phase oxygen atoms under ultra-high vacuum conditions to planar Rh(1 1 1), we are able to determine what role, if any, steps have on the capacity of a metal for subsurface oxygen formation. Despite the presence of regular defects, we found that only surface-bound oxygen formed on Pt(5 5 3). Alternatively, on the Rh(1 1 1) surface, oxygen readily absorbed into the selvedge of the metal. These results suggest that defects alone are insufficient for the formation of subsurface oxygen, and the ability of the metal to absorb oxygen is the primary factor in the formation and stabilization of subsurface oxygen.

  14. Distinguishing between chemical and physical promotion mechanisms by CeO{sub 2} in Pt, Rh three-way automotive catalysts under practical industrial conditions

    Energy Technology Data Exchange (ETDEWEB)

    Robota, H.J.; Nunan, J.G. [Allied-Signal Research and Technology, Des Plains, IL (United States)

    1993-12-31

    Under practical industrial conditions, aged, rather than fresh, catalyst performances is required to meet various regulatory emissions levels. While CeO{sub 2} is recognized as critical in allowing practically aged Pt, Rh catalysts to meet these performance targets, debate continues concerning the physicochemical mechanisms responsible for the performance enhancement. Suppressed precious metal sintering and stabilization of support {gamma}-Al{sub 2}O{sub 3} against surface area loss and structural phase changes are the principle physical mechanisms suggested. Chemical promotion by CeO2 has been attributed to oxygen storage, enhanced water gas shift activity, and enhanced CO oxidation activity through a precious metal-CeO2 coupling mechanisms. The authors have attempted to distinguish the relative contributions of these physical and chemical mechanisms to the performance of practical Pt, Rh catalysts. Two catalysts were aged in tandem using standard dynamometer methods. One was a fully formulated reference catalyst and the other was a CeO{sub 2}-free catalyst. Several potential chemical promotional mechanisms of CO oxidation via a more facile reaction pathway involving coupling between the precious metals and CeO{sub 2}.

  15. Exposure of Pt(5 5 3) and Rh(1 1 1) to atomic and molecular oxygen: do defects enhance subsurface oxygen formation?

    Science.gov (United States)

    Farber, Rachael G.; Turano, Marie E.; Oskorep, Eleanor C. N.; Wands, Noelle T.; Juurlink, Ludo B. F.; Killelea, Daniel R.

    2017-04-01

    Subsurface oxygen is known to form in transition metals, and is thought to be an important aspect of their ability to catalyze chemical reactions. The formation of subsurface oxygen is not, however, equivalent across all catalytically relevant metals. As a result, it is difficult to predict the stability and ease of the formation of subsurface oxygen in metals, as well as how the absorbed oxygen affects the chemical and physical properties of the metal. In comparing how a stepped platinum surface, Pt(5 5 3), responds to exposure to gas-phase oxygen atoms under ultra-high vacuum conditions to planar Rh(1 1 1), we are able to determine what role, if any, steps have on the capacity of a metal for subsurface oxygen formation. Despite the presence of regular defects, we found that only surface-bound oxygen formed on Pt(5 5 3). Alternatively, on the Rh(1 1 1) surface, oxygen readily absorbed into the selvedge of the metal. These results suggest that defects alone are insufficient for the formation of subsurface oxygen, and the ability of the metal to absorb oxygen is the primary factor in the formation and stabilization of subsurface oxygen.

  16. First principles study on the interfacial properties of NM/graphdiyne (NM = Pd, Pt, Rh and Ir): The implications for NM growing

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Zhansheng; Li, Shuo; Lv, Peng [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007 (China); He, Chaozheng, E-mail: hecz2013@nynu.edu.cn [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Ma, Dongwei [School of Physics, Anyang Normal University, Anyang 455000 (China); Yang, Zongxian, E-mail: yzx@henannu.edu.cn [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007 (China); Collaborative Innovation Center of Nano Functional Materials and Applications, Kaifeng (China)

    2016-01-01

    Graphical abstract: - Highlights: • The NM adatoms belong to embedded adsorption in 18C-hexagon of GDY. • The Rh and Ir/GDY can be applied to single metal catalysts or sensors. • A simple linear relationship between E{sub e-ads} and E{sub b} is presented. • The linear relationship can be used in the noble metal modified GDY. - Abstract: Based on the dispersion-corrected density functional calculations (DFT-D), we systematically studied the adsorption of noble metals (NM), Pd, Pt, Rh and Ir, on graphdiyne (GDY). We present a systematic study on the geometry, embedded adsorption energy and electronic structure of four different adatoms adsorbed on the GDY. The strong interaction between the NM adatoms and the GDY substrate is found with the NM embedded in the 18C-hexagon of the GDY. We investigated the mobility of the NM adatoms on the GDY, and found that the mobility barrier energy increases along with the increasing of the embedded adsorption energy. We present the NM adatoms growth of high concentrations on the GDY. Upon the analysis of the electronic structure and the frontier molecular orbitals, Rh and Ir adatoms of low concentrations (about 1.37 at%) on the GDY have the potential to be applied as single metal catalysts or gas molecule sensors.

  17. Determination of absorbed dose distribution in water for COC ophthalmic applicator of {sup 106}Ru/{sup 106}Rh using Monte Carlo code-MCNPX; Determinacao da distribuicao de dose absorvida na agua para o aplicador oftalmico COC de {sup 106}Ru/{sup 106}Rh utilizando o codigo de Monte Carlo - MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Nilseia A.; Rosa, Luiz A. Ribeiro da, E-mail: nilseia@ird.gov.br, E-mail: lrosa@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ),Rio de Janeiro, RJ (Brazil); Braz, Delson, E-mail: delson@nuclear.ufrj.br [Coordenacao dos programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2014-07-01

    The COC ophthalmic applicators using beta radiation source of {sup 106}Ru/{sup 106}Rh are used in the treatment of intraocular tumors near the optic nerve. In this type of treatment is very important to know the dose distribution in order to provide the best possible delivery of prescribed dose to the tumor, preserves the optic nerve region extremely critical, that if damaged, can compromise the patient's visual acuity, and cause brain sequelae. These dose distributions are complex and doctors, who will have the responsibility on the therapy, only have the source calibration certificate provided by the manufacturer Eckert and Ziegler BEBIG GmbH. These certificates provide 10 absorbed dose values at water depth along the central axis applicator with the uncertainties of the order of 20% isodose and in a plane located 1 mm from the applicator surface. Thus, it is important to know with more detail and precision the dose distributions in water generated by such applicators. To this end, the Monte Carlo simulation was used using MCNPX code. Initially, was validated the simulation by comparing the obtained results to the central axis of the applicator with those provided by the certificate. The different percentages were lower than 5%, validating the used method. Lateral dose profile was calculated for 6 different depths in intervals of 1 mm and the dose rates in mGy.min{sup -1} for the same depths.

  18. Fermi-liquid behavior of binary intermetallic compounds Y3 M (M  =  Co, Ni, Rh, Pd, Ir, Pt)

    Science.gov (United States)

    Strychalska-Nowak, Judyta; Wiendlocha, Bartłomiej; Hołowacz, Katarzyna; Reczek, Paula; Podgórski, Mateusz; Winiarski, Michał J.; Klimczuk, Tomasz

    2017-06-01

    A series of polycrystalline samples of Y3 M (M  =  Co, Ni, Rh, Pd, Ir, Pt), intermetallic binary compounds were synthesized by the arc-melting method. Powder x-ray diffraction (pXRD) confirmed the orthorhombic cementite-type crystal structure and allowed for the estimation of the lattice parameters. Physical properties were investigated by means of electrical resistivity and heat capacity measurements between 1.9 K and 300 K. All tested compounds show metallic-like behaviour with RRR values ranging from 1.3 to 8.3, and power-law ρ \\propto {{T}n} temperature dependence of resistivity was observed, with 1.6≤slant n≤slant 2.2 . No superconductivity was detected above 1.9 K. The Debye temperature, estimated from the low temperature heat capacity fit, ranged from 180 K (Y3Pt) to 222 K (Y3Co). The highest value of the Sommerfeld coefficient γ was found for Y3Pd (19.5 mJ mol-1 K-2). The pXRD pattern of Y3Rh indicated the presence of Y5Rh2, a previously unreported Pd5B2-type phase, whose unit cell parameters were refined using the LeBail method. Density functional theory calculations were performed and theoretical results revealed strong enhancement of the measured electronic specific heat, which was 30%-100% larger than computed. Quadratic temperature dependence of resistivity and enhanced electronic specific heat indicated a Fermi-liquid behavior of electrons in these materials.

  19. Anomalous metamagnetic-like transition in a FeRh/Fe3Pt interface occurring at T ≈ 120 K in the field-cooled-cooling curves for low magnetic fields

    Directory of Open Access Journals (Sweden)

    S. Salem-Sugui Jr.

    2012-09-01

    Full Text Available We report on the magnetic properties of a special configuration of a FeRh thin film. An anomalous behavior on the magnetisation vs. temperature was observed when low magnetic fields are applied in the plane of a thin layer of FeRh deposited on ordered Fe3Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetisation curve at temperatures near 120 K in samples without any heat treatment.

  20. Synthesis, characterization, and electronic structures of a series of two-dimensional trimetallic cluster complexes, Ru3(CO)9(mu-SnPh2)3[Pt(PBu(t)3)]x, x = 0-3.

    Science.gov (United States)

    Adams, Richard D; Captain, Burjor; Hall, Michael B; Trufan, Eszter; Yang, Xinzheng

    2007-10-10

    The triruthenium-tritin cluster complex, Ru3(CO)9(mu-SnPh2)3, 13 was obtained from the reaction of Ru3(CO)12 with Ph3SnH. Compound 13 reacts with Pt(PBut3)2 to yield three new Pt(PBut3) adducts of 13 Ru3(CO)9(mu-SnPh2)3[Pt(PBut3)]x, 14-16 x = 1 - 3 formed by the addition of Pt(PBut3) groups to the Ru-Sn bonds. The new complexes form a novel series of trimetallic complexes having planar arrangements of the metal atoms. The UV-vis absorptions of the four complexes shift progressively to longer wavelengths as the number of platinum atoms is added to the cluster. The electronic structures of these complexes have been investigated in the ground and excited states by density functional theory and time-dependent density functional theory, and this has provided a detailed understanding of the metal-metal bonding and electronic transitions that are responsible for their UV-vis absorption properties. The predicted absorption maximum for the model structures for 13, 14, 15, and 16 at 465, 508, 556, and 585 nm differ only 4-18 nm from the experimental values of 474, 490, 552, and 576 nm. The shift of principal UV-vis absorption can be explained by a lowering of the HOMO-LUMO energy gap due to interactions of the platinum atoms with the HOMO and LUMO of the Ru3Sn3 core.

  1. Study on the Leaching of Pt, Pd and Rh from Spent Auto-catalysts in Various Acidities

    Institute of Scientific and Technical Information of China (English)

    WAN Jing; YU Jianmin; QIAN Lin; WAN Huoyin; ZHAO Yunkun

    2012-01-01

    Auto-catalysts were the largest consumers of platinum group metals and the most important secondary resources,recovery of PGMs from spent auto-catalysts by leaching with various acidities were investigated.The leaching thermodynamics of PGMs at 363 K was first discussed.At 363 K the higher the acidities of HC1,the higher the leaching recoveries of PGMs,and the sequence of leaching recovery was Pd>Pt>Rh.When H2SO4 used alone,the leaching recoveries of PGMs was low,when the acidity of H2SO4 increasing,the leaching recovery of Rh kept stable.

  2. Microwave irradiation for the facile synthesis of transition-metal nanoparticles (NPs) in ionic liquids (ILs) from metal-carbonyl precursors and Ru-, Rh-, and Ir-NP/IL dispersions as biphasic liquid-liquid hydrogenation nanocatalysts for cyclohexene.

    Science.gov (United States)

    Vollmer, Christian; Redel, Engelbert; Abu-Shandi, Khalid; Thomann, Ralf; Manyar, Haresh; Hardacre, Christopher; Janiak, Christoph

    2010-03-22

    Stable chromium, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium, cobalt, rhodium, and iridium metal nanoparticles (M-NPs) have been reproducibly obtained by facile, rapid (3 min), and energy-saving 10 W microwave irradiation (MWI) under an argon atmosphere from their metal-carbonyl precursors [M(x)(CO)(y)] in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF(4)]). This MWI synthesis is compared to UV-photolytic (1000 W, 15 min) or conventional thermal decomposition (180-250 degrees C, 6-12 h) of [M(x)(CO)(y)] in ILs. The MWI-obtained nanoparticles have a very small (IL dispersions (characterization by transmission electron microscopy (TEM), transmission electron diffraction (TED), and dynamic light scattering (DLS)). The ruthenium, rhodium, or iridium nanoparticle/IL dispersions are highly active and easily recyclable catalysts for the biphasic liquid-liquid hydrogenation of cyclohexene to cyclohexane with activities of up to 522 (mol product) (mol Ru)(-1) h(-1) and 884 (mol product) (mol Rh)(-1) h(-1) and give almost quantitative conversion within 2 h at 10 bar H(2) and 90 degrees C. Catalyst poisoning experiments with CS(2) (0.05 equiv per Ru) suggest a heterogeneous surface catalysis of Ru-NPs.

  3. Performance PtSnRh electrocatalysts supported on carbon-Sb{sub 2}O{sub 5}.SbO{sub 2} for the electro-oxidation of ethanol, prepared by an alcohol-reduction process; Desempenho de eletrocatalisadores PtSnRh suportados em carbono-Sb{sub 2}O{sub 5}.SnO{sub 2} para a oxidacao eletroquimica do etanol, preparados pelo metodo de reducao por alcool

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Jose Carlos

    2013-07-01

    PtSnRh electrocatalysts supported on carbon-Sb{sub 2}O{sub 5}.SnO{sub 2}, with metal loading of 20 wt%, were prepared by an alcohol-reduction process, using H{sub 2}PtCl{sub 6}.6H{sub 2}O (Aldrich), RhCl{sub 3}.xH{sub 2}O (Aldrich) and SnCl{sub 2}.2H{sub 2}O (Aldrich), as source of metals; Sb{sub 2}O{sub 5}.SnO{sub 2} (ATO) and carbon Vulcan XC72, as support; and ethylene glycol as reducing agent. The electrocatalysts obtained were characterized physically by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The diffractograms showed which PtSnRh/C-ATO electrocatalysts had FCC structure of Pt and Pt alloys, besides several peaks associated with SnO{sub 2} and ATO. The average sizes of crystallites were between 2 and 4 nm. TEM micrographs showed a good distribution of the nanoparticles on the support. The average sizes of particles were between 2 and 3 nm, with good agreement for the average size of the crystallites. The performances of the electrocatalysts were analyzed by electrochemical techniques and in real conditions of operation using single direct ethanol fuel cell. In the chronoamperometry at 50 deg C, the electrocatalysts with carbon (85 wt%) and ATO (15 wt%) support, showed the best activity, and the atomic proportions which achieved the best results were PtSnRh(70:25:05) e (90:05:05). PtSnRh(70:25:05)/85C+15ATO electrocatalysts showed the best performance in a direct ethanol fuel cell. (author)

  4. Ferroelastic strain control of multiple nonvolatile resistance tuning in SrRuO3/PMN-PT(111) multiferroic heterostructures

    Science.gov (United States)

    Zheng, Ming; Ni, Hao; Qi, Yaping; Huang, Weiyi; Zeng, Jiali; Gao, Ju

    2017-05-01

    The electric-field-tunable resistance switching in elastically coupled SrRuO3 thin films grown on (111)-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 ferroelectric-crystal substrates has been investigated. During the ferroelectric poling process, the resistance evolution tracks the electric-field-induced in-plane strain of the film efficiently, revealing strain but not the electrostatic charge-mediated coupling mechanism. Using 109° and 71° ferroelastic domain switching of the substrate, multiple reversible and nonvolatile resistance states can be achieved at room temperature, which is closely related to the relative proportion of in-plane polarization vectors and induced distinct in-plane strain states after domain switching. Our findings provide an approach to elucidate electrically driven domain switching dynamics and design energy efficient, high-density spintronic memory devices.

  5. EVALUACIÓN DE CELDAS DE COMBUSTIBLE DE ELECTROLITO POLIMÉRICO CON ÁNODOS Pt-M (M= Sn, Ru e Ir PARA LA OXIDACIÓN DE H2 Y CO

    Directory of Open Access Journals (Sweden)

    BIBIAN HOYOS

    2008-01-01

    Full Text Available Se evaluó el desempeño de celdas de combustible de electrolito polimérico alimentadas con hidrógeno, CO y una mezcla H2-(2%CO, utilizando oxígeno en el cátodo. Para la oxidación de los combustibles, se probaron seis catalizadores: Pt, Pt85Ru15, Pt50Ru50, Pt90Ir10, Pt50Ir50 y Pt90Sn10. Como catalizador en el cátodo se usó platino puro. Todos los catalizadores fueron soportados en carbón Vulcan XC-72R ®. La composición de los catalizadores preparados fue verificada en un Microscopio Electrónico de Barrido (SEM y las pruebas de desempeño de las celdas construidas se realizaron mediante curvas corriente-potencial. Los resultados muestran que la técnica depreparación de los electrodos produce mezclas catalíticas con composiciones muy cercanas a las nominales. Las mezclas catalíticas Pt-Ir son las que presentan el desempeño más bajo para las condiciones evaluadas en este trabajo. La mezcla Pt90Sn10 presentó un desempeño similar al del platino a bajas corrientes cuando la celda de combustible fue alimentada con hidrógeno puro y superó el desempeño de los demás catalizadores cuando la celda se alimentó con H2/(2%CO. El electrodo Pt90Sn10 pierde actividad catalítica cuando se emplea CO puro.

  6. Effects of Ru Seed Layer on Structural Properties of CoCrPt-SiO2 Perpendicular Media%Ru籽晶层对CoCrPt-SiO2垂直记录层形貌及结构的影响

    Institute of Scientific and Technical Information of China (English)

    张俊敏; 王传军; 沈月; 谭志龙; 毕珺; 闻明; 周悓田

    2015-01-01

    CoCrPt-SiO2 perpendicular recording films were prepared by the magnetron sputtering with a series of Ru films as the seed layer. The microstructure of Ru seed layers and their effects on the grain size, roughness and surface morphology of CoCrPt-SiO2 granular films were also investigated. It was found that the microstructure of seed layer obviously affected the structure and grain isolation of recording layers. The grain size and roughness of CoCrPt-SiO2 recording layer increased with the increase of the thickness of Ru seed layer. The thin and rough Ru seed layer could be used for the high-density magnetic recording media, but the Ru seed layer with a proper thickness of 70 nm facilitated a perfect isolation, and consequently excellent magnetic properties could be acquired for the final products.%采用磁控溅射方法,制备了惣不同厚度Ru薄膜为籽晶层的CoCrPt-SiO2垂直磁记录薄膜。利用原子力显微镜(AFM)、透射电镜(TEM)分析 Ru 薄膜的结构和形貌,并悁究了其结构对CoCrPt-SiO2薄膜表面形貌、粗糙度及结构的愝响。结果表明,CoCrPt-SiO2记录层的晶粒尺寸和粗糙度均随着 Ru 籽晶层厚度的增加而增加,薄而粗糙的籽晶层适合于高密度磁记录介质。对于CoCrPt-SiO2记录层晶粒的优化,厚度为70 nm的Ru籽晶层有利于记录层薄膜晶粒的完全隔离,从而提高了磁记录性能。

  7. The silicides YT{sub 2}Si{sub 2} (T = Co, Ni, Cu, Ru, Rh, Pd). A systematic study by {sup 89}Y solid-state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hoeting, Christoph; Rodewald, Ute C.; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Matar, Samir F. [CNRS Bordeaux Univ., Pessac (France). ICMCB

    2014-03-15

    The ThCr{sub 2}Si{sub 2}-type silicides YT{sub 2}Si{sub 2} (T = Co, Ni, Cu, Ru, Rh, Pd) were synthesized from the elements by arc-melting. They were characterized by powder X-ray diffraction, and the structures were refined on the basis of single-crystal X-ray diffractometer data. The course of the lattice parameters shows a distinct anomaly for YRu{sub 2}Si{sub 2} which has by far the smallest c/a ratio along with elongated Y-Si distances. Systematic {sup 89}Y solid-state NMR spectra show large Knight shifts arising from unpaired conduction electron spin density near the Fermi edge. The Knight shift decreases with increasing valence electron count (VEC), reflecting the sensitivity of this parameter to electronic properties. The particularly strong structural distortion observed in YRu{sub 2}Si{sub 2} manifests itself in a sizeable magnetic shielding anisotropy. Electronic structure calculations for YRu{sub 2}Si{sub 2} and YRh{sub 2}Si{sub 2} reveal similar projected density of states (PDOS) shapes with an energy upshift of the Fermi level in YRh{sub 2}Si{sub 2} due to the extra electron brought in by Rh. As a consequence, the PDOS at the Fermi energy is twice as large in the Ru compound as in the Rh compound. While both compounds show the major bonding interaction within the T{sub 2}Si{sub 2} layers, YRh{sub 2}Si{sub 2} exhibits significantly stronger Y-Si bonding. (orig.)

  8. A solid-polymer-electrolyte direct methanol fuel cell (DMFC) with Pt-Ru nanoparticles supported onto poly(3,4-ethylenedioxythiophene) and polystyrene sulphonic acid polymer composite as anode

    Indian Academy of Sciences (India)

    K K Tintula; S Pitchumani; P Sridhar; A K Shukla

    2010-05-01

    Nano-sized Pt-Ru supported onto a mixed-conducting polymer composite comprising poly(3,4-ethylenedioxythiophene)-polystyrene sulphonic acid (PEDOT-PSSA) is employed as anode in a solid-polymer-electrolyte direct methanol fuel cell (SPE-DMFC) and its performance compared with the SPE-DMFC employing conventional Vulcan XC-72R carbon supported Pt-Ru anode. Physical characterization of the catalyst is conducted by Fourier-transform infra-red (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDAX) in conjunction with cyclic voltammetry and chronoamperometry. The study suggests that PEDOT-PSSA to be a promising alternative catalyst-support-material for SPE-DMFCs.

  9. Raman studies of Rh and Pt on La{sub 2}O{sub 3} catalysts used in a membrane reactor for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Cornaglia, L.M.; Munera, J.; Irusta, S.; Lombardo, E.A. [Instituto de Investigaciones en Catalisis y Petroquimica, (FIQ, UNL-CONICET), Santiago del Estero 2829-3000 Santa Fe (Argentina)

    2004-05-28

    Rh and Pt catalysts supported on lanthanum oxide were prepared by wet impregnation. The solids were used in a Pd-Ag membrane reactor to produce hydrogen through the carbon dioxide reforming of methane. The effect of the sweep gas flow rate and W/F upon the conversions of CO{sub 2} and CH{sub 4}, as well as on the production of H{sub 2} was studied. The best performing catalyst was Rh (0.6%). It yielded a methane conversion 38% higher than the thermodynamic value and the highest H{sub 2} permeate flux across the membrane. Lanthanum phases on the support and the catalysts were characterized by Laser Raman spectroscopy, FTIR, and XRD. The support and the calcined fresh catalysts exhibited a mixture of phases which were influenced by the metal type. Furthermore, platinum seemed to favor the formation of Ia-La{sub 2}O{sub 2}CO{sub 3} after a short treatment in flowing CO{sub 2}. However, the only remaining crystalline phase after 100h on stream was II-La{sub 2}O{sub 2}CO{sub 3}. A small amount of graphitic carbon was detected using Laser Raman spectroscopy, despite the fact that no carbon deposition was observed through TGA measurements. The graphite crystallization order seemed to be dependent upon the contact time of the reactants.

  10. Strain effect on the magnetic properties of SrRuO{sub 3} thin films on ferroelectric PMN-PT substrates

    Energy Technology Data Exchange (ETDEWEB)

    Herklotz, Andreas; Kataja, Mikko; Schultz, Ludwig; Doerr, Kathrin [IFW Dresden, IMW, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2011-07-01

    We investigate a two-component multiferroic system consisting of a ferroelectric 0.72PbMg{sub 1/3}Nb{sub 2/3}O{sub 3}-0.28PbTiO{sub 3} (PMN-PT) substrate and ferromagnetic SrRuO{sub 3} (SRO) thin films. The inverse piezoelectric effect of the substrate is used to reversibly vary the strain state of the epitaxial SRO films in order to clarify the strain dependence of the magnetic film properties. Buffer films of Sr{sub 1-x}Ba{sub x}TiO{sub 3} are introduced to vary the as-grown state of the SRO films and to cover a wider range from compressive to tensile strain. High resolution X-ray diffraction is deployed to structurally characterize the films and to determine Poisson's ratio of SRO, which is not known so far. SQUID magnetometry reveals that the Curie temperature is increasing with tensile strain, but starts to decrease again under high strain. Angular-dependent measurements provide that the easy axis orientation shows a complex dependence on strain and temperature. SQUID measurements on conventional substrates like SrTiO{sub 3} and LaAlO{sub 3} and electric transport measurements complete the data.

  11. Rh Disease

    Science.gov (United States)

    ... Loss > Birth defects & other health conditions > Rh disease Rh disease E-mail to a friend Please fill ... Rh-negative with a blood test. What is Rh factor? Rh factor is a protein that’s found ...

  12. Geometry matters: inverse cytotoxic relationship for cis/trans-Ru(ii) polypyridyl complexes from cis/trans-[PtCl2(NH3)2].

    Science.gov (United States)

    Wachter, Erin; Zamora, Ana; Heidary, David K; Ruiz, José; Glazer, Edith C

    2016-08-09

    Two thermally activated ruthenium(ii) polypyridyl complexes, cis-Ru(bpy)2Cl2 and trans-Ru(qpy)Cl2 were investigated to determine the impact of the geometric arrangement of the exchangable ligands on the potential of the compounds to act as chemotherapeutics. In contrast to the geometry requirements for cisplatin, trans-Ru(qpy)Cl2 was 7.1-9.5× more cytotoxic than cis-Ru(bpy)2Cl2. This discovery could open up a new area of metal-based chemotherapeutic research.

  13. Anomalous metamagnetic-like transition in a FeRh/Fe3Pt interface occurring at T approximate to 120 K in the field-cooled-cooling curves for low magnetic fields

    OpenAIRE

    Salem-Sugui Jr., S.; Alvarenga, A. D.; R. D. Noce; R. B. Guimarães; C. Salazar Mejia; Salim, H; Gandra, F. G.

    2012-01-01

    We report on the magnetic properties of a special configuration of a FeRh thin film. An anomalous behavior on the magnetisation vs. temperature was observed when low magnetic fields are applied in the plane of a thin layer of FeRh deposited on ordered Fe3Pt. The anomalous effect resembles a metamagnetic transition and occur only in the field-cooled-cooling magnetisation curve at temperatures near 120 K in samples without any heat treatment. Copyright 2012 Author(s). This article is distribute...

  14. Mutagenic activity of transition-metal complexes: relation structure-mutagenic and antibacterial activity for some Pd(II), Pt(II) and Rh(I) complexes. [Salmonella typhimurium; Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Aresta, M.; Treglia, S.; Collucia, M.; Correale, M.; Giordano, D.; Moscelli, S.

    1984-01-01

    The inhibitory and mutagenic action of some Pd(II), Pt(II) and Rh(I) complexes towards various bacterial strains has been evaluated, and some correlations have been found between the chemical behavior of the complexes and their selection biological activity; most of the complexes cause only a DNA damage repaired by the excision repair system. Particularly, the Rh(I) complexes used in this work show selective antibacterial effects on defective but no effect on wild-type strains. 19 references, 8 figures, 10 tables.

  15. Synthesis and evaluation of new salicylaldehyde-2-picolinylhydrazone Schiff base compounds of Ru(II), Rh(III) and Ir(III) as in vitro antitumor, antibacterial and fluorescence imaging agents.

    Science.gov (United States)

    Palepu, Narasinga Rao; Nongbri, S L; Premkumar, J Richard; Verma, Akalesh Kumar; Bhattacharjee, Kaushik; Joshi, S R; Forbes, Scott; Mozharivskyj, Yurij; Thounaojam, Romita; Aguan, K; Kollipara, Mohan Rao

    2015-06-01

    Reaction of salicylaldehyde-2-picolinylhydrazone (HL) Schiff base ligand with precursor compounds [{(p-cymene)RuCl2}2] 1, [{(C6H6)RuCl2}2] 2, [{Cp*RhCl2}2] 3 and [{Cp*IrCl2}2] 4 yielded the corresponding neutral mononuclear compounds 5-8, respectively. The in vitro antitumor evaluation of the compounds 1-8 against Dalton's ascites lymphoma (DL) cells by fluorescence-based apoptosis study and by their half-maximal inhibitory concentration (IC50) values revealed the high antitumor activity of compounds 3, 4, 5 and 6. Compounds 1-8 render comparatively lower apoptotic effect than that of cisplatin on model non-tumor cells, i.e., peripheral blood mononuclear cells (PBMC). The antibacterial evaluation of compounds 5-8 by agar well-diffusion method revealed that compound 6 is significantly effective against all the eight bacterial species considered with zone of inhibition up to 35 mm. Fluorescence imaging study of compounds 5-8 with plasmid circular DNA (pcDNA) and HeLa RNA demonstrated their fluorescence imaging property upon binding with nucleic acids. The docking study with some key enzymes associated with the propagation of cancer such as ribonucleotide reductase, thymidylate synthase, thymidylate phosphorylase and topoisomerase II revealed strong interactions between proteins and compounds 5-8. Conformational analysis by density functional theory (DFT) study has corroborated our experimental observation of the N, N binding mode of ligand. Compounds 5-8 exhibited a HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap 2.99-3.04 eV. Half-sandwich ruthenium, rhodium and iridium compounds were obtained by treatment of metal precursors with salicylaldehyde-2-picolinylhydrazone (HL) by in situ metal-mediated deprotonation of the ligand. Compounds under investigation have shown potential antitumor, antibacterial and fluorescence imaging properties. Arene ruthenium compounds exhibited higher activity compared to that of Cp*Rh

  16. Selective NO trapping in the pores of chain-type complex assemblies based on electronically activated paddlewheel-type [Ru2(II,II)]/[Rh2(II,II)] dimers.

