WorldWideScience

Sample records for cell noble metal

  1. Non-noble metal fuel cell catalysts

    CERN Document Server

    Chen, Zhongwei; Zhang, Jiujun

    2014-01-01

    Written and edited by a group of top scientists and engineers in the field of fuel cell catalysts from both industry and academia, this book provides a complete overview of this hot topic. It covers the synthesis, characterization, activity validation and modeling of different non-noble metal and metalfree electrocatalysts for the reduction of oxygen, as well as their integration into acid or alkaline polymer exchange membrane (PEM) fuel cells and their performance validation, while also discussing those factors that will drive fuel cell commercialization. With its well-structured app

  2. Studies on PEM fuel cell noble metal catalyst dissolution

    DEFF Research Database (Denmark)

    Andersen, S. M.; Grahl-Madsen, L.; Skou, E. M.

    2011-01-01

    A combination of electrochemical, spectroscopic and gravimetric methods was carried out on Proton Exchange Membrane (PEM) fuel cell electrodes with the focus on platinum and ruthenium catalysts dissolution, and the membrane degradation. In cyclic voltammetry (CV) experiments, the noble metals were...... found to dissolve in 1 M sulfuric acid solution and the dissolution increased exponentially with the upper potential limit (UPL) between 0.6 and 1.6 vs. RHE. 2-20% of the Pt (depending on the catalyst type) was found to be dissolved during the experiments. Under the same conditions, 30-100% of the Ru...... (depending on the catalyst type) was found to be dissolved. The faster dissolution of ruthenium compared to platinum in the alloy type catalysts was also confirmed by X-ray diffraction measurements. The dissolution of the carbon supported catalyst was found one order of magnitude higher than the unsupported...

  3. Studies on PEM Fuel Cell Noble Metal Catalyst Dissolution

    DEFF Research Database (Denmark)

    Ma, Shuang; Skou, Eivind Morten

    Incredibly vast advance has been achieved in fuel cell technology regarding to catalyst efficiency, improvement of electrolyte conductivity and optimization of cell system. With breathtakingly accelerating progress, Proton Exchange Membrane Fuel Cells (PEMFC) is the most promising and most widely...

  4. Examining changes in cellular communication in neuroendocrine cells after noble metal nanoparticle exposure.

    Science.gov (United States)

    Love, Sara A; Liu, Zhen; Haynes, Christy L

    2012-07-07

    As nanoparticles enjoy increasingly widespread use in commercial applications, the potential for unintentional exposure has become much more likely during any given day. Researchers in the field of nanotoxicity are working to determine the physicochemical nanoparticle properties that lead to toxicity in an effort to establish safe design rules. This work explores the effects of noble metal nanoparticle exposure in murine chromaffin cells, focusing on examining the effects of size and surface functionality (coating) in silver and gold, respectively. Carbon-fibre microelectrode amperometry was utilized to examine the effect of exposure on exocytosis function, at the single cell level, and provided new insights into the compromised functions of cells. Silver nanoparticles of varied size, between 15 and 60 nm diameter, were exposed to cells and found to alter the release kinetics of exocytosis for those cells exposed to the smallest examined size. Effects of gold were examined after modification with two commonly used 'bio-friendly' polymers, either heparin or poly (ethylene glycol), and gold nanoparticles were found to induce altered cellular adhesion or the number of chemical messenger molecules released, respectively. These results support the body of work suggesting that noble metal nanoparticles perturb exocytosis, typically altering the number of molecules and kinetics of release, and supports a direct disruption of the vesicle matrix by the nanoparticle. Overall, it is clear that various nanoparticle physicochemical properties, including size and surface coating, do modulate changes in cellular communication via exocytosis.

  5. Structural energetics of noble metals

    International Nuclear Information System (INIS)

    Mujibur Rahman, S.M.

    1982-06-01

    Structural energetics of the noble metals, namely Cu, Ag, and Au are investigated by employing a single-parameter pseudopotential. The calculations show that the lowest energy for all of these metals corresponds to FCC - their observed crystal structure. The one-electron contribution to the free energy is found to dominate the structural prediction for these metals. The present investigation strongly emphasizes that the effects due to band hybridization and core-core exchange play a significant role on the structural stability of the noble metals. (author)

  6. Noble-Metal Chalcogenide Nanotubes

    Directory of Open Access Journals (Sweden)

    Nourdine Zibouche

    2014-10-01

    Full Text Available We explore the stability and the electronic properties of hypothetical noble-metal chalcogenide nanotubes PtS2, PtSe2, PdS2 and PdSe2 by means of density functional theory calculations. Our findings show that the strain energy decreases inverse quadratically with the tube diameter, as is typical for other nanotubes. Moreover, the strain energy is independent of the tube chirality and converges towards the same value for large diameters. The band-structure calculations show that all noble-metal chalcogenide nanotubes are indirect band gap semiconductors. The corresponding band gaps increase with the nanotube diameter rapidly approaching the respective pristine 2D monolayer limit.

  7. Exotic species with explicit noble metal-noble gas-noble metal linkages.

    Science.gov (United States)

    Moreno, Norberto; Restrepo, Albeiro; Hadad, C Z

    2018-02-14

    We present a study of the isoelectronic Pt 2 Ng 2 F 4 and [Au 2 Ng 2 F 4 ] 2+ species with noble gas atoms (Ng = Kr, Xe, Rn) acting as links bridging the two noble metal atoms. The stability of the species is investigated using several thermodynamic, kinetic and reactivity indicators. The results are compared against [AuXe 4 ] 2+ , which is thermodynamically unstable in the gas phase but is stabilized in the solid state to the point that it has been experimentally detected as [AuXe 4 ](Sb 2 F 11 ) 2 (S. Seidel and K. Seppelt, Science, 2000, 290, 117-118). Our results indicate that improving upon [AuXe 4 ] 2+ , these exotic combinations between the a priori non-reactive noble metals and noble gases lead to metastable species, and, therefore, they have the possibility of existing in the solid state under adequate conditions. Our calculations include accurate energies and geometries at both the CCSD/SDDALL and MP2/SDDALL levels. We offer a detailed description of the nature of the bonding interactions using orbital and density-based analyses. The computational evidence suggests partially covalent and ionic interactions as the stabilization factors.

  8. Titanium-Niobium Oxides as Non-Noble Metal Cathodes for Polymer Electrolyte Fuel Cells

    Directory of Open Access Journals (Sweden)

    Akimitsu Ishihara

    2015-07-01

    Full Text Available In order to develop noble-metal- and carbon-free cathodes, titanium-niobium oxides were prepared as active materials for oxide-based cathodes and the factors affecting the oxygen reduction reaction (ORR activity were evaluated. The high concentration sol-gel method was employed to prepare the precursor. Heat treatment in Ar containing 4% H2 at 700–900 °C was effective for conferring ORR activity to the oxide. Notably, the onset potential for the ORR of the catalyst prepared at 700 °C was approximately 1.0 V vs. RHE, resulting in high quality active sites for the ORR. X-ray (diffraction and photoelectron spectroscopic analyses and ionization potential measurements suggested that localized electronic energy levels were produced via heat treatment under reductive atmosphere. Adsorption of oxygen molecules on the oxide may be governed by the localized electronic energy levels produced by the valence changes induced by substitutional metal ions and/or oxygen vacancies.

  9. Recovery and use of fission product noble metals

    International Nuclear Information System (INIS)

    Jensen, G.A.; Rohmann, C.A.; Perrigo, L.D.

    1980-06-01

    Noble metals in fission products are of strategic value. Market prices for noble metals are rising more rapidly than recovery costs. A promising concept has been developed for recovery of noble metals from fission product waste. Although the assessment was made only for the three noble metal fission products (Rh, Pd, Ru), there are other fission products and actinides which have potential value

  10. Carbon nanotubes and other nanostructures as support material for nanoparticulate noble-metal catalysts in fuel cells

    DEFF Research Database (Denmark)

    Veltzé, Sune; Larsen, Mikkel Juul; Elina, Yli-Rantala

    or platinum-alloy catalysts in the electrodes are required. To maximize the utilization of the noble metal it is frequently deposited as nanoparticles (1–5 nm) on a stabilizing support of carbon black. Carbon black provides good anchoring of the catalyst particles, but is prone to severe destructive oxidation...... at high electrical potentials encountered occasionally in fuel cells. Other nanostructures of carbon are being investigated as alternatives to carbon black as they have several beneficial properties. Multi-walled carbon nanotubes (MW-CNT) are an example of one type of these promising materials. Like...... of the fuel-cell electrodes. However, the low concentration of structural defects also poses challenges with regard to anchoring of the catalyst particles on the CNT surface. Thus, activation treatments introducing surface functional groups may be necessary. Also, the surface properties are responsible...

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

    International Nuclear Information System (INIS)

    Mao, Han; Huang, Tao; Yu, Aishui

    2016-01-01

    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"−"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. 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.

  13. Noble Metal Nanoparticles Applications in Cancer

    Directory of Open Access Journals (Sweden)

    João Conde

    2012-01-01

    Full Text Available Nanotechnology has prompted new and improved materials for biomedical applications with particular emphasis in therapy and diagnostics. Special interest has been directed at providing enhanced molecular therapeutics for cancer, where conventional approaches do not effectively differentiate between cancerous and normal cells; that is, they lack specificity. This normally causes systemic toxicity and severe and adverse side effects with concomitant loss of quality of life. Because of their small size, nanoparticles can readily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. This way, a variety of nanoparticles with the possibility of diversified modification with biomolecules have been investigated for biomedical applications including their use in highly sensitive imaging assays, thermal ablation, and radiotherapy enhancement as well as drug and gene delivery and silencing. Here, we review the available noble metal nanoparticles for cancer therapy, with particular focus on those already being translated into clinical settings.

  14. Recovery of noble metals from fission products

    International Nuclear Information System (INIS)

    Jenson, G.A.; Platt, A.M.; Mellinger, G.B.; Bjorklund, W.J.

    1982-11-01

    Scoping studies were started in 1979 to develop a cost-effective, waste-management-compatible process to extract noble metals from fission products. The process, involving the reaction with glassmelting chemicals, a metal oxide (PbO), and a reducing agent (charcoal), was demonstrated for recovering noble metals from simulated high-level waste oxides. The process has now been demonstrated on a laboratory scale (100 g) using irradiated fuels. Recoveries in the recovered lead averaged 80% for Pd, 60% for Rh, and 14% Ru. The resulting glass product was homogeneous in appearance, and the chemical durability was comparable to other waste oxides

  15. Noble Metal Nanoparticles for Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Pedro V. Baptista

    2012-02-01

    Full Text Available In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory.

  16. Preparation and immobilization of noble metal nanoparticles for plasmonic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruoli; Pitzer, Martin; Hu, DongZhi; Schaadt, Daniel M. [Institut fuer Angewandte Physik, Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); DFG Centrum fuer Funktionelle Nanostrukturen (CFN), KIT (Germany); Fruk, Ljiljana [DFG Centrum fuer Funktionelle Nanostrukturen (CFN), KIT (Germany)

    2011-07-01

    Thin-film solar cells are of high interest due to good electrical properties and low material consumption. Traditional thin-film cells, however, have considerable transmission losses because of the reduced absorption volume. A promising way to enhance absorption in the active layer is the light-trapping by plasmonic nanostructures. Metallic nanoparticles have in particular shown large enhancement of the photocurrent in thin-film devices. In this poster, we present preparation of Au,Ag and Pt nanoparticles by polyol method and seed mediated methods for use in plasmonic solar cells. Polyol method typically uses ethylene glycol as the solvent and reducing agent,and in seed-mediated synthesis small nanoparticle seeds are first prepared and then used to promote the growth of different shapes of nanoparticles. We particularly focus on the use of nanocubes and nanospheres for solar cell design. Following the nanoparticle preparation, a new method to immobilize particles on GaAs surfaces via covalent chemical bonds has been developed which prevents agglomerations and allows control of the surface density. Photocurrent spectra of GaAs pin solar cells with and without particles have been recorded. These measurements show the dependence of the photocurrent enhancement on particle material, shape and density.

  17. One parameter model potential for noble metals

    International Nuclear Information System (INIS)

    Idrees, M.; Khwaja, F.A.; Razmi, M.S.K.

    1981-08-01

    A phenomenological one parameter model potential which includes s-d hybridization and core-core exchange contributions is proposed for noble metals. A number of interesting properties like liquid metal resistivities, band gaps, thermoelectric powers and ion-ion interaction potentials are calculated for Cu, Ag and Au. The results obtained are in better agreement with experiment than the ones predicted by the other model potentials in the literature. (author)

  18. Engineering noble metal nanomaterials for environmental applications

    Science.gov (United States)

    Li, Jingguo; Zhao, Tingting; Chen, Tiankai; Liu, Yanbiao; Ong, Choon Nam; Xie, Jianping

    2015-04-01

    Besides being valuable assets in our daily lives, noble metals (namely, gold, silver, and platinum) also feature many intriguing physical and chemical properties when their sizes are reduced to the nano- or even subnano-scale; such assets may significantly increase the values of the noble metals as functional materials for tackling important societal issues related to human health and the environment. Among which, designing/engineering of noble metal nanomaterials (NMNs) to address challenging issues in the environment has attracted recent interest in the community. In general, the use of NMNs for environmental applications is highly dependent on the physical and chemical properties of NMNs. Such properties can be readily controlled by tailoring the attributes of NMNs, including their size, shape, composition, and surface. In this feature article, we discuss recent progress in the rational design and engineering of NMNs with particular focus on their applications in the field of environmental sensing and catalysis. The development of functional NMNs for environmental applications is highly interdisciplinary, which requires concerted efforts from the communities of materials science, chemistry, engineering, and environmental science.

  19. Engineering noble metal nanomaterials for environmental applications.

    Science.gov (United States)

    Li, Jingguo; Zhao, Tingting; Chen, Tiankai; Liu, Yanbiao; Ong, Choon Nam; Xie, Jianping

    2015-05-07

    Besides being valuable assets in our daily lives, noble metals (namely, gold, silver, and platinum) also feature many intriguing physical and chemical properties when their sizes are reduced to the nano- or even subnano-scale; such assets may significantly increase the values of the noble metals as functional materials for tackling important societal issues related to human health and the environment. Among which, designing/engineering of noble metal nanomaterials (NMNs) to address challenging issues in the environment has attracted recent interest in the community. In general, the use of NMNs for environmental applications is highly dependent on the physical and chemical properties of NMNs. Such properties can be readily controlled by tailoring the attributes of NMNs, including their size, shape, composition, and surface. In this feature article, we discuss recent progress in the rational design and engineering of NMNs with particular focus on their applications in the field of environmental sensing and catalysis. The development of functional NMNs for environmental applications is highly interdisciplinary, which requires concerted efforts from the communities of materials science, chemistry, engineering, and environmental science.

  20. Electrocatalysis of chemically synthesized noble metal nanoparticles on carbon electrodes

    DEFF Research Database (Denmark)

    Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

    Noble metal nanoparticles (NPs), such as platinum (Pt) and palladium (Pd) NPs are promising catalysts for dioxygen reduction and oxidation of molecules such as formic acid and ethanol in fuel cells. Carbon nanomaterials are ideal supporting materials for electrochemical catalysts due to their good...... by electrochemical SPM. This study offers promise for development of new high-efficiency catalyst types with low-cost for fuel cell technology...

  1. Polymer-noble metal nanocomposites: Review

    CSIR Research Space (South Africa)

    Folarin, OM

    2011-09-01

    Full Text Available because of their multi-functionality, ease of process-ability, potential for large-scale manufacturing, significantly lighter than metals, ease of synthesis when compared to the oxide/noble metal multi-layers (Gass et al., 2006; Lee et al., 2003.... their easy aggregation arising from their high surface free energy (Lee et al., 2006). In the design of nanocomposites, one must consider the properties of the polymer matrix as well as the stability of the nanoparticles and more importantly...

  2. TiN nanoparticles on CNT-graphene hybrid support as noble-metal-free counter electrode for quantum-dot-sensitized solar cells.