    Science.gov (United States)

    Kosaka, Wataru; Yamagishi, Kayo; Hori, Akihiro; Sato, Hiroshi; Matsuda, Ryotaro; Kitagawa, Susumu; Takata, Masaki; Miyasaka, Hitoshi

    2013-12-11

    The design of porous materials that undergo selective adsorption of a specific molecule is a critical issue in research on porous coordination polymers or metal-organic frameworks. For the purpose of the selective capture of molecules possessing an electron-acceptor character such as nitric oxide (NO), one-dimensional chain compounds possessing a high donor character have been synthesized using 4-chloroanisate-bridged paddlewheel-type dimetal(II, II) complexes with M = Ru and Rh and phenazine (phz) as the chain linker: [M2(4-Cl-2-OMePhCO2)4(phz)]·n(CH2Cl2) (M = Ru, 1; Rh, 2). These compounds are isostructural and are composed of chains with a [-{M2}-phz-] repeating unit and CH2Cl2 occupying the void space between the chains. Compounds 1 and 2 change to a new phase (1-dry and 2-dry) upon evacuating the crystallization solvent (CH2Cl2) and almost lose their pores in the drying process: no void space in 1-dry and 31.8 Å(3), corresponding to 2.9% of the cell volume, in 2-dry. Nevertheless, the compounds show a unique gas accommodation ability. Accompanied by a structural transformation (i.e., the first gate-opening) at low pressures of molecules per [M2] unit. In addition, the adsorption isotherm for NO (121 K) involves the first gate-opening followed by a second gate-opening anomaly at NO pressures of ≈52 kPa for 1-dry and ≈21 kPa for 2-dry. At the first gate-opening, the absorbed amount of NO is ca. 4 molecules per [M2] unit, and then it reaches 8.4 and 6.3 for 1-dry and 2-dry, respectively, at 95 kPa. Only the isotherm for NO exhibits hysteresis in the desorption process, and some of the NO molecules are trapped in pores even after evacuating at 121 K, although it recovers to the original dried sample on heating to room temperature. The adsorbed NO molecules accrue a significant electron donation from the host framework even in the [Rh2] derivative, indicating that such simple porous compounds with electron-donor characteristics are useful for the selective

  17. A Theoretical Study of Addition Reactions of L4M(M = Rh, Ir) and L2M(M = Pd, Pt) to Li+@C60.

    Science.gov (United States)

    Yang, Ming-Chung; Sharma, Akhilesh Kumar; Sameera, W M Chamil; Morokuma, Keiji; Su, Ming-Der

    2017-03-16

    The addition reaction of M(Cl)(CO)(PPh3)2 (M = Rh, Ir) and M(PPh3)2 (M = Pd, Pt) fragments with X@C60 (X = 0, Li+) were characterized by density functional theory (DFT) and the artificial force-induced reaction (AFIR) method. The calculated free energy profiles suggested that the η2[6:6]-addition is the most favorable reaction, which is consistent with the experimental observations. In the presence of Li+ ion, the reaction is highly exothermic, leading to η2[6:6] product of L4IrLi+@C60. In contrast, an endothermic reaction was observed in the absence of a Li+ ion. The encapsulated Li+ ion can enhance the thermodynamic stability of the η2[6:6] product. The energy decomposition analysis showed that the interaction between metal fragment and X@C60 fragment is the key for the thermodynamic stability. Among the group IA and IIA metal cations, Be2+ encapsulation is the best candidate for the development of new fullerene-transition metal complexes, which will be useful for future potential applications such as solar cells, catalysts, and electronic devices.

  18. Formation of substitutionalmetallofullerenes by laser ablation of externally doped fullerenes C60Mx (M=Sm, Pt,Ni and Rh)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni and Rh) by excimer laser ablation-TOF mass spectrometry shows that metallofullerenes C2nM and C2n+1M formed in both the positive and negative ionic medes.The isotopic distributions of the metallofullerenes C2nM and C2n+1M are consistent with the calculated spectra based on the natural abundance of isotopes of C and M, confirming the formation of metallofullerenes. The metal atom is supposed to be incorporated into the network of the fullerene cage to replace one carbon atom of the cage forming substitutional metallofullerene. Odd-numbered high carbon cluisters are observed in our laser ablation study of all the metal fullerides in the negative ion channel. Evolution of mass spectrum with irradiation laser shots shows that the formation of the substitutionally doped fullerenes is closely related to the production of metal carbide (MC). The structures, as well as formation mechanism, of metallofullerenes C2n+1Mand C2nM with even and odd numbers of total atoms respectively are discussed based on the structural optimization of the odd-numbered high carbon clusters.

  19. Strong anisotropic anomalous Hall effect and spin Hall effect in the chiral antiferromagnetic compounds Mn3X (X =Ge , Sn, Ga, Ir, Rh, and Pt)

    Science.gov (United States)

    Zhang, Yang; Sun, Yan; Yang, Hao; Železný, Jakub; Parkin, Stuart P. P.; Felser, Claudia; Yan, Binghai

    2017-02-01

    We have carried out a comprehensive study of the intrinsic anomalous Hall effect and spin Hall effect of several chiral antiferromagnetic compounds Mn3X (X = Ge, Sn, Ga, Ir, Rh and Pt) by ab initio band structure and Berry phase calculations. These studies reveal large and anisotropic values of both the intrinsic anomalous Hall effect and spin Hall effect. The Mn3X materials exhibit a noncollinear antiferromagnetic order which, to avoid geometrical frustration, forms planes of Mn moments that are arranged in a Kagome-type lattice. With respect to these Kagome planes, we find that both the anomalous Hall conductivity (AHC) and the spin Hall conductivity (SHC) are quite anisotropic for any of these materials. Based on our calculations, we propose how to maximize AHC and SHC for different materials. The band structures and corresponding electron filling, that we show are essential to determine the AHC and SHC, are compared for these different compounds. We point out that Mn3Ga shows a large SHC of about 600 (ℏ /e ) (Ωcm) -1 . Our work provides insights into the realization of strong anomalous Hall effects and spin Hall effects in chiral antiferromagnetic materials.

  20. Influence of Ce0.35Zr0.55Y0.10 Solid Solution on Performance of Pt-Rh Three-Way Catalysts

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ce0.35Zr0.55Y0.10 solid solution was prepared by co-precipitation technique and characterized by specific surface area measurements (BET) and X-ray diffraction (XRD). Ce0.35Zr0.55Y0.10 was used to prepare low Pt-Rh three-way catalyst (TWC), and its influence on the performance of TWC was investigated. The results revealed that Ce0.35Zr0.55Y0.10 had a cubic structure similar to Ce0.50Zr0.50O2 and its specific surface area can maintain higher than Ce0.50Zr0.50O2 after 1000 ℃ calcination for 5 h. Being hydrothermal aged at 1000 ℃ for 5 h, the catalyst containing Ce0.35Zr0.55Y0.10 still exhibited higher conversion of C3H8, CO and NO and lower light-off temperature in comparison with Ce0.50Zr0.50O2 TWC.

  1. Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order-disorder transitions in Pt-Rh nanoparticles.

    Science.gov (United States)

    Pohl, Johan; Stahl, Christian; Albe, Karsten

    2012-01-01

    Nanoparticles of Pt-Rh were studied by means of lattice-based Monte Carlo simulations with respect to the stability of ordered D0(22)- and 40-phases as a function of particle size and composition. By thermodynamic integration in the semi-grand canonical ensemble, phase diagrams for particles with a diameter of 7.8 nm, 4.3 nm and 3.1 nm were obtained. Size-dependent trends such as the lowering of the critical ordering temperature, the broadening of the compositional stability range of the ordered phases, and the narrowing of the two-phase regions were observed and discussed in the context of complete size-dependent nanoparticle phase diagrams. In addition, an ordered surface phase emerges at low temperatures and low platinum concentration. A decrease of platinum surface segregation with increasing global platinum concentration was observed, when a second, ordered phase is formed inside the core of the particle. The order-disorder transitions were analyzed in terms of the Warren-Cowley short-range order parameters. Concentration-averaged short-range order parameters were used to remove the surface segregation bias of the conventional short-range order parameters. Using this procedure, it was shown that the short-range order in the particles at high temperatures is bulk-like.

  2. Correlation between topological band character and chemical bonding in a Bi14Rh3I9-based family of insulators

    Science.gov (United States)

    Rasche, Bertold; Isaeva, Anna; Ruck, Michael; Koepernik, Klaus; Richter, Manuel; van den Brink, Jeroen

    2016-02-01

    Recently the presence of topologically protected edge-states in Bi14Rh3I9 was confirmed by scanning tunnelling microscopy consolidating this compound as a weak 3D topological insulator (TI). Here, we present a density-functional-theory-based study on a family of TIs derived from the Bi14Rh3I9 parent structure via substitution of Ru, Pd, Os, Ir and Pt for Rh. Comparative analysis of the band-structures throughout the entire series is done by means of a unified minimalistic tight-binding model that evinces strong similarity between the quantum-spin-Hall (QSH) layer in Bi14Rh3I9 and graphene in terms of -molecular orbitals. Topologically non-trivial energy gaps are found for the Ir-, Rh-, Pt- and Pd-based systems, whereas the Os- and Ru-systems remain trivial. Furthermore, the energy position of the metal -band centre is identified as the parameter which governs the evolution of the topological character of the band structure through the whole family of TIs. The -band position is shown to correlate with the chemical bonding within the QSH layers, thus revealing how the chemical nature of the constituents affects the topological band character.

  3. Separation Studies of Pd(II from Acidic Chloride Solutions of Pt(IV, Ni(II and Rh(III by Using 4-Aroyl-3-Phenyl-5-Isoxazolones

    Directory of Open Access Journals (Sweden)

    Koduru Janardhan Reddy

    2012-01-01

    Full Text Available This study examined the effect influence of various factors on the extraction of Pd(II to develop a new liquid-liquid extraction mechanism for the selective separation of palladium(II from its acidic chloride solutions using 4-aroyl-3-phenyl-5-isoxazolones (HA, such as 3-phenyl-4-(4-fluorobenzoyl-5- isoxazolone (HFBPI, 3-phenyl-4-benzoyl-5-isoxazolone (HPBI and 3-phenyl-4- (4-toluoyl-5-isoxazolone (HTPI. The extraction strength of Pd(II with HA were in the following order: HFBPI > HPBI > HTPI, which is opposite to that observed with their pKa values. HPBI was used to separate Pd(II from Pt(IV, Ni(II and Rh(III metal ions and calculated their separation factors (S.F. were followed in the order: Pd/Ni (40±0.4 > Pd/Pt (25±0.2 > Pd/Rh (15±0.3 > Rh/Ni (2.7±0.3 > Pt/Ni ≈ Rh/Pt (1.7±0.2. The loading and striping of Pd(II (1.12×10-4 mol L-1 were also examined using 1.0×10-3 mol L-1 HPBI in CHCl3 and 1.0 mol L-1 HCl, respectively. The results demonstrated that the maximum (97.5% extraction and desorption (89% of metal required at least 3.0 cycles. The developed method was applied successfully to the separation of palladium from synthetic water samples.

  4. Rh incompatibility

    Science.gov (United States)

    ... that develops when a pregnant woman has Rh-negative blood and the baby in her womb has Rh- ... against Rh-positive blood. However, women with Rh-negative blood type must get injections: During every pregnancy After ...

  5. Influence of aging time on thermodynamical, structural and microstructural properties of Pd{sub 100-(x+y)}Pt{sub x}Rh{sub y-}T{sub 2}(D{sub 2}) systems; Influence de la duree de stockage sur les proprietes thermodynamiques, structurales et microstructurales des systemes Pd{sub 100-(x+y)}Pt{sub x}Rh{sub y-}T{sub 2}(D{sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Thiebaut, S

    1998-12-31

    This study has demonstrated that substitution of palladium by a few atomic percent of platinum and/or rhodium induces great changes in tritium storage properties and aging phenomena in these systems. Before aging, equilibrium pressures only depend of the global substitution rate, and not at all of the substituents nature. During storage, the decrease of plateau pressures is stronger in Pd-Pt alloys, and even more in the ternary solid solution Pd{sub 90}Pt{sub 5}Rh{sub 5}. This substitution effect was explained by a difference in the nature of defects created by {sup 3}He bubbles formation. The presence of platinum, with or without rhodium, in the lattice stabilizes self interstitial atoms isolated or in dislocation loops. These defects induce a great lattice swelling, and the tritides stability is directly proportional to the metal lattice volume. On the contrary, in pure palladium and Pd-Rh alloys, self interstitial atoms are preferentially integrated in a dislocation network, so they are without effect on the lattice parameter and consequently on the tritides stability. In all cases, Pd-Pt-Rh systems are indeed perfectly suited for tritium storage thanks to their conservation of local order and thermodynamical properties during aging. (author) 81 refs.

  6. Strain-mediated electric-field control of exchange bias in a Co90Fe10/BiFeO3/SrRuO3/PMN-PT heterostructure

    Science.gov (United States)

    Wu, S. Z.; Miao, J.; Xu, X. G.; Yan, W.; Reeve, R.; Zhang, X. H.; Jiang, Y.

    2015-03-01

    The electric-field (E-field) controlled exchange bias (EB) in a Co90Fe10/BiFeO3 (BFO)/SrRuO3/PMN-PT heterostructure has been investigated under different tensile strain states. The in-plane tensile strain of the BFO film is changed from +0.52% to +0.43% as a result of external E-field applied to the PMN-PT substrate. An obvious change of EB by the control of non-volatile strain has been observed. A magnetization reversal driven by E-field has been observed in the absence of magnetic field. Our results indicate that a reversible non-volatile E-field control of a ferromagnetic layer through strain modulated multiferroic BFO could be achieved at room temperature.

  7. Nb2O5·nH2O—PtRu/C的制备及其对甲醇氧化的催化作用%Preparation and Activity of Nb2O5·nH2O-PtRu/C for Methanol Oxidation

    Institute of Scientific and Technical Information of China (English)

    李伟伟; 张向军; 卢世刚

    2012-01-01

    10%Nb2O5·onH2O-20%Pt10%Ru/C electro-catalyst for methanol oxidation was prepared by deposition method, followed with heat treatment in Ar atmosphere. The effect of heat treatment on morphology, structure and electrochemistry performance of the product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and chronoamperograms. No diffraction peaks of Ru were observed in the XRD patterns, while all the peaks of Pt were in accordance with the face centered cubic crystal structure. The binding energy of Pt was not affected by NbEO5.nH2O. Compared with 20%Pt10%Ru/C, in 10%Nb2O5.nH2O-20%Pt10%Ru/C samples, the activated particles were uniformly dispersed, and the performances of methanol oxidation and resistance to "CO" were better. The results indicated that the introduction of NbEO5.nH2O inhibited the growth of active particles, and decreased the alloying degree of Pt-Ru during heat treatment. Besides, NbEO5onH2O also provided active "-OH" and improved H+ transfer, leading to easier adsorption-desorption of methanol and its oxidation intermediates.%采用沉淀法制备了甲醇氧化电催化剂10%Nb2O5·nH2O.20%Pt10%Ru/C,并在Ar气氛下对它进行了热处理.用X射线衍射(XRD),透射电子显微镜(TEM)和X射线光电子谱(XPS)研究了热处理对催化剂的结构和形貌的影响,用循环伏安法和计时电流法研究了热处理对催化剂的电化学性能的影响.结果表明:催化剂中看不到Ru的衍射峰存在,Pt晶粒以面心立方体结构存在,Nb2O5·nH2O对Pt的结合能基本无影响;与20%Pt10%Ru/C相比,同温度热处理的条件下,10%Nb2O5.nH2O-20%Pt10%Ru/C催化剂中Pt,Ru合金化程度较差,活性组分颗粒较小、分散均匀,而且催化甲醇氧化性能和抗“CO”毒化性能较好,700℃热处理的10%Nb2O5.nH2O.20%Pt10

  8. Au/TiO2,Ru/TiO2,Pt/TiO2光阳极的电流-电压特性及制备%Preparation and Current-Potential Characteristics of Au/TiO2, Ra/TiO2, Pt/TiO2 Photoelectrodes

    Institute of Scientific and Technical Information of China (English)

    洪祖培; 刘蕙菁

    1982-01-01

    @@用碱性光电化学池观察到异常的Pt/TiO2I-V特性,可能是Pt-TiO2之间的相互作用对表面态的影响所致,和无金属的TiO2比较,Au/TiO2改变了阳极曲线的起始电位,有利于光阳极的析氧性能的改善,而Ru/TiO2,Pt/TiO2有助于阴极极化的减少。

  9. Atomically thick Pt-Cu nanosheets: self-assembled sandwich and nanoring-like structures.

    Science.gov (United States)

    Saleem, Faisal; Xu, Biao; Ni, Bing; Liu, Huiling; Nosheen, Farhat; Li, Haoyi; Wang, Xun

    2015-03-25

    Atomically thick and flexible Pt-Cu alloy nanosheets are prepared and loaded with either Pd or Pt to produce sandwich structures or nanoring-like nanosheet structures, respectively. Core-shell alloy nanoparticles containing Rh, Ir, and Ru are also prepared. All of these structures exhibit superior specific and mass activities for the oxidation of formic acid for fuel cells for portable electronic devices as compared to commercial Pd/C catalyst. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Many metals make the cut: quaternary rare-earth germanides RE4M2InGe4 (M = Fe, Co, Ni, Ru, Rh, Ir) and RE4RhInGe4 derived from excision of slabs in RE2InGe2.

    Science.gov (United States)

    Oliynyk, Anton O; Stoyko, Stanislav S; Mar, Arthur

    2015-03-16

    The formation of quaternary rare-earth (RE) germanides containing transition metals (M's) from groups 6 to 10 was investigated through arc-melting and annealing reactions at 800 °C; about 50 new compounds were obtained. These include several new series of quaternary germanides RE4M2InGe4 (M = Fe, Co, Ru, Rh, Ir), previously known only for M = Mn and Ni; additional members of RE4Ni2InGe4 extended to other RE substituents; and a different but closely related series RE4RhInGe4. Detailed crystal structures were determined by single-crystal X-ray diffraction studies for 20 compounds. Monoclinic structures in space group C2/m are adopted by RE4M2InGe4 (Ho4Ni2InGe4-type, a = 15.1-16.5 Å, b = 4.1-4.4 Å, c = 6.9-7.3 Å, β = 106.2-108.6°) and RE4RhInGe4 (own type, a = 20.0-20.2 Å, b = 4.2-4.3 Å, c = 10.1-10.2 Å, β = 105.0-105.3°). Both structures contain frameworks built from MGe4 tetrahedra, InGe4 square planes, and Ge2 dimers, delimiting tunnels occupied by RE atoms. These structures can also be derived by cutting slabs along different directions from the more symmetrical RE2InGe2 structure. Although the Ge2 dimers are relatively invariant, the InGe4 square planes can undergo distortion to form two sets of short versus long In-Ge distances. This distortion results from a competition between M-Ge bonding in the MGe4 tetrahedra and In-Ge bonding in the InGe4 square planes.

  11. Pd and Pt-Ru anode electrocatalysts supported on multi-walled carbon nanotubes and their use in passive and active direct alcohol fuel cells with an anion-exchange membrane (alcohol = methanol, ethanol, glycerol)

    Science.gov (United States)

    Bambagioni, Valentina; Bianchini, Claudio; Marchionni, Andrea; Filippi, Jonathan; Vizza, Francesco; Teddy, Jacques; Serp, Philippe; Zhiani, Mohammad

    Palladium and platinum-ruthenium nanoparticles supported on multi-walled carbon nanotubes (MWCNT) are prepared by the impregnation-reduction procedure. The materials obtained, Pd/ MWCNT and Pt-Ru/ MWCNT, are characterized by TEM, ICP-AES and XRPD. Electrodes coated with Pd/ MWCNT are scrutinized for the oxidation of methanol, ethanol or glycerol in 2 M KOH solution in half cells. The catalyst is very active for the oxidation of all alcohols, with glycerol providing the best performance in terms of specific current density and ethanol showing the lowest onset potential. Membrane-electrode assemblies have been fabricated using Pd/ MWCNT anodes, commercial cathodes and anion-exchange membrane and evaluated in both single passive and active direct alcohol fuel cells fed with aqueous solutions of 10 wt.% methanol, 10 wt.% ethanol or 5 wt.% glycerol. Pd/ MWCNT exhibits unrivalled activity as anode electrocatalyst for alcohol oxidation. The analysis of the anode exhausts shows that ethanol is selectively oxidized to acetic acid, detected as acetate ion in the alkaline media of the reaction, while methanol yields carbonate and formate. A much wider product distribution, including glycolate, glycerate, tartronate, oxalate, formate and carbonate, is obtained from the oxidation of glycerol. The results obtained with Pt-Ru/ MWCNT anodes in acid media are largely inferior to those provided by Pd/ MWCNT electrodes in alkaline media.

  12. CO2 capture and separation from N2/CH4 mixtures by Co@B8/Co@B8(-) and M@B9/M@B9(-) (M = Ir, Rh, Ru) clusters: a theoretical study.

    Science.gov (United States)

    Wang, Weihua; Zhang, Xiaoxiao; Li, Ping; Sun, Qiao; Li, Zhen; Ren, Cong; Guo, Chao

    2015-01-29

    The discovery of advanced materials with high selectivity and efficiency is essential to realize practical carbon capture and sequestration. Here, we have investigated the interactions of the Co@B8/Co@B8(-) and M@B9/M@B9(-) (M = Ir, Rh, Ru) clusters with CO2, N2, and CH4 gas molecules theoretically. We found that neutral boron clusters have weak interaction with CO2, N2, and CH4 molecules. Similarly, the clusters with their negative charge states have also weak interaction with N2 and CH4 molecules. However, anionic clusters have a strong interaction with CO2, which can be explained by the Lewis acid-base interaction as CO2 (Lewis acid) can gain electron easily from the electron-rich anionic clusters. Moreover, the kinetic stability of the formed complexes after CO2 capture has been validated by ab initio molecular dynamics. In all, the present study demonstrates, for the first time, that the anionic boron wheel ring clusters can be used as potential advanced materials for CO2 capture and separation from flue gas and natural gas mixtures.

  13. Eigen-like hydrated protons traveling with a local distortion through the water nanotube in new molecular porous crystals {[M(III)(H2bim)3](TMA)·20H2O}n (M = Co, Rh, Ru).

    Science.gov (United States)

    Matsui, Hiroshi; Tadokoro, Makoto

    2012-10-14

    In molecular porous crystals {[M(III)(H(2)bim)(3)](TMA)·20H(2)O}(n) (M = Co, Rh, Ru), the structural property of confined water network and the dynamics of mobile hydrated protons have been examined by the measurement of infrared spectrum and microwave conductivity. The water network undergoes first order phase transition from the ice nanotube (INT) to the water nanotube (WNT) around 200 K, while the infrared spectral features for these states are almost equivalent. Consequently, the water molecules in WNT dynamically fluctuate in the vicinity of the regulated position in INT with maintaining the O-O distance. The additional band observed around 2200 cm(-1) reveals the emergence of an Eigen-like protonic hydrate, around which the O-O distance locally shrinks to ~2.56 Å. The microwave conductivity exhibiting activation-type behavior, isotope effect and anisotropy indicates that the water nanotube is a quasi one-dimensional high proton conductor. Together with the neutron experimental results, we have clarified that the proton and protonic hole are generated by the self-dissociation in some water molecules just hydrated to the carboxylate oxygen atom of trimesic acid. The Eigen-like hydrated proton and protonic hole contribute to the intrinsic proton conduction accompanying local distortions. The carrier density dominated by the intrinsic ionic equilibrium is not large, whereas the actual mobility, which is higher than 1 × 10(-2) (cm(2)/Vs), yields the present high proton conductivity.

  14. Sum Frequency Generation Vibrational Spectroscopy of 1,3-Butadiene Hydrogenation on 4 nm Pt@SiO 2 , Pd@SiO 2 , and Rh@SiO 2 Core–Shell Catalysts

    KAUST Repository

    Krier, James M.

    2015-01-14

    © 2014 American Chemical Society. 1,3-Butadiene (1,3-BD) hydrogenation was performed on 4 nm Pt, Pd, and Rh nanoparticles (NPs) encapsulated in SiO2 shells at 20, 60, and 100 °C. The core-shells were grown around polyvinylpyrrolidone (PVP) coated NPs (Stöber encapsulation) prepared by colloidal synthesis. Sum frequency generation (SFG) vibrational spectroscopy was performed to correlate surface intermediates observed in situ with reaction selectivity. It is shown that calcination is effective in removing PVP, and the SFG signal can be generated from the metal surface. Using SFG, it is possible to compare the surface vibrational spectrum of Pt@SiO2 (1,3-BD is hydrogenated through multiple paths and produces butane, 1-butene, and cis/trans-2-butene) to Pd@SiO2 (1,3-BD favors one path and produces 1-butene and cis/trans-2-butene). In contrast to Pt@SiO2 and Pd@SiO2, SFG and kinetic experiments of Rh@SiO2 show a permanent accumulation of organic material.

  15. Resistance switching mode transformation in SrRuO3/Cr-doped SrZrO3/Pt frameworks via a thermally activated Ti out-diffusion process.

    Science.gov (United States)

    Jo, Yongcheol; Jung, Kyooho; Kim, Jongmin; Woo, Hyeonseok; Han, Jaeseok; Kim, Hyungsang; Hong, Jinpyo; Lee, Jeon-Kook; Im, Hyunsik

    2014-12-08

    This work reports on a mechanism for irreversible resistive switching (RS) transformation from bipolar to unipolar RS behavior in SrRuO3 (SRO)/Cr-doped SrZrO3 (SZO:Cr)/Pt capacitor structures prepared on a Ti/SiO2/Si substrate. Counter-clockwise bipolar RS memory current-voltage (I-V) characteristics are observed within the RS voltage window of -2.5 to +1.9 V, with good endurance and retention properties. As the bias voltage increases further beyond 4 V under a forward bias, a forming process occurs resulting in irreversible RS mode transformation from bipolar to unipolar mode. This switching mode transformation is a direct consequence of thermally activated Ti out-diffusion from a Ti adhesion layer. Transition metal Ti effectively out-diffuses through the loose Pt electrode layer at high substrate temperatures, leading to the unintended formation of a thin titanium oxide (TiO(x) where x < 2) layer between the Pt electrode and the SZO:Cr layer as well as additional Ti atoms in the SZO:Cr layer. Cross-sectional scanning electron microscopy, transmission electron microscopy and Auger electron spectroscopy depth-profile measurements provided apparent evidence of the Ti out-diffusion phenomenon. We propose that the out-diffusion-induced additional Ti atoms in the SZO:Cr layer contributes to the creation of the metallic filamentary channels.

  16. Synthesis and characterization of (smif)2M(n) (n = 0, M = V, Cr, Mn, Fe, Co, Ni, Ru; n = +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl).

    Science.gov (United States)

    Frazier, Brenda A; Bartholomew, Erika R; Wolczanski, Peter T; DeBeer, Serena; Santiago-Berrios, Mitk'El; Abruña, Hector D; Lobkovsky, Emil B; Bart, Suzanne C; Mossin, Susanne; Meyer, Karsten; Cundari, Thomas R

    2011-12-19

    A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)(2)M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe(3))(2)(THF)(n) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated ((o)Mesmif)(2)Fe (2-Fe) and ((o)Me(2)smif)(2)Fe (3-Fe) were similarly prepared. Metatheses of MX(2) variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl(3)(THF)(3) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl(3)(THF)(3) in the presence of NaBPh(4) gave [(smif)(2)Ir]BPh(4) (1(+)-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)(2)M]OTf (1(+)-M), and treatment of Rh(2)(O(2)CCF(3))(4) with 4 equiv Na(smif) and 2 AgOTf gave 1(+)-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC(nb) (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10,000-60,000 M(-1)cm(-1)), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.

  17. Ru[(bpy)₂(dppz)]²⁺ and Rh[(bpy)₂(chrysi)]³⁺ targeting double strand DNA: the shape of the intercalating ligand tunes the free energy landscape of deintercalation.

    Science.gov (United States)

    Franco, Duvan; Vargiu, Attilio V; Magistrato, Alessandra

    2014-08-04

    Octahedral metal complexes can bind to double strand (ds) DNA either by intercalation or by insertion, this latter mechanism being observed in the case of mismatched base pairs (bps). In this work we modeled the process of deintercalation from the major groove for Δ-Ru[(bpy)2(dppz)](2+) (1) and Δ-Rh[(bpy)2(chrysi)](3+) (2), prototypical examples of metallo-intercalators and metallo-insertors, respectively. By using advanced sampling techniques, we show that the two complexes have comparable deintercalation barriers and that in both systems the main cost of deintercalation is due to disruption of π-π stacking interactions between the intercalating moiety and the bps flanking the binding site. A striking difference between dppz and chrysi is found in their intercalation modes, being their longest axes, respectively, perpendicular and parallel to the P-P direction between opposite DNA strands. This leads the two ligands to deintercalate from the DNA through different mechanisms. Compound 1 goes through the formation of a metastable short-lived intermediate, with an overall free energy barrier of ~14.5 kcal/mol, in line with experimental findings. Due to the length of the dppz intercalating moiety, an extended plateau appears in the free energy landscape at ~3 kcal/mol above the most stable minimum. Compound 2 must cross a similar barrier (~15.5 kcal/mol), but does not form intermediates along the deintercalation path, and the deintercalation profile is steeper than that found for 1. Thus, the shape of the intercalating moiety affects the deintercalation mechanism of these inorganic molecules. This work is a first step to rationalize from a computational perspective the factors tuning the preferential binding mode of inorganic molecules (such as diagnostic probes, therapeutic agents, or regulators of DNA expression) to ds DNA.

  18. DFT Simulation of Structural and Optical Properties of 9-Aminoacridine Half-Sandwich Ru(II), Rh(III), and Ir(III) Antitumoral Complexes and Their Interaction with DNA.

    Science.gov (United States)

    Cerón-Carrasco, José Pedro; Ruiz, José; Vicente, Consuelo; de Haro, Concepción; Bautista, Delia; Zúñiga, José; Requena, Alberto

    2017-08-08

    In this work, we use DFT-based methods to simulate the chemical structures, optical properties, and interaction with DNA of a recently synthesized chelated C^N 9-aminoacridine arene Ru(II) anticancer agent and two new closely related Rh(III) and Ir(III) complexes using DFT-based methods. Four chemical models and a number of theoretical approaches, which representatively include the PBE0, B97D, ωB97X, ωB97X-D, M06, and M06-L density functionals and the LANL2DZ, def2-SVP, and def2-TZVP basis sets, are tested. The best overall accuracy/cost performance for the optimization process is reached at the ωB97X-D/def2-SVP and M06/def2-SVP levels of theory. Inclusion of explicit solvent molecules (CHCl3) further refines the geometry, while taking into account the crystal network gives no significant improvements of the computed bond distances and angles. The analysis of the excited states reveals that the M06 level matches better the experimental absorption spectra, compared to ωB97X-D. The use of the M06/def2-SVP approach is therefore a well-balanced method to study theoretically the bioactivity of this type of antitumoral complexes, so we couple this TD-DFT approach to molecular dynamics simulations in order to assess their reactivity with DNA. The reported results demonstrate that these drugs could be used to inject electrons into DNA, which might broaden their applications in photoactivated chemotherapy and as new materials for DNA-based electrochemical nanodevices.

  19. Counterion influence on the vibrational wavenumbers in ternary and quaternary metal hydride salts, A2MH6 (A = alkali metal, alkaline earth, and lanthanides; M = Ir, Fe, Ru, Os, Pt, Mn).

    Science.gov (United States)

    Gilson, Denis F R; Moyer, Ralph O

    2012-02-06

    The wavenumbers of the ν(3) metal-hydrogen stretching mode (T(1u)) in the IR spectra of both ternary and quaternary hexahydrido salts of transition metals from groups 7 to 10 ([Mn(I)H(6)](5-), [Fe(II)H(6)](4-), [Ru(II)H(6)](4-), [Os(II)H(6)](4-), [Ir(III)H(6)](3-), and [Pt(IV)H(6)](2-)) depend linearly upon the ionization energies of the counterions (alkali metal, alkaline earth, and lanthanide) with a separate line for each metal. This relationship provides quantitative support for the charge-transfer mechanism for explaining the stabilities of these compounds.

  20. Study on the preparation of Pt nanocapsules

    Science.gov (United States)

    Zhang, Yi-fan; Ji, Zhen; Chen, Ke; Liu, Bo-wen; Jia, Cheng-chang; Yang, Shan-wu

    2017-01-01

    Ag@Pt core-shell nanoparticles (Ag@Pt NPs) were prepared by a co-reduction method. Pt nanocapsules with diameters of less than 10 nm were obtained by an electrochemical method. Cyclic voltammetry (CV) scanning was used to cavitate the Ag@Pt NPs, and the morphology, structure, and cavitation conditions were studied. The results indicate that the effective cavitation conditions to obtain Pt nanoparticles from Ag@Pt NPs are a scanning voltage of 0 to 0.8 V and continuous CV scanning over 2 h. This cavitation method is also applicable for the syntheses of Ir, Ru, and Ru-Pt nanocapsules.

  1. Concentrations of Platinum Group Elements (Pt, Pd, Rh in Airborne Particulate Matter (PM2.5 and PM10-2.5 Collected at Selected Canadian Urban Sites: a Case Study

    Directory of Open Access Journals (Sweden)

    Celo V.

    2013-04-01

    Full Text Available Increasing environmental concentrations of platinum group elements (PGEs, in particular platinum (Pt, palladium (Pd and rhodium (Rh, from catalytic converters has been reported worldwide. Initially it was believed that the emitted PGEs remain in the roadside environment, but recent studies have shown that fine PGE-containing particles can be transported and distributed at regional and long-range levels. Therefore, the monitoring of PGEs in airborne particulate matter (PM is important for the estimation of potential risks to human health and to the ecosystem. The aim of this study is to present the first results from an analysis on the concentration and distribution of Pt, Pd and Rh in PM collected on Teflon filters at two selected urban sites (Toronto, Ontario; Edmonton, Alberta collected within the Canadian National Air Pollution Surveillance (NAPS network. In this work, a quadruple inductively coupled plasma mass spectrometry (ICP-MS, combined with microwave assisted acid digestion using aqua regia was used. A cation exchange separation was used to alleviate the matrix-induced spectral and nonspectral interferences prior to ICP-MS analysis. To obtain sufficient material needed for PGEs analysis, fine PM (particles with aerodynamic diameter less than 2.5 mm; PM2.5 and coarse PM (with aerodynamic diameter between 2.5 and 10 mm; PM10-2.5 samples were combined into composite samples on a seasonal basis. The obtained results will be discussed and compared with literature data.

  2. Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Kliewer, Christopher J.; Bieri, Marco; Somorjai, Gabor A.

    2008-03-04

    Sum-frequency generation (SFG) surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to study the adsorption and hydrogenation of pyrrole over both Pt(111) and Rh(111) single-crystal surfaces at Torr pressures (3 Torr pyrrole, 30 Torr H{sub 2}) to form pyrrolidine and the minor product butylamine. Over Pt(111) at 298 K it was found that pyrrole adsorbs in an upright geometry cleaving the N-H bond to bind through the nitrogen evidenced by SFG data. Over Rh(111) at 298 K pyrrole adsorbs in a tilted geometry relative to the surface through the p-aromatic system. A pyrroline surface reaction intermediate, which was not detected in the gas phase, was seen by SFG during the hydrogenation over both surfaces. Significant enhancement of the reaction rate was achieved over both metal surfaces by adsorbing 1-methylpyrrole before reaction. SFG vibrational spectroscopic results indicate that reaction promotion is achieved by weakening the bonding between the N-containing products and the metal surface because of lateral interactions on the surface between 1-methylpyrrole and the reaction species, reducing the desorption energy of the products. It was found that the ring-opening product butylamine was a reaction poison over both surfaces, but this effect can be minimized by treating the catalyst surfaces with 1-methylpyrrole before reaction. The reaction rate was not enhanced with elevated temperatures, and SFG suggests desorption of pyrrole at elevated temperatures.

  3. Comparative study of ethanol oxidation at Pt: Based nanoalloys and UPD modified Pt nanoparticles

    Directory of Open Access Journals (Sweden)

    Tripković Amalija V.

    2010-01-01

    Full Text Available The activity of two alloys, Pt3Sn/C and Pt3Ru2/C, was compared with the activity of Pt/C modified with corresponding amounts of SnUPD (≈25 % and RuUPD (≈40 % in oxidation of ethanol. Pt3Sn/C, Pt3Ru2/C and Pt/C catalysts were characterized by XRD. To establish the activity and stability of the catalysts, potentiodynamic, quasi steady-state and chronoamperometric measurements were performed. Both alloys are more active than SnUPD or RuUPD modified Pt/C catalysts. Electronic effect determining dominantly the activity of Pt3Sn/C is the main reason for its higher activity compared to Pt3Ru2/C. Since SnUPD and RuUPD do not provoke any significant modification of electronic environment, both modified Pt/C catalysts are less active than corresponding alloys. More pronounced difference in activity between Pt3Sn/C and SnUPD modified Pt/C than between Pt3Ru2/C and RuUPD modified Pt/C is caused by electronic effect in Pt3Sn/C. High activity of Pt3Sn/C modified with small amount of SnUPD (≈10% can be explained by combining the electronic effect, causing less strongly bonded adsorbate on Pt sites and easier mobility of SnUPD, with enhanced amount of oxygen-containing species on Sn sites resulting finally in reinforcement of bifunctional mechanism.

  4. Towards a comprehensive insight into efficient hydrogen production by self-assembled Ru(bpy)3(2+)-polymer-Pt artificial photosystems.

    Science.gov (United States)

    Lin, Huan; Liu, Dan; Long, Jinlin; Zhang, Zizhong; Zhuang, Huaqiang; Zheng, Yi; Wang, Xuxu

    2015-04-28

    The role of polymers in artificial photosystems has been studied in detail. The photosystems were composed of tris(2,2'-bipyridyl) ruthenium(II) chloride as a photosensitizer (PS), colloidal Pt stabilized by polymer as a hydrogen-evolving catalyst and sodium ascorbate as an electron donor, without the addition of a traditional molecular electron mediator. Comprehensive insights into the production of hydrogen on irradiation with visible light were achieved. Several polymers, including neutral polyvinyl pyrrolidone, anionic poly(sodium 4-styrene sulfonate) and poly(acrylic acid) not only stabilized the nanoparticles, but were also effective in the production of hydrogen. Under the optimum conditions, an outstanding apparent quantum efficiency of 12.8% for the evolution of hydrogen was achieved. The formation of self-assembled and spatially separated donor-acceptor complexes via the non-covalent intermolecular interaction between PS and the polymer-Pt was pivotal in the efficient conversion of solar energy to hydrogen fuel. Important details of the photo-induced electron and energy transfer processes in the self-assembled artificial photosystems were determined by nanosecond transient absorption spectrometry and time-resolved fluorescence spectrometry. The initial step in the photo-catalytic production of hydrogen was a reductive quenching of the triplet excited state of the PS by sodium ascorbate, leading to a reduced form of PS, which could then be quickly quenched by the polymer. The rate-determining step was the electron transfer from PS to the catalyst via the polymer bridge.

  5. Fabrication of MgAl2Si2O8 : M0.01 (M = Ni2+, Cu2+, Pd2+, Pt2+ and Ru3+): catalytic effects for the reduction of 2- or 4-nitroanilines in water

    Indian Academy of Sciences (India)

    Serkan Dayan; Sevgi Öztürk; Nilgün Kayaci; Nilgun Kalaycioglu Ozpozan; Esra Öztürk

    2015-10-01

    Five new MgAl2Si2O8 : M0.01 (M = Ni2+, Cu2+, Pd2+, Pt2+ and Ru3+) materials were developed for the reduction of nitroarenes as catalysts by conventional solid state reaction at 1300°C. The prepared materials were characterized by thermal analysis, Fourier transform infrared spectroscopy, X-ray powder diffraction analysis, scanning electron microscopy, energy-dispersive X-ray analysis and nitrogen adsorption–desorption analysis. The catalytic activities of the prepared catalysts were tested in the reduction of 2- or 4-nitroanilines in aqueous media at ambient temperature in the presence of NaBH4 by UV–vis spectrophotometer. Furthermore, the MgAl2Si2O8 : M0.01 catalysts can be recovered by filtration and reused for five cycles for the reduction of 2-nitroaniline. These results show that the MgAl2Si2O8 : M0.01 catalysts can be used in practical applications in the reduction of nitroanilines.

  6. Atomistic modeling of ternary additions to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt and Ni-Ti-Hf shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mosca, H.O., E-mail: hmosca@cnea.gov.ar [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, B1650KNA San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina); Bozzolo, G. [Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210 (United States); Grosso, M.F. del [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, B1650KNA San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, CONICET (Argentina)

    2012-08-15

    The behavior of ternary and quaternary additions to NiTi shape memory alloys is investigated using a quantum approximate method for the energetics. Ternary additions X to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt, and Ni-Ti-Hf alloys, for X=Au, Pt, Ir, Os, Re, W, Ta,Ag, Pd, Rh, Ru, Tc, Mo, Nb, Zr, Zn, Cu, Co, Fe, Mn, V, Sc, Si, Al and Mg are considered. Bulk properties such as lattice parameter, energy of formation, and bulk modulus of the B2 alloys are studied for variations due to the presence of one or two simultaneous additives.

  7. P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I, Ir(I, Pt(II, and Au(I Complexes Bearing P-Fluorous Phosphine Ligands

    Directory of Open Access Journals (Sweden)

    Shin-ichi Kawaguchi

    2017-01-01

    Full Text Available P-Fluorous phosphine (R2PRf, in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a promising ligand because it has a hybrid functionality, i.e., electron-poor and fluorous ligands. However, examples of P-fluorous phosphine–metal complexes are still rare, most probably because the P-fluorous group is believed to decrease the coordination ability of the phosphines dramatically. In contrast, however, we have succeeded in synthesizing a series of P-fluorous phosphine–coordinated metal complexes such as rhodium, iridium, platinum, and gold. Furthermore, the electronic properties of R2PnC10F21 are investigated by X-ray analysis of PtCl2(Ph2PnC10F212 and the infrared CO stretching frequency of RhCl(CO(R2PnC10F212. IrCl(CO(Ph2PnC10F212- and AuCl(R2PnC10F21-catalyzed reactions are also demonstrated.

  8. New methods of controlled monolayer-to-multilayer deposition of Pt for designing electrocatalysts at an atomic level

    Directory of Open Access Journals (Sweden)

    J. X. WANG

    2001-12-01

    Full Text Available Two new methods for monolayer-to-multileyer Pt deposition are presented. One involves Pt deposition by the replacement of an UPD metal monolayer on an electrode surface and the other the spontaneous deposition of Pt on Ru. The first method, exemplified by the replacement of a Cu monolayer on a Au(111 surface, occurs as a spontaneous irreversible redox reaction in which the Cu monolayer is oxidized by Pt cations, which are reduced and simultaneously deposited. The second method is illustrated by the deposition of Pt on a Ru(0001 surface and on carbon-supported Ru nanoparticles. This deposition takes place upon immersion of a UHV-prepared Ru(0001 crystal or Ru nanoparticles, reduced in H2, in a solution containing PtCl62- ions. The oxidation of Ru to RuOH by a local cell mechanism appears to be coupled with Pt deposition. This method facilitates the design of active Pt-Ru catalysts with ultimately low Pt loadings. Only a quarter of a monolayer of Pt on Ru nanoparticles yields an electrocatalyst with higher activity and CO tolerance for H2/CO oxidation than commercial Pt-Ru alloy electrocatalysts with considerably higher Pt loadings.

  9. Enthalpies of Formation of Noble Metal Binary Alloys Bearing Rh or Ir

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formationof random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or lr. The presentresults are in good agreement with those of Miedema theory, available experiments and the first-principles quantummechanics calculations. The present results indicate that Cu-Rh, Cu-lr, Ag-Rh, Ag-lr, Au-Rh, Au-lr, Pd-Rh and Pd-lrsystems are repulsive, however, Ni-Rh, Ni-lr, Pt-lr, Pt-Rh and Rh-lr systems form solid solutions and Ni-Rh, Ni-lrand Pt-Rh show ordering tendency.

  10. Methanol Electrooxidation on Smooth Platinum Modified with Ru: the Influence of Ru Coverage and Potentials on Oxidative Current and Products

    Institute of Scientific and Technical Information of China (English)

    WANG, Hong-Sen

    2003-01-01

    Methanol oxidation on smooth Pt electrode modified with different coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current efficiency of formed CO2 was calculated from faraday current and ion current of m/z = 44. The results show that Ru modified Pt electrode with the coverage of ca. 0.3 has the highest catalytic activity for methanol electrooxidation, I.e. Faraday current and the current efficiency of CO2at the low potentials reach to the maximum. In addition, Ru loses its co-catalytic properties at the high potentials.

  11. Electronic structures and vibrational properties of coronene on Ru(0001): first-principles study

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu-Yang; Du Shi-Xuan; Gao Hong-Jun

    2012-01-01

    We calculate the configurations,electronic structures,vibrational properties at the coronene/Ru(0001) interface,and adsorption of a single Pt atom on coronene/Ru(0001) based on density functional theory calculations.The geometric structures and electronic structures of the coronene on Ru(0001) are compared with those of the graphene/Ru(0001).The results show that the coronene/Ru(0001) can be a simplified model system used to describe the interaction between graphene and ruthenium.Further calculations of the vibrational properties of coronene molecule adsorbed on Ru(0001)suggest that the phonon properties of differently corrugated regions of graphene on Ru(0001) are different.This model system is also used to investigate the selective adsorption of Pt atoms on graphene/Ru(0001).The configurations of Pt on coronene/Ru(0001) with the lowest binding energy give clues to explain the experimental observation that a Pt cluster selectively adsorbs on the second highest regions of graphene/Ru(0001).This work provides a simple model for understanding the adsorption properties and vibrational properties of graphene on Ru(0001) substrate.

  12. Structure and catalytic reactivity of Rh oxides

    DEFF Research Database (Denmark)

    Gustafson, J.; Westerström, R.; Resta, A.;

    2009-01-01

    Using a combination of experimental and theoretical techniques, we show that a thin RhO2 surface oxide film forms prior to the bulk Rh2O3 corundum oxide on all close-packed single crystal Rh surfaces. Based on previous reports, we argue that the RhO2 surface oxide also forms on vicinal Rh surfaces...... as well as on Rh nanoparticles. The detailed structure of this film was previously determined using UHV based techniques and density functional theory. In the present paper, we also examine the structure of the bulk Rh2O3 corundum oxide using surface X-ray diffraction. Being armed with this structural...... surface oxide film. In the case of Pt25Rh75(1 0 0), our measurements demonstrate that the formation of bulk Rh2O3 corundum oxide poisons the reaction, and argue that this is also valid for all other Rh surfaces. Our study implies that the CO oxidation reaction over Rh surfaces at realistic conditions...

  13. Electrodeposition and electrocatalytic activity of Pt and Pt-alloy nanoparticles and thin films on highly oriented pyrolytic graphite (HOPG)

    Science.gov (United States)

    Lu, Guojin

    Pt and Pt-based alloy catalysts were synthesized by electrodeposition on HOPG. The nucleation and growth, morphology, composition and crystal structure, and electrocatalytic activity (towards relevant reactions in the frame of PEMFCs and DMFCs) of these model electrodes were systematically investigated. The presence of chlorides inhibits the Pt reduction processes. There is a transition from progressive to instantaneous nucleation with increasing overpotential for the deposition from 1 mM H2PtCl6 electrolytes. The possibility of instantaneous nucleation at large overpotential by using electrolytes with large chloride concentration is advantageous for the growth of small, well dispersed nanoparticles. The electrochemical data were confirmed by AFM and SEM imaging studies. Relatively narrow size distributed nanoparticles can be obtained from the current system. While MOR activity decreases with decreasing particle size, the HER and HOR activity of deposited Pt particles increases with decreasing deposition period. The ORR activity first increases then decreases with increasing deposition time. Interactions between Pt and Ru, or Ni or Co are observed and they form solid solution as verified by XRD. Underpotential deposition occurs for Pt-Ni or Pt-Co co-electrodeposition. Pt-Ru deposition can be described as progressive nucleation at low overpotential and instantaneous nucleation at high overpotentials. Through direct morphological observations, the Pt-Ni or Pt-Co nucleation can be approximately described as progressive. Pt-Ru deposits are superior to Pt towards MOR. The optimum Ru content is about 50 at.%. Pt-Ni and Pt-Co deposits are more active than Pt for ORR. The optimum content is about 30 at.% Ni or 50 at.% Co. Dealloying of Pt-Ru and Pt-Ni or Pt-Co electrodeposit is observed after electrochemical characterization. The extent of dealloying increases with the content of the alloying element.

  14. First-principle investigation of the interactions between PtxRu55-x (x = 0, 13, 42, 55) nanoparticles and [BMIM][PF6] ionic liquid

    Science.gov (United States)

    Cheng, Ping; Liu, Chuan; Yang, Yongpeng; Huang, Shiping

    2015-05-01

    Density functional theory calculations have been performed to characterize the interactions between [BMIM][PF6] ionic liquid and icosahedral PtxRu55-x (x = 0, 13, 42, 55) nanoparticles. In Ru13Pt42-[BMIM][PF6], only one F atom of the anion form the bond with nanoparticle, resulting in the smallest interaction energy (-0.56 eV). While in Pt13Ru42-[BMIM][PF6], two F atoms of the anion together with two C atoms of cation form the bonds with nanoparticle, resulting in the biggest interaction energy (-10.65 eV). The interaction between [BMIM][PF6] and Pt13Ru42 is so strong that it induces a significant distortion in the original core-shell structure of Pt13Ru42. Moreover, after interacting with [BMIM][PF6], the Pt55, Pt13Ru42 and Ru55 nanoparticles become more stable based on the negative relaxation energy. The d-band centers of Pt13Ru42 and Ru55 shift from -1.90, -1.78 eV up to -1.78, -1.56 eV, suggesting that the catalytic activities of Pt13Ru42 and Ru55 are enhanced.

  15. Living with Rh Incompatibility

    Science.gov (United States)

    ... Living With Rh Incompatibility If you have Rh-negative blood, injections of Rh immune globulin can reduce your ... baby or come in contact with Rh-positive blood. If you're Rh-negative, your risk of problems from Rh incompatibility is ...

  16. Pressure-induced instability of magnetic order in Kondo-lattice system. Neutron diffraction study of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2

    CERN Document Server

    Watanabe, K; Kanadani, C; Taniguchi, T; Kawarazaki, S; Uwatoko, Y; Kadowaki, H

    2003-01-01

    Neutron diffraction experiments have been carried out to study the nature of the magnetic order of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2. Response of the ordered atomic magnetic moment, mu, the transition temperature, T sub N , and the magnitude of the magnetic modulation vector, q, to the chemical pressure and also to the applied hydrostatic pressure, P, were examined at low temperatures. When y changes, all of mu, T sub N and q show a sudden alteration of the manner of the y-dependence at around y - 0.08. The P-dependence of q shows quite different features for different y's of 0.0, 0.2 and 0.25. On the basis of these observations the possibility of a pressure-induced alternation of the magnetic regime of the order is discussed. (author)

  17. ICP-MS Determination of Pt, Pd and Rh in Catalysts for Auto-exhaust-gas Purifier%电感耦合等离子体质谱法测定汽车尾气净化催化剂中铂、钯、铑含量

    Institute of Scientific and Technical Information of China (English)

    熊传信; 施意华; 杨仲平; 邱丽

    2011-01-01

    Sample of catalysts for auto-exhaust-gas purifier was fused with Na2 O2, and the melt was dissolved in hot water and acidified with HCL An aliquot of the sample solution was taken for ICP-MS determination of Pt, Pd and Rh. 111Cd and 203Tl were used as internal standards. Values of detection limit (3s) of Pt, Pd and Rh found were 0. 048, 0. 056, 0. 019 μg . G-1 respectively. The proposed method was used in the analysis of 5 catalyst samples, the results obtained were in conformity with those obtained by photometry. Values of recovery and RSD's (n=12) found were 100. 0% and 1. 3% for Pt, 100. 0% and 1. 0% for Pd, 99. 8% and 1. 6% for Rh respectively.%汽车尾气净化催化剂样品经过氧化钠熔融,用热水浸出,加入盐酸酸化后,分取部分试液用电感耦合等离子体质谱法测定其中铂、钯、铑的含量.选择镉(11Cd)和铊(203Tl)作为内标元素.铂、钯、铑的检出限(3s)分别为0.048,0.056,0.019μg·g-1.方法用于5件催化剂样品的分析,测定结果与光度法测定结果相一致.铂、钯、铑的平均回收率分别为100.0%,100.0%,99.8%;相对标准偏差(n=12)分别为1.3%,1.0%,1.6%.

  18. Rh Incompatibility (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Rh Incompatibility KidsHealth > For Parents > Rh Incompatibility Print A ... this information early in your pregnancy. About the Rh Factor People with different blood types have proteins ...

  19. Fabrication of metal nanoclusters on graphene grown on Ru(0001)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; FU Qiang; CUI Yi; TAN DaLi; BAO XinHe

    2009-01-01

    Monolayer graphene was epitaxially grown on Ru(0001) through exposure of the Ru(0001) to ethylene at room temperature followed by annealing in ultrahigh vacuum at elevated temperatures. The resulting graphene structures were studied by scanning tunneling microscopy (STM), X-ray photoelectron spec-troscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). The graphene/Ru(0001) surface was used as a periodic template for growth of metal nanoclusters. Highly dispersed Pt clusters with well controlled size and spatial distribution were fabricated on the surface.

  20. Direct neutron decay of analogue resonances in 105Rh

    Institute of Scientific and Technical Information of China (English)

    Hu Bi-Tao; P.P.Zarubin; U.U.Juravlev

    2006-01-01

    A new method, while takes into account the contribution of direct neutron decay of analogue resonances to the isomeric ratio resulting from (p,n) reaction, is used to analyse the published experimental data for the reaction 104Ru(p,n)104Rh and also estimate a minimum probability of direct decay.

  1. Electrocatalytic activity of atomic layer deposited Pt–Ru catalysts onto N-doped carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Anne-Charlotte Elisabeth Birgitta; Larsen, Jackie Vincent; Verheijen, Marcel A.

    2014-01-01

    (ethylcyclopentadienyl)ruthenium (Ru(EtCp)2), respectively. O2 was used as the reactant in both processes. The composition of the catalysts was easily tuned by varying the Pt-to-Ru ALD cycle ratio. The catalysts were tested toward the CO oxidation and methanol oxidation reaction (MOR) in a three-electrode electrochemical set...

  2. 甲醇在欠电位沉积Ru修饰Pt电极上的催化氧化%Methanol Oxidation on a Pt Electrode Modified by Underpotential Deposition of Ru

    Institute of Scientific and Technical Information of China (English)

    李兰兰; 魏子栋; 严灿; 罗义辉; 尹光志; 孙才新

    2007-01-01

    采用欠电位沉积(upd)方法在Pt表面沉积亚单层的Ru制备出upd-Ru/Pt电极.通过欠电位沉积前后电极在0.5 mol·L-1 H2SO4溶液中循环伏安图-152-128 mV(vs Ag/AgCl)电位范围内对氢区的数值积分确定Pt表面Ru的覆盖度.用电化学方法测试了甲醇在upd-Ru/Pt电极上的催化氧化,并讨论分析了欠电位沉积电位和Ru的表面覆盖度对甲醇氧化的影响.结果表明,Ru能够欠电位沉积到Pt表面.Pt表面欠电位沉积少量的Ru即能大大促进甲醇的氧化.只要控制upd-Ru的沉积量,upd-Ru原子就能大大促进甲醇氧化而与沉积电位无关.Ru原子对甲醇氧化的促进作用与Ru和Pt是否形成合金无关,而取决于Ru在Pt表面的百分含量.

  3. Convergent study of Ru-ligand interactions through QTAIM, ELF, NBO molecular descriptors and TDDFT analysis of organometallic dyes

    Science.gov (United States)

    Sánchez-Coronilla, Antonio; Sánchez-Márquez, Jesús; Zorrilla, David; Martín, Elisa I.; de los Santos, Desireé M.; Navas, Javier; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Martín-Calleja, Joaquín

    2014-08-01

    We report a theoretical study of a series of Ru complexes of interest in dye-sensitised solar cells, in organic light-emitting diodes, and in the war against cancer. Other metal centres, such as Cr, Co, Ni, Rh, Pd, and Pt, have been included for comparison purposes. The metal-ligand trends in organometallic chemistry for those compounds are shown synergistically by using three molecular descriptors: quantum theory of atoms in molecules (QTAIM), electron localisation function (ELF) and second-order perturbation theory analysis of the natural bond orbital (NBO). The metal-ligand bond order is addressed through both delocalisation index (DI) of QTAIM and fluctuation index (λ) of ELF. Correlation between DI and λ for Ru-N bond in those complexes is introduced for the first time. Electron transfer and stability was also assessed by the second-order perturbation theory analysis of the NBO. Electron transfer from the lone pair NBO of the ligands toward the antibonding lone pair NBO of the metal plays a relevant role in stabilising the complexes, providing useful insights into understanding the effect of the 'expanded ligand' principle in supramolecular chemistry. Finally, absorption wavelengths associated to the metal-to-ligand charge transfer transitions and the highest occupied molecular orbital (HOMO)--lowest unoccupied molecular orbital (LUMO) characteristics were studied by time-dependent density functional theory.