    Science.gov (United States)

    Youn, Duck Hyun; Seol, Minsu; Kim, Jae Young; Jang, Ji-Wook; Choi, Youngwoo; Yong, Kijung; Lee, Jae Sung

    2013-02-01

    The development of an efficient noble-metal-free counter electrode is crucial for possible applications of quantum-dot-sensitized solar cells (QDSSCs). Herein, we present TiN nanoparticles on a carbon nanotube (CNT)-graphene hybrid support as a noble-metal-free counter electrode for QDSSCs employing a polysulfide electrolyte. The resulting TiN/CNT-graphene possesses an extremely high surface roughness, a good metal-support interaction, and less aggregation relative to unsupported TiN; it also has superior solar power conversion efficiency (4.13 %) when applying a metal mask, which is much higher than that of the state-of-the-art Au electrode (3.35 %). Based on electrochemical impedance spectroscopy measurements, the enhancement is ascribed to a synergistic effect between TiN nanoparticles and the CNT-graphene hybrid, the roles of which are to provide active sites for the reduction of polysulfide ions and electron pathways to TiN nanoparticles, respectively. The combination of graphene and CNTs leads to a favorable morphology that prevents stacking of graphene or bundling of CNTs, which maximizes the contact of the support with TiN nanoparticles and improves electron-transfer capability relative to either carbon material alone. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Spectrophotometric methods for determining noble metals

    International Nuclear Information System (INIS)

    Gur'eva, R.F.; Savvin, S.B.

    2002-01-01

    The main trends of the development of spectrophotometric methods for determining noble metals (NMs) including ruthenium are considered. One of these trends is the synthesis and study of new, highly sensitive and selective organic reagents for determining NMs in solutions and solid phase. Another trend is the search for and developing of new methodological approaches (techniques) and color reactions, including those that involve modified and immobilized reagents. The third trend includes the improvement of equipment and automation. It is shown that the present-day spectrophotometry can provide the determination of NMs in samples with concentrations from several to 10 -4 % (photometry and differential photometry) and down to 10 -7 % (test and sorption-spectroscopic methods based on photometry and diffuse-reflectance spectroscopy, including the use of chromaticity functions) [ru

  4. Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum

    Science.gov (United States)

    Ray, Siba P.; Liu, Xinghua

    2000-01-01

    An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

  5. Noble Metal/Ceramic Composites in Flame Processes

    DEFF Research Database (Denmark)

    Schultz, Heiko; Madler, Lutz; Strobel, Reto

    conditions influence the resulting noble metal particles size in those systems [1]. For every specific application the particle size and the metal/metal oxide interaction affect the performance of these nano-composite materials [2]. Recently, aerosol processes have been successfully used to produce platinum...

  6. Biomimetic synthesis of noble metal nanocrystals

    Science.gov (United States)

    Chiu, Chin-Yi

    At the nanometer scale, the physical and chemical properties of materials heavily depend on their sizes and shapes. This fact has triggered considerable efforts in developing controllable nanomaterial synthesis. The controlled growth of colloidal nanocrystal is a kinetic process, in which high-energy facets grow faster and then vanish, leading to a nanocrystal enclosed by low-energy facets. Identifying a surfactant that can selectively bind to a particular crystal facet and thus lower its surface energy, is critical and challenging in shape controlled synthesis of nanocrystals. Biomolecules exhibiting exquisite molecular recognition properties can be exploited to precisely engineer nanostructured materials. In the first part of my thesis, we employed the phage display technique to select a specific multifunctional peptide sequence which can bind on Pd surface and mediate Pd crystal nucleation and growth, achieving size controlled synthesis of Pd nanocrystals in aqueous solution. We further demonstrated a rational biomimetic approach to the predictable synthesis of nanocrystals enclosed by a particular facet in the case of Pt. Specifically, Pt {100} and Pt {111} facet-specific peptides were identified and used to synthesize Pt nanocubes and Pt nano-tetrahedrons, respectively. The mechanistic studies of Pt {111} facet-specific peptide had led us to study the facet-selective adsorption of aromatic molecules on noble metal surfaces. The discoveries had achieved the development of design strategies to select facet-selective molecules which can synthesize nanocrystals with expected shapes in both Pt and Pd system. At last, we exploited Pt facet-specific peptides and controlled the molecular interaction to produce one- and three- dimensional nanostructures composed of anisotropic nanoparticles in synthetic conditions without supramolecular pre-organization, demonstrating the full potential of biomolecules in mediating material formation process. My research on biomimetic

  7. Recovery of noble metals from HLLW using photocatalytic reduction

    International Nuclear Information System (INIS)

    Nishi, T.; Uetake, N.; Kawamura, F.; Yusa, H.

    1987-01-01

    In high-level liquid waste (HLLW) from fuel reprocessing plants, noble metals (palladium, rhodium, and ruthenium), which account for ∼ 10 wt% of fission products, exist as ions. These metals are very useful as catalytic material in automobile exhaust systems and other chemical processes, but they are rare in nature, making their recovery from fission products highly desirable. The ions of noble metals in solution have the feature that their reduction potential from ion to metal is relatively high compared with that of other fission product ions, so they can be selectively separated as a metal by a reduction process. The authors think a photoreduction process using a photocatalysts, which functions as photon-electron conversion agent, is suitable for the recovery of noble metals from HLLW for three reasons: (1) this process uses no reduction agents, which usually degrade the nitric acid, so that coprecipitation of other fission products does not occur. (2) The reactions are induced by light, which does not contaminate the reaction system, and in contrast with ordinary photo-redox reactions, the quantum yield is quite high. (3) As the photocatalyst does not change in the reaction, it can be used again and again. The report shows the results of fundamental experiments on the application of photocatalytic reduction to the recovery of noble metal ions in nitric acid solution

  8. Niobium-based catalysts prepared by reactive radio-frequency magnetron sputtering and arc plasma methods as non-noble metal cathode catalysts for polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    Ohnishi, Ryohji; Katayama, Masao; Takanabe, Kazuhiro; Kubota, Jun; Domen, Kazunari

    2010-01-01

    Two vacuum methods, reactive radio-frequency (RF) magnetron sputtering and arc plasma deposition, were used to prepare niobium-based catalysts for an oxygen reduction reaction (ORR) as non-noble metal cathodes for polymer electrode fuel cells (PEFCs). Thin films with various N and O contents, denoted as NbO x and Nb-O-N, were prepared on glassy carbon plates by RF magnetron sputtering with controlled partial pressures of oxygen and nitrogen. Electrochemical measurements indicated that the introduction of the nitrogen species into the thin film resulted in improved ORR activity compared to the oxide-only film. Using an arc plasma method, niobium was deposited on highly oriented pyrolytic graphite (HOPG) substrates, and the sub-nanoscale surface morphology of the deposited particles was investigated using scanning tunneling microscopy (STM). To prepare practical cathode catalysts, niobium was deposited on carbon black (CB) powders by arc plasma method. STM and transmission electron microscopy observations of samples on HOPG and CB indicated that the prepared catalysts were highly dispersed at the atomic level. The onset potential of oxygen reduction on Nb-O-N/CB was 0.86 V vs. a reversible hydrogen electrode, and the apparent current density was drastically improved by the introduction of nitrogen.

  9. Supported noble metals on hydrogen-treated TiO2 nanotube arrays as highly ordered electrodes for fuel cells.

    Science.gov (United States)

    Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Gao, Yuan; Zhao, Yun; Song, Wei; Shao, Zhigang; Yi, Baolian

    2013-04-01

    Hydrogen-treated TiO2 nanotube (H-TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H-TNTs increases by approximately one order of magnitude in comparison to air-treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H-TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H-TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H-TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H-TNT support. The as-prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H-TNT-loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as-prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X-ray photoelectron spectroscopy shows that after the H-TNT-loaded Pt catalysts are annealed in H2 for the second time, the strong metal-support interaction between the H-TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel-cell testing shows that the power density reaches a maximum of 500 mWcm(-2) when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra-low Pt loading, the new electrode generates a specific power density of 2.68 kWg(Pt) (-1) . It is indicated that H-TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports

  10. Neutron activation analysis for noble metals in matte leach residues

    International Nuclear Information System (INIS)

    Hart, R.J.

    1978-01-01

    The development of the neutron activation analysis technique as a method for rapid and precise determinations of platinum group metals in matte leach residues depends on obtaining a method for effecting complete and homogeneous sample dilution. A simple method for solid dilution of metal samples is outlined in this study, which provided a basis for the accurate determination of all the noble metals by the Neutron Activation Analysis technique

  11. Noble metal alloys for metal-ceramic restorations.

    Science.gov (United States)

    Anusavice, K J

    1985-10-01

    A review of the comparative characteristics and properties of noble metal alloys used for metal-ceramic restorations has been presented. Selection of an alloy for one's practice should be based on long-term clinical data, physical properties, esthetic potential, and laboratory data on metal-ceramic bond strength and thermal compatibility with commercial dental porcelains. Although gold-based alloys, such as the Au-Pt-Pd, Au-Pd-Ag, and Au-Pd classes, may appear to be costly compared with the palladium-based alloys, they have clearly established their clinical integrity and acceptability over an extended period of time. Other than the relatively low sag resistance of the high gold-low silver content alloys and the potential thermal incompatibility with some commercial porcelain products, few clinical failures have been observed. The palladium-based alloys are less costly than the gold-based alloys. Palladium-silver alloys require extra precautions to minimize porcelain discoloration. Palladium-copper and palladium-cobalt alloys may also cause porcelain discoloration, as copper and cobalt are used as colorants in glasses. The palladium-cobalt alloys are least susceptible to high-temperature creep compared with all classes of noble metals. Nevertheless, insufficient clinical data exist to advocate the general use of the palladium-copper and palladium-cobalt alloys at the present time. One should base the selection and use of these alloys in part on their ability to meet the requirements of the ADA Acceptance Program. A list of acceptable or provisionally acceptable alloys is available from the American Dental Association and is published annually in the Journal of the American Dental Association. Dentists have the legal and ethical responsibility for selection of alloys used for cast restorations. This responsibility should not be delegated to the dental laboratory technician. It is advisable to discuss the criteria for selection of an alloy with the technician and the

  12. Noble metals in cretaceous/tertiary sediments from El Kef

    International Nuclear Information System (INIS)

    Kuslys, M.; Kraehenbuehl, U.

    1983-01-01

    Sediments from El Kef, Tunisia, were analysed by RNAA for Au, Ir and Os. All three elements show a 10-20 fold enrichment at the Cretaceous/Tertiary boundary. This enrichment must be the result of the addition of material with a high concentration of noble metals. It is plausible that this exotic material has an extra-terrestrial origin. (orig.)

  13. Noble metals in Cretaceous/Tertiary sediments from El Kef

    International Nuclear Information System (INIS)

    Kuslys, M.; Kraehenbuehl, U.

    1983-01-01

    Sediments from El Kef, Tunisia, were analysed by RNAA for Au, Ir and Os. All three elements show a 10-20 fold enrichment at the Cretaceous/Tertiary boundary. This enrichment must be the result of the addition of material with a high concentration of noble metals. It is plausible that this exotic material has an extraterrestrial origin. (orig.)

  14. Interaction between Nafion ionomer and noble metal catalyst for PEMFCs

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    The implement of polymer impregnation in electrode structure (catalyst layer) decreasing the noble metal catalyst loading by a factor of ten , , is one of the essential mile stones in the evolution of Proton Exchange Membrane Fuel Cells’ development among the application of catalyst support and e...

  15. Spectrochemical determination of impurities and noble metal traces in carnallite

    International Nuclear Information System (INIS)

    Goldbart, Z.; Carmi, U.; Harrel, A.

    1978-02-01

    A spectrochemical method was developed for the determination of impurities and noble metal traces in carnallite by DC arc excitation. The investigated sample is brought to a standard form of potassium-magnesium sulphate mixed with graphite. Detection limits of 1-10 ppm were determined for 27 elements; the dynamical detection range is 1-400 ppm

  16. Magneto-optical Kerr spectroscopy of noble metals

    Science.gov (United States)

    Uba, L.; Uba, S.; Antonov, V. N.

    2017-12-01

    Magneto-optical (MO) response of the noble metals Cu, Ag, and Au in the joint experimental and ab initio theoretical study is reported. The magneto-optical polar Kerr effect (MOKE) spectra of the noble-metal films were measured with the high sensitivity in the applied magnetic field of 1.5 T over the photon energy range 0.74-5.8 eV. Complete set of the optical conductivity tensor elements was determined precisely from the MOKE and the optical spectra measured at the same energy points. The importance of the off-diagonal intraband Drude-type transitions is demonstrated explicitly for each noble metal and found to be a substantial contribution to the observed spectra. It is shown that the first-principles calculations using the spin-polarized fully relativistic Dirac linear-muffin-tin-orbital method with the inclusion of correlation effects by GGA+U approach reproduce well the experimental spectra and allow to explain the microscopic origin of the noble metals' magneto-optical response in terms of interband transitions. Although the energy band structures of Cu, Ag, and Au are very similar, there are some distinctive differences in bandwidths and the energy positions of the bands (especially in X and L symmetry points), mainly due to different spin-orbit splitting and differences in the spatial extent of 3 d , 4 d , and 5 d valence wave functions of noble metals. It was found that the small differences in the band positions lead to significant differences in the MO properties of three noble metals. Although the spin-orbit interaction in Au is about six times larger than in Cu, and approximately two times larger than in Ag, the absolute value of Kerr rotation in Au is of the same magnitude as in Cu and one order of magnitude smaller as compared to Ag. The sharp Kerr effect spectral peak in Ag is not due to the electronic interband transitions, but rather to the plasma-edge splitting. The band-by-band decomposition of the Cu, Ag, and Au MO spectra is presented and the

  17. Noble metal extraction and sorption concentrating

    International Nuclear Information System (INIS)

    Petrukhin, O.M.; Malofeeva, G.I.

    1985-01-01

    Works performed in the USSR Academy of Sciences GEOCHI laboratory of extraction methods and devoted to selectivity problems of extraction and sorption methods of platinum metal, cadmium and indium concentrating in analytical chemistry are discussed. On choosing complexino. reagent main attention is paid to the selectivity variation based on different stability of metal complexes. Platinum metals are extracted in the form of ion associates when usinq hard, mainly oxyqen-containing, extractants. Coordination-solvated metal complexes are extracted white usinq extractants containing sulfur, trivalent phosphorus and aromatic nitroqen as donor anions. Selectivity is maximum for sulfur- and nitroren-containinq extractants and sorbents. In case of the group extraction of platinum metals sorption is preferable and in case of selective extraction of individual metals, especially, in case of need of relative concentratinq extraction is preferable

  18. Carbon Nanotubes and Other Nanostructures as Support Material for Nanoparticulate Noble-Metal Catalysts in Fuel Cells

    DEFF Research Database (Denmark)

    Larsen, Mikkel Juul; Veltzé, Sune; Skou, Eivind Morten

    In polymer electrolyte membrane fuel cells (PEMFC) a fuel - usually hydrogen - and oxygen are combined to produce electricity and water in an electrochemical process, which is commonly carried out at 60-80 °C. For oxygen reduction and fuel oxidation to occur at such low temperatures platinum or p...

  19. A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

    KAUST Repository

    Jin, Zhao; Xiao, Manda; Bao, Zhihong; Wang, Peng; Wang, Jianfang

    2012-01-01

    Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO 2/0.1 mol Pd microspheres showed the highest turnover frequency in NaBH 4 reduction of 4-nitrophenol (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

    KAUST Repository

    Jin, Zhao

    2012-04-26

    Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO 2/0.1 mol Pd microspheres showed the highest turnover frequency in NaBH 4 reduction of 4-nitrophenol (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Preparation and Heat-Treatment of DWPF Simulants With and Without Co-Precipitated Noble Metals

    International Nuclear Information System (INIS)

    Koopman, David C.:Eibling, Russel E

    2005-01-01

    The Savannah River National Laboratory is in the process of investigating factors suspected of impacting catalytic hydrogen generation in the Chemical Process Cell of the Defense Waste Processing Facility, DWPF. Noble metal catalyzed hydrogen generation in simulation work constrains the allowable acid addition operating window in DWPF. This constraint potentially impacts washing strategies during sludge batch preparation. It can also influence decisions related to the addition of secondary waste streams to a sludge batch. Noble metals have historically been added as trim chemicals to process simulations. The present study investigated the potential conservatism that might be present from adding the catalytic species as trim chemicals to the final sludge simulant versus co-precipitating the noble metals into the insoluble sludge solids matrix. Parallel preparations of two sludge simulants targeting the composition of Sludge Batch 3 were performed in order to evaluate the impact of the form of noble metals. Identical steps were used except that one simulant had dissolved palladium, rhodium, and ruthenium present during the precipitation of the insoluble solids. Noble metals were trimmed into the other stimulant prior to process tests. Portions of both sludge simulants were held at 97 C for about eight hours to qualitatively simulate the effects of long term storage on particle morphology and speciation. The simulants were used as feeds for Sludge Receipt and Adjustment Tank, SRAT, process simulations. The following conclusions were drawn from the simulant preparation work: (1) The first preparation of a waste slurry simulant with co-precipitated noble metals was successful, based on the data obtained. It appears that 99+% of the noble metals were retained in the simulant. (2) Better control of carbonate, hydroxide, and post-wash trim chemical additions is needed before the new method of simulant preparation will be as reproducible as the old method. (3) The two new

  2. Combinatorial discovery of new methanol-tolerant non-noble metal cathode electrocatalysts for direct methanol fuel cells.