  4. RuS2-OsS2-IrS2的类质同象矿物系列和PdS-PtS矿物系列

    Institute of Scientific and Technical Information of China (English)

    任英忱; 邓禹仁

    1973-01-01

    Based on the results from, studies of minerals belonging to these two systems ,and by reference to pertinent data available, the authors are of thc following opinious: The system RiS2-Os4S2-IrS2 is a complete isomorphous series. Unit cell parameters and physical properties of the mincrals vary with chemical compositions in a systematic manner. PdS-FtS is a limited isomorphous series. Two groups, cooperite [including(Pd0-0.113Pt1-0.387)1.00S1.00] platinum.bearing palladium sulfides [chemical formula(Pd0.86-0.39Pt0.14-0.61)1.00S1.00] can be distinguished within this system. Beeause of differences in crystal structures between the two groups, which is also responsible for the significant differences in physical properties of these minerals, the system PdS-PtS is discontinuous, but each group itself constitutes a complete isomorphous series.

  5. Electrochemical evaluation of Pt-Based binary catalysts on various supports for the direct methanol fuel cell

    CSIR Research Space (South Africa)

    Khotseng, L

    2016-01-01

    Full Text Available patterns similar to that of the Pt/C electrocatalyst, an indication that the catalysts have predominantly the Pt face-centered cubic (fcc) crystal structure. High-resolution transmission electron microscopy (HRTEM) images showed spherical PtRu and Pt...

  6. Ru isotope heterogeneity in the solar protoplanetary disk

    Science.gov (United States)

    Fischer-Gödde, Mario; Burkhardt, Christoph; Kruijer, Thomas S.; Kleine, Thorsten

    2015-11-01

    Nucleosynthetic isotope anomalies in bulk chondrites and differentiated meteorites reflect variable proportions of isotopically diverse presolar components in bulk planetary bodies, but the origin of these heterogeneities is not well understood. Here, the Ru isotope composition of a comprehensive suite of iron meteorites and bulk samples of ordinary, enstatite and carbonaceous chondrites, as well as acid leachates and an insoluble residue of the Allende chondrite are examined using newly developed multi-collector inductively coupled plasma mass spectrometry techniques. Except for IAB iron meteorites and enstatite chondrites, all investigated meteorites show well-resolved Ru isotope anomalies. Of these, within-group Ru isotopic variations observed for samples from a given chemical group of iron meteorites reflect secondary neutron capture induced Ru isotope shifts during prolonged cosmic ray-exposure. After correction of these cosmogenic effects using Pt isotopes as a neutron-dose monitor, the remaining Ru isotope anomalies are nucleosynthetic in nature and are consistent with a deficit in s-process Ru in iron meteorite parent bodies. Similarly, Ru isotope anomalies in bulk ordinary and carbonaceous chondrites also reflect a deficiency in s-process Ru. The sequential dissolution of Allende reveals the presence of an HF-soluble s-process carrier, which is either an unidentified presolar phase or a component that incorporated s-process Ru liberated from SiC grains during nebular or parent body processes. We show that varying proportions of the s-process carrier identified in Allende resulted in the correlated Ru isotope anomalies observed for bulk meteorites, and that all meteorites (except possibly IAB irons and enstatite chondrites) are depleted in this s-process component relative to Ru from the Earth's mantle. Bulk meteorites exhibit correlated Ru and Mo isotope anomalies, reflecting variable deficits of a common s-process component, but some iron meteorites and

  7. Investigation of nano Pt and Pt-based alloys electrocatalysts for direct methanol fuel cells and their properties

    Directory of Open Access Journals (Sweden)

    Chunguang Suo

    2014-03-01

    Full Text Available The electrocatalysts used in micro direct methanol fuel cell (μDMFC, such as Pt/C and Pt alloy/C, prepared by liquid-phase NaBH4 reduction method have been investigated. XC-72 (Cobalt corp. Company, U.S.A is chosen as the activated carrier for the electrocatalysts to keep the catalysts powder in the range of several nanometers. The XRD, SEM, EDX analyses indicated that the catalysts had small particle size in several nanometers, in excellent dispersed phase and the molar ratio of the precious metals was found to be optimal. The performances of the DMFCs using cathodic catalyst with Pt percentage of 30wt% and different anodic catalysts (Pt-Ru, Pt-Ru-Mo were tested. The polarization curves and power density curves of the cells were measured to determine the optimal alloy composition and condition for the electrocatalysts. The results showed that the micro direct methanol fuel cell with 30wt% Pt/C as the cathodic catalyst and n(Pt:n(Ru:n(Mo = 3:2:2 PtRuMo/C as the anodic catalyst at room temperature using 2.0mol/L methanol solution has the best performances.

  8. Rh Factor Blood Test

    Science.gov (United States)

    Tests and Procedures Rh factor blood test By Mayo Clinic Staff Rhesus (Rh) factor is an inherited protein found on the surface of ... If your blood has the protein, you're Rh positive. If your blood lacks the protein, you' ...

  9. Electrochemical oxidation of methanol on Pt/(RuxSn1-xO2 nanocatalyst

    Directory of Open Access Journals (Sweden)

    Krstajić Mila N.

    2013-01-01

    Full Text Available The Ru-doped SnO2 powder, (RuxSn1-xO2, with the Sn:Ru atomic ratio of 9:1 was synthesized and used as a support for Pt nanoparticles (30 mass% loading. The (RuxSn1-xO2 support and Pt/(RuxSn1-xO2 catalyst were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM. (RuxSn1-xO2 was found to be two-phase material consisting of probably solid solution of RuO2 in SnO2 and pure RuO2. The average Pt particle size determined by TEM was 5.3 nm. Cyclic voltammetry of Pt/(RuxSn1-xO2 indicated good conductivity of the sup-port and displayed usual features of Pt. The results of the electrochemical oxidation of COads and methanol on Pt/(RuxSn1-xO2 were compared with those on commercial Pt/C and PtRu/C catalysts. Oxidation of COads on Pt/(RuxSn1-xO2 starts at less positive potentials than on PtRu/C and Pt/C. Potentiodynamic polarization curves and chronoamperometric curves of methanol oxidation indicated higher initial activity of Pt/(RuxSn1-xO2 catalyst compared to PtRu/C, but also a greater loss in the current density over time. Potentiodynamic stability test of the catalysts revealed that deactivation of the Pt/(RuxSn1-xO2 and Pt/C was primarily caused by the poisoning of Pt surface by the methanol oxidation residues, which mostly occurred during the first potential cycle. In the case of PtRu/C the poisoning of the surface was minor and deactivation was caused by the PtRu surface area loss. [Projekat Ministarstva nauke Republike Srbije, br. ON-172054

  10. Preparation of Pt–Ru/C as an Oxygen-Reduction Electrocatalyst in Microbial Fuel Cells for Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Gaixiu Yang

    2016-09-01

    Full Text Available Carbon-supported Pt–Ru alloys with a Pt/Ru ratio of 1:1 were prepared by NaBH4 reduction at room temperature. X-ray diffraction (XRD measurements indicate that the as-prepared Pt–Ru nanoparticles had a face-centered cubic (fcc structure. X-ray photoelectron spectroscopy (XPS analyses demonstrate that alloying with Ru can decrease the 4f electron density of Pt, which results in a positive binding energy shift of 0.2 eV for the Pt 4f peaks. The catalytic properties of the synthesized Pt–Ru alloy catalysts were compared with those of commercial Pt/C catalysts by linear sweep voltammetry (LSV. The results show that the mass activity of the oxygen reduction reaction (ORR is enhanced by 2.3 times as much mass activity of Pt relative to the commercial Pt/C catalyst. Single-chambered microbial fuel cell tests also confirm that the Pt–Ru alloys as cathode catalysts have better performance than that of commercial Pt/C catalysts.

  11. Low-Pt-Content Anode Catalyst for Direct Methanol Fuel Cells

    Science.gov (United States)

    Narayanan, Sekharipuram; Whitacre, Jay

    2008-01-01

    Combinatorial experiments have led to the discovery that a nanophase alloy of Pt, Ru, Ni, and Zr is effective as an anode catalyst material for direct methanol fuel cells. This discovery has practical significance in that the electronic current densities achievable by use of this alloy are comparable or larger than those obtained by use of prior Pt/Ru catalyst alloys containing greater amounts of Pt. Heretofore, the high cost of Pt has impeded the commercialization of direct methanol fuel cells. By making it possible to obtain a given level of performance at reduced Pt content (and, hence, lower cost), the discovery may lead to reduction of the economic impediment to commercialization.

  12. Ru dye functionalized Au-SiO2@TiO2 and Au/Pt-SiO2@TiO2 nanoassemblies for surface-plasmon-induced visible light photocatalysis.

    Science.gov (United States)

    Theil, Frank; Dellith, Andrea; Dellith, Jan; Undisz, Andreas; Csáki, Andrea; Fritzsche, Wolfgang; Popp, Jürgen; Rettenmayr, Markus; Dietzek, Benjamin

    2014-05-01

    The most commonly used material in photocatalysis is TiO2. Since TiO2 absorbs only UV-light, photosensitizers are used to extend these catalysts' absorption properties into the Vis/NIR spectral range. In this work we merge the commonly used approach of dye sensitization with the only recently developed approach of functionalizing the catalyst with plasmonically active metal nanoparticles in order to achieve synergistic effects between these two types of visible light sensitization. To this end SiO2@TiO2 nanostructures are functionalized with gold nanoparticles or a combination of gold/platinum nanoparticles loaded with Ru dyes and thoroughly characterized by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) imaging as well as energy dispersive X-ray spectroscopy (EDX), UV/VIS and surface enhanced resonance Raman scattering (SERRS) spectroscopy. The photocatalytic performance is tested by applying the benchmark experiment of methylene blue degradation. Spectroscopic investigations and electron microscopy proof the successful synthesis of the envisioned structure. The photocatalytic activity of the nanostructures shows up to 52% higher first order rate constants compared to the corresponding nanostructures without further dye functionalization.

  13. Electrocatalysis of fuel cells reaction on Pt and Pt-bimetallic anode catalysts: A selective review

    Directory of Open Access Journals (Sweden)

    Stamenković Vojislav

    2002-01-01

    Full Text Available In this review we selectively summarize recent progress, primarily from our laboratory, in the development of interrelationships between the kinetics of the fuel cells reactions and the structure/composition of anode catalysts. The focus is placed on two types of metallic surfaces: platinum single crystals and bimetallic surfaces based on Pt. In the first part it was illustrated that the hydcogen reaction is structure sensitive process, with Pt(110 being an order of magnitude more active than either of the atomically "flatter" (100 and (111 surfaces. The hydrogen reaction on Pt(hkl modified by pseudomorphic Pd (submonolayers shows the "volcano-like" behavior, having the maximum rate on Pt(111 modified by 1 ML of Pd. The Pt(111-Pd system is used to demonstrate how the energetics of intermediates formed in the hydrogen reaction is affected by interfacial bonding and energetic constraints produced between pseudomorphic Pd films and the Pt(111 substrate. In the second part it was shown that the oxidation of Ha in the presence of CO occurs concurrently with CO oxidation on Pt and Pt bimetallic surfaces. The Pt-Ru system is used to demonstrate that both the bifunctional effect and the ligand effect contribute to the influence of Ru on the CO oxidation rate and for Hz oxidation process in the presence of CO. The knowledge is then used to create the real-life catalyst with the catalytic activities which are, to the greatest extend possible similar to the tailor-made surface.

  14. Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts for ethanol electro-oxidation in alkaline medium

    CSIR Research Space (South Africa)

    Modibedi, RM

    2011-04-01

    Full Text Available the coverage of the adsorbed ethoxy (CH3COads) species on the nanocatalyst surface, thus yielding an increase in current density. Pd-Sn/C displayed better electrocatalytic activity and stability towards poisoning than Pd-Ru-Sn/C and Pt-Ru/C (E-TEK Inc...

  15. Identification of {sup 166}Pt and {sup 167}Pt

    Energy Technology Data Exchange (ETDEWEB)

    Bingham, C.R.; Toth, K.S.; Batchelder, J.C.; Blumenthal, D.J.; Brown, L.T.; Busse, B.C.; Conticchio, L.F.; Davids, C.N.; Davinson, T.; Henderson, D.J.; Irvine, R.J.; Seweryniak, D.; Walters, W.B.; Woods, P.J.; Zimmerman, B.E. [The University of Tennessee, Knoxville, Tennessee 37996 (United States)]|[Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)]|[Louisiana State University, Baton Rouge, Louisiana 70803 (United States)]|[Argonne National Laboratory, Argonne, Illinois 60439 (United States)]|[Vanderbilt University, Nashville, Tennessee 37235 (United States)]|[Oregon State University, Corvallis, Oregon 97331 (United States)]|[University of Maryland, College Park, Maryland 20742 (United States)]|[Edinburgh University, Edinburgh, EH9 3JZ (United Kingdom)

    1996-07-01

    In a series of {sup 78}Kr bombardments of {sup 92}Mo the new isotopes {sup 166}Pt and {sup 167}Pt were identified via their {alpha}-decay properties. The {alpha}-decay energies and half-lives of these two nuclides are as follows. (1) {sup 166}Pt, {ital E}{sub {alpha}} = 7110(15) keV, {ital T}{sub 1/2} = 0.3(1) ms, and (2) {sup 167}Pt, {ital E}{sub {alpha}} = 6988(10) keV, {ital T}{sub 1/2} = 0.7(2) ms. Also, the half-life of {sup 168}Pt, which was previously unknown, was determined to be 2.0(4) ms. In a separate but concurrent experiment involving {sup 78}Kr + {sup 96}Ru reactions, {sup 170}Pt was made and a half-life of 14.7(5) ms was measured for it; the one published value is 6{sub {minus}2}{sup +5} ms. Results for {sup 162{minus}164}Os contained in the same data sets were also analyzed and by using mother-daughter correlations, the {alpha} branches of {sup 162,163,164}Os were established to be near 100{percent}. {copyright} {ital 1996 The American Physical Society.}

  16. Highly Active and Stable MgAl2O4 Supported Rh and Ir Catalysts for Methane Steam Reforming: A Combined Experimental and Theoretical Study

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Donghai; Glezakou, Vassiliki Alexandra; Lebarbier, Vanessa MC; Kovarik, Libor; Wan, Haiying; Albrecht, Karl O.; Gerber, Mark A.; Rousseau, Roger J.; Dagle, Robert A.

    2014-07-01

    In this work we present a combined experimental and theoretical investigation of stable MgAl2O4 spinel-supported Rh and Ir catalysts for the steam methane reforming (SMR) reaction. Firstly, catalytic performance for a series of noble metal catalysts supported on MgAl2O4 spinel was evaluated for SMR at 600-850°C. Turnover rate at 850°C follows the order: Pd > Pt > Ir > Rh > Ru > Ni. However, Rh and Ir were found to have the best combination of activity and stability for methane steam reforming in the presence of simulated biomass-derived syngas. It was found that highly dispersed ~2 nm Rh and ~1 nm Ir clusters were formed on the MgAl2O4 spinel support. Scanning Transition Electron Microscopy (STEM) images show that excellent dispersion was maintained even under challenging high temperature conditions (e.g. at 850°C in the presence of steam) while Ir and Rh catalysts supported on Al2O3 were observed to sinter at increased rates under the same conditions. These observations were further confirmed by ab initio molecular dynamics (AIMD) simulations which find that ~1 nm Rh and Ir particles (50-atom cluster) bind strongly to the MgAl2O4 surfaces via a redox process leading to a strong metal-support interaction, thus helping anchor the metal clusters and reduce the tendency to sinter. Density functional theory (DFT) calculations suggest that these supported smaller Rh and Ir particles have a lower work function than larger more bulk-like ones, which enables them to activate both water and methane more effectively than larger particles, yet have a minimal influence on the relative stability of coke precursors. In addition, theoretical mechanistic studies were used to probe the relationship between structure and reactivity. Consistent with the experimental observations, our theoretical modeling results also suggest that the small spinel-supported Ir particle catalyst is more active than the counterpart of Rh catalyst for SMR. This work was financially supported by the

  17. Determination of the half-life of sup 1 sup 0 sup 5 sup m Rh

    CERN Document Server

    Kronenberg, A K; Weber, R; Esterlund, R A; Patzelt, P

    1998-01-01

    Following a fast chemical separation of Ru isotopes from a fission-product mixture, sup 1 sup 0 sup 5 sup m Rh was periodically extracted from its precursor (4.44-h sup 1 sup 0 sup 5 Ru) for measurements of its half-life. The new value for the T sub 1 sub / sub 2 of sup 1 sup 0 sup 5 sup m Rh of (43.0+-0.3) s resolves the long-standing conflict in the literature between the two earlier measured values of 45 and 30 s.

  18. RH Mixing observable?

    CERN Document Server

    Achiman, Yoav

    1999-01-01

    Asymmetric mass matrices can induce large RH mixings. Those are non -measurable in the SM but are there and play an important role in its extensions. The RH rotations are in particular relevant for the proton decay, neutrino properties and baryon asymmetry. E.g. large RH mixings lead to kaon dominated proton decay even without SUSY and could be the reason for a large neutrino mixing. By studying those phenomena one can learn about the RH rotation matrices and this can reduce considerably the arbitrariness in the present fermionic mass study.

  19. Obtención y caracterización de MEAs con aleaciones amorfas de base NiNbPtX como catalizadores para celdas de combustibles PEM

    OpenAIRE

    Ruiz Jiménez, Noelia

    2014-01-01

    Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada. Fecha de lectura: 23-05-2014 En la presente tesis, se ha realizado un estudio comparativo, en primer lugar, entre dos tipos de monoceldas, de 9 cm2 y de 25 cm2. En ambas se han empleado catalizadores amorfos de composición general Ni59Nb40Pt1-xYx (x= 0 ó 0.4% at.; Y= Ru, Sn, Pd, Rh, Co) como ánodos y como cátodos. Se han soportado en tres tipos de membranas de i...

  20. Ru(ii)-Catalyzed C-H activation and annulation of salicylaldehydes with monosubstituted and disubstituted alkynes.

    Science.gov (United States)

    Baruah, Swagata; Kaishap, Partha Pratim; Gogoi, Sanjib

    2016-10-27

    The Ru(ii)-catalyzed C-H activation and annulation reaction of salicylaldehydes and disubstituted alkynes affords chromones in high yields. This reaction also works with terminal alkynes and tolerates a wide range of sensitive functional groups. The selectivity pattern of this Ru(ii)-catalyzed annulation reaction is different from the known Au(i), Rh(iii)-catalyzed annulation reactions of salicylaldehydes and terminal alkynes.

  1. Construction of a visible light-driven hydrocarboxylation cycle of alkenes by the combined use of Rh(i) and photoredox catalysts.

    Science.gov (United States)

    Murata, Kei; Numasawa, Nobutsugu; Shimomaki, Katsuya; Takaya, Jun; Iwasawa, Nobuharu

    2017-03-09

    A visible light driven catalytic cycle for hydrocarboxylation of alkenes with CO2 was established using a combination of a Rh(i) complex as a carboxylation catalyst and [Ru(bpy)3](2+) (bpy = 2,2'- bipyridyl) as a photoredox catalyst. Two key steps, the generation of Rh(i) hydride species and nucleophilic addition of π-benzyl Rh(i) species to CO2, were found to be mediated by light.

  2. Selective deposition of Pt onto supported metal clusters for fuel cell electrocatalysts

    Science.gov (United States)

    Jeon, Tae-Yeol; Pinna, Nicola; Yoo, Sung Jong; Ahn, Docheon; Choi, Sun Hee; Willinger, Marc-Georg; Cho, Yong-Hun; Lee, Kug-Seung; Park, Hee-Young; Yu, Seung-Ho; Sung, Yung-Eun

    2012-09-01

    We report a new method for deposition of Pt on a metal core to develop real electrocatalysts with significantly reduced amounts of expensive Pt as well as enhanced activity for oxygen reduction reaction. Ru and Pd have different crystal structures and modify the electronic structure of Pt to a different extent (shifts in d-band center). They were chosen as core materials to examine whether hydroquinone dissolved in ethanol can be used to deposit additional Pt atoms onto preformed core nanoparticles, and whether the modified d-character of Pt on different host metals can result in the enhanced ORR activity. The physicochemical characteristics of Pd-Pt and Ru-Pt core-shell nanoparticles are investigated. The core-shell structure was identified through a combination of experimental methods, employing electron microscopy, electrochemical measurements, and synchrotron X-ray measurements such as powder X-ray diffraction, X-ray absorption fine structure, and X-ray photoelectron spectroscopy. The hydroquinone reduction method proved to be an excellent route for the epitaxial growth of a Pt shell on the metal cores, leading to enhanced ORR activities.We report a new method for deposition of Pt on a metal core to develop real electrocatalysts with significantly reduced amounts of expensive Pt as well as enhanced activity for oxygen reduction reaction. Ru and Pd have different crystal structures and modify the electronic structure of Pt to a different extent (shifts in d-band center). They were chosen as core materials to examine whether hydroquinone dissolved in ethanol can be used to deposit additional Pt atoms onto preformed core nanoparticles, and whether the modified d-character of Pt on different host metals can result in the enhanced ORR activity. The physicochemical characteristics of Pd-Pt and Ru-Pt core-shell nanoparticles are investigated. The core-shell structure was identified through a combination of experimental methods, employing electron microscopy

  3. Nitrogen Scattering at Ru Surfaces

    NARCIS (Netherlands)

    Zaharia, T.; Ueta, H.; Kleyn, A.W.; Gleeson, M.A.

    2013-01-01

    Results on the scattering of hyperthermal N2 molecules from bare and N-covered Ru(0001) surfaces are presented. These are compared with Ar scattering from the same surfaces as a reference nonreactive system. In the case of bare Ru(0001) the measured angular distributions are consistent with scatteri

  4. Nitrogen Scattering at Ru Surfaces

    NARCIS (Netherlands)

    Zaharia, T.; Ueta, H.; Kleyn, A. W.; Gleeson, M. A.

    2013-01-01

    Results on the scattering of hyperthermal N2 molecules from bare and N-covered Ru(0001) surfaces are presented. These are compared with Ar scattering from the same surfaces as a reference non-reactive system. In the case of bare Ru(0001) the measured angular distributions are consistent with scatter

  5. Nitrogen Scattering at Ru Surfaces

    NARCIS (Netherlands)

    Zaharia, T.; Ueta, H.; Kleyn, A.W.; Gleeson, M.A.

    2013-01-01

    Results on the scattering of hyperthermal N-2 molecules from bare and N-covered Ru(0001) surfaces are presented. These are compared with Ar scattering from the same surfaces as a reference non-reactive system. In the case of bare Ru(0001) the measured angular distributions are consistent with scatte

  6. Reactions of ethanol on Ru

    NARCIS (Netherlands)

    Sturm, Jacobus Marinus; Liu, Feng; Lee, Christopher James; Bijkerk, Frederik

    2012-01-01

    The adsorption and reactions of ethanol on Ru(0001) were studied with temperatureprogrammed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS). Ethanol was found to adsorb intact onto Ru(0001) below 100 K. Heating to 250 K resulted in formation of ethoxy groups, which undergo

  7. A facile and general strategy for the synthesis of porous flowerlike Pt-based nanocrystals as effective electrocatalysts for alcohol oxidation

    Science.gov (United States)

    Huang, Da-Bing; Yuan, Qiang; He, Pei-Lei; Wang, Kai; Wang, Xun

    2016-08-01

    In this paper, porous flowerlike Pt-based (Pt, PdPt, RhPt and RhPdPt) nanocrystals were successfully achieved by a simple, economic, environmentally friendly route under the same synthetic conditions at 85 °C. The electrocatalytic properties of these flowerlike Pt-based nanocrystals toward alcohols (glycol, glycerol, methanol and ethanol) oxidation were investigated and they displayed enhanced catalytic performance compared with commercial Pt black. Among them, porous Pd45.5Pt54.5 nanoflowers showed the best catalytic performance with significant mass activity and long-term stability. More importantly, the current synthesis strategy can be easily amplified to gram-scale production.In this paper, porous flowerlike Pt-based (Pt, PdPt, RhPt and RhPdPt) nanocrystals were successfully achieved by a simple, economic, environmentally friendly route under the same synthetic conditions at 85 °C. The electrocatalytic properties of these flowerlike Pt-based nanocrystals toward alcohols (glycol, glycerol, methanol and ethanol) oxidation were investigated and they displayed enhanced catalytic performance compared with commercial Pt black. Among them, porous Pd45.5Pt54.5 nanoflowers showed the best catalytic performance with significant mass activity and long-term stability. More importantly, the current synthesis strategy can be easily amplified to gram-scale production. Electronic supplementary information (ESI) available: Experimental details, digital photos, TEM, XRD, CVs, EDX and tables. See DOI: 10.1039/c6nr04927c

  8. Partial Thermodynamic Properties of gamma-(Ni,Pt)3Al in the Ni-Al-Pt System (Preprint)

    Science.gov (United States)

    2006-02-01

    phases belonging to the Cu family, Journal of Alloys and Compounds , 353, 2003, 207. 4. J. Kamm, W. Milligan, Phase stability in (Ni, Pt)3Al alloys...in the Al-Ni-Ru system by direct reaction synthesis calorimetry, Journal of Alloys and Compounds , 403(1-2), 2005, 217-222. 15 Tables Table 1

  9. RH Packaging Operations Manual

    Energy Technology Data Exchange (ETDEWEB)

    Washington TRU Solutions LLC

    2003-09-17

    This procedure provides operating instructions for the RH-TRU 72-B Road Cask, Waste Shipping Package. In this document, ''Packaging'' refers to the assembly of components necessary to ensure compliance with the packaging requirements (not loaded with a payload). ''Package'' refers to a Type B packaging that, with its radioactive contents, is designed to retain the integrity of its containment and shielding when subject to the normal conditions of transport and hypothetical accident test conditions set forth in 10 CFR Part 71. Loading of the RH 72-B cask can be done two ways, on the RH cask trailer in the vertical position or by removing the cask from the trailer and loading it in a facility designed for remote-handling (RH). Before loading the 72-B cask, loading procedures and changes to the loading procedures for the 72-B cask must be sent to CBFO at sitedocuments@wipp.ws for approval.

  10. How Is Rh Compatibility Diagnosed?

    Science.gov (United States)

    ... status, your doctor may do a test called amniocentesis. For this test, your doctor inserts a hollow ... whether the baby is Rh-positive. (Rarely, an amniocentesis can expose you to Rh-positive blood). Your ...

  11. Isolation and X-ray structures of four Rh(PCP) complexes including a Rh(I) dioxygen complex with a short O-O bond

    KAUST Repository

    Hayashi, Yukiko

    2013-07-01

    The reaction of RhCl3·H2O with tBu2P(CH2)5PtBu 2 afforded several complexes including [RhIII(H)Cl{ tBu2- P(CH2)2CH(CH2) 2PtBu2}] (1), [RhIIIHCl 2{tBu2P(CH2)5P tBu2}]2 (2), [RhICl{ tBu2P(CH2)2CH=CHCH2P tBu2}] (3) and [RhICl{tBu 2PCH2C(O)CH=CHCH2PtBu2}] (4). X-ray crystal structures of 3 and 4 showed that the C=C bond on the C 5 unit of tBu2P(CH2) 5PtBu2 is bound to Rh(I) in a η2 configuration. In 4, the Rh atom has a trigonal pyramidal coordination geometry. The X-ray crystal structure of 2 consists of two rhodium( III) centers bridged by two tBu2P(CH2)5P tBu2 ligands with two phosphorus atoms, one from each ligand, trans to one another. The crystal structure of the rhodium oxygen adduct with 1,3-bis(di-t-butylphosphinomethyl) benzene [RhO2{ tBu2PCH2(C6H3)CH 2PtBu2}] (5) was also investigated. In this species the O2 is η2 coordinated to the Rh(I) center with asymmetric Rh-O bond lengths (2.087(7) and 1.998(8) Å). The O-O bond distance is short (1.337(11) Å) with νO-O of 990.5 cm -1. DFT calculations on complex 5 yielded two η2- O2 structures that differed in energy by only 0.76 kcal/mol. The lower energy one (5a) had near C2 symmetry, and had nearly equal Rh-O bond lengths, while the higher energy structure (5b) had near Cs symmetry and generally good agreement with the experimental structure. The calculated UV-Vis and IR spectra of complex 5 are in excellent agreement with experiment. © 2012 Elsevier Ltd. All rights reserved.