    Science.gov (United States)

    Yu, Jong-Sung; Kim, Min-Sik; Kim, Jung Ho

    2010-12-14

    Combinatorial synthesis and screening were used to identify methanol-tolerant non-platinum cathode electrocatalysts for use in direct methanol fuel cells (DMFCs). Oxygen reduction consumes protons at the surface of DMFC cathode catalysts. In combinatorial screening, this pH change allows one to differentiate active catalysts using fluorescent acid-base indicators. Combinatorial libraries of carbon-supported catalyst compositions containing Ru, Mo, W, Sn, and Se were screened. Ternary and quaternary compositions containing Ru, Sn, Mo, Se were more active than the "standard" Alonso-Vante catalyst, Ru(3)Mo(0.08)Se(2), when tested in liquid-feed DMFCs. Physical characterization of the most active catalysts by powder X-ray diffraction, gas adsorption, and X-ray photoelectron spectroscopy revealed that the predominant crystalline phase was hexagonal close-packed (hcp) ruthenium, and showed a surface mostly covered with oxide. The best new catalyst, Ru(7.0)Sn(1.0)Se(1.0), was significantly more active than Ru(3)Se(2)Mo(0.08), even though the latter contained smaller particles.

  3. Measuring the noble metal and iodine composition of extracted noble metal phase from spent nuclear fuel using instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Palomares, R.I.; Dayman, K.J.; Landsberger, S.; Biegalski, S.R.; Soderquist, C.Z.; Casella, A.J.; Brady Raap, M.C.; Schwantes, J.M.

    2015-01-01

    Masses of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis. Nuclide presence is predicted using fission yield analysis, and radionuclides are identified and the masses quantified using neutron activation analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO 2 fuel dissolved in nitric acid and UO 2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. - Highlights: • The noble metal phase was chemically extracted from spent nuclear fuel and analyzed non-destructively. • Noble metal phase nuclides and long-lived iodine were identified and quantified using neutron activation analysis. • Activation to shorter-lived radionuclides allowed rapid analysis of long-lived fission products in spent fuel using gamma spectrometry

  4. Liquid state properties of certain noble and transition metals

    International Nuclear Information System (INIS)

    Bhuiyan, G.M.; Rahman, A.; Khaleque, M.A.; Rashid, R.I.M.A.; Mujibur Rahman, S.M.

    1998-07-01

    Certain structural, thermodynamic and atomic transport properties of a number of liquid noble and transition metals are reported. The underlying theory combines together a simple form of the N-body potential and the thermodynamically self-consistent variational modified hypernetted chain (VMHNC) theory of liquid. The static structure factors calculated by using the VMHNC resemble the hard sphere (HS) values. Consequently the HS model is used to calculate the thermodynamic properties viz. specific heat, entropy, isothermal compressibility and atomic transport properties. (author)

  5. Near transferable phenomenological n-body potentials for noble metals.

    Science.gov (United States)

    Pontikis, Vassilis; Baldinozzi, Gianguido; Luneville, Laurence; Simeone, David

    2017-09-06

    We present a semi-empirical model of cohesion in noble metals with suitable parameters reproducing a selected set of experimental properties of perfect and defective lattices in noble metals. It consists of two short-range, n-body terms accounting respectively for attractive and repulsive interactions, the former deriving from the second moment approximation of the tight-binding scheme and the latter from the gas approximation of the kinetic energy of electrons. The stability of the face centred cubic versus the hexagonal compact stacking is obtained via a long-range, pairwise function of customary use with ionic pseudo-potentials. Lattice dynamics, molecular statics, molecular dynamics and nudged elastic band calculations show that, unlike previous potentials, this cohesion model reproduces and predicts quite accurately thermodynamic properties in noble metals. In particular, computed surface energies, largely underestimated by existing empirical cohesion models, compare favourably with measured values, whereas predicted unstable stacking-fault energy profiles fit almost perfectly ab initio evaluations from the literature. All together the results suggest that this semi-empirical model is nearly transferable.

  6. Solvent extraction of noble metals by formazans

    International Nuclear Information System (INIS)

    Grote, M.; Hueppe, U.; Kettrup, A.

    1984-01-01

    The extraction properties of ion-pairs composed of quaternary ammonium cations and a sulphonated formazan were compared with those of an unsulphonated formazan, for various solvent media. In dichloromethane the combined system behaves as a 'coloured anion-exchanger', with displacement of the sulphonated formazan, whereas in toluene Pd(II) and Ag(I) are extracted as the metal formazan chelates from aqueous medium. The rates of extraction are remarkably higher than with the simple extractants. Because of the higher stability only the simple chelating extraction systems afford satisfactory separation of Pd(II) from excess of Pt(IV) and of Ag(I) from Cu(II). The extracted metals can be stripped and the extractant regenerated. (author)

  7. NOBLE METAL CHEMISTRY AND HYDROGEN GENERATION DURING SIMULATED DWPF MELTER FEED PREPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D

    2008-06-25

    Simulations of the Defense Waste Processing Facility (DWPF) Chemical Processing Cell vessels were performed with the primary purpose of producing melter feeds for the beaded frit program plus obtaining samples of simulated slurries containing high concentrations of noble metals for off-site analytical studies for the hydrogen program. Eight pairs of 22-L simulations were performed of the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles. These sixteen simulations did not contain mercury. Six pairs were trimmed with a single noble metal (Ag, Pd, Rh, or Ru). One pair had all four noble metals, and one pair had no noble metals. One supporting 4-L simulation was completed with Ru and Hg. Several other 4-L supporting tests with mercury have not yet been performed. This report covers the calculations performed on SRNL analytical and process data related to the noble metals and hydrogen generation. It was originally envisioned as a supporting document for the off-site analytical studies. Significant new findings were made, and many previous hypotheses and findings were given additional support as summarized below. The timing of hydrogen generation events was reproduced very well within each of the eight pairs of runs, e.g. the onset of hydrogen, peak in hydrogen, etc. occurred at nearly identical times. Peak generation rates and total SRAT masses of CO{sub 2} and oxides of nitrogen were reproduced well. Comparable measures for hydrogen were reproduced with more variability, but still reasonably well. The extent of the reproducibility of the results validates the conclusions that were drawn from the data.

  8. The behavior and effects of the noble metals in the DWPF melter system

    International Nuclear Information System (INIS)

    Hutson, N.D.; Smith, M.E.

    1992-01-01

    Fission-product noble metals have caused severe operating problems in numerous worldwide waste vitrification facilities. These dense, highly conductive noble metals have tended to accumulate on the floor of joule-heated glass melters causing electrical distortions which have, in some occurrences, rendered the melter inoperable. A pilot scale vitrification research facility at the U.S. Department of Energy's Savannah River Laboratory has been operated for more than a year with simulated feed streams containing noble metals. In this paper the behavior of these noble metals in the melter system and final glass product and their effects on the scaled DWPF-type melter are discussed

  9. Comparison of the tensile bond strength of high-noble, noble, and base metal alloys bonded to enamel.

    Science.gov (United States)

    Sen, D; Nayir, E; Pamuk, S

    2000-11-01

    Although the bond strengths of various resin composite luting materials have been reported in the literature, the evaluation of these systems with various cast alloys of different compositions has not been completely clarified. To evaluate the tensile bond strength of sandblasted high-noble, noble, and base metal alloys bonded to etched enamel by 2 different bonding agents of different chemical composition: Panavia-Ex (BIS-GMA) and Super-Bond (4-META acrylic). Flat enamel surfaces were prepared on buccal surfaces of 60 extracted noncarious human incisors. Teeth were divided into 3 groups of 20 each. Twenty circular disks of 5 mm diameter were prepared for casting for each group. Group I was cast with a high-noble, group II with a noble, and group III with a base metal alloy. The surfaces of the disks were sandblasted with 250 microm Al(2)O(3). Ten disks of each group were bonded to exposed enamel surfaces with Super-Bond and 10 disks with Panavia-Ex as recommended by the manufacturer. The tensile bond strength was measured with an Instron universal testing machine with a crosshead speed of 0.5 mm/min until failure occurred. Two-way ANOVA was used to evaluate the results. The differences in bond strengths of Super-Bond and Panavia-Ex with different alloys were not significant. The highest bond strengths were obtained in base metal alloys, followed by noble and high-noble alloys. These results were significant. Panavia-Ex and Super-Bond exhibited comparable tensile bond strengths. For both luting agents, the highest bond strengths were achieved with base metal alloys and the lowest with high-noble alloys.

  10. Nanoparticles of noble metals in the supergene zone

    Science.gov (United States)

    Zhmodik, S. M.; Kalinin, Yu. A.; Roslyakov, N. A.; Mironov, A. G.; Mikhlin, Yu. L.; Belyanin, D. K.; Nemirovskaya, N. A.; Spiridonov, A. M.; Nesterenko, G. V.; Airiyants, E. V.; Moroz, T. N.; Bul'bak, T. A.

    2012-04-01

    Formation of noble metal nanoparticles is related to various geological processes in the supergene zone. Dispersed mineral phases appear during weathering of rocks with active participation of microorganisms, formation of soil, in aqueous medium and atmosphere. Invisible gold and other noble metals are incorporated into oxides, hydroxides, and sulfides, as well as in dispersed organic and inorganic carbonic matter. Sulfide minerals that occur in bedrocks and ores unaltered by exogenic processes and in cementation zone are among the main concentrators of noble metal nanoparticles. The ability of gold particles to disaggregate is well-known and creates problems in technological and analytical practice. When Au and PGE nanoparticles and clusters occur, these problems are augmented because of their unusual reactions and physicochemical properties. The studied gold, magnetite, titanomagnetite and pyrite microspherules from cementation zone and clay minerals of laterites in Republic of Guinea widen the knowledge of their abundance and inferred formation conditions, in particular, in the contemporary supergene zone. Morphology and composition of micrometer-sized Au mineral spherules were studied with SEM and laser microprobe. The newly formed segregations of secondary gold on the surface of its residual grains were also an object of investigation. The character of such overgrowths is the most indicative for nanoparticles. The newly formed Au particles provide evidence for redistribution of ultradispersed gold during weathering. There are serious prerequisites to state that microorganisms substantially control unusual nano-sized microspherical morphology of gold particles in the supergene zone. This is supported by experiments indicating active absorption of gold by microorganisms and direct evidence for participation of Ralstonia metallidurans bacteria in the formation of peculiar corroded bacteriomorphic surface of gold grains. In addition, the areas enriched in carbon

  11. Rational design of binder-free noble metal/metal oxide arrays with nanocauliflower structure for wide linear range nonenzymatic glucose detection

    KAUST Repository

    Li, Zhenzhen; Xin, Yanmei; Zhang, Zhonghai; Wu, Hongjun; Wang, Peng

    2015-01-01

    One-dimensional nanocomposites of metal-oxide and noble metal were expected to present superior performance for nonenzymatic glucose detection due to its good conductivity and high catalytic activity inherited from noble metal and metal oxide

  12. Classical and quantum effects in noble metal and graphene plasmonics

    DEFF Research Database (Denmark)

    Mortensen, N. Asger

    2015-01-01

    Plasmonics — the interaction of light with free electrons in metals — is commonly understood within classical electrodynamics using local-response constitutive laws (such as Ohm's law). However, the tight localization of plasmons to small volumes is revealing intriguing new physics such as noncla......Plasmonics — the interaction of light with free electrons in metals — is commonly understood within classical electrodynamics using local-response constitutive laws (such as Ohm's law). However, the tight localization of plasmons to small volumes is revealing intriguing new physics...... such as nonclassical electrodynamics with a nonlocal response of the plasmons. Nonlocal effects are being explored both theoretically and experimentally in different charge-conducting material systems with examples ranging from sub-10 nanometer noble metal particles to one-atom thin disks of doped graphene....

  13. Behavior of shut-down dose rate of recirculation piping of BWR under noble metal application

    International Nuclear Information System (INIS)

    Fuse, Motomasa; Nagase, Makoto; Aizawa, Motohiro; Wada, Yoichi; Ishida, Kazushige; Hosokawa, Hideyuki; Hettiarachchi, Samson; Weber, Christoph

    2014-01-01

    The cause of shut-down dose rate change of the recirculation piping observed in KKM (Kern Kraftwerk Mühleberg) after application of noble metal injection method is analyzed. The plant experienced the sharp decrease of piping dose rate in the cycle just after the application of noble metal(classic NobleChem TM ) and re-buildup of radioactivity in the subsequent several cycles. After the application of online noble metal injection (online NobleChem TM ), gradual decrease of dose rate has been observed. The presence of a certain amount of noble metal on the iron rich oxide film promotes the dissolution of the oxide under hydrogen addition, resulting in a decrease of deposited noble metal on the oxide film surface as well as of radioactive species in the film. Under the condition of lower amount of noble metal on the surface oxides, the oxidant species, especially hydrogen peroxide, slightly increases facilitating the re-growth of iron rich oxides along with re-buildup of radioactivity. After the application of online noble metal injection during each cycle, gradual dissolution of iron rich oxides and gradual decrease of radioactivity in the oxides proceed to decrease the piping dose rate. In the radioactivity decreasing phase, the presence of zinc is considered to assist the suppression of radioactivity buildup in the oxide film. From the analysis, treating piping surface with platinum after chemical decontamination process is expected to work well for suppression of the piping dose rate. (author)

  14. Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

    International Nuclear Information System (INIS)

    Zhu, S.; Zhou, W.

    2010-01-01

    Noble metal, especially gold (Au) and silver (Ag) nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR). In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA) method, and finite-difference time domain (FDTD) method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL) and focused ion beam (FIB) are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs)-potential Alzheimer's disease (AD) biomarkers, and staphylococcal enterotoxin B (SEB) in nano-Moore per liter (nM) concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

  15. Modification of titanium electrodes by a noble metal deposit

    Energy Technology Data Exchange (ETDEWEB)

    Devilliers, D.; Mahe, E. [Pierre et Marie Curie Univ., Paris (France). Laboratoire LI2C, UMR CNRS

    2008-07-01

    Titanium is commonly used as a substrate for dimensionally stable anodes (DSAs) because it is corrosion-resistant in acid media and because a passive titanium oxide (TiO2) film can be formed on the surface. This paper reported on a study in which titanium substrates were first covered by anodization with a TiO2 layer. The electrochemical properties of the Ti/TiO2 electrodes were investigated. The modification of the substrates by cathodic electrodeposition of a noble metal was described. The reactivity of the Ti/TiO2/Pt structures were illustrated by impedance spectroscopy experiments. The impedance studies performed with Ti/ TiO2 electrodes in the presence of a redox couple in solution (Fe3+/Fe2+ system in sulphuric acid) showed that the electronic transfer is very slow. It was concluded that the deposition of a noble metal coating on Ti/TiO2 substrates leads to modified titanium electrodes that exhibit electrocatalytic behaviour versus specific electrochemical reactions. 1 ref., 3 figs.

  16. Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Shaoli Zhu

    2010-01-01

    Full Text Available Noble metal, especially gold (Au and silver (Ag nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR. In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA method, and finite-difference time domain (FDTD method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL and focused ion beam (FIB are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs-potential Alzheimer's disease (AD biomarkers, and staphylococcal enterotixn B (SEB in nano-Moore per liter (nM concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

  17. Metal-organic frameworks for adsorption and separation of noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Greathouse, Jeffery A.; Staiger, Chad

    2017-05-30

    A method including exposing a gas mixture comprising a noble gas to a metal organic framework (MOF), including an organic electron donor and an adsorbent bed operable to adsorb a noble gas from a mixture of gases, the adsorbent bed including a metal organic framework (MOF) including an organic electron donor.

  18. Noble Metal Arsenides and Gold Inclusions in Northwest Africa 8186

    Science.gov (United States)

    Srinivasan, P.; McCubbin, F. M.; Rahman, Z.; Keller, L. P.; Agee, C. B.

    2016-01-01

    CK carbonaceous chondrites are a highly thermally altered group of carbonaceous chondrites, experiencing temperatures ranging between approximately 576-867 degrees Centigrade. Additionally, the mineralogy of the CK chondrites record the highest overall oxygen fugacity of all chondrites, above the fayalite-magnetite-quartz (FMQ) buffer. Me-tallic Fe-Ni is extremely rare in CK chondrites, but magnetite and Fe,Ni sulfides are commonly observed. Noble metal-rich inclusions have previously been found in some magnetite and sulfide grains. These arsenides, tellurides, and sulfides, which contain varying amounts of Pt, Ru, Os, Te, As, Ir, and S, are thought to form either by condensation from a solar gas, or by exsolution during metamorphism on the chondritic parent body. Northwest Africa (NWA) 8186 is a highly metamorphosed CK chondrite. This meteorite is predominately composed of NiO-rich forsteritic olivine (Fo65), with lesser amounts of plagioclase (An52), augite (Fs11Wo49), magnetite (with exsolved titanomagnetite, hercynite, and titanohematite), monosulfide solid solution (with exsolved pentlandite), and the phosphate minerals Cl-apatite and merrillite. This meteorite contains coarse-grained, homogeneous silicates, and has 120-degree triple junctions between mineral phases, which indicates a high degree of thermal metamorphism. The presence of NiO-rich olivine, oxides phases all bearing Fe3 plus, and the absence of metal, are consistent with an oxygen fugacity above the FMQ buffer. We also observed noble metal-rich phases within sulfide grains in NWA 8186, which are the primary focus of the present study.

  19. Noble metal catalysts in the production of biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, A.

    2013-11-01

    The energy demand is increasing in the world together with the need to ensure energy security and the desire to decrease greenhouse gas emissions. While several renewable alternatives are available for the production of electricity, e.g. solar energy, wind power, and hydrogen, biomass is the only renewable source that can meet the demand for carbon-based liquid fuels and chemicals. The technology applied in the conversion of biomass depends on the type and complexity of the biomass, and the desired fuel. Hydrogen and hydrogen-rich mixtures (synthesis gas) are promising energy sources as they are more efficient and cleaner than existing fuels, especially when they are used in fuel cells. Hydrotreatment is a catalytic process that can be used in the conversion of biomass or biomass-derived liquids into fuels. In autothermal reforming (ATR), catalysts are used in the production of hydrogen-rich mixtures from conventional fuels or bio-fuels. The different nature of biomass and biomass-derived liquids and mineral oil makes the use of catalysts developed for the petroleum industry challenging. This requires the improvement of available catalysts and the development of new ones. To overcome the limitations of conventional hydrotreatment and ATR catalysts, zirconia-supported mono- and bimetallic rhodium, palladium, and platinum catalysts were developed and tested in the upgrading of model compounds for wood-based pyrolysis oil and in the production of hydrogen, using model compounds for gasoline and diesel. Catalysts were also tested in the ATR of ethanol. For comparative purposes commercial catalysts were tested and the results obtained with model compounds were compared with those obtained with real feedstocks (hydrotreatmet tests with wood-based pyrolysis oil and ATR tests with NExBTL renewable diesel). Noble metal catalysts were active and selective in the hydrotreatment of guaiacol used as the model compound for the lignin fraction of wood-based pyrolysis oil and wood

  20. Process for Making a Noble Metal on Tin Oxide Catalyst

    Science.gov (United States)

    Davis, Patricia; Miller, Irvin; Upchurch, Billy

    2010-01-01

    To produce a noble metal-on-metal oxide catalyst on an inert, high-surface-area support material (that functions as a catalyst at approximately room temperature using chloride-free reagents), for use in a carbon dioxide laser, requires two steps: First, a commercially available, inert, high-surface-area support material (silica spheres) is coated with a thin layer of metal oxide, a monolayer equivalent. Very beneficial results have been obtained using nitric acid as an oxidizing agent because it leaves no residue. It is also helpful if the spheres are first deaerated by boiling in water to allow the entire surface to be coated. A metal, such as tin, is then dissolved in the oxidizing agent/support material mixture to yield, in the case of tin, metastannic acid. Although tin has proven especially beneficial for use in a closed-cycle CO2 laser, in general any metal with two valence states, such as most transition metals and antimony, may be used. The metastannic acid will be adsorbed onto the high-surface-area spheres, coating them. Any excess oxidizing agent is then evaporated, and the resulting metastannic acid-coated spheres are dried and calcined, whereby the metastannic acid becomes tin(IV) oxide. The second step is accomplished by preparing an aqueous mixture of the tin(IV) oxide-coated spheres, and a soluble, chloride-free salt of at least one catalyst metal. The catalyst metal may be selected from the group consisting of platinum, palladium, ruthenium, gold, and rhodium, or other platinum group metals. Extremely beneficial results have been obtained using chloride-free salts of platinum, palladium, or a combination thereof, such as tetraammineplatinum (II) hydroxide ([Pt(NH3)4] (OH)2), or tetraammine palladium nitrate ([Pd(NH3)4](NO3)2).

  1. The prevalent synthesis of one-dimensional noble metal nanostructures based on sulfonated polyaniline at room temperature

    International Nuclear Information System (INIS)

    Xia Youyi

    2011-01-01

    We describe a prevalent method of synthesizing one-dimensional (1D) noble metal nanostructures (silver nanobelts and palladium nanowires) by treatment of corresponding noble metal ions only in the presence of the conductive sulfonated polyaniline without using any other reducing agents or energies. The results show that the sulfonated polyaniline provides the dual reductant and “soft template” roles to promoting noble metal ions to form shape-controlled 1D noble metal nanostructures in high yield. The employed approach may also shed some light on the preparation of other noble metal nanostructure by using conductive polymer.

  2. Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

    KAUST Repository

    Shaikh Ali, Anaam

    2016-01-01

    to TOL has only been achieved using the noble Pt-based catalysts. The aim of this study is to develop non-noble, cost-effective metal catalysts that can show excellent catalytic performance, mainly maintaining high TOL selectivity achievable by Pt based

  3. On the methodology of radiochemical neutron activation analysis of noble metals

    International Nuclear Information System (INIS)

    Chai, C.F.; Ma, S.L.; Mao, X.Y.; Liao, K.N.; Liu, W.C.

    1986-01-01

    Two different radiochemical procedures were developed: chelate ion resin exchange and amine solvent extraction. Two kinds of new Chinese chelate resins (NANKAI-3926 and BEI-5) and a new long-chain primary amine N 1923 were compared with Srafion NMRR and the tertiary amine N 235 in absorption performance of noble metals, respectively. Influences of various experimental conditions, e.g. sample digestion, acidity, equilibrium time, as well as elution of noble metals, on analytical sensitivity and chemical yield were discussed. Combining with neutron activation, the radiochemical separation procedures developed were used to determine the noble metal contents in the geological samples from Permina/Triassic boundary in South China. (author)

  4. The efficacy of noble metal alloy urinary catheters in reducing catheter-associated urinary tract infection

    Directory of Open Access Journals (Sweden)

    Alanood Ahmed Aljohi

    2016-01-01

    Results: A 90% relative risk reduction in the rate of CAUTI was observed with the noble metal alloy catheter compared to the standard catheter (10 vs. 1 cases, P = 0.006. When considering both catheter-associated asymptomatic bacteriuria and CAUTI, the relative risk reduction was 83% (12 vs. 2 cases, P = 0.005. In addition to CAUTI, the risk of acquiring secondary bacteremia was lower (100% for the patients using noble metal alloy catheters (3 cases in the standard group vs. 0 case in the noble metal alloy catheter group, P = 0.24. No adverse events related to any of the used catheters were recorded. Conclusion: Results from this study revealed that noble metal alloy catheters are safe to use and significantly reduce CAUTI rate in ICU patients after 3 days of use.

  5. Exploring methods for compositional and particle size analysis of noble metal nanoparticles in Daphnia manga

    NARCIS (Netherlands)

    Krystek, P.W.; Brandsma, S.H.; Leonards, P.E.G.; de Boer, J.

    2016-01-01

    The identification and quantification of the bioaccumulation of noble metal engineered nanoparticles (ENPs) by aquatic organisms is of great relevance to understand the exposure and potential toxicity mechanisms of nanoscale materials. Four analytical scenarios were investigated in relation to

  6. Ab initio theory of noble gas atoms in bcc transition metals.

    Science.gov (United States)

    Jiang, Chao; Zhang, Yongfeng; Gao, Yipeng; Gan, Jian

    2018-06-18

    Systematic ab initio calculations based on density functional theory have been performed to gain fundamental understanding of the interactions between noble gas atoms (He, Ne, Ar and Kr) and bcc transition metals in groups 5B (V, Nb and Ta), 6B (Cr, Mo and W) and 8B (Fe). Our charge density analysis indicates that the strong polarization of nearest-neighbor metal atoms by noble gas interstitials is the electronic origin of their high formation energies. Such polarization becomes more significant with an increasing gas atom size and interstitial charge density in the host bcc metal, which explains the similar trend followed by the unrelaxed formation energies of noble gas interstitials. Upon allowing for local relaxation, nearby metal atoms move farther away from gas interstitials in order to decrease polarization, albeit at the expense of increasing the elastic strain energy. Such atomic relaxation is found to play an important role in governing both the energetics and site preference of noble gas atoms in bcc metals. Our most notable finding is that the fully relaxed formation energies of noble gas interstitials are strongly correlated with the elastic shear modulus of the bcc metal, and the physical origin of this unexpected correlation has been elucidated by our theoretical analysis based on the effective-medium theory. The kinetic behavior of noble gas atoms and their interaction with pre-existing vacancies in bcc transition metals have also been discussed in this work.

  7. Hydrogen production during processing of radioactive sludge containing noble metals

    International Nuclear Information System (INIS)

    Ha, B.C.; Ferrara, D.M.; Bibler, N.E.

    1992-01-01

    Hydrogen was produced when radioactive sludge from Savannah River Site radioactive waste containing noble metals was reacted with formic acid. This will occur in a process tank in the Defense Waste Facility at SRS when waste is vitrified. Radioactive sludges from four tanks were tested in a lab-scale apparatus. Maximum hydrogen generation rates varied from 5 x10 -7 g H 2 /hr/g of sludge from the least reactive sludge (from Waste Tank 51) to 2 x10 -4 g H 2 /hr/g of sludge from the most reactive sludge (from Waste Tank 11). The time required for the hydrogen generation to reach a maximum varied from 4.1 to 25 hours. In addition to hydrogen, carbon dioxide and nitrous oxide were produced and the pH of the reaction slurry increased. In all cases, the carbon dioxide and nitrous oxide were generated before the hydrogen. The results are in agreement with large-scale studies using simulated sludges

  8. The predicted effectiveness of noble metal treatment at the Chinshan boiling water reactor

    International Nuclear Information System (INIS)

    Yeh Tsungkuang; Chu Fang; Chang Ching; Huang Chiashen

    2000-01-01

    The technique of noble metal treatment (NMT) available in a form of noble metal cooling (NMC) or noble metal chemical addition (NMCA), was introduced to enhance effectiveness of hydrogen water chemistry. Since it is technically difficult to gain access to an entire primary heat transport circuit (PHTC) of a BWR and monitor variation on electrochemical corrosion potential (ECP), a question whether the NMC technology is indeed effective for lowering the ECP of every location in a BWR is not still well understood at the moment. Then, computer modeling is so far the best tool to help investigate effectiveness of the NMT along PHCT of the BWR. Here was discussed on how the computer model was calibrated by using measured chemistry data obtained from No. 2 unit (BWR) in the Kuosheng Plant. The effect of noble metal treatment coupled with hydrogen water chemistry has been quantitatively molded, on a base of two different sets of ECD enhancement data. It was predicted that No. 1 unit in the Chinshan could be protected by noble metal treatment with lower [H 2 ] FW . In the case of competitive enhancing factors for the ECDs of oxygen reduction, hydrogen peroxide reduction, and hydrogen oxidation reactions, HWC had always to be present for noble metal treatment to be effective for protecting a reactor. Otherwise, according to a model calculation based upon the results from Kim's work, the ECP might instead be increased due to the enhanced reduction reaction rate of oxygen and hydrogen peroxide, especially in the near core regions. (G.K.)

  9. Synthesis of Hydrophilic Sulfur-Containing Adsorbents for Noble Metals Having Thiocarbonyl Group Based on a Methacrylate Bearing Dithiocarbonate Moieties

    Directory of Open Access Journals (Sweden)

    Haruki Kinemuchi

    2018-01-01

    Full Text Available Novel hydrophilic sulfur-containing adsorbents for noble metals were prepared by the radical terpolymerization of a methacrylate bearing dithiocarbonate moieties (DTCMMA, hydrophilic monomers, and a cross-linker. The resulting adsorbents efficiently and selectively adsorbed noble metals (Au, Ag, and Pd from various multielement aqueous solutions at room temperature owing to the thiocarbonyl group having high affinity toward noble metals. The metal adsorption by the adsorbents was proceeded by simple mixing followed by filtration. The noble metal selectivity of the adsorbent obtained from DTCMMA and N-isopropylacrylamide was higher than that of the adsorbent obtained from DTCMMA and N,N-dimethylacrylamide due to the lower nonspecific adsorption.

  10. Application of noble metals on line in Cofrentes NPP and operation experience; Aplicacion de metales nobles en linea en C.N. Cofrentes y experiencia de operacion

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Zapata, J. D.

    2015-07-01

    Cofrentes NPP implemented in 2010 the Noble Metal Chemistry as a mitigation technique for the Primary System materials protection against IGSCC. the paper describes briefly the technology fundamentals, the implementation of the specific project, the initial application and the operating experience along the last 3 cycles of the plant. (Author)

  11. Properties and application of noble metal catalysts for heterogeneous catalytic hydrogenations

    Energy Technology Data Exchange (ETDEWEB)

    Horn, G; Frohning, C D; Cornils, B [Ruhrchemie A.G., Oberhausen (Germany, F.R.)

    1976-07-01

    The special properties of the six platinum group elements - ruthenium, rhodium, palladium, osmium, iridium, platinum - make them useful as active metals for catalytic reactions. Especially valuable is their property of favouring a single reaction even when the possibility of a number of parallel reactions exists under certain reaction conditions. This selectivity of the noble metal catalyst may be directed or enhanced through appropriate choise of the metal, the reaction conditions, the duration of the reaction, the amount of hydrogen etc. Even the physical state of the catalyst - supported or unsupported - is of influence when using noble metal catalysts as described in this report.

  12. Enriching Silver Nanocrystals with a Second Noble Metal.

    Science.gov (United States)

    Wu, Yiren; Sun, Xiaojun; Yang, Yin; Li, Jumei; Zhang, Yun; Qin, Dong

    2017-07-18

    Noble-metal nanocrystals have received considerable interests owing to their fascinating properties and promising applications in areas including plasmonics, catalysis, sensing, imaging, and medicine. As demonstrated by ample examples, the performance of nanocrystals in these and related applications can be augmented by switching from monometallic to bimetallic systems. The inclusion of a second metal can enhance the properties and greatly expand the application landscape by bringing in new capabilities. Seeded growth offers a powerful route to bimetallic nanocrystals. This approach is built upon the concept that preformed nanocrystals with uniform, well-controlled size, shape, and structure can serve as seeds to template and direct the deposition of metal atoms. Seeded growth is, however, limited by galvanic replacement when the deposited metal is less reactive than the seed. The involvement of galvanic replacement not only makes it difficult to control the outcome of seeded growth but also causes degradation to some properties. We have successfully addressed this issue by reducing the salt precursor(s) into atoms with essentially no galvanic replacement. In the absence of self-nucleation, the atoms are preferentially deposited onto the seeds to generate bimetallic nanocrystals with controlled structures. In this Account, we use Ag nanocubes as an example to demonstrate the fabrication of Ag@M and Ag@Ag-M (M = Au, Pd, or Pt) nanocubes with a core-frame or core-shell structure by controlling the deposition of M atoms. A typical synthesis involves the titration of M n+ (a precursor to M) ions into an aqueous suspension containing Ag nanocubes, ascorbic acid, and poly(vinylpyrrolidone) under ambient conditions. In one approach, aqueous sodium hydroxide is introduced to increase the initial pH of the reaction system. At pH = 11.9, ascorbic acid is dominated by ascorbate monoanion, a much stronger reductant, to suppress the galvanic replacement between M n+ and Ag. In

  13. Formation of noble metal nanocrystals in the presence of biomolecules

    Science.gov (United States)

    Burt, Justin Lockheart

    One of the most promising, yet least studied routes for producing biocompatible nanostructures involves synthesis in the presence of biomolecules. I hypothesized that globular proteins could provide a suitable framework to regulate the formation of noble metal nanocrystals. As proof of concept, I designed two novel synthesis protocols utilizing bovine serum albumin (BSA) protein to regulate the formation of gold nanocrystals. In the first case, the standard protocol for polyol reduction was modified by replacing ethylene glycol with glycerin, replacing synthetic polymers with BSA as protecting agent, and decreasing the reaction temperature. In the second case, the Brust-Schiffrin two-phase reduction was modified by replacing alkylthiols with BSA as protecting agent, which facilitated a strictly aqueous phase synthesis. Due to superior product yield and rapid reduction at room temperature, the aqueous protocol became the foundation for subsequent studies. I extended this approach to produce well-dispersed ˜2nm silver, gold, and platinum nanocrystals. Having demonstrated the feasibility of BSA-functionalized nanocrystals, some potential uses were explored. BSA-functionalized silver nanocrystals were employed in a broader study on the interaction of silver nanocrystals with HIV. BSA-functionalized gold nanocrystals were utilized for in vivo dosage of a contrast enhancing agent to bacteria. BSA-functionalized platinum nanocrystals were studied as hydrogenation catalysts. Since many intriguing uses for protein-functionalized nanocrystals involve incorporation into biosystems, I sought to enhance biocompatibility by using ascorbic acid as reducing agent. Initial experiments revealed elongated and branched nanocrystals. Such structures were not observed in previous synthesis protocols with BSA, so I hypothesized ascorbic acid was driving their formation. To test my assertion, I reduced ionic gold in an aqueous solution of ascorbic acid, thereby discovering a new method

  14. Transparent and conductive electrodes by large-scale nanostructuring of noble metal thin-films

    DEFF Research Database (Denmark)

    Linnet, Jes; Runge Walther, Anders; Wolff, Christian

    grid, and nano-wire thin-films [1]. The indium and carbon films do not match the chemical stability nor the electrical performance of the noble metals, and many metal films are not uniform in material distribution leading to significant surface roughness and randomized transmission haze. We demonstrate...