  12. Steam reforming of fast pyrolysis-derived aqueous phase oxygenates over Co, Ni, and Rh metals supported on MgAl2O4

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Rong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Dagle, Vanessa Lebarbier [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Flake, Matthew [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Kovarik, Libor [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Albrecht, Karl O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Deshmane, Chinmay [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Dagle, Robert A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis

    2016-07-01

    In this study we examine feasibility for steam reforming the mixed oxygenate aqueous fraction derived from mildly hydrotreated fast pyrolysis bio-oils. Catalysts selective towards hydrogen formation and resistant to carbon formation utilizing feeds with relatively low steam-to-carbon (S/C) ratios are desired. Rh (5 wt%), Pt (5 wt%), Ru (5 wt%), Ir (5 wt%), Ni (15 wt%), and Co (15 wt%) metals supported on MgAl2O4 were evaluated for catalytic performance at 500°C and 1 atm using a complex feed mixture comprising of acids, polyols, cycloalkanes, and phenolic compounds. The Rh catalyst was found to be the most active and resistant to carbon formation. The Ni and Co catalysts were found to be more active than the other noble metal catalysts investigated (Pt, Ru, and Ir). However, Ni was found to form significantly more carbon (coke) on the catalyst surface. Furthermore, Co was found to be the most selective towards H2 formation. Evaluating the effect of temperature on stability for the Rh catalyst we found that catalyst stability was best when operated at 500°C as compared to the higher temperatures investigated (700, 800°C). When operating at 700°C significantly more graphitic formation was observed on the spent catalyst surface. Operating at 800°C resulted in reactor plugging as a result of thermal decomposition of the reactants. Thus, a concept analogous to the petroleum industries’ use of a pre-reformer, operated at approximately 500°C for steam reforming of the heavier naphtha components, followed by a high temperature methane reforming operated in the 600-850°C temperature range, could be applied in the case of steam reforming biomass derived oxygenates. Moreover, stability evaluations were performed over the Rh, Ni, and Co catalysts at 500°C and 1 atm, under similar initial conversions, reveal the Co catalyst to be the most stable and selective towards H2 production. Conversion and selectivity to CH4

  13. Communication between remote moieties in linear Ru-Ru-Ru trimetallic cyanide-bridged complexes.

    Science.gov (United States)

    Pieslinger, German E; Albores, Pablo; Slep, Leonardo D; Coe, Benjamin J; Timpson, Cliff J; Baraldo, Luis M

    2013-03-18

    In this article, we report the structural, spectroscopic, and electrochemical properties of the cyanide-bridged complex salts trans-[(NC)Ru(II)(L)4(μ-CN)Ru(II)(py)4Cl]PF6 and trans-[Ru(II)(L)4{(μ-CN)Ru(II)(py)4Cl}2](PF6)2 (L = pyridine or 4-methoxypyridine). The mixed-valence forms of these compounds show a variety of metal-to-metal charge-transfer bands, including one arising from charge transfer between the remote ruthenium units. The latter is more intense when L = 4-methoxypyridine and points to the role of the bridging ruthenium unit in promoting mixing between the dπ orbitals of the terminal fragments.

  14. Methanol oxidation at carbon paste electrodes modified with (Pt–Ru)/carbon aerogels nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Fort, Carmen I., E-mail: iladiu@chem.ubbcluj.ro [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Cotet, Liviu C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Vasiliu, Florin [The National Institute of Materials Physics, Atomistilor str. 105 bis, PO Box MG. 7, Magurele, RO 077125, Bucharest (Romania); Marginean, Petre [National Institute for Research and Development of Isotopic and Molecular Technologies, RO 400293, Cluj-Napoca (Romania); Danciu, Virginia; Popescu, Ionel C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania)

    2016-04-01

    Mesoporous carbon aerogels (CAs) impregnated with (Pt–Ru) nanoparticles were prepared, incorporated into carbon paste electrodes (CPEs) and investigated as electrocatalysts for CH{sub 3}OH electro-oxidation. The sol–gel method, followed by supercritical drying with liquid CO{sub 2} and thermal pyrolysis in an inert atmosphere, was used to obtain high mesoporous CAs. (Pt–Ru)/CAs nanocomposites with various (Pt–Ru) loading were prepared by using Ru(AcAc){sub 3} and H{sub 2}PtCl{sub 6} as metal precursors and the impregnation method. The morpho-structural peculiarities of the so prepared (Pt–Ru)/CAs electrocatalysts were examined by using elemental analysis, N{sub 2} adsorption-desorption isotherms, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and selected area electron diffraction (SAED). Cyclic voltammetry measurements, carried out at (Pt–Ru)/CA-CPEs incorporating nanocomposites with various Pt–Ru loading and different specific surface areas, showed that CA with the highest specific surface area (843 m{sup 2}/g) and impregnated with 6% (w/w) (Pt–Ru) nanoparticles exhibit the best CH{sub 3}OH electro-oxidation efficiency. The Michaelis–Menten formalism was used to describe the dependence of the oxidation peak current on the CH{sub 3}OH concentration, allowing the estimation of the modified electrodes sensitivities. Thus, for (Pt–Ru, 10%)/CA{sub 535}-CPE was observed the highest sensitivity (12.5 ± 0.8 mA/M) and, at the same time, the highest maximum current density ever reported (153.1 mA/cm{sup 2} for 2 M CH{sub 3}OH and an applied potential of 600 mV vs. SHE). - Highlights: • (Pt–Ru) nanoparticles were deposited on high mesoporous carbon aerogels (CAs). • (Pt–Ru)/CAs were characterized by TEM, EDX, SAED and N{sub 2} adsorption-desorption. • Carbon paste electrodes modified with (Pt–Ru)/CA were used for CH{sub 3}OH oxidation. • (Pt–Ru, 10

  15. Valence state of Ce and the magnetism in CeRh3B2

    Science.gov (United States)

    Malik, S. K.; Umarji, A. M.; Shenoy, G. K.; Montano, P. A.; Reeves, M. E.

    1985-04-01

    The compound CeRh3B2 orders magnetically with a high Curie temperature (TC) of 115 K but with a low moment of only absorption edge measurements show a dominant absorption peak at the energy corresponding to trivalent cerium. Magnetic studies on the compounds Ce(Rhsub1-xTsubx)sub3Bsub2 with T=Ru and Os reveal that the magnetic state is very rapidly broken up with the replacement of Rh by Ru and Os. These results along with the observation of a high TsubC in CeRhsub3Bsub2 suggest that magnetism in this compound arises from a strong hybridization of nearly localized or slightly delocalized Ce 4f electrons with conduction electrons. The small moment may be due to a Kondo-type interaction coupled with crystal-field effects.

  16. RH Packaging Program Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Washington TRU Solutions LLC

    2008-01-12

    The purpose of this program guidance document is to provide the technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package (also known as the "RH-TRU 72-B cask") and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the C of C shall govern. The C of C states: "...each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application." It further states: "...each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application." Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M&O) Contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with Title 10 Code of Federal Regulations (CFR) §71.8, "Deliberate Misconduct." Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the U.S. Department of Energy (DOE) Carlsbad Field Office (CBFO) shall be notified immediately. The CBFO will evaluate the issue and notify the NRC if required.In accordance with 10 CFR Part 71, "Packaging and Transportation of Radioactive Material," certificate holders, packaging users, and contractors or subcontractors who use, design, fabricate, test, maintain, or modify the packaging shall post copies of (1) 10 CFR Part 21, "Reporting of Defects and Noncompliance," regulations, (2) Section 206 of the Energy Reorganization Act of 1974, and (3) NRC Form 3, Notice to Employees. These documents must be posted in a

  17. Promotional effect of upper Ru oxides as methanol tolerant electrocatalyst for the oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, M.; Hernandez-Fernandez, P.; Ocon, P. [Departamento de Quimica-Fisica Aplicada C-II, Campus UAM, 28049 Madrid (Spain); Fierro, J.L.G.; Rojas, S. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, 28049 Madrid (Spain)

    2009-06-15

    The role of Ru on the oxygen reduction reaction in the presence of methanol has been investigated. To this end a series of carbon supported Pt based electrocatalysts containing Ru and Co have been prepared and thoroughly characterized. The catalytic performance on the oxygen reduction reaction (ORR) both in the presence and in the absence of methanol by linear sweep voltammetry on rotating disk electrode has been studied. In spite of its documented ability towards methanol and CO oxidation, when Ru-containing catalysts are subjected to excursions to potentials more positive than 0.8 V vs. NHE they develop a certain tolerance to the presence of methanol. This feature is attributed to the formation of upper oxide Ru species that impede the methanol oxidation reaction to occur under the typical reaction conditions of the oxygen reduction process, i.e. potentials more positive than 0.7 V vs. NHE and oxygen saturated atmospheres. The evolution of Ru species with the applied potential has been investigated by XPS, identifying the presence of upper oxidized Ru phases. (author)

  18. Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei-Zhen; Nie, Lei; Cheng, Yingwen; Kovarik, Libor; Liu, Jun; Wang, Yong

    2017-04-01

    With the capability of MgAl2O4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. A dynamic stabilization mechanism involving wetting\

  19. Kinetics of methanol electrooxidation on Pt/C and PtRu/C catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, V.; Ohanian, M. [Instituto de Ingenieria Quimica, Facultad de Ingenieria, J. Herrera y Reissig 565, Universidad de la Republica, 11300 Montevideo (Uruguay); Zinola, C.F. [Laboratorio de Electroquimica Fundamental, Facultad de Ciencias, Igua 4225, Universidad de la Republica, 11400 Montevideo (Uruguay)

    2010-10-15

    This paper analyzes the performance of platinum and platinum:ruthenium carbon-supported catalysts modified by the application of in-situ cathodic polarizations towards the methanol oxidation reaction. These new electrodes are characterized by electrochemical techniques together with transmission electron microscopy images to envisage the dispersion of the catalyst. We measure methanol electrooxidation current transients, fitting the results with a general kinetic equation for a mixed mass and charge transfer processes for adsorbed reactant species. The kinetic equation also helps to predict the exponent of the chronoamperometric decay as directly related to the fractal dimension of the catalyst surface and to discuss the possible processes involved in the electrocatalytic reaction. (author)

  20. Significantly Enhanced Hydrogen Evolution Activity of Freestanding Pd-Ru Distorted Icosahedral Clusters with less than 600 Atoms.

    Science.gov (United States)

    Dai, Zhihui; Liu, Suli; Zhang, Qinghua; Bao, Jianchun; Li, Yafei; Gu, Lin

    2017-07-24

    Freestanding metal nanoclusters can tune, precisely and effectively, the Gibbs free energy (ΔGH) of atomic hydrogen on the surface of materials. This enables the enhancement of hydrogen evolution activity. In this paper, we report a study of freestanding Pd-Ru distorted icosahedral clusters (ico-clusters) with less than 600 atoms using a simple one-pot synthesis method. This Pd-Ru ico-cluster can be used as an efficient electrocatalyst for the hydrogen evolution reaction (HER) in acidic water, which is a promising alternative to Pt. The experimental and theoretical results suggest that the fcc freestanding Pd-Ru distorted ico-clusters with less than 600 atoms ensure increased active edges and distorted defect sites that reduce the coordination number for the atoms on the catalyst surface. Furthermore, Ru is a more effective hydrogen dissociation source, while Pd has a better hydrogen storage function. Pd-Ru can tune the ΔGH of atomic hydrogen adsorbed on a catalyst and reach an optimal equilibrium state that improves the HER performance. Our studies represent a robust approach towards the development of freestanding Pd-Ru distorted ico-clusters and advanced catalysts with non-Pt content for HER and many other heterogeneous reactions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Round table on RU486.

    Science.gov (United States)

    Shallat, L

    1993-01-01

    As a non-invasive means of early abortion, RU-486 has the potential to increase women's reproductive options; at the same time, the "abortion pill" has stimulated debate about the ethics and safety of new medical technologies. When combined with a prostaglandin (PG), the success rate for RU-486 is 96% for pregnancies of up to 9 weeks' gestation. In France, over 120,000 women have used RU-486/PG to terminate pregnancy, and this regimen is now used in about 25% of abortions. Clinical trials of RU-486 are underway in Cuba, China, India, Singapore, and Zambia. The Program for Appropriate Technology has identified four considerations for introducing RU-486 to developing countries: whether abortion or menstrual regulation is legal; whether women find the method acceptable and can comply with the multiple visit treatment regimen; whether the health infrastructure can support safe method use, including prevention of misuse and provision of appropriate medical backup personnel and facilities; and whether the cost of the regimen is affordable to individuals and/or programs --conditions unlikely to be met in most such countries. Ideal would be development of a medical abortifacient that is single dose and the lowest possible dose of each drug, provokes miscarriage within a more predictable time frame with less acute and prolonged bleeding, is safe and effective beyond two months, has minimal side effects, and maximizes short-term safety and minimizes long-term effects. Technological advances are being undermined, however, by political and religious attacks on the method. Even some feminists have expressed concerns about potential long-term effects of RU-486 use.

  2. Effect of Ru thickness on spin pumping in Ru/Py bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Behera, Nilamani; Singh, M. Sanjoy; Chaudhary, Sujeet; Pandya, Dinesh K., E-mail: dkpandya@physics.iitd.ac.in; Muduli, P. K. [Department of Physics, Thin Film Laboratory, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2015-05-07

    We report the effect of Ru thickness (t{sub Ru}) on ferromagnetic resonance (FMR) line-width of Ru(t{sub Ru})/Py(23 nm) bilayer samples grown on Si(100)/SiO{sub 2} substrates at room temperature by magnetron sputtering. The FMR line-width is found to vary linearly with frequency for all thicknesses of Ru, indicating intrinsic origin of damping. For Ru thicknesses below 15 nm, Gilbert-damping parameter, α is almost constant. We ascribe this behavior to spin back flow that is operative for Ru thicknesses lower than the spin diffusion length in Ru, λ{sub sd}. For thicknesses >15 nm (>λ{sub sd}), the damping constant increases with Ru thickness, indicating spin pumping from Py into Ru.

  3. Rh nanoparticles supported on ultrathin carbon nanosheets for high-performance oxygen reduction reaction and catalytic hydrogenation.

    Science.gov (United States)

    Lin, Chong; Wu, Guanghao; Li, Huiqin; Geng, Yanmin; Xie, Gang; Yang, Jianhui; Liu, Bin; Jin, Jian

    2017-02-02

    We reported a facile and scalable salt-templated approach to produce monodisperse Rh nanoparticles (NPs) on ultrathin carbon nanosheets with the assistance of calcination under inert gas. More importantly, in spite of the essentially poor ORR activity of Rh/C, the acquired Rh/C hybrid nanosheets display a comparable ORR activity to the optimal commercial Pt/C catalyst, which may be due to the extra-small size of Rh NPs and the 2D defect-rich amorphous carbon nanosheets that can facilitate the charge transfer and reactive surface exposure. Moreover, Rh/C nanosheets present the optimal current density and best durability with the minimum decline during the entire test, so that ∼93% activity after 20 000 s is achieved, indicating a good lifetime for ORR. In contrast, commercial Pt/C and commercial Rh/C exhibited worse durability, so that ∼74% and ∼85% activities after 20 000 s are maintained. What's more, in the model system of reduction of 4-nitrophenol (4-NP), the kinetic constant k for Rh/C nanosheets is 3.1 × 10(-3), which is 4.5 times than that of the commercial Rh/C catalyst, revealing that our Rh/C hybrid nanosheets can be potentially applied in industrial catalytic hydrogenation. This work opens a novel and facile way for the rest of the precious metal NPs to be supported on ultrathin carbon nanosheets for heterogeneous catalysis.

  4. RH Packaging Program Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Washington TRU Solutions LLC

    2006-11-07

    The purpose of this program guidance document is to provide the technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the C of C shall govern. The C of C states: "...each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application." It further states: "...each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application." Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M&O) Contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with 10 Code of Federal Regulations (CFR) §71.8, "Deliberate Misconduct." Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the U.S. Department of Energy (DOE) Carlsbad Field Office (CBFO) shall be notified immediately. CBFO will evaluate the issue and notify the NRC if required. In accordance with 10 CFR Part 71, "Packaging and Transportation of Radioactive Material," certificate holders, packaging users, and contractors or subcontractors who use, design, fabricate, test, maintain, or modify the packaging shall post copies of (1) 10 CFR Part 21, "Reporting of Defects and Noncompliance," regulations, (2) Section 206 of the Energy Reorganization Act of 1974, and (3) NRC Form 3, Notice to Employees. These documents must be posted in a conspicuous location where the activities subject to

  5. RH Packaging Program Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Washington TRU Solutions, LLC

    2003-08-25

    The purpose of this program guidance document is to provide technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the SARP and/or C of C shall govern. The C of C states: ''...each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, ''Operating Procedures,'' of the application.'' It further states: ''...each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, ''Acceptance Tests and Maintenance Program of the Application.'' Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M&O) contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC approved, users need to be familiar with 10 CFR {section} 71.11, ''Deliberate Misconduct.'' Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the Carlsbad Field Office (CBFO) shall be notified immediately. CBFO will evaluate the issue and notify the NRC if required. This document details the instructions to be followed to operate, maintain, and test the RH-TRU 72-B packaging. This Program Guidance standardizes instructions for all users. Users shall follow these instructions. Following these instructions assures that operations are safe and meet the requirements of the SARP. This document is available on the Internet at: ttp://www.ws/library/t2omi/t2omi.htm. Users are responsible for ensuring they are using the current

  6. A tauberian approach to RH

    CERN Document Server

    Cloitre, Benoit

    2011-01-01

    The aim of this paper is twofold. Firstly we present our main discovery arising from experiments which is the tauberian concept of functions of good variation (FGV). Secondly we propose to use these FGV for proving RH is true via some conjectures. More precisely we give an implicit definition of FGV and we provide several smooth and nontrivial exemples from experiments. Then using a conjectured family of FGV involving functions approaching the floor function we derive RH is true. We make also a tauberian conjecture allowing us to prove RH is true for L-functions (the generalized RH) and automorphic L-functions (the grand RH) and we discuss the linear independance conjecture. The method is inspired by the Ingham summation process and the experimental support is provided using pari-gp.

  7. Characterization of RuO sub 2 electrodes for ferroelectric thin films prepared by metal-organic chemical-vapor deposition using Ru(C sub 1 sub 1 H sub 1 sub 9 O sub 2) sub 3

    CERN Document Server

    Lee, J M; Shin, J C; Hwang, C S; Kim, H J; Suk, C G

    1999-01-01

    Pure and conducting RuO sub 2 thin films were deposited on Si substrates at 250 approx 450 .deg. C using Ru(C sub 1 sub 1 H sub 1 sub 9 O sub 2) sub 3 as a precursor by low-pressure metal-organic chemical-vapor deposition (LP-MOCVD). At a lower deposition temperature,smoother and denser RuO sub 2 thin films were deposited. The RuO sub 2 thin films, which were crack free, adhered well onto the substrates and showed very low resistivities around 45 approx 60 mu OMEGA cm. RuO sub 2 thin films on (Ba, Sr)/TiO sub 3 /Pt/SiO sub 2 /Si showed good properties, indicating that MOCVD RuO sub 2 thin films from Ru(C sub 1 sub 1 H sub 1 sub 9 O sub 2) sub 3 can be applied as electrodes of high-dielectric thin films for capacitors in ultra-large-scale DRAMs.

  8. Improvement of the ultra-trace voltammetric determination of Rh in environmental samples using signal transformation.

    Science.gov (United States)

    Almécija, C; Cobelo-García, A; Santos-Echeandía, J

    2016-01-01

    Rhodium (Rh) is present at the Earth's surface at ultra-trace concentrations (0.06 ng g(-1)); however, its use in catalytic converters has increased its deposition nearby traffic pressure and therefore the interest in analytical techniques for Rh determination has raised in the recent years. In this study we propose an improvement of Rh measurement by adsorptive voltammetry applying second-derivative signal transformation. The optimization of experimental parameters affecting the voltammetric analysis were carried out using sediment samples; these include the amount of sample digest used, the hydrochloric acid and formaldehyde concentrations, deposition potential and equilibration time. The use of the second derivative transformation provided well-defined peaks due to the minimization of background interferences, leading to a significant decrease in the detection limits. Accordingly, a detection limit of 200 fM Rh in the cell was obtained, which corresponds to 14 pg g(-1) of Rh for 200mg of sediments. The optimized methodology was applied to the analysis of Rh in a sediment core collected close to a motorway bridge from Tagus Estuary (Lisbon, Portugal). Here, Rh concentrations ranged from 0.06 to 0.47 ng g(-1), showing a surface Rh-enrichment linked to traffic, which was consistent with a Pt superficial peak. Reference materials were also analyzed, including road dust (BCR-723) and river sediment (JSD-2), and values obtained were in agreement with certified concentrations and previously values reported in the literature. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Search for the low-lying (π1g(9)/(2))4 62+ state in Ru94

    Science.gov (United States)

    Mills, W. J.; Ressler, J. J.; Austin, R. A. E.; Chakrawarthy, R. S.; Cross, D. S.; Heinz, A.; McCutchan, E. A.; Strange, M. D.

    2007-04-01

    Excitations in Ru94 were populated through the β+/ɛ decay of Rh94 following the fusion evaporation reaction Ni58(Ca40,3pn)Rh94. Recoiling nuclei were implanted on the Yale moving tape collector at the Wright Nuclear Structure Laboratory, and delayed γ-rays were observed via an array of four Compton suppressed HPGe clover detectors. Nine new γ-transitions and five new levels were added to the level scheme of (π1g(9)/(2))Jπ=6+4 level, in close agreement with prediction.

  10. Prothrombin time (PT)

    Science.gov (United States)

    PT; Pro-time; Anticoagulant-prothrombin time; Clotting time: protime; INR; International normalized ratio ... PT is measured in seconds. Most of the time, results are given as what is called INR ( ...

  11. Adsorption of Rh(III) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion-exchange resin Diaion WA21J

    Energy Technology Data Exchange (ETDEWEB)

    Shen Shaobo, E-mail: shaoboshen@metall.ustb.edu.cn [Key Laboratory of Ecological and Recycling Metallurgy, Ministry of Education of China, Beijing 100083 (China); Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Pan Tonglin; Liu Xinqiang; Yuan Lei [Key Laboratory of Ecological and Recycling Metallurgy, Ministry of Education of China, Beijing 100083 (China); Wang Jinchao [Key Laboratory of Ecological and Recycling Metallurgy, Ministry of Education of China, Beijing 100083 (China); Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang Yongjian; Guo Zhanchen [Key Laboratory of Ecological and Recycling Metallurgy, Ministry of Education of China, Beijing 100083 (China)

    2010-07-15

    It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K{sub d}) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q{sub max} based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81 mg/g for temperatures 18, 28 and 40 deg. C, respectively. The apparent adsorption energy of Rh was about -7.6 kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54 J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process.

  12. Novel RuCoSe as non-platinum catalysts for oxygen reduction reaction in microbial fuel cells

    Science.gov (United States)

    Rozenfeld, Shmuel; Schechter, Michal; Teller, Hanan; Cahan, Rivka; Schechter, Alex

    2017-09-01

    Microbial electrochemical cells (MECs) are explored for the conversion of acetate directly to electrical energy. This device utilizes a Geobacter sulfurreducens anode and a novel RuCoSe air cathode. RuCoSe synthesized in selected compositions by a borohydride reduction method produces amorphous structures of powdered agglomerates. Oxygen reduction reaction (ORR) was measured in a phosphate buffer solution pH 7 using a rotating disc electrode (RDE), from which the kinetic current (ik) was measured as a function of potential and composition. The results show that ik of RuxCoySe catalysts increases in the range of XRu = 0.25 > x > 0.7 and y < 0.15 for all tested potentials. A poisoning study of RuCoSe and Pt catalysts in a high concentration acetate solution shows improved tolerance of RuCoSe to this fuel at acetate concentration ≥500 mM. MEC discharge plots under physiological conditions show that ∼ RuCo2Se (sample S3) has a peak power density of 750 mW cm-2 which is comparable with Pt 900 mW cm-2.

  13. Half-life of the electron-capture decay of 97Ru: Precision measurement shows no temperature dependence

    CERN Document Server

    Goodwin, J R; Iacob, V E; Hardy, J C; 10.1103/PhysRevC.80.045501

    2009-01-01

    We have measured the half-life of the electron-capture (ec) decay of 97Ru in a metallic environment, both at low temperature (19K), and also at room temperature. We find the half-lives at both temperatures to be the same within 0.1%. This demonstrates that a recent claim that the ec decay half-life for 7Be changes by $0.9% +/- 0.2% under similar circumstances certainly cannot be generalized to other ec decays. Our results for the half-life of 97Ru, 2.8370(14)d at room temperature and 2.8382(14)d at 19K, are consistent with, but much more precise than, previous room-temperature measurements. In addition, we have also measured the half-lives of the beta-emitters 103Ru and 105Rh at both temperatures, and found them also to be unchanged.

  14. Unusual optical properties of graphene on an Rh surface

    Science.gov (United States)

    Rut'kov, E. V.; Gall, N. R.

    2015-01-01

    Single- and multilayer graphene films formed on the surface of a number of metals (Rh, Pt, Ir, and Re) at the thermal decomposition of benzene molecules have been studied. A surprising phenomenon has been revealed: these films with thicknesses up to 15 layers do not absorb light emitted by the surface and affect neither brightness nor true temperatures of the surface, which contradicts the fundamental results obtained by A. Geim and K. Novoselov. At larger thicknesses, absorption occurs in agreement with the commonly accepted concepts.

  15. Facile synthesis of Rh-Pd alloy nanodendrites as highly active and durable electrocatalysts for oxygen reduction reaction.

    Science.gov (United States)

    Qi, Yue; Wu, Jianbo; Zhang, Hui; Jiang, Yingying; Jin, Chuanhong; Fu, Maoshen; Yang, Hong; Yang, Deren

    2014-06-21

    In addition to activity, durability of Pd-based catalysts in a highly corrosive medium has become one of the most important barriers to limit their industrial applications such as low-temperature fuel cell technologies. Here, Rh with a unique capability to resist against oxidation etching was incorporated into Pd-based catalysts to enhance both their activity and durability for oxygen reduction reaction (ORR). This idea was achieved through the synthesis of the Rh-Pd alloy nanodendrites by co-reducing Rh and Pd salt precursors in oleylamine (OAm) containing cetyltrimethylammonium bromide (CTAB). In this synthesis, Rh-Pd alloy nanostructures with Rh-Pd atomic ratios from 19 : 1 to 1 : 4 were generated by varying the molar ratios of Rh and Pd salt precursors. Interestingly, this variation of the molar ratios of the precursors from Rh rich to Pd rich would lead to the shape evolution of Rh-Pd alloy from dendritic nanostructures to spherical aggregations. We found that Br(-) ions derived from CTAB were also indispensible to the production of Rh-Pd alloy nanodendrites. Owing to the addition of highly stable Rh as well as the radical structure with a large number of low-coordinated sites on the arms, Rh-Pd alloy nanodendrites with a Rh-Pd atomic ratio of 4 : 1 (Rh80Pd20) exhibited a substantially enhanced electrocatalytic performance towards ORR with a 5% loss of mass activity during the accelerated stability test for 10 000 cycles compared to ∼ 50% loss of the commercial Pt/C (E-TEK).

  16. Why is metallic Pt the best catalyst for methoxy decomposition?

    Institute of Scientific and Technical Information of China (English)

    Ruipeng Ren; Cuiyu Niu; Shaoyue Bu; Yuhua Zhou; Yongkang Lu; Guichang Wang

    2011-01-01

    The decomposition of methoxy on Cu(111),Ag(111),Au(111),Ni(111),Pt(111),Pd(111),and Rh(111)has been studied in detail by the density functional theory calculations.The calculated activation barriers were successfully correlated with the coupling matrix element V2ad and the d-band center(εd)for the group IB metals and group Ⅷ metals,respectively.By comparison of the activation energy barriers of the methoxy decomposition on different metals,it was found that Pt is the best catalyst for methoxy decomposition.The possible reason why the metallic Pt is the best catalyst has been analyzed from both the energetic data and the electronic structure information,that is,methoxy decomposition on Pt(111)has the largest exothermic behavior due to the closest p-band center of the CH3O among all metals after the adsorption.

  17. Balance of Nanostructure and Bimetallic Interactions in Pt Model Fuel Cell Catalysts: An in Situ XAS and DFT Study

    Energy Technology Data Exchange (ETDEWEB)

    Friebel, Daniel; Viswanathan, Venkatasubramanian; Miller, Daniel James; Anniyev, Toyli; Ogasawara, Hirohito; Larsen, Ask Hjorth; O' Grady, Christopher P.; Norskov, Jens K.; Nilsson, Anders

    2012-05-31

    We have studied the effect of nanostructuring in Pt monolayer model electrocatalysts on a Rh(111) single-crystal substrate on the adsorption strength of chemisorbed species. In situ high energy resolution fluorescence detection X-ray absorption spectroscopy at the Pt L(3) edge reveals characteristic changes of the shape and intensity of the 'white-line' due to chemisorption of atomic hydrogen (H(ad)) at low potentials and oxygen-containing species (O/OH(ad)) at high potentials. On a uniform, two-dimensional Pt monolayer grown by Pt evaporation in ultrahigh vacuum, we observe a significant destabilization of both H(ad) and O/OH(ad) due to strain and ligand effects induced by the underlying Rh(111) substrate. When Pt is deposited via a wet-chemical route, by contrast, three-dimensional Pt islands are formed. In this case, strain and Rh ligand effects are balanced with higher local thickness of the Pt islands as well as higher defect density, shifting H and OH adsorption energies back toward pure Pt. Using density functional theory, we calculate O adsorption energies and corresponding local ORR activities for fcc 3-fold hollow sites with various local geometries that are present in the three-dimensional Pt islands.