  15. Integrated DWPF Melter System (IDMS) campaign report: The first two noble metals operations

    International Nuclear Information System (INIS)

    Hutson, N.D.; Zamecnik, J.R.; Smith, M.E.; Miller, D.H.; Ritter, J.A.

    1991-01-01

    The Integrated DWPF Melter System (IDMS) is designed and constructed to provide an engineering-scale representation of the DWPF melter and its associated feed preparation and off-gas systems. The facility is the first pilot-scale melter system capable of processing mercury, and flowsheet levels of halides and noble metals. In order to characterize the processing of noble metals (Pd, Rh, Ru, and Ag) on a large scale, the IDMS will be operated batchstyle for at least nine feed preparation cycles. The first two of these operations are complete. The major observation to date occurred during the second run when significant amounts of hydrogen were evolved during the feed preparation cycle. The runs were conducted between June 7, 1990 and March 8, 1991. This time period included nearly six months of ''fix-up'' time when forced air purges were installed on the SRAT MFT and other feed preparation vessels to allow continued noble metals experimentation

  16. Noble metal behavior during melting of simulated high-level nuclear waste glass feeds

    International Nuclear Information System (INIS)

    Anderson, L.D.; Dennis, T.; Elliott, M.L.; Hrma, P.

    1993-04-01

    Noble metals and their oxides can settle in waste glass melters and cause electrical shorting. Simulated waste feeds from Hanford, Savannah River, and Germany were heat treated for 1 hour in a gradient furnace at temperatures ranging from approximately 600 degrees C--1000 degrees C and examined by electron microscopy to determine shapes, sizes, and distribution of noble metal particles as a function of temperature. Individual noble metal particles and agglomerates of rhodium (Rh), ruthenium (RuO 2 ), and palladium (Pd), as well as their alloys, were seen. the majority of particles and agglomerates were generally less than 10 microns; however, large agglomerations (up to 1 mm) were found in the German feed. Detailed particle distribution and characterization was performed for a Hanford waste to provide input to computer modeling of particle settling in the melter

  17. Noble metal behavior during melting of simulated high-level nuclear waste glass feeds

    International Nuclear Information System (INIS)

    Anderson, L.D.; Dennis, T.; Elliott, M.L.; Hrma, P.

    1994-01-01

    Noble metals and their oxides can settle in waste glass melters and cause electrical shorting. Simulate waste feeds from Hanford, Savannah River, and Kernforschungszentrum Karlsruhe were heat treated for 1 hour in a gradient furnace at temperatures ranging from approximately 600 degrees C to 1000 degrees C and examined by electron microscopy to determine shapes, sizes, and distribution of noble metal particles as a function of temperature. Individual noble metal particles and agglomerates of rhodium (Rh), ruthenium (RuO 2 ), and palladium (Pd), as well as their alloys, were seen. The majority of particles and agglomerates were generally less than 10 μm; however, large agglomerations (up to 1 mm) were found in the German feed. 5 refs., 6 figs., 2 tabs

  18. Oxidation behaviour of noble-metal inclusions in used UO2 nuclear fuel

    International Nuclear Information System (INIS)

    McEachern, R.

    1997-07-01

    The literature on the chemistry of the noble-metal (Mo-Rh-Ru-Pd-Tc) inclusions found in used nuclear fuel has been reviewed. The Mo-Ru-Pd phase diagram is reasonably well understood, and the pseudoternary Mo-(Tc+Ru)-Rh+Pd) system can be used to qualitatively understand the phase chemistry of the noble-metal inclusions. The kinetics of the oxidation reaction are not particularly well understood, but they are of limited applicability to understanding the properties of used fuel. In contrast, it is important to determine the thermodynamic activity of molybdenum in noble-metal inclusions, so that analysis of their molybdenum content can be used as a probe of the local oxygen potential of the used fuel. (author)

  19. Nano-structured noble metal catalysts based on hexametallate architecture for the reforming of hydrocarbon fuels

    Science.gov (United States)

    Gardner, Todd H.

    2015-09-15

    Nano-structured noble metal catalysts based on hexametallate lattices, of a spinel block type, and which are resistant to carbon deposition and metal sulfide formation are provided. The catalysts are designed for the reforming of hydrocarbon fuels to synthesis gas. The hexametallate lattices are doped with noble metals (Au, Pt, Rh, Ru) which are atomically dispersed as isolated sites throughout the lattice and take the place of hexametallate metal ions such as Cr, Ga, In, and/or Nb. Mirror cations in the crystal lattice are selected from alkali metals, alkaline earth metals, and the lanthanide metals, so as to reduce the acidity of the catalyst crystal lattice and enhance the desorption of carbon deposit forming moieties such as aromatics. The catalysts can be used at temperatures as high as 1000.degree. C. and pressures up to 30 atmospheres. A method for producing these catalysts and applications of their use also is provided.

  20. Vitrification of noble metals containing NCAW simulant with an engineering scale melter (ESM): Campaign report

    Energy Technology Data Exchange (ETDEWEB)

    Grunewald, W.; Roth, G.; Tobie, W.; Weisenburger, S.; Weiss, K.; Elliott, M.; Eyler, L.L.

    1996-03-01

    ESM has been designed as a 10th-scale model of the DWPF-type melter, currently the reference melter for nitrification of Hanford double shell tankwaste. ESM and related equipment have been integrated to the existing mockup vitrification plant VA-WAK at KfK. On June 2-July 10, 1992, a shakedown test using 2.61 m{sup 3} of NCAW (neutralized current acid waste) simulant without noble metals was performed. On July 11-Aug. 30, 1992, 14.23 m{sup 3} of the same simulant with nominal concentrations of Ru, Rh, and Pd were vitrified. Objective was to investigate the behavior of such a melter with respect to discharge of noble metals with routine glass pouring via glass overflow. Results indicate an accumulation of noble metals in the bottom area of the flat-bottomed ESM. About 65 wt% of the noble metals fed to the melter could be drained out, whereas 35 wt% accumulated in the melter, based on analysis of glass samples from glass pouring stream in to the canisters. After the melter was drained at the end of the campaign through a bottom drain valve, glass samples were taken from the residual bottom layer. The samples had significantly increased noble metals content (factor of 20-45 to target loading). They showed also a significant decrease of the specific electric resistance compared to bulk glass (factor of 10). A decrease of 10- 15% of the resistance between he power electrodes could be seen at the run end, but the total amount of noble metals accumulated was not yet sufficient enough to disturb the Joule heating of the glass tank severely.

  1. Solid polymer electrolyte composite membrane comprising a porous support and a solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide

    Science.gov (United States)

    Liu, Han; Mittelsteadt, Cortney K; Norman, Timothy J; Griffith, Arthur E; LaConti, Anthony B

    2015-02-24

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a thin, rigid, dimensionally-stable, non-electrically-conducting support, the support having a plurality of cylindrical, straight-through pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores are unevenly distributed, with some or no pores located along the periphery and more pores located centrally. The pores are completely filled with a solid polymer electrolyte, the solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide. The solid polymer electrolyte may also be deposited over the top and/or bottom surfaces of the support.

  2. Electrospun Polymer Nanofibers Decorated with Noble Metal Nanoparticles for Chemical Sensing.

    Science.gov (United States)

    Chen, Chen; Tang, Yongan; Vlahovic, Branislav; Yan, Fei

    2017-12-01

    The integration of different noble metal nanostructures, which exhibit desirable plasmonic and/or electrocatalytic properties, with electrospun polymer nanofibers, which display unique mechanical and thermodynamic properties, yields novel hybrid nanoscale systems of synergistic properties and functions. This review summarizes recent advances on how to incorporate noble metal nanoparticles into electrospun polymer nanofibers and illustrates how such integration paves the way towards chemical sensing applications with improved sensitivity, stability, flexibility, compatibility, and selectivity. It is expected that further development of this field will eventually make a wide impact on many areas of research.

  3. Characterisation and radiolysis of modified lithium orthosilicate pebbles with noble metal impurities

    DEFF Research Database (Denmark)

    Tamulevičius, Sigitas; Zariņš, A.; Valtenbergs, O.

    2017-01-01

    Modified lithium orthosilicate (Li4SiO4) pebbles with additions of titanium dioxide (TiO2) are suggested as an alternative tritium breeding ceramic for the European solid breeder test blanket module. The noble metals – platinum (Pt), gold (Au) and rhodium (Rh), can be introduced into the modified...... Li4SiO4 pebbles during the melt-based process, due to the corrosion of Pt-Rh and Pt-Au alloy crucible components. In this study, the surface microstructure, chemical and phase composition of the modified Li4SiO4 pebbles with different contents of the noble metals was analysed. The influence...

  4. The preparation of primary standard solutions for each of the noble metals

    International Nuclear Information System (INIS)

    Mallett, R.C.; Wall, G.J.; Jones, E.A.; Royal, S.J.

    1977-01-01

    A revised method for the preparation of primary standard solutions for each of the noble metals is described. It is now recommended that standard noble-metal solutions should be made from the pure metals and not from salts as previously described. Metals should have a certified purity of 99,95 per cent or better, and the purity should be confirmed by analysis, the techniques of emission spectography or spark-source mass spectrography being used. After the metals have been dissolved, the solutions are made up to volume and the metal content of the standard solutions is checked. For most instrumental techniques for which the standards are intended, the check analysis should be within 0,3 per cent of the certified value

  5. Autoradiographic techniques to determine noble metal distribution in automotive catalyst substrates

    International Nuclear Information System (INIS)

    Lange, W.H.

    1976-01-01

    The distribution of noble metals in the ceramic substrates of automotive catalytic converter systems is important to the functional characteristics of the systems. A radiotracer technique involving microtomy of bead substrate samples and autoradiography using the resultant thin sections was developed to produce detailed images of the metal distributions. The method is particularly valuable to determine the distribution of one metal in the presence of another to aid in the development of more efficient systems

  6. Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

    Science.gov (United States)

    Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

    2017-02-07

    The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

  7. Structural and plasmonic properties of noble metal doped ZnO nanomaterials

    Science.gov (United States)

    Pathak, Trilok K.; Swart, H. C.; Kroon, R. E.

    2018-04-01

    Noble metal doped ZnO has been synthesized by the combustion method and the effect of different metals (Ag, Au, Pd) on the structural, morphological, optical, photoluminescence and localized surface plasmon resonance (LSPR) properties has been investigated. X-ray diffraction analysis revealed that the ZnO had a hexagonal wurtzite structure and the crystallite sizes were affected by the doping. The formation of noble metal nanoparticles (NPs) was investigated using transmission electron microscopy and diffuse reflectance spectra. The LSPR of the metallic NPs was predicted using Mie theory calculations. The absorption spectra were calculated using the Kubelka-Munk function and the optical bandgap varied from 3.06 to 3.18 eV for the different doping materials. The experimental results suggest that the origin of enhanced emission was due to direct interaction between the laser photons and the noble material NPs which in turn leads to photoemission transfer of electrons from the noble metals NPs to the conduction band of ZnO.

  8. The Behavior and Effects of the Noble Metals in the DWPF Melter System

    International Nuclear Information System (INIS)

    Smith, M.E.; Bickford, D.F.

    1997-01-01

    Governments worldwide have committed to stabilization of high-level nuclear waste (HLW) by vitrification to a durable glass form for permanent disposal. All of these nuclear wastes contain the fission-product noble metals: ruthenium, rhodium, and palladium. SRS wastes also contain natural silver from iodine scrubbers. Closely associated with the noble metals are the fission products selenium and tellurium which are chemical analogs of sulfur and which combine with noble metals to influence their behavior and properties. Experience has shown that these melt insoluble metals and their compounds tend to settle to the floor of Joule-heated ceramic melters. In fact, almost all of the major research and production facilities have experienced some operational problem which can be associated with the presence of dense accumulations of these relatively conductive metals and/or their compounds. In most cases, these deposits have led to a loss of production capability, in some cases, to the point that melter operation could not continue. HLW nuclear waste vitrification facilities in the United States are the Department of Energy's Defense Waste Processing Facility (DWPF) at the Savannah River Site, the planned Hanford Waste Vitrification Plant (HWVP) at the Hanford Site and the operating West Valley Demonstration Project (WVDP) at West Valley, NY. The Integrated DWPF Melter System (IDMS) is a vitrification test facility at the Savannah River Technology Center (SRTC). It was designed and constructed to provide an engineering-scale representation of the DWPF melter and its associated feed preparation and off-gas treatment systems. An extensive noble metals testing program was begun in 1990. The objectives of this task were to explore the effects of the noble metals on the DWPF melter feed preparation and waste vitrification processes. This report focuses on the vitrification portion of the test program

  9. The Role of Noble Metal Addition Methods on BWR Shut Down Dose Rates

    International Nuclear Information System (INIS)

    Cowan, Robert L.; Garcia Susan, E.

    2012-09-01

    Noble metal addition technology was developed for the BWR as a means of establishing low electrochemical corrosion potentials (ECP) on structural materials to mitigate intergranular stress corrosion cracking (IGSCC). When the reactor water molar ratio of H 2 / (O 2 +H 2 O 2 ) is > 2 on noble metal treated surfaces, the resulting ECP is near -500 mV (SHE), well into the mitigation range. This ratio can be achieved in most areas of the reactor with feedwater hydrogen additions in the range of 0.2 mg/kg, a condition that does not increase the radiation level in the main steam, a side effect of conventional hydrogen water chemistry (HWC). The resulting low ECP on the surface of stainless steel piping and components results in a change in form of the stable corrosion film to a spinel structure. Since it is the 60 Co incorporated into the corrosion film that is the primary source term of shutdown dose rates in BWRs, the structure and composition of the film can have a large influence in the resulting dose rates. The results of the first generation of noble metal technology, noble metal chemical addition (NMCA), showed that the reactor water ratio of 60 Co (s)/Zn (s) was a key parameter in determining shut down dose rate values. This paper will review that history and provide mechanistic understanding of how initial post NMCA dose rates are established and change with time. On-line noble metal chemical addition (OLNC) is the second generation of noble metal technology. The method utilizes the on-line injection of dilute Na 2 Pt (OH) 6 into the feedwater over a period of approximately 10 days. The first application of OLNC occurred at a European reactor in July of 2005 and to date over 20 BWRs have applied the technology, with many more applications scheduled. It is expected that OLNC will become the de facto standard because it eliminates 60 hours of outage application time and it addresses the crack flanking concerns that can arise under certain conditions. Because both

  10. Geological structure and prospects of noble metal ore mineralization of the Khayrkhan gabbroid massif (Western Mongolia)

    Science.gov (United States)

    Kurumshieva, K. R.; Gertner, I. F.; Tishin, P. A.

    2017-12-01

    An analysis of the distribution of noble metals in zones of sulfide mineralization makes it possible to justify the isolation of four ore-bearing horizons with a specific geochemical zonation. A rise in the gold content relative to palladium and platinum is observed from the bottom upwards along the section of the stratified series of gabbroids. The study of the mineral phases of sulphides and the noble minerals itself indicates the evolution of hydrothermal solutions, which determines the different activity and mobility of the fluid (mercury, tellurium, sulfur) and ore (copper, nickel, iron, platinum, gold and silver) components.

  11. Techniques for the quantitative analysis of fission-product noble metals

    International Nuclear Information System (INIS)

    Lautensleger, A.W.; Hara, F.T.

    1982-08-01

    Analytical procedures for the determination of ruthenium, rhodium, and palladium in precursor waste, solvent metal, and final glass waste forms have been developed. Two procedures for the analysis of noble metals in the calcine and glass waste forms are described in this report. The first is a fast and simple technique that combines inductively coupled argon plasma atomic emission spectrometry (ICP) and x-ray fluorescence techniques and can only be used on nonradioactive materials. The second procedure is based on a noble metal separation step, followed by an analysis using ICP. This second method is more complicated than the first, but it will work on radioactive materials. Also described is a procedure for the ICP analysis of noble metals in the solvent metal matrix. The only solvent metal addressed in this procedure is lead, but with minor changes the procedure could be applied to any of the solvent metals being considered in the Pacific Northwest Laboratory (PNL) extraction process. A brief explanation of atomic spectroscopy and the ICP analytical process, as well as of certain aspects of ICP performance (interelement spectral line interferences and certain matrix effects) is given

  12. Wigner Distribution Functions as a Tool for Studying Gas Phase Alkali Metal Plus Noble Gas Collisions

    Science.gov (United States)

    2014-03-27

    WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR STUDYING GAS PHASE ALKALI METAL PLUS NOBLE GAS COLLISIONS THESIS Keith A. Wyman, Second Lieutenant, USAF...the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENP-14-M-39 WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR...APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT-ENP-14-M-39 WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR STUDYING GAS PHASE ALKALI METAL PLUS

  13. Dispersion forces and small-angle neutron scattering from liquid noble metals

    International Nuclear Information System (INIS)

    March, N.H.

    1988-01-01

    Maggs and Ashcroft [Phys. Rev. letts., 59,113 (1987)] have re-opened the question of the analogy between the cohesion of a molecular crystal, in which dispersion forces play a major role, and that in a metal crystal with polarizable ion cores. It is pointed out that small-angle neutron scattering from liquid noble metals could be used to test their predictions. (author)

  14. Electrical resistivity of noble-metal alloys: Roles of pseudopotential refinements

    International Nuclear Information System (INIS)

    Mujibar Rahman, S.M.

    1983-08-01

    The electrical resistivity of liquid noble-metal alloys i.e. CuAu and AgAu is calculated as a function of concentration. The calculations employ transition-metal-pseudopotentials that include nonlocal effects, hybridization and corrections due to orthogonalization hole and use the hard-sphere structure factors; the optimal values of the hard-sphere diameters are being determined by variational calculations. The calculated resistivities are comparable to the experimental values and to the available theoretical results. (author)

  15. Role of noble metal nanoparticles in DNA base damage and catalysis: a radiation chemical investigation

    International Nuclear Information System (INIS)

    Sharma, Geeta K.

    2011-01-01

    In the emerging field of nanoscience and nanotechnology, tremendous focus has been made by researcher to explore the applications of nanomaterials for human welfare by converting the findings into technology. Some of the examples have been the use of nanoparticles in the field of opto-electronic, fuel cells, medicine and catalysis. These wide applications and significance lies in the fact that nanoparticles possess unique physical and chemical properties very different from their bulk precursors. Numerous methods for the synthesis of noble nanoparticles with tunable shape and size have been reported in literature. The goal of our group is to use different methods of synthesis of noble metal nanoparticles (Au, Ag, Pt and Pd) and test their protective/damaging role towards DNA base damage induced by ionizing radiation (Au and Ag) and to test the catalytic activity of nanoparticles (Pt and Pd) in certain known organic synthesis/electron transfer reactions. Using radiation chemical techniques such as pulse radiolysis and steady state radiolysis complemented by the product analysis using HPLC/LC-MS, a detailed mechanism for the formation of transient species, kinetics leading to the formation of stable end products is studied in the DNA base damage induced by ionizing radiation in presence and absence of Au and Ag nanoparticles. Unraveling the complex interaction between catalysts and reactants under operando conditions is a key step towards gaining fundamental insight in catalysis. The catalytic activity of Pt and Pd nanoparticles in electron transfer and Suzuki coupling reactions has been determined. Investigations are currently underway to gain insight into the interaction between catalysts and reactants using time resolved spectroscopic measurements. These studies will be detailed during the presentation. (author)

  16. Modeling impurity-assisted chain creation in noble-metal break junctions

    International Nuclear Information System (INIS)

    Di Napoli, S; Thiess, A; Blügel, S; Mokrousov, Y

    2012-01-01

    In this work we present the generalization of the model for chain formation in break junctions, introduced by Thiess et al (2008 Nano Lett. 8 2144), to zigzag transition-metal chains with s and p impurities. We apply this extended model to study the producibility trends for noble-metal chains with impurities, often present in break junction experiments, namely, Cu, Ag and Au chains with H, C, O and N adatoms. Providing the material-specific parameters for our model from systematic full-potential linearized augmented plane-wave first-principles calculations, we find that the presence of such impurities crucially affects the binding properties of the noble-metal chains. We reveal that both the impurity-induced bond strengthening and the formation of zigzag bonds can lead to a significantly enhanced probability for chain formation in break junctions. (paper)

  17. Preliminary investigation of a technique to separate fission noble metals from fission-product mixtures

    International Nuclear Information System (INIS)

    Mellinger, G.B.; Jensen, G.A.

    1982-08-01

    A variation of the gold-ore fire assay technique was examined as a method for recovering Pd, Rh and Ru from fission products. The mixture of fission product oxides is combined with glass-forming chemicals, a metal oxide such as PbO (scavenging agent), and a reducing agent such as charcoal. When this mixture is melted, a metal button is formed which extracts the noble metals. The remainder cools to form a glass for nuclear waste storage. Recovery depended only on reduction of the scavenger oxide to metal. When such reduction was achieved, no difference in noble metal recovery efficiency was found among the scavengers studied (PbO, SnO, CuO, Bi 2 O 3 , Sb 2 O 3 ). Not all reducing agents studied, however, were able to reduce all scavenger oxides to metal. Only graphite would reduce SnO and CuO and allow noble metal recovery. The scavenger oxides Sb 2 O 3 , Bi 2 O 3 , and PbO, however, were reduced by all of the reducing agents tested. Similar noble metal recovery was found with each. Lead oxide was found to be the most promising of the potential scavengers. It was reduced by all of the reducing agents tested, and its higher density may facilitate the separation. Use of lead oxide also appeared to have no deterimental effect on the glass quality. Charcoal was identified as the preferred reducing agent. As long as a separable metal phase was formed in the melt, noble metal recovery was not dependent on the amount of reducing agent and scavenger oxide. High glass viscosities inhibited separation of the molten scavenger, while low viscosities allowed volatile loss of RuO 4 . A viscosity of approx. 20 poise at the processing temperature offered a good compromise between scavenger separation and Ru recovery. Glasses in which PbO was used as the scavenging agent were homogeneous in appearance. Resistance to leaching was close to that of certain waste glasses reported in the literature. 12 figures. 7 tables

  18. Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes

    Science.gov (United States)

    Wang, Xuyang; Wang, Ranran; Wu, Qiang; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Cheng, Yajun; Chu, Haibin

    2016-07-01

    In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter.

  19. Development of supported noble metal catalyst for U(VI) to U(IV) reduction

    International Nuclear Information System (INIS)

    Tyagi, Deepak; Varma, Salil; Bhattacharyya, K.; Tripathi, A.K.; Bharadwaj, S.R.; Jain, V.K.; Sahu, Avinash; Vincent, Tessy; Jagatap, B.N.; Wattal, P.K.

    2015-01-01

    Uranium-plutonium separation is an essential step in the PUREX process employed in spent nuclear fuel reprocessing. This partitioning in the PUREX process is achieved by selective reduction of Pu(IV) to Pu(III) using uranous nitrate as reductant and hydrazine as stabilizer. Currently in our Indian reprocessing plants, the requirement of uranous nitrate is met by electrolytic reduction of uranyl nitrate. This process, however, suffers from a major drawback of incomplete reduction with a maximum conversion of ~ 60%. Catalytic reduction of U(VI) to U(IV) is being considered as one of the promising alternatives to the electro-reduction process due to fast kinetics and near total conversion. Various catalysts involving noble metals like platinum (Adams catalyst, Pt/Al 2 O 3 , Pt/SiO 2 etc.) have been reported for the reduction. Sustained activity and stability of the catalyst under harsh reaction conditions are still the issues that need to be resolved. We present here the results on zirconia supported noble metal catalyst that is developed in BARC for reduction of uranyl nitrate to uranous nitrate. Supported noble metal catalysts with varying metal loadings (0.5 - 2 wt%) were prepared via support precipitation and noble metal impregnation. The green catalysts were reduced either by chemical reduction using hydrazine hydrate or by heating in hydrogen flow or combination of both the steps. These catalysts were characterized by various techniques such as, XRD, SEM, TEM, N 2 adsorption and H 2 chemisorption. Performance of these catalysts was evaluated for U(VI) to U(IV) reduction with uranyl nitrate feed using hydrazine as reductant. The results with the most active catalyst are named as 'BARC-CAT', which was developed in our lab. (author)

  20. The role of noble metals in electric melting of nuclear waste glass

    International Nuclear Information System (INIS)

    Roth, G.; Weisenburger, S.

    1990-01-01

    Electrical melting of nuclear waste glass in ceramic melters applies Joule heating, with the molten glass acting as the conductive medium. The local energy release inside the melt relieves from the restriction of external heat addition, allowing to scale up the melter to industrial units. Certainly, that principle makes the melter operation susceptible for changes of the electrical properties of the glass melt. Hence, the melt properties are required to be locally uniform and constant with time. Temporary fluctuations in the feed composition, however, are usually attenuated by the high retention times being in the order of a day and more. More essential for the melter operation are segregation effects occurring systematically. This behaviour can be observed in the case of the so-called noble metal elements Ruthenium, Palladium and Rhodium, belonging to the Platinum metal group. The subject of this paper is to describe the behaviour of the noble metals in electric melting and the problems they can contribute to. The discussion is based on detailed knowledge gained from PAMELA's LEWC processing and from large-scale vitrification of commercial-like waste simulate at INE/KfK. Finally, ways are indicated to solve the noble metal problem technically

  1. Flameless atomic absorption determination of noble metals after extraction by mixture of di-2-ethylhexyldithiophosphoric acid and n-octylaniline

    International Nuclear Information System (INIS)

    Yukhin, Yu.M.; Udalova, T.A.; Tsimbalist, V.G.; AN SSSR, Novosibirsk. Inst. Geologii i Geofiziki)

    1985-01-01

    A possibility of using the mixture of di-2-ethylhexyl dithiophosphoric acid (D2EHDTPA) and p-octylaniline (OA) (extractants of acid and basic character) for extraction atomic absorption determination of noble metals is studied. The mixture of D2EHDTPA with OA is shown to extract noble metals from hydrochloric acid solutions with distribution factors > 10 3 . An extraction atomic absorption method for determination of noble metals in copperbearing materials is suggested. The minimum determined contents of noble metals at the initial sample equal to 100 for gold, silver, platinum, palladium, rhodium and ruthenium make up (g/t) 0.0005, 0.0001, 0.015, 0.005, 0.002 and 0.015 respectively. Relative standard deviation constitutes Ssub(r)<0.2

  2. Effect of noble metal doping on the structural properties of lanthanum cobaltite

    International Nuclear Information System (INIS)

    Dharmadhikari, Dipti V.; Athawal, Anjali A.

    2016-01-01

    Pristine and Noble metal (Ag and Pd) doped lanthanum cobaltite samples have been synthesised by Hydrothermal method. Lanthanum in the A-Site and Co at B-site of Lanthanum cobaltite (LaCoO 3 ) perovskites were partially doped by silver and palladium (4%). Crystal structure analysis revealed that the hydrothermal synthesis led to the formation of pure nanocrystalline perovskite structure. Morphological analysis of the samples shows that the noble metal doping affects the morphology of the samples. Pristine sample shows spherical to oval shaped particles while the doping results in the formation of irregular shaped, spherical and rod shaped particles. Silver doping results in the agglomeration of particles. The particles were observed to be fused with each other to form rod shaped structures in case of palladium doped samples. (author)

  3. Concentration of noble metals by sublimation during the analysis of massive samples

    International Nuclear Information System (INIS)

    Chuburkov, Yu.T.; Zhujkov, B.L.; Gehrbish, Sh.; Al'pert, L.K.; Chan Zuj Ty

    1990-01-01

    The possibility of concentrating noble metals from terrestrial samples of various composition by chemical sublimation in an air stream at a temperature of 1000-1200 deg C was examined. It was found that the chemical yields of Au, Pt, Ir, Ru, Os and Re for all the samples increased by introducing solid additives of FeCl 2 , TiO 2 and Nb 2 O 5 . The concentration technique provides the possibility of determining some noble metals in massive samples (up to 50 g) with widely ranging element contents. By using gamma and neutron activation on a microtron, the detection limits of 3x10 -2 ppm for Pt and Ir and 4x10 -3 ppm for Au were achieved. In the case of X-ray fluorescence analysis, the detection limit for these elements was 0.4 ppm

  4. Methane oxidation over noble metal catalysts as related to controlling natural gas vehicle exhaust emissions

    International Nuclear Information System (INIS)

    Oh, S.H.; Mitchell, P.J.; Siewert, R.M.

    1992-01-01

    Natural gas has considerable potential as an alternative automotive fuel. This paper reports on methane, the principal hydrocarbon species in natural-gas engine exhaust, which has extremely low photochemical reactivity but is a powerful greenhouse gas. Therefore, exhaust emissions of unburned methane from natural-gas vehicles are of particular concern. This laboratory reactor study evaluates noble metal catalysts for their potential in the catalytic removal of methane from natural-gas vehicle exhaust. Temperature run-up experiments show that the methane oxidation activity decreases in the order Pd/Al 2 O 3 > Rh/Al 2 O 3 > Pt/Al 2 O 3 . Also, for all the noble metal catalysts studied, methane conversion can be maximized by controlling the O 2 concentration of the feedstream at a point somewhat rich (reducing) of stoichiometry

  5. Noble Metal Catalysts Supported on Nanofibrous Polymeric Membranes for Environmental Applications

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Topka, Pavel; Hejtmánek, Vladimír; Petráš, D.; Valeš, V.; Šolcová, Olga

    2014-01-01

    Roč. 236, NOV 1 (2014), s. 3-11 ISSN 0920-5861 R&D Projects: GA ČR GPP106/11/P459; GA ČR GP13-24186P Institutional support: RVO:67985858 Keywords : electrospinning * noble metals * catalytic oxidation * volatile organic compoundas Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.893, year: 2014

  6. Determination of noble metals in geological materials by radiochemical neutron-activation analysis

    International Nuclear Information System (INIS)

    Ahmad, I.; Ahmad, S.; Morris, D.F.C.

    1977-01-01

    A method for the determination of platinum, palladium, gold and iridium in geological materials following activation with thermal neutrons is described. Radionuclides formed from the elements are separated by a scheme based largely on liquid-liquid extractions. The procedure has been applied to the analysis of US Geological Survey standard rocks and to studies of the distribution of the noble metals in lateritic nickel ores. (author)

  7. Analysis of noble metal on automotive exhaust catalysts by radioisotope-induce x-ray fluorescence

    International Nuclear Information System (INIS)

    Elgart, M.F.

    1976-01-01

    A technique was developed for the in-situ analysis of noble metals deposited on monolithic automotive exhaust catalysts. This technique is based on radioisotope-induced x-ray fluorescence, and provides a detailed picture of the distribution of palladium and platinum on catalyst samples. The experimental results for the cross section of a monolithic exhaust catalyst, analyzed in increments of 0.2 cm 3 , are compared with analyses for palladium and platinum obtained by instrumental neutron activation analysis

  8. Oxidation of tritium in packed bed of noble metal catalyst for detritiation from system gases

    International Nuclear Information System (INIS)

    Nishikawa, Masabumi; Takeishi, Toshiharu; Munakata, Kenzo; Kotoh, Kenji; Enoeda, Mikio

    1985-01-01

    Catalytic oxidation rates of tritium in the bed of the noble metal catalysts are obtained and compared with the oxidation rates observed for the packed bed of spongy copper oxide or hopcalites. Use of Pt- or Pd-aluminia catalysts is recommended in this study because they give effective oxidation rates of tritium in the ambient temperature range. The adsorption performance of tritiated water in the catalyst bed is also discussed. (orig.)