  18. Ru-Sn/AC for the Aqueous-Phase Reduction of Succinic Acid to 1,4-Butanediol under Continuous Process Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Vardon, Derek R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Settle, Amy E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Vorotnikov, Vassili [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Menart, Martin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Eaton, Todd R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Steirer, Kenneth X [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wood, Kevin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cleveland, Nicholas S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moyer, Kathleen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Michener, William E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Beckham, Gregg T [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Unocic, Kinga A. [Oak Ridge National Laboratory

    2017-08-01

    Succinic acid is a biomass-derived platform chemical that can be catalytically converted in the aqueous phase to 1,4-butanediol (BDO), a prevalent building block used in the polymer and chemical industries. Despite significant interest, limited work has been reported regarding sustained catalyst performance and stability under continuous aqueous-phase process conditions. As such, this work examines Ru-Sn on activated carbon (AC) for the aqueous-phase conversion of succinic acid to BDO under batch and flow reactor conditions. Initially, powder Ru-Sn catalysts were screened to determine the most effective bimetallic ratio and provide a comparison to other monometallic (Pd, Pt, Ru) and bimetallic (Pt-Sn, Pd-Re) catalysts. Batch reactor tests determined that a ~1:1 metal weight ratio of Ru to Sn was effective for producing BDO in high yields, with complete conversion resulting in 82% molar yield. Characterization of the fresh Ru-Sn catalyst suggests that the sequential loading method results in Ru sites that are colocated and surface-enriched with Sn. Postbatch reaction characterization confirmed stable Ru-Sn material properties; however, upon a transition to continuous conditions, significant Ru-Sn/AC deactivation occurred due to stainless steel leaching of Ni that resulted in Ru-Sn metal crystallite restructuring to form discrete Ni-Sn sites. Computational modeling confirmed favorable energetics for Ru-Sn segregation and Ni-Sn formation at submonolayer Sn incorporation. To address stainless steel leaching, reactor walls were treated with an inert silica coating by chemical vapor deposition. With leaching reduced, stable Ru-Sn/AC performance was observed that resulted in a molar yield of 71% BDO and 15% tetrahydrofuran for 96 h of time on stream. Postreaction catalyst characterization confirmed low levels of Ni and Cr deposition, although early-stage islanding of Ni-Sn will likely be problematic for industrially relevant time scales (i.e., thousands of hours). Overall

  19. GnRH tandem peptides for inducing an immunogenic response to GnRH-I without cross-reactivity to other GnRH isoforms

    NARCIS (Netherlands)

    Turkstra, J.A.; Schaaper, W.M.M.; Oonk, H.B.; Meloen, R.H.

    2005-01-01

    Gonadotropin releasing hormone (GnRH) occurs in various isoforms in mammals, i.e. GnRH-I (mammalian GnRH), GnRH-II (chicken GnRH-II), GnRH-III (salmon GnRH) and two forms of lamprey GnRH. The function of the latter four molecules have only been partially investigated. Also not much is known about th

  20. Formation of graphene on Ru(0001) surface

    Institute of Scientific and Technical Information of China (English)

    Pan Yi; Shi Dong-Xia; Gao Hong-Jun

    2007-01-01

    We report on the formation of a graphene monolayer on a Ru(0001) surface by annealing the Ru(0001) crystal.The samples are characterized by scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES). STM images show that the Moiré pattern is caused by the graphene layer mismatched with the underlying Ru(0001) surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru(0001) surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru(0001) surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.

  1. Invisibility and PT symmetry

    OpenAIRE

    MOSTAFAZADEH, Ali

    2013-01-01

    PHYSICAL REVIEW A 87, 012103 (2013) Invisibility and PT symmetry Ali Mostafazadeh* Department of Mathematics, Koc¸ University, Sarıyer 34450, Istanbul, Turkey (Received 9 July 2012; published 3 January 2013) For a general complex scattering potential defined on a real line, we show that the equations governing invisibility of the potential are invariant under the combined action of parity and time-reversal (PT ) transformation. We determine the PT -symmetric as well as no...

  2. Electrochemical surface characterization and O2 reduction kinetics of Se surface-modified ru nanoparticle-based RuSe(y)/C catalysts.

    Science.gov (United States)

    Colmenares, L; Jusys, Z; Behm, R J

    2006-12-05

    The electrochemical properties of Se surface-modified Ru/C catalysts (RuSey/C with y = 0 to 1) and their O2 reduction characteristics were determined in model studies under well-defined mass transport conditions, combining quantitative differential electrochemical mass spectrometry and double-disk electrode thin-layer flow-cell measurements. Surface characterization of the catalysts including the quantitative evaluation of the active surface area was performed by electrochemical/mass spectrometric (combined H-upd adsorption, preadsorbed CO monolayer oxidation, Cu-upd adsorption/stripping, and RuOx formation) methods. The suitability of these methods for the determination of the active surface area in the high and low Se coverage regime are discussed, and COad stripping is found to be the most relevant method for the present catalysts. The kinetic parameters for the ORR (activity and selectivity) under quasi-steady-state conditions and their variation with Se modification were evaluated in potentiostatic flow-cell measurements. Modification of Ru/C catalyst by Se improves the O2 reduction activity and reduces the tendency for H2O2 formation in the technically relevant potential region of 0.6-0.8 VRHE, but even for the best catalyst compositions a significant ( approximately 0.2 VRHE) overpotential for O2 reduction on the RuSey/C catalysts remains compared to that for the Pt/C catalyst, and we find H2O2 yields of at least 1% at typical cathode operation potentials. Consequences of the relatively high H2O2 yields for membrane/electrode stability in practical applications are discussed.

  3. Rh isoimmunization during pregnancy: antenatal prophylaxis.

    Science.gov (United States)

    Bowman, J M; Chown, B; Lewis, M; Pollock, J M

    1978-03-18

    Of 3533 Rh-negative women who began a pregnancy without detectable Rh antibodies, 62 (1.8%) demonstrated evidence of Rh isoimmunization during pregnancy or within 3 days after delivery. All denied transfusions as well as abortions or previous pregnancies not followed by the administration of Rh immune globulin. Rh isoimmunization during pregnancy or within 3 days after delivery, which will not be prevented by the administration of Rh immune globulin after delivery, is the most important cause of residual Rh isoimmunization. A clinical trial of antenatal administration of Rh immune globulin, initially at 34 weeks's and subsequently at 28 and 34 weeks' gestation, in 1357 Rh-negative pregnant women who were delivered of Rh-positive babies, was effective in preventing the development of Rh isoimmunization during pregnancy or within 3 days after delivery. Antenatal prophylaxis with Rh immune globulin will be necessary if the incidence of Rh isoimmunization is to be reduced to its lowest possible level. Antenatal prophylaxis at 28 weeks' gestation is now an insured service in Manitoba.

  4. Characterization of highly (110)- and (111)-oriented Pb(Zr ,Ti)O3 films on BaPbO3 electrode using Ru conducting barrier

    Science.gov (United States)

    Liang, Chun-Sheng; Wu, Jenn-Ming

    2005-07-01

    Highly non-(001)-oriented Pb(Zr ,Ti)O3 (PZT) films have been fabricated by rf-magnetron sputtering. The preferential (110)-oriented BaPbO3 (BPO) deposited on Ru buffer layer induces the growth of (110)-oriented PZT film. With the aid of self-organized growth of PZT, the orientation of the film deposited on random-oriented BPO /Pt(111)/Ru(002) is (111)-preferred. The insertion of Pt layer between BPO and Ru changes the orientation of PZT from (110) to (111) and prevents the oxygen diffusion. These non-(001)-oriented PZT films possess more superior ferroelectric, fatigue, and retention properties than those of (001)-oriented PZT films.

  5. Scanning tunnelling microscope studies of growth of RuO2(110) thin layer on Ru(0001)

    Institute of Scientific and Technical Information of China (English)

    Zhang Han-Jie; Lü Bin; Lu Yun-Hao; Huang Han; Li Hai-Yang; Bao Shi-Ning; He Pei-Mo

    2006-01-01

    This paper reports that the growth of RuO2(110) thin layer growth on Ru(0001) has been investigated by means of scanning tunnelling microscope (STM). The STM images showed a domain structure with three rotational domains of RuO2(110) rotated by an angle of 120°. The as-grown RuO2(110) thin layer is expanded from the bulk-truncated RuCO2(110) due to the large mismatch between RuCO2(110) and the Ru(0001) substrate. The results also indicate that growth of RuO2(110) thin layer on the Ru(0001) substrate by oxidation tends first to formation of the Ru-O (oxygen) chains in the [001] direction of RuO2(110).

  6. Thermodynamic assessment of the Al-Ru system

    CSIR Research Space (South Africa)

    Prins, SN

    2003-03-01

    Full Text Available describes the order disorder transformation with one Gibbs energy function. The RuAl6 phase was described as a stoichiometric phase and the remaining intermetallic phases (Ru4Al13, RuAl2 and Ru2Al3) were modelled with the sublattice model. The solubility...

  7. Rh(0)/Rh(iii) core-shell nanoparticles as heterogeneous catalysts for cyclic carbonate synthesis.

    Science.gov (United States)

    Jung, Younjae; Shin, Taeil; Kim, Kiseong; Byun, Hyeeun; Cho, Sung June; Kim, Hyunwoo; Song, Hyunjoon

    2016-12-22

    Rh(0)/Rh(iii) core-shell nanoparticles were prepared by surface oxidation of Rh nanoparticles with N-bromosuccinimide. They were employed as heterogeneous catalysts for cyclic carbonate synthesis from propylene oxide and CO2, and exhibited high activity and excellent recyclability due to Lewis acidic Rh(iii) species on the shells.

  8. Magnetic properties of the Ce-Rh binary phases

    Energy Technology Data Exchange (ETDEWEB)

    Kappler, J.P.; Lehmann, P.; Schmerber, G. (Strasbourg-1 Univ., 67 (FR). Groupe d' Etude des Materiaux Metalliques); Nieva, G.; Sereni, J.G. (Comision Nacional de Energia Atomica, San Carlos de Bariloche (AR). Centro Atomico Bariloche)

    1988-12-01

    Crystallographic, magnetic and resistivity studies on the Ce-Rh binary phases clearly define two Ce ground state regions: (i) CeRh{sub 3}, CeRh{sub 2} and CeRh as intermediate valence compounds and (ii) Ce{sub 5}Rh{sub 4}, Ce{sub 3}Rh{sub 2} Ce{sub 5}Rh{sub 3} and Ce{sub 7}Rh{sub 3} with magnetic transitions at low temperature.

  9. Measurement of flux-weighted average cross-sections and isomeric yield ratios for 103Rh(γ,xn) reactions in the bremsstrahlung end-point energies of 55 and 60 MeV

    Science.gov (United States)

    Shakilur Rahman, Md.; Kim, Kwangsoo; Kim, Guinyun; Naik, Haladhara; Nadeem, Muhammad; Thi Hien, Nguyen; Shahid, Muhammad; Yang, Sung-Chul; Cho, Young-Sik; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun; Woo Lee, Man; Kang, Yeong-Rok; Yang, Gwang-Mo; Ro, Tae-Ik

    2016-07-01

    We measured the flux-weighted average cross-sections and the isomeric yield ratios of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions with the bremsstrahlung end-point energies of 55 and 60MeV by the activation and the off-line γ-ray spectrometric technique, using the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The flux-weighted average cross-sections were calculated by using the computer code TALYS 1.6 based on mono-energetic photons, and compared with the present experimental data. The flux-weighted average cross-sections of 103Rh( γ, xn) reactions in intermediate bremsstrahlung energies are the first time measurement and are found to increase from their threshold value to a particular value, where the other reaction channels open up. Thereafter, it decreases with bremsstrahlung energy due to its partition in different reaction channels. The isomeric yield ratios (IR) of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions from the present work were compared with the literature data in the 103Rh(d, x), 102-99Ru(p, x) , 103Rh( α, αn) , 103Rh( α, 2p3n) , 102Ru(3He, x), and 103Rh( γ, xn) reactions. It was found that the IR values of 102, 101, 100, 99Rh in all these reactions increase with the projectile energy, which indicates the role of excitation energy. At the same excitation energy, the IR values of 102, 101, 100, 99Rh are higher in the charged particle-induced reactions than in the photon-induced reaction, which indicates the role of input angular momentum.

  10. Nanoscale decomposition of Nb-Ru-O

    Science.gov (United States)

    Music, Denis; Geyer, Richard W.; Chen, Yen-Ting

    2016-11-01

    A correlative theoretical and experimental methodology has been employed to explore the decomposition of amorphous Nb-Ru-O at elevated temperatures. Density functional theory based molecular dynamics simulations reveal that amorphous Nb-Ru-O is structurally modified within 10 ps at 800 K giving rise to an increase in the planar metal - oxygen and metal - metal population and hence formation of large clusters, which signifies atomic segregation. The driving force for this atomic segregation process is 0.5 eV/atom. This is validated by diffraction experiments and transmission electron microscopy of sputter-synthesized Nb-Ru-O thin films. Room temperature samples are amorphous, while at 800 K nanoscale rutile RuO2 grains, self-organized in an amorphous Nb-O matrix, are observed, which is consistent with our theoretical predictions. This amorphous/crystalline interplay may be of importance for next generation of thermoelectric devices.

  11. PHARMACOKINETICS OF RU486 IN RABBITS

    Institute of Scientific and Technical Information of China (English)

    ZHANGMing-Hua; CHUYun-Hong; LIQui; CHANGLi-Min; FANGZhen; JINGZuao-Ying

    1989-01-01

    Intravaginal release of contraceptive steroid by avoiding the first-pass effect may provide a suitable route of administration, thus leading to higher bioavailabilities. RU486 is significantly metabolizlcd by the first-pass metabolism. We have studied its pharmacokinetics

  12. Perpendicular magnetic tunnel junctions with a synthetic storage or reference layer: A new route towards Pt- and Pd-free junctions

    Science.gov (United States)

    Cuchet, Léa; Rodmacq, Bernard; Auffret, Stéphane; Sousa, Ricardo C.; Prejbeanu, Ioan L.; Dieny, Bernard

    2016-02-01

    We report here the development of Pt and Pd-free perpendicular magnetic tunnel junctions (p-MTJ) for STT-MRAM applications. We start by studying a p-MTJ consisting of a bottom synthetic Co/Pt reference layer and a synthetic FeCoB/Ru/FeCoB storage layer covered with an MgO layer. We first investigate the evolution of RKKY coupling with Ru spacer thickness in such a storage layer. The coupling becomes antiferromagnetic above 0.5 nm and its strength decreases monotonously with increasing Ru thickness. This contrasts with the behavior of Co-based systems for which a maximum in interlayer coupling is generally observed around 0.8 nm. A thin Ta insertion below the Ru spacer considerably decreases the coupling energy, without basically changing its variation with Ru thickness. After optimization of the non-magnetic and magnetic layer thicknesses, it appears that such a FeCoB/Ru/FeCoB synthetic storage layer sandwiched between MgO barriers can be made stable enough to actually be used as hard reference layer in single or double magnetic tunnel junctions, the storage layer being now a single soft FeCoB layer. Finally, we realize Pt- or Pd-free robust perpendicular magnetic tunnel junctions, still keeping the advantage of a synthetic reference layer in terms of reduction of stray fields at small pillar sizes.

  13. High-Performance Rh 2 P Electrocatalyst for Efficient Water Splitting

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Haohong; Li, Dongguo; Tang, Yan; He, Yang; Ji, Shufang; Wang, Rongyue; Lv, Haifeng; Lopes, Pietro P.; Paulikas, Arvydas P.; Li, Haoyi; Mao, Scott X.; Wang, Chongmin; Markovic, Nenad M.; Li, Jun; Stamenkovic, Vojislav R.; Li, Yadong

    2017-04-05

    Search for active, stable and cost-efficient electrocatalysts for hydrogen production via water splitting could make substantial impact to the energy technologies that do not rely on fossil fuels. Here we report the synthesis of rhodium phosphide electrocatalyst with low metal loading in the form of nanocubes (NCs) dispersed in high surface area carbon (Rh2P/C) by a facile solvo-thermal approach. The Rh2P/C NCs exhibit remarkable performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to Rh/C and Pt/C catalysts. The atomic structure of the rhodium phosphide nanocubes was directly observed by annular dark-field scanning transmission electron microscopy (ADF-STEM), which revealed phosphorous-rich outermost atomic layer. Combined experimental and computational studies suggest that surface phosphorous plays crucial role in determining the robust catalyst properties.

  14. Fluorocarbene, fluoroolefin, and fluorocarbyne complexes of Rh.

    Science.gov (United States)

    Pell, Christopher J; Zhu, Yanjun; Huacuja, Rafael; Herbert, David E; Hughes, Russell P; Ozerov, Oleg V

    2017-04-01

    The manuscript reports the synthesis, characterization, and analysis of electronic structure in a series of complexes of small perfluorocarbon ligands with the (PNP)Rh fragment (where PNP is a diarylamido/bis(phosphine) pincer ligand). Reactions of (PNP)Rh(TBE) as the source of (PNP)Rh with CHF3 and C2HF5 produced perfluoroalkylidene complexes (PNP)Rh 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CF2 and (PNP)RhC(F)(CF3). (PNP)RhCF2 could also be obtained via the reaction of (PNP)Rh(TBE) with Me3SiCF3/CsF, with an admixture of (PNP)Rh(C2F4), where TBE = tert-butylethylene. Abstraction of fluoride from these neutral (PNP)RhC x F y complexes was successful, although only abstraction from (PNP)RhCF2 allowed unambiguous identification of the Rh product, [(PNP)Rh 0000000000000000000000000000000000 0000000000000000000000000000000000

  15. Beta decay of {sup 94}Pd and of the 71s isomer of {sup 94}Rh

    Energy Technology Data Exchange (ETDEWEB)

    Batist, L. [St. Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Department of Physics of the University ' ' Federico II' ' , Napoli (Italy); Blazhev, A. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); University of Sofia, Sofia (Bulgaria); Doering, J. [University of Sofia, Sofia (Bulgaria); Grawe, H.; Kirchner, R.; Mazzocchi, C.; Plettner, C.; Roeckl, E. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Kavatsyuk, M.; Kavatsyuk, O. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); National Taras Shevchenko University of Kyiv, Kyiv (Ukraine); La Commara, M.; Romoli, M. [Department of Physics of the University ' ' Federico II' ' , Napoli (Italy); Mukha, I. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); University of Seville, Sevilla (Spain)

    2006-08-15

    The {beta} decay of {sup 94}Pd and of the 71s isomer of {sup 94}Rh was investigated by using total {gamma}-ray absorption techniques. Several levels in {sup 94}Rh are established, including a new low-lying isomer characterized by a half-life of 0.48(3) {mu}s and a de-exciting transition of 55keV. E2 multipolarity is determined for this transition by measuring the intensities of its {gamma}-rays and the characteristic X-rays from its electron conversion. On the basis of the measured reduced {beta}-decay transition rates to known {sup 94}Ru levels and shell model considerations, the spin-parity of the 71s and the 0.48{mu}s isomers of {sup 94}Rh is assigned to be (4{sup +}) and (2{sup +}), respectively. The {beta}-decay strength distributions measured for {sup 94}Pd and the 71s isomer of {sup 94}Rh yield Q{sub EC} values of 6700(320) and 9750(320)keV for these decays and give evidence for the population of those states below and above the magic N=50 gap that belong to both components of the 0g spin-orbit doublet. (orig.)

  16. Electrocatalysts based on Ru nanoparticles : effect of methanol on the ORR Tafel slope

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Leyva-Noyola, F.; Galvan-Valencia, M. [Univ. Autonoma de Zacatecas, Guadalupe, Zacatecas (Mexico). U.A. de Ciencias Quimicas; Solorza-Feria, O. [Centro de Investigacion y Estudios Avanzados del I.P.N., Col. San Pedro Zacatenco (Mexico). Depto. de Quimica

    2008-04-15

    Proton Exchange Membrane Fuel Cells (PEMFCs) are promising candidates in systems that require small-sized power sources such as non-stationary electronic equipment and transportation. However, the scientific and technical challenges of PEMFC which include diminution of catalytic charges, catalyst substitution, membrane development, optimization of bipolar plates and a global cost decrease require further study. A strategic approach that will help with the diffusion and assimilation of the PEMFC technology involves the use of fuel other than hydrogen in cells such as methanol. However, the use of methanol in direct methanol fuel cells (DMFC) presents further challenges including slow kinetics in both anodic and cathodic reactions, and fuel crossover due to exchange membrane alcohol permeability, meaning a lower global efficiency of DMFC as compared with the hydrogen fuel cell. This article provided a contribution to the synthesis and characterization of novel catalytic materials research for DMFC. A series of materials based on ruthenium (Ru) nanoparticles were produced and catalytically studied in a multielectron charge transfer process. These materials are electroactive for the oxygen reduction reaction (ORR) in acid medium and methanol tolerant as well. The Ru nanoparticles and some binary and ternary mixtures with platinum (Pt) and cobalt (Co) were obtained by a pyrolysis procedure of solid precursors at 190 degrees Celsius. Physiochemical characterization was conducted by using a scanning electronic microscopy and energy dispersion spectroscopy mapping. Kinetic parameters of the cathodic reaction in a 0.5M sulfuric acid solution at different methanol concentrations were compared using electrochemical characterization with cyclic voltammetry and rotating disc electrodes. It was concluded that methanol has a major effect on the ORR electrocatalytic activity on binary Ru-Pt materials with a higher Pt proportion. In addition, the methanol effect on the Tafel slope

  17. PT-symmetric strings

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo, E-mail: paolo.amore@gmail.com [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico); Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Garcia, Javier [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Gutierrez, German [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico)

    2014-04-15

    We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)≡∑{sub n=1}{sup ∞}1/E{sub n}{sup p}, with p=1,2,… and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •We study PT-symmetric strings with complex density. •They exhibit regions of unbroken PT symmetry. •We calculate the critical parameters at the boundaries of those regions. •There are exact real sum rules for some particular complex densities.

  18. Reactivity of diaminogermylenes with ruthenium carbonyl: Ru3Ge3 and RuGe2 derivatives.

    Science.gov (United States)

    Cabeza, Javier A; García-Álvarez, Pablo; Polo, Diego

    2011-07-04

    The nature of the products of the reactions of [Ru(3)(CO)(12)] with diaminogermylenes depends upon the volume and the cyclic or acyclic structure of the latter. Thus, the triruthenium cluster [Ru(3){μ-Ge(NCH(2)CMe(3))(2)C(6)H(4)}(3)(CO)(9)], which has a planar Ru(3)Ge(3) core and an overall C(3h) symmetry, has been prepared in quantitative yield by treating [Ru(3)(CO)(12)] with an excess of the cyclic 1,3-bis(neo-pentyl)-2-germabenzimidazol-2-ylidene in toluene at 100 °C, but under analogous reaction conditions, the acyclic and bulkier Ge(HMDS)(2) (HMDS = N(SiMe(3))(2)) quantitatively leads to the mononuclear ruthenium(0) derivative [Ru{Ge(HMDS)(2)}(2)(CO)(3)]. Mixtures of products have been obtained from the reactions of [Ru(3)(CO)(12)] with the cyclic and very bulky 1,3-bis(tert-butyl)-2-germaimidazol-2-ylidene under various reaction conditions. The Ru(3)Ge(3) and RuGe(2) products reported in this paper are the first ruthenium complexes containing diaminogermylene ligands.

  19. Ru-NQR Study for Novel Phase Transition in CeRu2Al10

    Science.gov (United States)

    Matsumura, Masahiro; Tomita, Naoya; Matsuoka, Junichirou; Kishimoto, Yasuki; Kato, Harukazu; Kitagawa, Kentaro; Nishioka, Takashi; Tanida, Hiroshi; Sera, Masafumi

    2014-10-01

    We have performed Ru-NQR measurements on CeRu2Al10 exhibiting novel phase transition at an abnormally high temperature T0 = 27.3 K and on NdRu2Al10 with a magnetic transition temperature Tm = 2.4 K as a reference RKKY system. The splitting of the NQR line due to internal fields below T0 shows a mean-field-like monotonic increase, indicating no change in the magnetic structure below T0. The internal field strength is one order larger than those at Al sites in CeRu2Al10, and is comparable to that at the Ru site in NdRu2Al10 despite the sevenfold smaller magnitude of the 4f moment, being indicative of an enhanced conduction electron polarization at the Ru site. One of the causes of the high T0 might be the enhanced exchange coupling through the Ce-Ru-Ce path mediated by the enhanced conduction electron polarization. Being similar to that in the Al site, the nuclear spin-lattice relaxation rate 1/T1 shows a gap-like decrease below T0 without enhancement owing to a critical slowing down at T0, in contrast to the mean field 2nd-order transition.

  20. Magnetic moment distribution of ferromagnetic Ni--Rh alloys. [3 to 35 at. % Rh

    Energy Technology Data Exchange (ETDEWEB)

    Cable, J.W.; Wollan, E.O.

    1976-08-01

    The diffuse scattering of polarized and unpolarized neutrons was used to determine the spatial distribution of the magnetic moment for ferromagnetic Ni-Rh alloys. The average Ni moment remains near 0.6 ..mu../sub B/ to 12 at. percent Rh and then decreases toward zero at the critical concentration of 37 at. percent Rh. There is an initial rapid decrease in the Rh moment that follows a P/sub 12/ dependence and corresponds to a moment of 2..mu../sub B/ for isolated Rh atoms. The data indicate moment fluctuations at both the Ni and the Rh sites that are associated with local environment.

  1. Supported Pt-based nanoparticulate catalysts for the electro-oxidation of methanol: An experimental protocol for quantifying its activity

    DEFF Research Database (Denmark)

    Hernandez-Fernandez, Patricia; Lund, Peter Brilner; Kallesøe, Christian

    2014-01-01

    In here, we propose a simple methodology to evaluate the activity of supported nano-particulate catalysts on the electro-oxidation of methanol in a three-electrode cell. The proof of concept has been made on carbon supported Pt and PtRu commercial catalysts, but the protocol can be extended to all...... kinds of Pt-based nanoparticles. Even though the electro-oxidation of methanol has been studied for many years, there is no established electrochemical procedure for measuring the performance of a catalyst in such reaction. The conditions in which the measurements are carried out differ between research...

  2. Hydrogen bonding and proton transfer to ruthenium hydride complex CpRuH(dppe): metal and hydride dichotomy.

    Science.gov (United States)

    Silantyev, Gleb A; Filippov, Oleg A; Tolstoy, Peter M; Belkova, Natalia V; Epstein, Lina M; Weisz, Klaus; Shubina, Elena S

    2013-02-18

    The combination of variable temperature (190-297 K) IR and NMR spectroscopy studies with quantum-chemical calculations at the DFT/B3PW91 and AIM level had the aim to determine the mechanism of proton transfer to CpRuH(dppe) (1, dppe = Ph(2)P(CH(2))(2)PPh(2)) and the structures of intermediates. Dihydrogen bond (DHB) formation was established in the case of interaction with weak proton donors like CF(3)CH(2)OH. Low-temperature protonation (at about 200 K) by stronger proton donors leads via DHB complex to the cationic nonclassical complex [CpRu(η(2)-H(2))(dppe)](+) (2). Thermodynamic parameters of DHB formation (for CF(3)CH(2)OH: ΔH°(HB) = -4.9 ± 0.2 kcal·mol(-1), ΔS°(HB) = -17.8 ± 0.7 cal·mol(-1)·K(-1)) and proton transfer (for (CF(3))(2)CHOH: ΔH°(PT) = -5.2 ± 0.3 kcal·mol(-1), ΔS°(PT) = -23 ± 1 cal·mol(-1)·K(-1)) were determined. Above 240 K 2 transforms into trans-[CpRu(H)(2)(dppe)](+) (3) yielding a mixture of 2 and 3 in 1:2 ratio. Kinetic analysis and activation parameters for the "[Ru(η(2)-H(2))](+) → trans-[Ru(H)(2)](+)" transformation indicate reversibility of this process in contrast to irreversible intramolecular isomerization of the Cp* analogue. Calculations show that the driving force of this process is greater stability (by 1.5 kcal·mol(-1) in ΔE scale) of the dihydride cation in comparison with the dihydrogen complex. The calculations of the potential energy profile indicate the low barrier for deprotonation of 2 suggesting that the formation of trans-[CpRu(H)(2)(dppe)](+) proceeds via deprotonation of [Ru(η(2)-H(2))](+) to DHB complex, formation of hydrogen bond with Ru atom and subsequent proton transfer to the metal site.

  3. Ru(0) and Ru(II) nitrosyl pincer complexes: structure, reactivity, and catalytic activity.

    Science.gov (United States)

    Fogler, Eran; Iron, Mark A; Zhang, Jing; Ben-David, Yehoshoa; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2013-10-07

    Despite considerable interest in ruthenium carbonyl pincer complexes and their substantial catalytic activity, there has been relatively little study of the isoelectronic ruthenium nitrosyl complexes. Here we describe the synthesis and reactivity of several complexes of this type as well as the catalytic activity of complex 6. Reaction of the PNP ligand (PNP = 2,6-bis((t)Bu2PCH2)pyridine) with RuCl3(NO)(PPh3)2 yielded the Ru(II) complex 3. Chloride displacement by BAr(F-) (BAr(F-) = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) gave the crystallographicaly characterized, linear NO Ru(II) complex 4, which upon treatment with NaBEt3H yielded the Ru(0) complexes 5. The crystallographically characterized Ru(0) square planar complex 5·BF4 bears a linear NO ligand located trans to the pyridilic nitrogen. Further treatment of 5·BF4 with excess LiOH gave the crystallographicaly characterized Ru(0) square planar, linear NO complex 6. Complex 6 catalyzes the dehydrogenative coupling of alcohols to esters, reaching full conversion under air or under argon. Reaction of the PNN ligand (PNN = 2-((t)Bu2PCH2)-6-(Et2NCH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave an equilibrium mixture of isomers 7a and 7b. Further treatment of 7a + 7b with 2 equivalent of sodium isopropoxide gave the crystallographicaly characterized, bent-nitrosyl, square pyramidal Ru(II) complex 8. Complex 8 was also synthesized by reaction of PNN with RuCl3(NO)(H2O)2 and Et3N in ethanol. Reaction of the "long arm" PN(2)N ligand (PN(2)N = 2-((t)Bu2PCH2-)-6-(Et2NCH2CH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave complex 9, which upon treatment with 2 equiv of sodium isopropoxide gave complex 10. Complex 10 was also synthesized directly by reaction of PN(2)N with RuCl3(NO)(H2O)2 and a base in ethanol. A noteworthy aspect of these nitrosyl complexes is their preference for the Ru(0) oxidization state over Ru(II). This preference is observed with both aromatized and dearomatized pincer ligands, in

  4. Cactus-Like Hollow Cu2-x S@Ru Nanoplates as Excellent and Robust Electrocatalysts for the Alkaline Hydrogen Evolution Reaction.