  9. Deposition and characterization of noble metal onto surfaces of 304l stainless steel

    International Nuclear Information System (INIS)

    Contreras R, A.; Arganis J, C. R.; Aguilar T, J. A.; Medina A, A. L.

    2010-10-01

    Noble metal chemical addition (NMCA) plus hydrogen water chemistry is an industry-wide accepted approach for potential intergranular stress corrosion cracking mitigation of BWR internals components. NMCA is a method of applying noble metal onto BWR internals surfaces using reactor water as the transport medium that causes the deposition of noble metal from the liquid onto surfaces. In this work different platinum concentration solutions were deposited onto pre-oxidized surfaces of 304l steel at 180 C during 48 hr in an autoclave. In order to simulate the zinc water conditions, deposits of Zn and Pt-Zn were also carried out. The solutions used to obtain the deposits were: sodium hexahydroxyplatinate (IV), zinc nitrate hydrate and zinc oxide. The deposits obtained were characterized by scanning electron microscopy and X-ray diffraction. Finally, the electrochemical corrosion potential of pre-oxidized samples with Pt deposit were obtained and compared with the electrochemical corrosion potential of only pre-oxidized samples. (Author)

  10. Oxidation of ethoxylated fatty alcohols to alkylpolyglycol carboxylic acids using noble metals as catalysts

    Directory of Open Access Journals (Sweden)

    Sagredos, Angelos

    2009-09-01

    Full Text Available The conversion of ethoxylated fatty alcohols to the corresponding carboxylic acids through dehydrogenation/ oxidation using noble-metal catalysts has been studied. Ethoxylated primary aliphatic alcohols, ethoxylated random secondary aliphatic alcohols and ethoxylated alkylphenols have been converted to the corresponding acids in the presence of a base. The noble metal catalysts Palladium and Platinum were used without significant degradation of the ethoxyl chain in yields that exceeded 90%. On the other hand, the catalysts Rhodium and Ruthenium gave yields of about 80% and 60% respectively.La conversión de alcoholes grasos etoxilados a los correspondientes ácidos carboxílicos por deshidrogenación/ oxidación con metales nobles como catalizador ha sido estudiada. Alcoholes primarios alifáticos etoxilados, alcoholes alifáticos secundarios etoxilados al azar y alquilfenoles etoxilados han sido convertidos a los correspondientes ácidos en presencia de base. Los catalizadores paladio y platino fueron usados sin degradación significativa de las cadenas etoxiladas con un rendimiento que excedió del 90%. Por otra parte catalizadores de rodio y rutenio produjeron rendimientos del 80 y 60%, respectivamente.

  11. The role of van der Waals interactions in the adsorption of noble gases on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Chen, De-Li; Al-Saidi, W A; Johnson, J Karl

    2012-10-03

    Adsorption of noble gases on metal surfaces is determined by weak interactions. We applied two versions of the nonlocal van der Waals density functional (vdW-DF) to compute adsorption energies of Ar, Kr, and Xe on Pt(111), Pd(111), Cu(111), and Cu(110) metal surfaces. We have compared our results with data obtained using other density functional approaches, including the semiempirical vdW corrected DFT-D2. The vdW-DF results show considerable improvements in the description of adsorption energies and equilibrium distances over other DFTbased methods, giving good agreement with experiments. We have also calculated perpendicular vibrational energies for noble gases on the metal surfaces using vdWDF data and found excellent agreement with available experimental results. Our vdW-DF calculations show that adsorption of noble gases on low-coordination sites is energetically favored over high-coordination sites, but only by a few meV. Analysis of the 2-dimensional potential energy surface shows that the high-coordination sites are local maxima on the 2-dimensional potential energy surface and therefore unlikely to be observed in experiments, which provides an explanation of the experimental observations. The DFT-D2 approach with the standard parameterization was found to overestimate the dispersion interactions, and to give the wrong adsorption site preference for four of the nine systems we studied.

  12. Visible light active TiO2 films prepared by electron beam deposition of noble metals

    International Nuclear Information System (INIS)

    Hou Xinggang; Ma Jun; Liu Andong; Li Dejun; Huang Meidong; Deng Xiangyun

    2010-01-01

    TiO 2 films prepared by sol-gel method were modified by electron beam deposition of noble metals (Pt, Pd, and Ag). Effects of noble metals on the chemical and surface characteristics of the films were studied using XPS, TEM and UV-Vis spectroscopy techniques. Photocatalytic activity of modified TiO 2 films was evaluated by studying the degradation of methyl orange dye solution under visible light UV irradiation. The result of TEM reveals that most of the surface area of TiO 2 is covered by tiny particles of noble metals with diameter less than 1 nm. Broad red shift of UV-Visible absorption band of modified photocatalysts was observed. The catalytic degradation of methyl orange in aqueous solutions under visible light illumination demonstrates a significant enhancement of photocatalytic activity of these films compared with the un-loaded films. The photocatalytic efficiency of modified TiO 2 films by this method is affected by the concentration of impregnating solution.

  13. Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study

    Science.gov (United States)

    Liu, Ying; Liu, Xiaoheng; Wang, Xin

    2011-12-01

    Herein, the generation of gold, silver, and silver-gold (Ag-Au) bimetallic nanoparticles was carried out in collagen (gelatin) solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated by TEM, UV-visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of noble metal/bimetallic nanoparticle growth to form nanometer-sized device.

  14. Graphene–Noble Metal Nano-Composites and Applications for Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Sukumar Basu

    2017-10-01

    Full Text Available Graphene based nano-composites are relatively new materials with excellent mechanical, electrical, electronic and chemical properties for applications in the fields of electrical and electronic devices, mechanical appliances and chemical gadgets. For all these applications, the structural features associated with chemical bonding that involve other components at the interface need in-depth investigation. Metals, polymers, inorganic fibers and other components improve the properties of graphene when they form a kind of composite structure in the nano-dimensions. Intensive investigations have been carried out globally in this area of research and development. In this article, some salient features of graphene–noble metal interactions and composite formation which improve hydrogen gas sensing properties—like higher and fast response, quick recovery, cross sensitivity, repeatability and long term stability of the sensor devices—are presented. Mostly noble metals are effective for enhancing the sensing performance of the graphene–metal hybrid sensors, due to their superior catalytic activities. The experimental evidence for atomic bonding between metal nano-structures and graphene has been reported in the literature and it is theoretically verified by density functional theory (DFT. Multilayer graphene influences gas sensing performance via intercalation of metal and non-metal atoms through atomic bonding.

  15. Noble Metal Immersion Spectroscopy of Silica Alcogels and Aerogels

    Science.gov (United States)

    Smith, David D.; Sibille, Laurent; Cronise, Raymond J.; Noever, David A.

    1998-01-01

    We have fabricated aerogels containing gold and silver nanoparticles for gas catalysis applications. By applying the concept of an average or effective dielectric constant to the heterogeneous interlayer surrounding each particle, we extend the technique of immersion spectroscopy to porous or heterogeneous media. Specifically, we apply the predominant effective medium theories for the determination of the average fractional composition of each component in this inhomogeneous layer. Hence, the surface area of metal available for catalytic gas reaction is determined. The technique is satisfactory for statistically random metal particle distributions but needs further modification for aggregated or surfactant modified systems. Additionally, the kinetics suggest that collective particle interactions in coagulated clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  16. Bare and protected sputtered-noble-metal films for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Talaga, David; Bonhommeau, Sébastien

    2014-11-01

    Sputtered silver and gold films with different surface morphologies have been prepared and coated with a benzenethiol self-assembled monolayer. Rough noble metal films showed strong Raman features assigned to adsorbed benzenethiol molecules upon irradiation over a wide energy range in the visible spectrum, which disclosed the occurrence of a significant surface-enhanced Raman scattering with maximal enhancement factors as high as 6 × 106. In addition, the adsorption of ethanethiol onto silver surfaces hinders their corrosion over days while preserving mostly intact enhancement properties of naked silver. This study may be applied to develop stable and efficient metalized probes for tip-enhanced Raman spectroscopy.

  17. The secondary electron yield of noble metal surfaces

    Directory of Open Access Journals (Sweden)

    L. A. Gonzalez

    2017-11-01

    Full Text Available Secondary electron yield (SEY curves in the 0-1000 eV range were measured on polycrystalline Ag, Au and Cu samples. The metals were examined as introduced in the ultra-high vacuum chamber and after having been cleaned by Ar+ ion sputtering. The comparison between the curves measured on the clean samples and in the presence of contaminants, due to the permanence in atmosphere, confirmed that the SEY behavior is strongly influenced by the chemical state of the metal surface. We show that when using very slow primary electrons the sample work function can be determined with high accuracy from the SEY curves. Moreover we prove that SEY is highly sensitive to the presence of adsorbates even at submonolayer coverage. Results showing the effect of small quantities of CO adsorbed on copper are presented. Our findings demonstrate that SEY, besides being an indispensable mean to qualify technical materials in many technological fields, can be also used as a flexible and advantageous diagnostics to probe surfaces and interfaces.

  18. Bioactivity of noble metal nanoparticles decorated with biopolymers and their application in drug delivery.

    Science.gov (United States)

    Rai, Mahendra; Ingle, Avinash P; Gupta, Indarchand; Brandelli, Adriano

    2015-12-30

    The unique properties of nanomaterials can be applied to solve different problems including new ways of drug delivery. Noble metal nanoparticles are most promising because they have been used for medicinal purposes since ancient time. It is evident from the past studies that the metallic nanoparticles are much more effective against various microorganisms when compared to their conventional counterparts. However, decoration of such nanoparticles with biomaterials add more advantages to their antimicrobial activity. Decoration of metal nanoparticles with biopolymers is a quite new area of research. Studies performed hitherto shown that nanoparticles of noble metals like silver, gold and platinum demonstrated better antibacterial, antifungal and antiviral activities when conjugated with biopolymers. The development of such technology has potential to develop materials that are more effective in the field of health science. Considering the importance and uniqueness of this concept, the present review aims to discuss the use of biopolymer-decorated metal nanoparticles for combating various diseases caused by microbial pathogens. Moreover, the nanotoxicity aspect has also been discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Defense by-products production and utilization program: noble metal recovery screening experiments

    International Nuclear Information System (INIS)

    Hazelton, R.F.; Jensen, G.A.; Raney, P.J.

    1986-03-01

    Isotopes of the platinum metals (rutheium, rhodium, and palladium) are produced during uranium fuel fission in nuclear reactors. The strategic values of these noble metals warrant considering their recovery from spent fuel should the spent fuel be processed after reactor discharge. A program to evaluate methods for ruthenium, rhodium, and palladium recovery from spent fuel reprocessing liquids was conducted at Pacific Northwest Laboratory (PNL). The purpose of the work reported in this docuent was to evaluate several recovery processes revealed in the patent and technical literature. Beaker-scale screening tests were initiated for three potential recovery processes: precipitation during sugar denitration of nitric acid reprocessing solutions after plutonium-uranium solvent extraction, adsorption using nobe metal selective chelates on active carbon, and reduction forming solid noble metal deposits on an amine-borane reductive resin. Simulated reprocessing plant solutions representing typical nitric acid liquids from defense (PUREX) or commercial fuel reprocessing facilities were formulated and used for evaluation of the three processes. 9 refs., 3 figs., 9 tabs

  20. Optical and structural properties of noble-metal nanoparticles; Optische und strukturelle Eigenschaften von Edelmetallnanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Dahmen, C

    2006-06-23

    Noble-metal nanoparticles exhibit rich optical behavior, such as resonant light scattering and absorption and non-linear signal enhancement. This makes them attractive for a multitude of physical, chemical, and biophysical applications. For instance, recent biomedical experiments demonstrate the suitability of noble-metal nanoparticles for selective photothermal apoptosis by heat transport by laser irradiation. The applications of nanoparticles largely exploit that plasmons, i. e. collective oscillations of the conduction electrons, can be optically excited in these nanoparticles. In optical spectroscopy, these are seen as pronounced resonances. In the first part of this work, model calculations are employed to elucidate how radiation damping in noble-metal nanoparticles, i. e. the transformation of plasmons into photons, depends on particle size, particle shape, and on electromagnetic coupling between individual particles. Exact electrodynamic calculations are carried out for individual spheroidal particles and for pairs of spherical particles. These calculations for spheroidal particles demonstrate for the first time that radiative plasmon decay is determined by both the particle volume and the particle shape. Model calculations for pairs of large spherical particles reveal that the electromagnetic fields radiated by the particles mediate electromagnetic coupling at interparticle distances in the micrometer range. This coupling can lead to immense modulations of the plasmonic linewidth. The question whether this coupling is sufficiently strong to mediate extended, propagating, plasmon modes in nanoparticle arrays is addressed next. Detailed analysis reveals that this is not the case; instead, for the particle spacings regarded here, a non-resonant, purely diffractive coupling is observed, which is identified by steplike signatures in reflection spectra of the particle arrays. In the second part of this work, structural and optical properties of noble-metal

  1. Investigation of noble metal deposition behaviour in boiling water reactors. The NORA project

    International Nuclear Information System (INIS)

    Ritter, Stefan; Karastoyanov, Vasil; Abolhassani-Dadras, Sousan; Guenther-Leopold, Ines; Kivel, Niko

    2010-01-01

    NobleChem trademark is a technology developed by General Electric to reduce stress corrosion cracking (SCC) in reactor internals and recirculation pipes of boiling water reactors (BWRs) while preventing the negative side effects of classic hydrogen water chemistry. Noble metals (Pt, Rh) acting as electrocatalysts for the recombination of O 2 and H 2 O 2 with H 2 to H 2 O and thus reducing the corrosion potential more efficiently are injected into the feedwater during reactor shutdown (classic method) or on-line during power operation. They are claimed to deposit as very fine metallic particles on all water-wetted surfaces, including the most critical regions inside existing cracks, and to stay electrocatalytic over long periods of time. The effectiveness of this technology in plants still remains to be demonstrated. Based on highly credible laboratory experiments down to the sub-μg . kg -1 Pt concentration range, SCC mitigation may be expected, provided that a stoichiometric excess of H 2 and a sufficient surface coverage with very fine Pt particles exist simultaneously at the critical locations [1]. Very little is known about the deposition and (re-)distribution behaviour of the Pt in the reactor. For the validation of this technique the research project NORA (noble metal deposition behaviour in BWRs) has been started at the Paul Scherrer Institute (PSI) with two main objectives: (i) to gain phenomenological insights and a better basic understanding of the Pt distribution and deposition behaviour in BWRs; (ii) to develop and qualify a non-destructive technique to characterise the size and distribution of the Pt particles and the local concentration of Pt on reactor components. This paper presents the objectives of the project, the planned work and a brief description of the status of the project. (orig.)

  2. Investigation of the noble metal deposition behaviour in boiling water reactors - the NORA project

    International Nuclear Information System (INIS)

    Ritter, S.; Karastoyanov, V.; Abolhassani-Dadras, S.; Guenther-Leopold, I.; Kivel, N.

    2010-01-01

    NobleChem™ is a technology developed by General Electric to reduce stress corrosion cracking (SCC) in reactor internals and recirculation pipes of boiling water reactors (BWRs) while preventing the negative side effects of classical hydrogen water chemistry. Noble metals (Pt, Rh) acting as electrocatalysts for the recombination of O 2 and H 2 O 2 with H 2 to H 2 O and thus reducing the corrosion potential more efficiently are injected into the feed water during reactor shut-down (classical method) or on-line during power operation. They are claimed to deposit as very fine metallic particles on all water-wetted surfaces including the most critical regions inside existing cracks and to stay electrocatalytic over long periods of time. The effectiveness of this technology in plants remains still to be demonstrated. Based on highly credible laboratory experiments down to the sub-ppb Pt concentration range, SCC mitigation may be expected, provided that a stoichiometric excess of H 2 and a sufficient surface coverage with very fine Pt particles exist simultaneously at the critical locations. Very little is known about the deposition and (re-)distribution behaviour of the Pt in the reactor. For the validation of this technique the research project NORA (noble metal deposition behaviour in BWRs) has been started at PSI with two main objectives: (i) to gain phenomenological insights and a better basic understanding of the Pt distribution and deposition behaviour in BWRs; (ii) to develop and qualify a non-destructive technique to characterise the size and distribution of the Pt particles and its local concentration on reactor components. This paper presents the objectives of the project, the planned work and a brief description of the status of the project. (author)

  3. Development of guidelines on the application of noble metals to BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Wood, C.J. [EPRI, Palo Alto, CA (United States); Cowan, R.L

    2002-07-01

    Water Chemistry plays a critical role in determining the economics of BWR (boiling water reactor) operation. The chemistry controls the probability of repairs due to stress corrosion cracking of piping and internals, the operating and shutdown dose rates (and thus personnel exposure), radiation waste generation and fuel corrosion performance. Simultaneously addressing the adverse effects from these phenomena requires a delicate balance of chemistry variables. Earlier papers have reviewed the technologies that have evolved to provide this balance including specific impurity limits, hydrogen water chemistry, and isotopically depleted zinc injection. This paper addresses the experience with the latest technology, noble metal chemical addition (NMCA). (authors)

  4. Efficient recovery of gold and other noble metals from electronic and other scraps

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hidetoshi

    1987-01-01

    Pure gold is extracted from crude gold by the solvent extraction method in the recovery and refining process for Noble metals recovered from electronic and other scraps. This solvent extraction method is advantageous in that it facilitates rapid processing, thereby reducing the interest burden of gold staying too long in the unit. Therefore, the method is also used in the refining of platinum and palladium. Technological innovation has created more complex and diversified types of scraps, and efforts are being made to accommodate ourselves to such a trend.