    Science.gov (United States)

    Yoon, Donghwan; Lee, Jaeyoung; Seo, Bora; Kim, Byeongyoon; Baik, Hionsuck; Joo, Sang Hoon; Lee, Kwangyeol

    2017-08-01

    The development of Pt-free electrocatalysts for the hydrogen evolution reaction (HER) recently is a focus of great interest. While several strategies are developed to control the structural properties of non-Pt catalysts and boost their electrocatalytic activities for the HER, the generation of highly reactive defects or interfaces by combining a metal with other metals, or with metal oxides/sulfides, can lead to notably enhanced catalytic performance. Herein, the preparation of cactus-like hollow Cu2-x S@Ru nanoplates (NPs) that contain metal/metal sulfide heterojunctions and show excellent catalytic activity and durability for the HER in alkaline media is reported. The initial formation of Ru islands on presynthesized Cu1.94 S NPs, via cation exchange between three Cu(+) ions and one Ru(3+) , induces the growth of the Ru phase, which is concomitant with the dissolution of the Cu1.94 S nanotemplate, culminating in the formation of a hollow nanostructure with numerous thin Ru pillars. Hollow Cu2-x S@Ru NPs exhibit a small overpotential of 82 mV at a current density of -10 mA cm(-2) and a low Tafel slope of 48 mV dec(-1) under alkaline conditions; this catalyst is among state-of-the-art HER electrocatalysts in alkaline media. The excellent performance of hollow Cu2-x S@Ru NPs originates from the facile dissociation of water in the Volmer step. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Successful treatment of Rh alloimmunization in a twin pregnancy: case report

    Directory of Open Access Journals (Sweden)

    Rahimi Sharbaf F

    2008-09-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Background: The prevalence of Rh alloimmunization has decreased following the use of anti-D immunoglobulin. With serial amniocentesis, Doppler sonography of the middle cerebral artery and treatment of anemia with intrauterine blood transfusion, perinatal mortality has declined. However, Rh alloimmunization in twin pregnancies poses a diagnostic and therapeutic challenge."n"n Case report: We are reporting, for the first time in Iran, the successful treatment of severe Rh alloimmunization in a dichorionic- diamnionic twin pregnancy leading to the live births of both neonates. Before treatment, the fetal hemoglobin levels were 3.1g/dL and 3.9g/dL, with ascites in both fetuses. The fetuses were treated with several IUTs."n"n Results: After treatment, the neonates were delivered, weighing 2200 and 2300g, with good Apgar scores, at a gestational age of 34 weeks. "n"n Conclusion: 10% of population in Iran is Rh-negative, although Prophylaxis for Rh alloimmunization is universal, as other part of the world it cannot irrigated. For the best management of these cases, we need a well-equipped referral center."n"n Keywords: Twin, pregnancy, Rh alloimmunization, intrauterine blood transfusion, Doppler, middle cerebral

  6. Synthesis and photocatalytic activity of Pt-ZnO hybrid nanocomposite by solution plasma technology

    Science.gov (United States)

    Hu, Xiulan; Xu, QiuCheng; Ge, Chao; Su, Nan; Zhang, Jianbo; Huang, Huihong; Zhu, Shoufeng; Xu, Yanqiu; Cheng, Jiexu

    2017-01-01

    In this paper, Pt-ZnO hybrid nanocomposites were prepared by solution plasma technology. X-ray diffraction (XRD) and energy dispersive x-ray analysis (EDX) were used to verify their chemical composition. The size and morphology of the Pt-ZnO hybrid nanocomposites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These results indicate that about 2-3 nm Pt nanoparticles (NPs) were synthesized and dispersed on the pyramid-like ZnO (20-60 nm) surface. Photodegradation of Rhodamine B (RhB) demonstrates that the Pt (5 wt%)-ZnO hybrid nanocomposite has better photocatalytic activity than commercial P25 because Pt NPs restrain the photogenerated electron/hole recombination and increase the catalyst activity.

  7. Synthesis and photocatalytic activity of Pt-ZnO hybrid nanocomposite by solution plasma technology.

    Science.gov (United States)

    Hu, Xiulan; Xu, QiuCheng; Ge, Chao; Su, Nan; Zhang, Jianbo; Huang, Huihong; Zhu, Shoufeng; Xu, Yanqiu; Cheng, Jiexu

    2017-01-27

    In this paper, Pt-ZnO hybrid nanocomposites were prepared by solution plasma technology. X-ray diffraction (XRD) and energy dispersive x-ray analysis (EDX) were used to verify their chemical composition. The size and morphology of the Pt-ZnO hybrid nanocomposites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These results indicate that about 2-3 nm Pt nanoparticles (NPs) were synthesized and dispersed on the pyramid-like ZnO (20-60 nm) surface. Photodegradation of Rhodamine B (RhB) demonstrates that the Pt (5 wt%)-ZnO hybrid nanocomposite has better photocatalytic activity than commercial P25 because Pt NPs restrain the photogenerated electron/hole recombination and increase the catalyst activity.

  8. PT quantum mechanics.

    Science.gov (United States)

    Bender, Carl M; DeKieviet, Maarten; Klevansky, S P

    2013-04-28

    PT-symmetric quantum mechanics (PTQM) has become a hot area of research and investigation. Since its beginnings in 1998, there have been over 1000 published papers and more than 15 international conferences entirely devoted to this research topic. Originally, PTQM was studied at a highly mathematical level and the techniques of complex variables, asymptotics, differential equations and perturbation theory were used to understand the subtleties associated with the analytic continuation of eigenvalue problems. However, as experiments on PT-symmetric physical systems have been performed, a simple and beautiful physical picture has emerged, and a PT-symmetric system can be understood as one that has a balanced loss and gain. Furthermore, the PT phase transition can now be understood intuitively without resorting to sophisticated mathematics. Research on PTQM is following two different paths: at a fundamental level, physicists are attempting to understand the underlying mathematical structure of these theories with the long-range objective of applying the techniques of PTQM to understanding some of the outstanding problems in physics today, such as the nature of the Higgs particle, the properties of dark matter, the matter-antimatter asymmetry in the universe, neutrino oscillations and the cosmological constant; at an applied level, new kinds of PT-synthetic materials are being developed, and the PT phase transition is being observed in many physical contexts, such as lasers, optical wave guides, microwave cavities, superconducting wires and electronic circuits. The purpose of this Theme Issue is to acquaint the reader with the latest developments in PTQM. The articles in this volume are written in the style of mini-reviews and address diverse areas of the emerging and exciting new area of PT-symmetric quantum mechanics.

  9. PERCENTAGE OF SANGUIN GROUP (ABO, RH

    Directory of Open Access Journals (Sweden)

    M.Mirdamadi

    1978-09-01

    Full Text Available The ABO and Rh Blood groups of 9753 pregnant women were determined in the Amin Maternity Hospital, Isfahan, Iran, from March 23, 1976 to July 11, 1977. Their ABO blood group frequencies were calculated as follows: 0=38.20%, A=30.67%, B=23.84% and AB=7.26%. Also, 90.02% of the women were Rh positive and the rest, namely, 9.98% were Rh negative.

  10. Hydrothermal synthesis of highly crystalline RuS{sub 2} nanoparticles as cathodic catalysts in the methanol fuel cell and hydrochloric acid electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanjuan [Key Laboratory of Marine Chemistry Theory and Technology, Minisry of Education Ocean University of China, Qingdao, 266100 (China); College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Li, Nan, E-mail: lin@jlu.edu.cn [College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Yanagisawa, Kazumichi [Research Laboratory of Hydrothermal Chemistry, Kochi University, Kochi 780-8520 (Japan); Li, Xiaotian [College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Yan, Xiao [Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012 (China)

    2015-05-15

    Highlights: • Highly crystalline RuS{sub 2} nanoparticles have been first synthesized by a “one-step” hydrothermal method. • The product presents a pure cubic phase of stoichiometric ratio RuS{sub 2} with average particle size of 14.8 nm. • RuS{sub 2} nanoparticles were used as cathodic catalysts in methanol fuel cell and hydrochloric acid electrolysis. • The catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl{sup −}. - Abstract: Highly crystalline ruthenium sulfide (RuS{sub 2}) nanoparticles have been first synthesized by a “one-step” hydrothermal method at 400 °C, using ruthenium chloride and thiourea as reactants. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy/energy disperse spectroscopy (SEM/EDS), thermo gravimetric-differential thermal analyze (TG-DTA), transmission electron microscopy equipped with selected area electron diffraction (TEM/SAED). Fourier transform infrared spectra (IR), and X-ray photoelectron spectroscopy (XPS). XRD result illustrates that the highly crystalline product presents a pure cubic phase of stoichiometric ratio RuS{sub 2} and the average particle size is 14.8 nm. SEM and TEM images display the products have irregular shape of 6–25 nm. XPS analyst indicates that the sulfur exists in the form of S{sub 2}{sup 2−}. Cyclic voltammetry (CV), rotating disk electrode (RDE), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements are conducted to evaluate the electrocatalytic activity and stability of the highly crystalline RuS{sub 2} nanoparticles in oxygen reduction reaction (ORR) for methanol fuel cell and hydrochloric acid electrolysis. The results illustrate that RuS{sub 2} is active towards oxygen reduction reaction. Although the activity of RuS{sub 2} is lower than that of Pt/C, the RuS{sub 2} catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl{sup −}.

  11. Effect of aging and annealing on perpendicular magnetic anisotropy of ultra-thin CoPt films

    Science.gov (United States)

    Hara, R.; Hayakawa, K.; Ebata, K.; Sugita, R.

    2016-05-01

    The effect of aging and annealing on the magnetic properties of ultra-thin CoPt films with a Ru underlayer was investigated. For the 3 nm thick CoPt film aged in the air, the decrease of the saturation magnetic moment ms, the drastic increase of the perpendicular coercivity Hc⊥ and the perpendicular anisotropy were observed. This is because the surface layer of the CoPt film was oxidized and the bottom layer with high perpendicular anisotropy due to lattice distortion remained. For the annealed 3 nm thick CoPt film with a Pt protective layer, rising the annealing temperature Ta led to the decrease of ms, the decrease after increase of Hc⊥, and the decrease of the perpendicular squareness ratio S⊥ at Ta of 400 ∘C. The origins of effect of annealing were considered to be the grain boundary diffusion and the bulk diffusion of Ru and Pt into the CoPt film, and relaxation of the lattice distortion.

  12. Effect of aging and annealing on perpendicular magnetic anisotropy of ultra-thin CoPt films

    Directory of Open Access Journals (Sweden)

    R. Hara

    2016-05-01

    Full Text Available The effect of aging and annealing on the magnetic properties of ultra-thin CoPt films with a Ru underlayer was investigated. For the 3 nm thick CoPt film aged in the air, the decrease of the saturation magnetic moment ms, the drastic increase of the perpendicular coercivity Hc⊥ and the perpendicular anisotropy were observed. This is because the surface layer of the CoPt film was oxidized and the bottom layer with high perpendicular anisotropy due to lattice distortion remained. For the annealed 3 nm thick CoPt film with a Pt protective layer, rising the annealing temperature Ta led to the decrease of ms, the decrease after increase of Hc⊥, and the decrease of the perpendicular squareness ratio S⊥ at Ta of 400 ∘C. The origins of effect of annealing were considered to be the grain boundary diffusion and the bulk diffusion of Ru and Pt into the CoPt film, and relaxation of the lattice distortion.

  13. A Guide to Terminology for Rh Immunoprophylaxis.

    Science.gov (United States)

    Sandler, S Gerald; Queenan, John T

    2017-09-01

    Rh immunoprophylaxis for Rh-negative women requires an understanding of terminology used for Rh blood typing laboratory reports. The pathophysiology of Rh hemolytic disease of the fetus and newborn was elucidated by studies in rhesus monkeys. Subsequent studies revealed that the human blood group antigen responsible for Rh hemolytic disease of the newborn (D antigen) is related to, but different from, the rhesus monkey antigen. Weak expression of the D antigen on red cells, originally termed D, is currently reported by laboratories as a "serologic weak D phenotype," which can be further defined by RHD genotyping to be either a weak D type or a partial D phenotype. Weak D types 1, 2, or 3 are molecularly defined RHD weak D types, which have an adequate number of intact D antigens to be managed safely as Rh-positive. Partial D phenotypes result from mutations causing loss of one or more D epitopes. Most persons with a partial D phenotype have sufficient D antigen to type as Rh-positive. Some women with a partial D phenotype are detected as serologic weak D phenotypes by routine Rh typing. Whether they type as Rh-positive or serologic weak D phenotype, after being exposed to Rh-positive red cells by transfusion or pregnancy, women with partial D phenotype can form anti-D antibodies and, if they do, are at risk for hemolytic disease of the fetus and newborn. A pregnant woman with a laboratory report of a serologic weak D phenotype should be further tested for her RHD genotype to resolve whether her case should be managed as Rh-positive or Rh-negative. For more than five decades, the practice of Rh immunoprophylaxis has remained unchanged in terms of the dose of Rh immune globulin and timing of injections. In contrast, advances in the science of Rh blood typing have resulted in a continuously evolving terminology, obliging obstetricians to update their vocabulary to guide their practice. The following review and glossary provide guidance for current Rh terminology and

  14. The MNS glycophorin variant GP.Mur affects differential erythroid expression of Rh/RhAG transcripts.

    Science.gov (United States)

    Hsu, K; Kuo, M-S; Yao, C-C; Cheng, H-C; Lin, H-J; Chan, Y-S; Lin, M

    2017-08-24

    The band 3 macrocomplex (also known as the ankyrin-associated complex) on the red cell membrane comprises two interacting subcomplexes: a band 3/glycophorin A subcomplex, and a Rh/RhAG subcomplex. Glycophorin B (GPB) is a component of the Rh/RhAG subcomplex that is also structurally associated with glycophorin A (GPA). Expression of glycophorin B-A-B hybrid GP.Mur enhances band 3 expression and is associated with lower levels of Rh-associated glycoprotein (RhAG) and Rh polypeptides. The goal of this study was to determine whether GP.Mur influenced erythroid Rh/RhAG expression at the transcript level. GP.Mur was serologically determined in healthy participants from Taitung County, Taiwan. RNA was extracted from the reticulocyte-enriched fraction of peripheral blood, followed by reverse transcription and quantitative PCR for RhAG, RhD and RhCcEe. Quantification by real-time PCR revealed significantly fewer RhAG and RhCcEe transcripts in the reticulocytes from subjects with homozygous GYP*Mur. Independent from GYP.Mur, both RhAG and RhD transcript levels were threefold or higher than that of RhCcEe. Also, in GYP.Mur and the control samples alike, direct quantitative associations were observed between the transcript levels of RhAG and RhD, but not between that of RhAG and RhCcEe. Erythroid RhD and RhCcEe were differentially expressed at the transcript levels, which could be related to their different degrees of interaction or sensitivity to RhAG. Further, the reduction or absence of glycophorin B in GYP.Mur erythroid cells affected transcript expressions of RhAG and RhCcEe. Thus, GPB and GP.Mur differentially influenced Rh/RhAG expressions prior to protein translation. © 2017 International Society of Blood Transfusion.

  15. Investigation of the magnetic properties in thin Fe50Pt50-xRhx films by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, J.; Lott, D.; Schreyer, A. [GKSS Research Centre (Germany); Mankey, G.J. [University of Alabama, MINT Center (United States); Schmidt, W.; Schmalzl, K. [Juelich Research Centre (Germany); Tartakowskaya, E. [Institute for Magnetism, National Accademy of Science (United States)

    2009-07-01

    FePt-based alloys are typically the material of choice for magnetic information storage media. The high magnetic moment of Fe gives a large magnetization and the large atomic number of Pt results in a high magnetic anisotropy. This combination enables the written bits to be smaller than ever before, since magnetic grains with a high magnetic anisotropy are more thermally stable. One way to control the magnetic properties in these materials is through the introduction of a third element into the crystal matrix, e.g. Rh. When Rh is added to replace Pt in the equiatomic alloy, new magnetic phases emerge. Bulk samples of Fe{sub 50}Pt{sub 40}Rh{sub 10} for example, studied by magnetization measurements refer to an antiferromagnetic (AF)/ferromagnetic (FM) phase transition at about 150 K when heated. Additional magnetostriction measurements indicate that the phase transition could also be induced by applying a magnetic field. Here we present results on several Fe{sub 50}Pt{sub 50-x}Rh{sub x} films. These films were examined by neutron diffraction in dependence of temperature and magnetic field. The observed magnetic behaviours differ significant from the behaviour of the bulk system.

  16. Leptin facilitates lordosis behavior through GnRH-1 and progestin receptors in estrogen-primed rats.

    Science.gov (United States)

    García-Juárez, Marcos; Beyer, Carlos; Soto-Sánchez, Alfonso; Domínguez-Ordoñez, Raymundo; Gómora-Arrati, Porfirio; Lima-Hernández, Francisco Javier; Eguibar, José R; Etgen, Anne M; González-Flores, Oscar

    2011-02-01

    Dose response curves for leptin facilitation of estrous behavior (lordosis and proceptivity) were made by infusing the peptide into the lateral ventricle (icv) of ovariectomized (ovx), ad libitum-fed rats injected 40h previously with 5μg of estradiol benzoate. Leptin doses of 1 and 3μg produced significant lordosis quotient at 60min post-injection, with maximal lordosis being displayed at 120min. Yet the intensity of lordosis was weak, and a high incidence of rejection behaviors was found. Moreover, leptin did not induce significant proceptive behaviors at any dose. The leptin doses of 1 and 3μg were selected for determining whether antide, a GnRH-1 receptor antagonist, or the progestin receptor antagonist RU486 could modify the lordosis response to leptin. Icv injection of either antide or RU486 1h before leptin significantly depressed leptin facilitation of lordosis. The results suggest that leptin stimulates lordosis by releasing GnRH, which in turn activates GnRH-1 and progestin receptors. The physiological role of leptin in the control of estrous behavior remains to be determined. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. GnRH-agonist versus GnRH-antagonist IVF cycles

    DEFF Research Database (Denmark)

    Papanikolaou, E G; Pados, G; Grimbizis, G

    2012-01-01

    In view of the current debate concerning possible differences in efficacy between the two GnRH analogues used in IVF stimulated cycles, the current study aimed to explore whether progesterone control in the late follicular phase differs when GnRH antagonist is used as compared with GnRH agonist...

  18. Rh Variability in Multi-Ethnic Perspective: Consequences for RH Genotyping

    NARCIS (Netherlands)

    G.H.M. Tax

    2006-01-01

    textabstractThe RhD bloodgroup was first described by Levine en Stetson in 1939 after the manifestation of a hemolytic transfusion reaction in a woman who recently gave birth, after transfusion with her husbands red cells. The RhD-negative woman produced antibodies against the RhD present on the r

  19. An isolated nitridyl radical-bridged {Rh(N.)Rh} complex

    NARCIS (Netherlands)

    Gloaguen, Yann; Rebreyend, Christophe; Lutz, Martin|info:eu-repo/dai/nl/304828971; Kumar, Pravin; Huber, Martina; Vandervlugt, Jarl Ivar; Schneider, Sven; Debruin, Bas

    2014-01-01

    Photochemical activation of [(PNNH)Rh(N3)] (PNNH=6-di-(tert- butyl)phosphinomethyl-2,2′-bipyridine) complex2 produced the paramagnetic (S=1/2), [(PNN)Rh-N.-Rh(PNN)] complex3 (PNN-=methylene- deprotonated PNNH), which could be crystallographically characterized. Spectroscopic investigation of 3

  20. Rh Variability in Multi-Ethnic Perspective: Consequences for RH Genotyping

    NARCIS (Netherlands)

    G.H.M. Tax

    2006-01-01

    textabstractThe RhD bloodgroup was first described by Levine en Stetson in 1939 after the manifestation of a hemolytic transfusion reaction in a woman who recently gave birth, after transfusion with her husbands red cells. The RhD-negative woman produced antibodies against the RhD present on the

  1. Al 2O 3 supported Ru catalysts prepared by thermolysis of Ru 3(CO) 12 for catalytic wet air oxidation

    Science.gov (United States)

    Yu, Chaoying; Zhao, Peiqing; Chen, Gexin; Hu, Bin

    2011-06-01

    Low loading catalysts Ru/γ-Al 2O 3 and Ru-Ce/γ-Al 2O 3 were prepared by thermolysis of Ru 3(CO) 12 on γ-Al 2O 3. The catalysts were characterized by XPS, XRD and SEM. Two new Ru species (Ru A and Ru B) were detected during the Ru 3(CO) 12 decomposition process due to chemical interaction with the active OH groups on the surface of Al 2O 3 support, and the reduction of them can lead to more dispersed metallic phases. The sample was completely decomposed at 673 K in H 2, and RuO 2 was formed with minor amounts of Ru 0. When the temperature was increased to 773 K to heat the sample, the ratio of Ru 0 to RuO 2 increased. However, after the addition of CeO 2, only RuO 2 was detected on surface. The catalysts exhibited high activities in Catalytic Wet Air Oxidation (CWAO) of different organic compounds at high concentration such as isopropyl alcohol, phenol, acetic acids and N,N-dimethylformamide, which is attributed to the better dispersion of Ru particles and the addition of CeO 2 further enhanced number of effectively active sites on the cluster-derived catalyst surface.

  2. Shape transitions in neutron-rich Ru isotopes: spectroscopy of 109,110,111,112Ru

    Energy Technology Data Exchange (ETDEWEB)

    Hua, H; Cline, D; Hayes, A B; Teng, R; Riley, D; Clark, R M; Fallon, P; Goergen, A; Macchiavelli, A O; Vetter, K

    2005-06-29

    The spectroscopy of neutron-rich {sup 109,110,111,112}Ru nuclei was studied by measuring the prompt {gamma} rays originated from fission fragments, produced by the {sup 238}U({alpha},f) fusion-fission reaction, in coincidence with the detection of both fragments. For {sup 109,111}Ru, both the negative-parity (h{sub 11/2} orbitals) and positive-parity (g{sub 7/2} and/or d{sub 5/2} orbitals) bands were extended to substantially higher spin and excitation energy than known previously. The ground-state and {gamma}-vibrational bands of {sup 110,112}Ru also were extended to higher spin, allowing observation of the second band crossing at the rotational frequency of {approx}450 keV in {sup 112}Ru, which is {approx}50 keV above the first band crossing. At a similar rotational frequency, the first band crossing for the h{sub 11/2} band in {sup 111}Ru was observed, which is absent in {sup 109}Ru. These band crossings most likely are caused by the alignment of the g{sub 9/2} proton pair. This early onset of the band crossing for the aligned {pi}g{sub 9/2} orbitals may be evidence of a triaxial shape transition from prolate to oblate occurring in {sup 111}Ru. The data together with a comparison of cranked shell model predictions are presented.

  3. The applicability of the catalytic wet-oxidation to CELSS

    Science.gov (United States)

    Takahashi, Y.; Nitta, K.; Ohya, H.; Oguchi, M.

    1987-01-01

    The wet oxidation catalysis of Au, Pd, Pt, Rh or Ru on a ceramic honeycomb carrier was traced in detail by 16 to 20 repetitive batch tests each. As a result, Pt or Pd on a honeycomb carrier was shown to catalyze complete nitrogen gasification as N2. Though the catalysts which realize both complete nitrogen gasification and complete oxidation could not be found, the Ru+Rh catalyst was found to be most promising. Ru honeycomb catalyzed both nitrification and nitrogen gasification.

  4. Variant RH alleles and Rh immunisation in patients with sickle cell disease

    Science.gov (United States)

    Sippert, Emilia; Fujita, Claudia R.; Machado, Debora; Guelsin, Glaucia; Gaspardi, Ane C.; Pellegrino, Jordão; Gilli, Simone; Saad, Sara S.T.O.; Castilho, Lilian

    2015-01-01

    Background Alloimmunisation is a major complication in patients with sickle cell disease (SCD) receiving red blood cell (RBC) transfusions and despite provision of Rh phenotyped RBC units, Rh antibodies still occur. These antibodies in patients positive for the corresponding Rh antigen are considered autoantibodies in many cases but variant RH alleles found in SCD patients can also contribute to Rh alloimmunisation. In this study, we characterised variant RH alleles in 31 SCD patients who made antibodies to Rh antigens despite antigen-positive status and evaluated the clinical significance of the antibodies produced. Materials and methods RHD and RHCE BeadChip™ from BioArray Solutions and/or amplification and sequencing of exons were used to identify the RH variants. The serological features of all Rh antibodies in antigen-positive patients were analysed and the clinical significance of the antibodies was evaluated by retrospective analysis of the haemoglobin (Hb) levels before and after transfusion; the change from baseline pre-transfusion Hb and the percentage of HbS were also determined. Results We identified variant RH alleles in 31/48 (65%) of SCD patients with Rh antibodies. Molecular analyses revealed the presence of partial RHD alleles and variant RHCE alleles associated with altered C and e antigens. Five patients were compound heterozygotes for RHD and RHCE variants. Retrospective analysis showed that 42% of antibodies produced by the patients with RH variants were involved in delayed haemolytic transfusion reactions or decreased survival of transfused RBC. Discussion In this study, we found that Rh antibodies in SCD patients with RH variants can be clinically significant and, therefore, matching patients based on RH variants should be considered. PMID:24960646

  5. Variant RH alleles and Rh immunisation in patients with sickle cell disease.

    Science.gov (United States)

    Sippert, Emilia; Fujita, Claudia R; Machado, Debora; Guelsin, Glaucia; Gaspardi, Ane C; Pellegrino, Jordão; Gilli, Simone; Saad, Sara S T O; Castilho, Lilian

    2015-01-01

    Alloimmunisation is a major complication in patients with sickle cell disease (SCD) receiving red blood cell (RBC) transfusions and despite provision of Rh phenotyped RBC units, Rh antibodies still occur. These antibodies in patients positive for the corresponding Rh antigen are considered autoantibodies in many cases but variant RH alleles found in SCD patients can also contribute to Rh alloimmunisation. In this study, we characterised variant RH alleles in 31 SCD patients who made antibodies to Rh antigens despite antigen-positive status and evaluated the clinical significance of the antibodies produced. RHD and RHCE BeadChip™ from BioArray Solutions and/or amplification and sequencing of exons were used to identify the RH variants. The serological features of all Rh antibodies in antigen-positive patients were analysed and the clinical significance of the antibodies was evaluated by retrospective analysis of the haemoglobin (Hb) levels before and after transfusion; the change from baseline pre-transfusion Hb and the percentage of HbS were also determined. We identified variant RH alleles in 31/48 (65%) of SCD patients with Rh antibodies. Molecular analyses revealed the presence of partial RHD alleles and variant RHCE alleles associated with altered C and e antigens. Five patients were compound heterozygotes for RHD and RHCE variants. Retrospective analysis showed that 42% of antibodies produced by the patients with RH variants were involved in delayed haemolytic transfusion reactions or decreased survival of transfused RBC. In this study, we found that Rh antibodies in SCD patients with RH variants can be clinically significant and, therefore, matching patients based on RH variants should be considered.

  6. Comparison of hydration reactions for "piano-stool" RAPTA-B and [Ru(η6- arene)(en)Cl]+ complexes: Density functional theory computational study

    Science.gov (United States)

    Chval, Zdeněk; Futera, Zdeněk; Burda, Jaroslav V.

    2011-01-01

    The hydration process for two Ru(II) representative half-sandwich complexes: Ru(arene)(pta)Cl2 (from the RAPTA family) and [Ru(arene)(en)Cl]+ (further labeled as Ru_en) were compared with analogous reaction of cisplatin. In the study, quantum chemical methods were employed. All the complexes were optimized at the B3LYP/6-31G(d) level using Conductor Polarizable Continuum Model (CPCM) solvent continuum model and single-point (SP) energy calculations and determination of electronic properties were performed at the B3LYP/6-311++G(2df,2pd)/CPCM level. It was found that the hydration model works fairly well for the replacement of the first chloride by water where an acceptable agreement for both Gibbs free energies and rate constants was obtained. However, in the second hydration step worse agreement of the experimental and calculated values was achieved. In agreement with experimental values, the rate constants for the first step can be ordered as RAPTA-B > Ru_en > cisplatin. The rate constants correlate well with binding energies (BEs) of the Pt/Ru-Cl bond in the reactant complexes. Substitution reactions on Ru_en and cisplatin complexes proceed only via pseudoassociative (associative interchange) mechanism. On the other hand in the case of RAPTA there is also possible a competitive dissociation mechanism with metastable pentacoordinated intermediate. The first hydration step is slightly endothermic for all three complexes by 3-5 kcal/mol. Estimated BEs confirm that the benzene ligand is relatively weakly bonded assuming the fact that it occupies three coordination positions of the Ru(II) cation.

  7. Application of Pt/SiO2-CNTs Nano Catalysts in EthanolElectro-oxidation%乙醇在Pt/SiO2-CNTs纳米催化剂上的电催化氧化

    Institute of Scientific and Technical Information of China (English)

    朱静; 李路; 韦小刚

    2011-01-01

    通过溶胶凝胶方法制备SiO2修饰的碳纳米管(SiO2-CNTs)为载体材料,利用微波辅助加热化学还原方法制备Pt/SiO2-CNTs电催化剂。然后分别利用扫描电子显微镜和能量散射谱仪对Pt/SiO2-CNTs电催化剂的表面形貌和元素组成进行了表征。在酸性介质中,采用循环伏安法研究了Pt/SiO2-C电催化剂对乙醇氧化的电催化活性。与商用催化剂PtRu/C电催化剂相比,在相同催化剂载量和实验条件下,Pt/SiO2-CNTs电催化剂具有更好的催化活性和抗CO中毒能力。%The SiO2 modified carbon nanotubes were prepared through sol-gel method and used as catalyst support.The Pt/SiO2-CNTs were synthesized by microwave-assisted chemical reduction method.The micrograph and the elemental composition of Pt/SiO2-CNTs nanoparticles were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy,respectively.The electrocatalytic properties of Pt/SiO2-CNTs electrocatalyst for ethanol oxidation were investigated by cyclic voltammetry in acidic solution.Under the same catalyst loading mass and experimental conditions,the Pt/SiO2-C electrocatalyst shows higher catalytic activities than PtRu/C catalyst.It also possesses good anti-poisoning ability.

  8. Rh-catalyzed linear hydroformylation of styrene

    NARCIS (Netherlands)

    Boymans, E.; Janssen, Michèle; Müller, Christian; Lutz, M.|info:eu-repo/dai/nl/304828971; Vogt, D.

    2012-01-01

    Usually the Rh-catalyzed hydroformylation of styrene predominantly yields the branched, chiral aldehyde. An inversion of regioselectivity can be achieved using strong π-acceptor ligands. Binaphthol-based diphosphite and bis(dipyrrolyl-phosphorodiamidite) ligands were applied in the Rh-catalyzed hydr

  9. Evaluation of the Rh(II)-Rh(II) bond dissociation enthalpy for [(TMTAA)Rh]2 by 1H NMR T2 measurements: application in determining the Rh-C(O)- BDE in [(TMTAA)Rh]2C═O.

    Science.gov (United States)

    Imler, Gregory H; Zdilla, Michael J; Wayland, Bradford B

    2013-10-07

    Toluene solutions of the rhodium(II) dimer of dibenzotetramethylaza[14]annulene ([(TMTAA)Rh]2; (1)) manifest an increase in the line widths for the singlet methine and methyl (1)H NMR resonances with increasing temperature that result from the rate of dissociation of the diamagnetic Rh(II)-Rh(II) bonded dimer (1) dissociating into paramagnetic Rh(II) monomers (TMTAA) Rh (2). Temperature dependence of the rates of Rh(II)-Rh(II) dissociation give the activation parameters for bond homolysis ΔH(‡)(app) = 24(1) kcal mol(-1) and ΔS(‡)(app) = 10 (1) cal K(-1) mol(-1) and an estimate for the Rh(II)-Rh(II) bond dissociation enthalpy (BDE) of 22 kcal mol(-1). Thermodynamic values for reaction of 1 with CO to form (TMTAA)Rh-C(O)-Rh(TMTAA) (3) ΔH1° = -14 (1) kcal mol(-1), ΔS1°= -30(3) cal K(-1) mol(-1)) were used in deriving a (TMTAA)Rh-C(O)- BDE of 53 kcal mol(-1).

  10. Temperature-induced transformation of electrochemically formed hydrous RuO2 layers over Ru(0001) model electrodes

    Science.gov (United States)

    Krause, Philipp P. T.; Camuka, Hava; Leichtweiss, Thomas; Over, Herbert

    2016-07-01

    Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001).Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001). Electronic supplementary information (ESI) available. See DOI: 10

  11. GnRH agonist triggering

    DEFF Research Database (Denmark)

    Kol, Shahar; Humaidan, Peter; Al Humaidan, Peter Samir Heskjær

    2013-01-01

    The concept that a bolus of gonadotrophin-releasing hormone agonist (GnRHa) can replace human chorionic gonadotrophin (HCG) as a trigger of final oocyte maturation was introduced several years ago. Recent developments in the area strengthen this premise. GnRHa trigger offers important advantages...... triggering concept should be challenged and that the GnRHa trigger is the way to move forward with thoughtful consideration of the needs, safety and comfort of our patients. Routinely, human chorionic gonadotrophin (HCG) is used to induce ovulation in fertility treatments. This approach deviates...... significantly from physiology and often results in insufficient hormonal support in early pregnancy and in ovarian hyperstimulation syndrome (OHSS). An alternative approach is to use a gonadotrophin-releasing hormone (GnRH) agonist which allows a more physiological trigger of ovulation and, most importantly...

  12. RH ISOIMMUNIZATION BY MULTIPLE ANTIGENS

    OpenAIRE

    2005-01-01

    RESUMO A doença hemolítica perinatal isoimune (DHP) resulta da destruição dos eritrócitos fetais e do recém-nascido por anticorpos maternos dirigidos especificamente contra os antigénios de membrana dessas células. Os autores apresentam um caso de isoimunização Rh a antigénios múltiplos, anti-C, D e E, num 2º filho de um casal com antecedentes de abortamento espontâneo e um 1º filho com DHP anti- CDE e necessidade de transfusão permuta. Apesar da gravidade, com necessidade de várias tra...

  13. Kisspeptin Excitation of GnRH Neurons

    Science.gov (United States)

    Rønnekleiv, Oline K.; Kelly, Martin J.

    2014-01-01

    Kisspeptin binding to its cognate G protein-coupled receptor (GPR54, aka Kiss1R) in gonadotropin-releasing hormone (GnRH) neurons stimulates peptide release and activation of the reproductive axis in mammals. Kisspeptin has pronounced pre- and postsynaptic effects, with the latter dominating the excitability of GnRH neurons. Presynaptically, kisspeptin increases the excitatory drive (both GABA-A and glutamate) to GnRH neurons and postsynaptically, kisspeptin inhibits an A-type and inwardly rectifying K + (Kir 6.2 and GIRK) currents and activates nonselective cation (TRPC) currents to cause long-lasting depolarization and increased action potential firing. The signaling cascades and the multiple intracellular targets of kisspeptin actions in native GnRH neurons are continuing to be elucidated. This review summarizes our current state of knowledge about kisspeptin signaling in GnRH neurons. PMID:23550004

  14. PT symmetry and supersymmetry

    CERN Document Server

    Znojil, M

    2002-01-01

    A re-formulated, non-Hermitian version of the Witten's supersymmetric quantum mechanics is presented. Its use of pseudo-Hermitian (so called PT symmetric) Hamiltonians is reviewed and illustrated via several forms of an innovated supersymmetric partnership between strongly singular ("spiked") harmonic oscillators.

  15. Improved electrocatalytic ethanol oxidation activity in acidic and alkaline electrolytes using size-controlled Pt-Sn nanoparticles.

    Science.gov (United States)

    St John, Samuel; Boolchand, Punit; Angelopoulos, Anastasios P

    2013-12-31

    The promotion of the electrocatalytic ethanol oxidation reaction (EOR) on extended single-crystal Pt surfaces and dispersed Pt nanoparticles by Sn under acidic conditions is well known. However, the correlation of Sn coverage on Pt nanoparticle electrocatalysts to their size has proven difficult. The reason is that previous investigations have typically relied on commercially difficult to reproduce electrochemical treatments of prepared macroscopic electrodes to adsorb Sn onto exposed Pt surfaces. We demonstrate here how independent control over both Sn coverage and particle size can yield a significant enhancement in EOR activity in an acidic electrolyte relative to previously reported electrocatalysts. Our novel approach uses electroless nanoparticle synthesis where surface-adsorbed Sn is intrinsic to Pt particle formation. Sn serves as both a reducing agent and stabilizing ligand, producing particles with a narrow particle size distribution in a size range where the mass-specific electrocatalytic activity can be maximized (ca. 1-4 nm) as a result of the formation of a fully developed Sn shell. The extent of fractional Sn surface coverage on carbon-supported Pt nanoparticles can be systematically varied through wet-chemical treatment subsequent to nanoparticle formation but prior to incorporation into macroscopic electrodes. EOR activity for Pt nanoparticles is found to be optimum at a fractional Sn surface coverage of ca. 0.6. Furthermore, the EOR activity is shown to increase with Pt particle size and correlate with the active area of available Pt (110) surface sites for the corresponding Sn-free nanoparticles. The maximum area- and mass-specific EOR activities for the most active catalyst investigated were 17.9 μA/cm(2)Pt and 12.5 A/gPt, respectively, after 1 h of use at 0.42 V versus RHE in an acidic electrolyte. Such activity is a substantial improvement over that of commercially available Pt, Pt-Sn, and Pt-Ru alloy catalysts under either acidic or alkaline

  16. A general route for RuO2 deposition on metal oxides from RuO4

    DEFF Research Database (Denmark)

    Kleiman-Shwarsctein, Alan; Laursen, Anders Bo; Cavalca, Filippo;

    2012-01-01

    A novel method for the deposition of RuO2 from RuO4(g) on diverse metal oxides has been developed by grafting dopamine onto the otherwise un-reactive metal oxide surface. Oxygen evolution reaction on TiO2 and the photoelectrochemical improvement of WO3 by deposition of RuO2 are just a few examples...

  17. Electrooxidation of CO on Ru(0001) and RuO2(100) Electrode Surfaces

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The electrooxidation of CO on Ru (0001) and RuO2 (100) electrode surfaces were characterized by cyclic voltammetry, AES and RHEED. The CO adlayer was first partially oxidized at 0.8 V, which is controlled by the attack of oxygen species toward the Ru(0001) surface. The remaining CO adlayer oxidation at 0.55 V is related to the combination of CO molecules with oxygen species already located on the surface. In contrast, successive peaks on RuO2(100) at 0.4 V and 0.72 V are observed, which shows that CO molecules can directly react with two different lattice-oxygen on the surface to carbon dioxide.

  18. High-Density Stacked Ru Nanocrystals for Nonvolatile Memory Application

    Institute of Scientific and Technical Information of China (English)

    MAO Ping; ZHANG Zhi-Gang; PAN Li-Yang; XU Jun; CHEN Pei-Yi

    2009-01-01

    @@ Stacked ruthenium (Ru) nanocrystals (NCs) are formed by rapid thermal annealing for the whole gate stacks and embedded in memory structure, which is compatible with conventional CMOS technology. Ru NCs with high density (3×1012 cm-2 ), small size (2-4 nm) and good uniformity both in aerial distribution and morphology are formed. Attributed to the higher surface trap density, a memory window of 5.2 V is obtained with stacked Ru NCs in comparison to that of 3.5 V with single-layer samples. The stacked Ru NCs device also exhibits much better retention performance because of Coulomb blockade and vertical uniformity between stacked Ru NCs.

  19. Carbon coated face-centered cubic Ru-C nanoalloys.

    Science.gov (United States)

    Zhao, Zhisheng; Meng, Chuanmin; Li, Peifang; Zhu, Wenjun; Wang, Qianqian; Ma, Yanming; Shen, Guoyin; Bai, Ligang; He, Hongliang; He, Duanwei; Yu, Dongli; He, Julong; Xu, Bo; Tian, Yongjun

    2014-09-07

    Carbon-encapsulated ruthenium-carbon (Ru-C) nanoalloys were synthesized by dynamic shocks. The Ru-C alloy shows a new fcc structure different from the original hcp structure of metal Ru. This fcc phase is assigned to a Ru32C4 solid solution with a lattice parameter of 3.868(2) Å and a bulk modulus KT0 of 272(12) GPa. The small amount of carbon in the solid solution enhances the thermodynamic and chemical stabilities with respect to pure Ru, as well as induces changes in the electronic properties, which have direct applications in improving the material's catalytic activity and selectivity.

  20. CO oxidation on fully oxygen covered Ru(0001)

    DEFF Research Database (Denmark)

    Sljivancanin, Zeljko; Hammer, Bjørk

    2010-01-01

    We present a reaction mechanism for CO oxidation at the Ru(0001)-(1×1) surface. By means of density-functional theory studies, we compare the reactivity of flat and stepped regions of the Ru(0001). We find that at saturation oxygen coverage, where the flat parts are unreactive toward CO adsorption...... an intricate reaction pathway for CO adsorption and CO2 formation exists at the monatomic Ru step. By suggesting an efficient mechanism for CO oxidation on nonoxidic Ru, our results offer an explanation for the controversy in the experimental literature regarding how nonoxidic Ru may be as active in CO...

  1. Valence modulations in CeRuSn

    NARCIS (Netherlands)

    Feyerherm, R.; Dudzik, E.; Prokeš, K.; Mydosh, J.A.; Huang, Y.K.; Pöttgen, R.

    2014-01-01

    CeRuSn exhibits an extraordinary room temperature structure at 300 K with the coexistence of two types of Ce ions, namely trivalent Ce3+ and intermediate-valent Ce(4−δ)+, in a metallic environment. The ordered arrangement of these two Ce types on specific crystallographic sites results in a doubling

  2. Electroreflectance study of RuSe 2

    Science.gov (United States)

    Huang, Y. S.; Lin, S. S.; Sheu, J. S.; Shen, W. M.; Pollak, Fred H.

    1990-12-01

    We report the first electrolyte-electroreflectance (EER) study of a RuSe 2 single crystal in the photon energy region of 0.9-5.5 eV. The EER spectrum exhibits differential like structure in the vicinity of interband transitions. The transition energies are determined accurately. A probable energy-band structure is constructed.

  3. Ruthenium redox equilibria: 1. Thermodynamic stability of Ru(III and Ru(IV hydroxides

    Directory of Open Access Journals (Sweden)

    Igor Povar

    2016-04-01

    Full Text Available On the basis of the selected thermodynamic data for Ru(III and Ru(IV compounds in addition to original thermodynamic and graphical approach used in this paper, the thermodynamic stability areas of sparingly soluble hydroxides as well as the repartition of their soluble and insoluble chemical species towards the solution pH and initial concentrations of ruthenium in heterogeneous mixture solid phase–saturated solution have been investigated. By means of the ΔG–pH diagrams, the areas of thermodynamic stability of Ru(III and Ru(IV hydroxides have been established for a number of analytical concentrations in heterogeneous mixtures. The diagrams of heterogeneous and homogeneous chemical equilibria have been used for graphical representation of complex equilibria in aqueous solutions containing Ru(III and Ru(IV. The obtained results, based on the thermodynamic analysis and graphic design of the calculated data in the form of the diagrams of heterogeneous chemical equilibria, are in good agre­ement with the available experimental data.

  4. Magneto-optical properties for antiferromagnetically coupled CoPt stacked films with hexagonal anti-dot lattices

    Science.gov (United States)

    Yamane, Haruki; Kobayashi, Masanobu

    2014-01-01

    The influence of two-dimensional array structures (hexagonal anti-dot lattices) on magneto-optical (MO) properties was investigated in perpendicular antiferromagnetically coupled Co80Pt20 stacked films containing ZnO optical interference layers. Antiferromagnetic exchange coupling was generated in a [CoPt/Ru/CoPt] tri-layered structure, and anti-dot lattices were formed on both CoPt layers. The exchange coupling between the CoPt layers across a very thin 0.46-nm Ru interlayer was maintained even after nanofabrication. Characteristic MO hysteresis loops were measured by a 405-nm wavelength incident light on samples containing a 50-nm ZnO optical interference layer. The anti-dot lattice with a 200-nm diameter hole exhibited an increase in the residual Kerr rotation angle owing to the antiparallel magnetization alignment of the CoPt layers. Furthermore, compared with samples without the interference layer, the figure of merit for the anti-dot lattice with a 200-nm diameter hole was enhanced by inserting a 100-nm ZnO interference layer. These improvements are attributed to MO interference effects inside the stacked films.

  5. Lubiprostone: RU 0211, SPI 0211.

    Science.gov (United States)

    2005-01-01

    Lubiprostone [RU 0211, SPI 0211] is a bicyclic fatty acid that acts as a chloride channel opener, increasing intestinal water secretion. Lubiprostone, an orally-administered formulation, is one of a series of functional fatty acid compounds discovered by Dr Ryuji Ueno, and is currently undergoing development for the treatment of constipation, constipation-predominant irritable bowel syndrome (IBS-C) and postoperative ileus with Sucampo Pharmaceutical's. Lubiprostone activates a specific chloride channel (CLC2) on cells lining the gut, thereby naturally increasing intestinal fluid secretion. The increased fluid level softens the stool, promotes spontaneous bowel movements, and reduces abdominal discomfort/pain and bloating. The chloride channel is a protein that controls cell membrane transport of chloride ion. Lubiprostone acts on the ClC-2 chloride channel, which is located in the apical intestinal membrane. In November 2004, Takeda Pharmaceuticals entered into a collaboration and licensing agreement for Lubiprostone with Sucampo Pharmaceuticals for the treatment of chronic constipation and constipation-predominant Irritable Bowel Syndrome (c-IBS). Under the terms of the agreement, Takeda received the right to market the product in the US and Canada, while Sucampo reserved the co-promotion rights for these countries. Takeda's wholly-owned US subsidiary, Takeda Pharmaceuticals North America Inc., will sell lubiprostone once the product is approved by the US FDA. Takeda will also receive an option for marketing rights in other territories, including Japan and Europe. Takeda and Sucampo agreed on the exclusive manufacturing and supply of Lubiprostone by R-Tech Ueno, Ltd, a member of the Sucampo Group. Sucampo has the potential to receive up to dollar US 210 million in initial and milestone payments, some of which are contingent upon the successful achievement of several milestones. Takeda will fund a major part of development costs not only for chronic constipation

  6. Reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women

    DEFF Research Database (Denmark)

    Clausen, Frederik Banch; Krog, Grethe Risum; Rieneck, Klaus;

    2005-01-01

    The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis.......The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis....

  7. Promotion of catalytic activity for methanol electro-oxidation on CoPc-Pt/C co-catalysts

    Institute of Scientific and Technical Information of China (English)

    WU JingJie; XU YiMin; PAN Mu; MA WenTao; TANG HaoLin

    2009-01-01

    The catalytic activity for methanol electro-oxidation on CoPc-Pt/C co-catalysts, prepared by impregnation method, was studied in details through electrochemical methods. Cyclic voltammetry (CV) result demonstrates that CoPc has higher forward anodic peak current density and jf/jb value (forward anodic peak current density/backward anodic peak current density) than Pt/C. Chronoamperometry (CA) analysis indicates that CoPc-Pt/C exhibits both excellent transient current density and stable current density for methanol electro-oxidation compared with Pt/C. Two main mechanisms related to the promotion of catalytic activity are as follows: CoPc-Pt/C has the activity of tolerance to carbonaceous intermediates, thus inhibiting the self-poisoning of catalysts; CoPc-Pt/C owns prominent intrinsic catalytic activity indicated by the apparent activation energy for methanol oxidation on CoPc-Pt/C, which is 18 kJ/mol, less than that on Pt and PtRu catalysts as reported.

  8. Microstructure and magnetic properties of FePt film with combined MoC/(Mg-X)O (X=Cu, Ni, Co) intermediate layers

    Science.gov (United States)

    Tsai, Jai-Lin; Tzeng, Jie-Lin; Hu, Keng-Chun; Li, Hsu-Kang; Pan, Zu-Yu; Chang, Yuan-Shuo; Liao, Chang-Chun

    2017-01-01

    The magnetic properties and microstructure of FePt films grown on MoC layer and MoC/(Mg-X)O (X=Cu, Ni, Co) combined intermediate layers were studied. The (Mg-X)O (X=Cu, Ni, Co) layer with thickness of 5 nm was deposited on CrRu seed layer at 395 °C. The CrRu (200) texture was enhanced which may due to well grains growth in specific orientation and small lattice mismatch with (Mg-X)O (X=Cu, Ni, Co). Finally, the FePt/MoC layers were deposited on (Mg-X)O layer at 425 °C. Using MoC/MgCuO combined intermediate layers, the rocking width of FePt (001) and CrRu (200) diffraction peak were changed from 7.1° to 6.1°, and 5.7° to 3.8°, respectively. For MoC/MgCoO dual intermediate layers, the rocking width of FePt (001) and CrRu (200) diffraction peak were 6.7° and 4.1°. The FePt/MoC/MgCoO film illustrates perpendicular magnetic anisotropy with out-of plane coercivity of 9.3 kOe which is higher than FePt film deposited on MoC layer (8.5 kOe) and the in-plane loops is linear. From microstructure, the FePt grains were more separated on MoC/(Mg-X)O (X=Cu, Ni, Co) combined intermediate layers.

  9. A RhIII-N-heterocyclic carbene complex from metal-metal singly bonded [RhII−RhII] precursor

    Indian Academy of Sciences (India)

    Arup Sinha; Abir Sarbajna; Shrabani dinda; Jitendra K Bera

    2011-11-01

    Metal-metal singly bonded [Rh2(CO)4(acac)2][OTf]2 (1) has been synthesized and characterized by spectroscopic and analytical techniques. A density functional theory (DFT) optimized structure has been computed for the unbridged centro-symmetric structure. Reaction of 1 with PIN.HBr results in the [Rh(PIN)2(H2O)Br][OTf]2 (2) in high yield. The reaction involves metal-oxidation from RhII to RhIII accompanied by the metal-metal bond cleavage. The X-ray structure of 2 has been determined which reveals the incorporation of two N-heterocyclic carbene (NHC) ligands to each rhodium. This work demonstrates the general utility of the metal-metal bonded compounds for the easy synthesis of metal-NHC compounds.

  10. Growth and maturational changes in dense fibrous connective tissue following 14 days of rhGH supplementation in the dwarf rat

    Science.gov (United States)

    Kyparos, Antonios; Orth, Michael W.; Vailas, Arthur C.; Martinez, Daniel A.

    2002-01-01

    The purpose of this study was to investigate the impact of recombinant human growth hormone (rhGH) on patella tendon (PT), medial collateral ligament (MCL), and lateral collateral ligament (LCL) on collagen growth and maturational changes in dwarf GH-deficient rats. Twenty male Lewis mutant dwarf rats, 37 days of age, were randomly assigned to Dwarf + rhGH (n = 10) and Dwarf + vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt twice daily for 14 days. rhGH administration stimulated dense fibrous connective tissue growth, as demonstrated by significant increases in hydroxyproline specific activity and significant decreases in the non-reducible hydroxylysylpyridinoline (HP) collagen cross-link contents. The increase in the accumulation of newly accreted collagen was 114, 67, and 117% for PT, MCL, and LCL, respectively, in 72 h. These findings suggest that a short course rhGH treatment can affect the rate of new collagen production. However, the maturation of the tendon and ligament tissues decreased 18-25% during the rapid accumulation of de novo collagen. We conclude that acute rhGH administration in a dwarf rat can up-regulate new collagen accretion in dense fibrous connective tissues, while causing a reduction in collagen maturation. Copyright 2002 Elsevier Science Ltd.

  11. Single-phase aqueous approach toward Pd sub-10 nm nanocubes and Pd-Pt heterostructured ultrathin nanowires.

    Science.gov (United States)

    Yuan, Qiang; Zhuang, Jing; Wang, Xun

    2009-11-21

    Monodisperse, highly-selective sub-10 nm Pd and Rh nanocubes have been successfully synthesized and, for the first time, bimetallic Pd-Pt heterostructured ultrathin nanowires have been achieved through using Pd nanocubes as seeds by a one-pot, single-phase aqueous method.

  12. Gonadotropin-releasing hormone (GnRH) variants in a lizard brain: is mammalian GnRH being expressed?

    Science.gov (United States)

    Montaner, A D; Gonzalez, O; Paz, D A; Affanni, J M; Somoza, G M

    2000-08-01

    In reptiles as in other vertebrates, multiple forms of gonadotropin-releasing hormone (GnRH) within a single brain have been identified. In this group the following GnRH molecular variants have been characterized either by direct or indirect methods: chicken GnRH I (cGnRH-I), chicken GnRH II (cGnRH-II), salmon GnRH (sGnRH) and several unidentified GnRH-like forms. In the present study GnRH variants were investigated in brain extracts of the lizard Tupinambis teguixin (= T. merinae) by combining high-performance liquid chromatography (RP-HPLC) followed by radioimmunoassays (RIA). Two peaks showing GnRH immunoreactivity with the elution position of synthetic mammalian GnRH (mGnRH) and cGnRH-II were detected. Both peaks were further analyzed with different radioimmunoassay systems specific for mGnRH, cGnRH-I, and cGnRH-II. Pooled fractions corresponding to the first eluting peak showed no crossreactivity when analyzed with a cGnRH-I specific assay and logit-log displacement curves were not significantly different from those of synthetic mGnRH with homologous RIA systems. The second peak showed immunological characteristics of cGnRH-II when analyzed with a specific antiserum. The first ir-GnRH peak was selected for further RP-HPLC purification showing similar chromatographic behavior as mGnRH synthetic standard. We demonstrated the absence of cGnRH-I in this lizard using well-characterized antisera.

  13. Rh-flash acquisition card

    CERN Document Server

    Bourrion, O

    2003-01-01

    The rh-flash card main purpose is to convert and store the image of the analog data present at input into an output buffer, namely in a given timing window besides a stop signal (like a digital oscilloscope). It is conceived in VME format 1U wide with an additional connector. Novelty of this card is its ability to sample at a high frequency, due to flash coders, and this at a high repetition rate. To do that the card allows the storage of the data considered 'useful' and that is done by storing only the data exceeding a certain threshold. This can be useful for instance for viewing peaks in a spectrum, and obtaining their relative location. The goal is to stock and process the data sampled before and after the arrival of a stop signal (what entails a storage depth). A threshold is defined and any peak exceeding its level will really be stored in the output buffer which is readable through the VME bus. The peak values will be stored as well as m preceding and n subsequent values (both programmable). Obviously,...

  14. The Rh oxide ultrathin film on Rh(100): an x-ray photoelectron diffraction study.

    Science.gov (United States)

    Zhan, Rong Rong; Vesselli, Erik; Baraldi, Alessandro; Lizzit, Silvano; Comelli, Giovanni

    2010-12-07

    The surface and interface structure of the RhO(2) ultrathin film grown on Rh(100) is investigated by means of x-ray photoelectron diffraction. Experimental and simulated one- and two-dimensional angular distribution intensities of the O1s and Rh3d(5/2) chemically shifted core levels are quantitatively analyzed. The previously proposed O-Rh-O trilayer model is independently confirmed. A rippled buckling of the metal surface is observed at the oxide-metal interface, with a mean interfacial Rh-O distance which is 0.2 Å larger with respect to previous findings. The link between the local atomic rearrangement and the overall geometric and electronic properties of the oxide is discussed on the basis of a thorough comparison with the corresponding RhO(2) rutile structure.

  15. Re-Evaluation of HSE DATA in Light of High P-T Partitioning Data: Late Chondritic Addition to Inner Solar System Bodies Not Always Required for HSE

    Science.gov (United States)

    Righter, K.

    2015-01-01

    Studies of terrestrial peridotite and martian and achondritic meteorites have led to the conclusion that addition of chondritic material to growing planets or planetesimals, after core formation, occurred on Earth, Moon, Mars, asteroid 4 Vesta, and the parent body of the angritic meteorites. One study even proposed that this was a common process in the final stages of growth. These conclusions are based al-most entirely on the 8 highly siderophile elements (HSE; Re, Au, Pt, Pd, Rh, Ru, Ir, Os), which have been used to argue for late accretion of chondritic material to the Earth after core formation was complete. This idea was originally proposed because the D(metal/silicate) values for the HSE are very high (greater than 10,000), yet their concentration in the terrestrial mantle is too high to be consistent with such high Ds. The HSE in the terrestrial mantle also are present in chondritic relative abundances and hence require similar Ds if this was the result of core-mantle equilibration. The conclusion that late chondritic additions are required for all five of these bodies is based on the chondritic relative abundances of the HSE, as well as their elevated concentrations in the samples. An easy solution is to call upon addition of chondritic material to the mantle of each body, just after core formation; however, in practice this means similar additions of chondritic materials to each body just after core formation which ranges from approximately 4-5 Ma after T(sub 0) for 4 Vesta and the angrites, to 10-25 Ma for Mars, to 35 to 60 Ma for Moon and perhaps the Earth. Since the work of there has been a realization that high PT conditions can lower the partition coefficients of many siderophile elements, indicating that high PT conditions (magma ocean stage) can potentially explain elevated siderophile element abundances. However, detailed high PT partitioning data have been lacking for many of the HSE to evaluate whether such ideas are viable for all four bodies

  16. Detection of Doping with rhGH

    Institute of Scientific and Technical Information of China (English)

    Wu Mou-tian

    2009-01-01

    This presentation reviewed most articles recently pub lished in peer reviewed international scientific journals related to detection doping with rhGH. Four parts were in it: First part was the brief introduction about the background of do ping,special doping with rhGH. Second part summarized the development of "indirect method", markers approach. Third was focused on the development of "direct method", isoform approach. Finally, some potential alternatives have been discussed.

  17. Photocatalytic activity of Pt-modified Bi{sub 2}WO{sub 6} nanoporous wall under sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ya-Nan; Lu, Shi-Yu; Bao, Shu-Juan, E-mail: baoshj@swu.edu.cn [Southwest University, Faculty of Material & Energy, Institute for Clean Energy & Advanced Materials (China)

    2015-07-15

    In this work, Bi{sub 2}WO{sub 6} nanoporous wall was synthesized by using Bi{sub 2}O{sub 3} as template and Bi source. Pt nanoparticles whose average size is about 8 nm were further immobilized on the Bi{sub 2}WO{sub 6