  5. Development of guidelines on the application of noble metals to BWRs

    International Nuclear Information System (INIS)

    Wood, C.J.; Cowan, R.L.

    2002-01-01

    Water Chemistry plays a critical role in determining the economics of BWR (boiling water reactor) operation. The chemistry controls the probability of repairs due to stress corrosion cracking of piping and internals, the operating and shutdown dose rates (and thus personnel exposure), radiation waste generation and fuel corrosion performance. Simultaneously addressing the adverse effects from these phenomena requires a delicate balance of chemistry variables. Earlier papers have reviewed the technologies that have evolved to provide this balance including specific impurity limits, hydrogen water chemistry, and isotopically depleted zinc injection. This paper addresses the experience with the latest technology, noble metal chemical addition (NMCA). (authors)

  6. Expeditious Synthesis of Noble Metal Nanoparticles Using Vitamin B12 under Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Changseok Han

    2015-08-01

    Full Text Available A greener synthesis protocol for noble nanometals is developed using vitamin B12 as a reducing and capping agent in conjunction with the use of microwaves. Successful assembly of nanoparticles or microparticles with varied shapes and sizes have been demonstrated. The synthesized Ag, Au, and Pd samples were thoroughly characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high resolution transmission microscopy, and UV-visible spectrophotometry, confirming that metallic Ag, Au, and Pd were synthesized by the green chemistry method.

  7. Simulated optical properties of noble metallic nanopolyhedra with different shapes and structures

    Science.gov (United States)

    Zhang, An-Qi; Qian, Dong-Jin; Chen, Meng

    2013-11-01

    The optical properties of nanostructured architectures are highly sensitive to their compositions, structures, dimensions, geometries and embedding mediums. Nanopolyhedra, including homogeneous metal nanoparticles and core-shell structures, have unique optical properties. In the beginning of this study, Discrete Dipole Approximation (DDA) method has been introduced. Then the simulated extinction spectra of single-component metal nanoparticles and Au@Ag polyhedra were calculated using both Mie and DDA methods. The influence of morphology and components on the optical response is discussed and well-supported by previously published experimental results. It is observed that the Localized Surface Plasmon Resonance peaks are mainly decided by sharp vertexes and symmetry of noble metallic polyhedra, as well as the structure of the Au@Ag core-shell nanoparticles.

  8. Dithiocarbamate Self-Assembled Monolayers as Efficient Surface Modifiers for Low Work Function Noble Metals

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Dominik; Schäfer, Tobias; Schulz, Philip; Jung, Sebastian; Rittich, Julia; Mokros, Daniel; Segger, Ingolf; Maercks, Franziska; Effertz, Christian; Mazzarello, Riccardo; Wuttig, Matthias

    2016-09-06

    Tuning the work function of the electrode is one of the crucial steps to improve charge extraction in organic electronic devices. Here, we show that N,N-dialkyl dithiocarbamates (DTC) can be effectively employed to produce low work function noble metal electrodes. Work functions between 3.1 and 3.5 eV are observed for all metals investigated (Cu, Ag, and Au). Ultraviolet photoemission spectroscopy (UPS) reveals a maximum decrease in work function by 2.1 eV as compared to the bare metal surface. Electronic structure calculations elucidate how the complex interplay between intrinsic dipoles and dipoles induced by bond formation generates such large work function shifts. Subsequently, we quantify the improvement in contact resistance of organic thin film transistor devices with DTC coated source and drain electrodes. These findings demonstrate that DTC molecules can be employed as universal surface modifiers to produce stable electrodes for electron injection in high performance hybrid organic optoelectronics.

  9. Some remarks on the use of the effective medium approximation for the resistivity calculations in liquid noble metals

    International Nuclear Information System (INIS)

    Gorecki, J.

    1982-09-01

    The application of the effective medium approximation (EMA) to the muffin-tin model of liquid metal is considered. The triple correlation function is included in the expression for electrical resistivity. Good agreement with experimental data can be expected for liquid noble metals. (author)

  10. Transparent and conductive electrodes by large-scale nano-structuring of noble metal thin-films

    DEFF Research Database (Denmark)

    Linnet, Jes; Runge Walther, Anders; Wolff, Christian

    2018-01-01

    grid, and nano-wire thin-films. The indium and carbon films do not match the chemical stability nor the electrical performance of the noble metals, and many metal films are not uniform in material distribution leading to significant surface roughness and randomized transmission haze. We demonstrate...

  11. Effects of halogens on interactions between a reduced TiO{sub 2} (110) surface and noble metal atoms: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Kohei, E-mail: k-tada@aist.go.jp [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka, 563-8577 (Japan); Koga, Hiroaki [Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto, 615-8245 (Japan); Hayashi, Akihide; Kondo, Yudai; Kawakami, Takashi; Yamanaka, Shusuke [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Okumura, Mitsutaka [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto, 615-8245 (Japan)

    2017-07-31

    Highlights: • We investigated the halogen effect on the interactions of noble metals with TiO{sub 2}. • Halogen atoms inhibit electron transfer from TiO{sub 2} to noble metals. • Iodine stabilizes the adsorption of noble metals especially for Ag and Cu. • Electron transfer from the TiO{sub 2} is effective in anchoring Au and Pt atoms. • Covalent interaction with the support is effective in anchoring Ag and Cu atoms. - Abstract: Using DFT calculation, we investigate the effects of halogens on the interactions between rutile TiO{sub 2} (110) and noble metal atoms (Au, Ag, Cu, Pt, and Pd). Fluorine, chlorine, and bromine atoms occupy the oxygen defect sites of TiO{sub 2}, decreasing the stability of noble metal atoms on the surface. This decrease occurs because the halogens inhibit electron transfer from TiO{sub 2} to the noble metal atoms; the electron transfer from reduced TiO{sub 2} to the noble metal atom stabilizes the noble metal atom adsorption. In contrast, iodine strengthens the interactions between TiO{sub 2} and some noble metal atoms, namely Ag and Cu. This stabilization occurs because of the covalent interaction between iodine-doped TiO{sub 2} and the noble metal atom. Therefore, the stabilization is explained well by chemical hardness. This result suggests that iodine-doping of a TiO{sub 2} surface would be an effective method for the preparation of highly stabilized noble metal clusters.

  12. Rational design of binder-free noble metal/metal oxide arrays with nanocauliflower structure for wide linear range nonenzymatic glucose detection

    KAUST Repository

    Li, Zhenzhen

    2015-06-12

    One-dimensional nanocomposites of metal-oxide and noble metal were expected to present superior performance for nonenzymatic glucose detection due to its good conductivity and high catalytic activity inherited from noble metal and metal oxide respectively. As a proof of concept, we synthesized gold and copper oxide (Au/CuO) composite with unique one-dimensional nanocauliflowers structure. Due to the nature of the synthesis method, no any foreign binder was needed in keeping either Au or CuO in place. To the best of our knowledge, this is the first attempt in combining metal oxide and noble metal in a binder-free style for fabricating nonenzymatic glucose sensor. The Au/CuO nanocauliflowers with large electrochemical active surface and high electrolyte contact area would promise a wide linear range and high sensitive detection of glucose with good stability and reproducibility due to its good electrical conductivity of Au and high electrocatalytic activity of CuO.

  13. Noble metals-compatible melter features development Phase 1: Establishing functional and design criteria and design concepts

    International Nuclear Information System (INIS)

    Elmore, M.R.; Siemens, D.H.; Chapman, C.C.

    1996-03-01

    Premature failures have occurred in melters at Japan's Tokai Mockup Facility and at the Federal Republic of Germany (FRG) PAMELA plant during processing of feeds with high levels of noble metals. Melter failure was due to the accumulation of an electrically conductive, noble metals-containing precipitates in the glass, that then resulted in short circuiting of the electrodes. A comparison was made of the anticipated Hanford Waste Vitrification Plant (HWVP) feed with the feeds processed in the FRG and Japanese melters. The evaluation showed that comparable levels of noble metals and other potential precipitate-forming components (e.g. Cr/Fe/Ni-spinels) exist in the HWVP feed. As a result, the HWVP project made a decision to modify the present reference melter design to include features to prevent the precipitation and accumulation or otherwise accommodate precipitated phases on a routine basis without loss of production capacity

  14. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    Directory of Open Access Journals (Sweden)

    X. H. Liu

    2015-10-01

    Full Text Available We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  15. Understanding the superior photocatalytic activity of noble metals modified titania under UV and visible light irradiation.

    Science.gov (United States)

    Bumajdad, Ali; Madkour, Metwally

    2014-04-28

    Although TiO2 is one of the most efficient photocatalysts, with the highest stability and the lowest cost, there are drawbacks that hinder its practical applications like its wide band gap and high recombination rate of the charge carriers. Consequently, many efforts were directed toward enhancing the photocatalytic activity of TiO2 and extending its response to the visible region. To head off these attempts, modification of TiO2 with noble metal nanoparticles (NMNPs) received considerable attention due to their role in accelerating the transfer of photoexcited electrons from TiO2 and also due to the surface plasmon resonance which induces the photocatalytic activity of TiO2 under visible light irradiation. This insightful perspective is devoted to the vital role of TiO2 photocatalysis and its drawbacks that urged researchers to find solutions such as modification with NMNPs. In a coherent context, we discussed here the characteristics which qualify NMNPs to possess a great enhancement effect for TiO2 photocatalysis. Also we tried to understand the reasons behind this effect by means of photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra, and Density Functional Theory (DFT) calculations. Then the mechanism of action of NMNPs upon deposition on TiO2 is presented. Finally we introduced a survey of the behaviour of these noble metal NPs on TiO2 based on the particle size and the loading amount.

  16. Automated ion-exchange system for the radiochemical separation of the noble metals

    International Nuclear Information System (INIS)

    Parry, S.J.

    1980-01-01

    Ion-exchange separation is particularly suitable for mechanisation and automated ion exchange has been applied to the activation analysis of biological and environmental samples. In this work a system has been designed for experimental studies, which can be adapted for different modes of operation. The equipment is based on a large-volume sampler for the automatic presentation of 500 ml of liquid to a sampling probe. The sample is delivered to the ion-exchange column by means of a peristaltic pump. The purpose of this work was to automate a procedure for separating the noble metals from irradiated geological samples, for neutron-activation analysis. The process of digesting the rock sample is carried out manually in 30 min and is not suited to unattended operation. The volume of the resulting liquid sample may be 100 ml and so the manual separation step may take as long as 1.25 h per sample. The reason for automating this part of the procedure is to reduce the separation time for a group of five samples and consequently to improve the sensitivity of the analysis for radionuclides with short half-lives. This paper describes the automatic ion-exchange system and the ways in which it can be used. The mode of operation for the separation of the noble metals is given in detail. The reproducibility of the system has been assessed by repeated measurements on a standard reference matte. (author)

  17. Tailoring the supercapacitive performances of noble metal oxides, porous carbons and their composites

    Directory of Open Access Journals (Sweden)

    Panić Vladimir V.

    2013-01-01

    Full Text Available Porous electrochemical supercapacitive materials, as an important type of new-generation energy storage devices, require a detailed analysis and knowledge of their capacitive performances upon different charging/discharging regimes. The investigation of the responses to dynamic perturbations of typical representatives, noble metal oxides, carbonaceous materials and RuO2-impregnated carbon blacks, by electrochemical impedance spectroscopy (EIS is presented. This presentation follows a brief description of supercapacitive behavior and origin of pseudocapacitive response of noble metal oxides. For all investigated materials, the electrical charging/discharging equivalent of the EIS response was found to obey the transmission line model envisaged as so-called „resistor/capacitor (RC ladder“. The ladder features are correlated to material physicochemical properties, its composition and the composition of the electrolyte. Fitting of the EIS data of different supercapacitive materials to appropriate RC ladders enables the in-depth profiling of the capacitance and pore resistance of their porous thin-layers and finally the complete revelation of capacitive energy storage issues. [Projekat Ministarstva nauke Republike Srbije, br. 172060

  18. Catalytic Activities of Noble Metal Phosphides for Hydrogenation and Hydrodesulfurization Reactions

    Directory of Open Access Journals (Sweden)

    Yasuharu Kanda

    2018-04-01

    Full Text Available In this work, the development of a highly active noble metal phosphide (NMXPY-based hydrodesulfurization (HDS catalyst with a high hydrogenating ability for heavy oils was studied. NMXPY catalysts were obtained by reduction of P-added noble metals (NM-P, NM: Rh, Pd, Ru supported on SiO2. The order of activities for the hydrogenation of biphenyl was Rh-P > NiMoS > Pd-P > Ru-P. This order was almost the same as that of the catalytic activities for the HDS of dibenzothiophene. In the HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT, the HDS activity of the Rh-P catalyst increased with increasing reaction temperature, but the maximum HDS activity for the NiMoS catalyst was observed at 270 °C. The Rh-P catalyst yielded fully hydrogenated products with high selectivity compared with the NiMoS catalyst. Furthermore, XRD analysis of the spent Rh-P catalysts revealed that the Rh2P phase possessed high sulfur tolerance and resistance to sintering.

  19. TiO2 structures doped with noble metals and/or graphene oxide to improve the photocatalytic degradation of dichloroacetic acid.

    Science.gov (United States)

    Ribao, Paula; Rivero, Maria J; Ortiz, Inmaculada

    2017-05-01

    Noble metals have been used to improve the photocatalytic activity of TiO 2 . Noble metal nanoparticles prevent charge recombination, facilitating electron transport due to the equilibration of the Fermi levels. Furthermore, noble metal nanoparticles show an absorption band in the visible region due to a high localized surface plasmon resonance (LSPR) effect, which contributes to additional electron movements. Moreover, systems based on graphene, titanium dioxide, and noble metals have been used, considering that graphene sheets can carry charges, thereby reducing electron-hole recombination, and can be used as substrates of atomic thickness. In this work, TiO 2 -based nanocomposites were prepared by blending TiO 2 with noble metals (Pt and Ag) and/or graphene oxide (GO). The nanocomposites were mainly characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, and photocurrent analysis. Here, the photocatalytic performance of the composites was analyzed via oxidizing dichloroacetic acid (DCA) model solutions. The influence of the noble metal load on the composite and the ability of the graphene sheets to improve the photocatalytic activity were studied, and the composites doped with different noble metals were compared. The results indicated that the platinum structures show the best photocatalytic degradation, and, although the presence of graphene oxide in the composites is supposed to enhance their photocatalytic performance, graphene oxide does not always improve the photocatalytic process. Graphical abstract It is a schematic diagram. Where NM is Noble Metal and LSPR means Localized Surface Plasmon Resonance.

  20. Synthesis, fabrication, and spectroscopy of nano-scale photonic noble metal materials

    Science.gov (United States)

    Egusa, Shunji

    Nanometer is an interesting scale for physicists, chemists, and materials scientists, in a sense that it lies between the macroscopic and the atomic scales. In this regime, materials exhibit distinct physical and chemical properties that are clearly different from those of atoms or macroscopic bulk. This thesis is concerned about both physics and chemistry of noble metal nano-structures. Novel chemical syntheses and physical fabrications of various noble metal nano-structures, and the development of spectroscopic techniques for nano-structures are presented. Scanning microscopy/spectroscopy techniques inherently perturbs the true optical responses of the nano-structures. However, by using scanning tunneling microscope (STM) tip as the nanometer-confined excitation source of surface plasmons in the samples, and subsequently collecting the signals in the Fourier space, it is shown that the tip-perturbed part of the signals can be deconvoluted. As a result, the collected signal in this approach is the pure response of the sample. Coherent light is employed to study the optical response of nano-structures, in order to avoid complication from tip-perturbation as discussed above. White-light super-continuum excites the nano-structure, the monolayer of Au nanoparticles self-assembled on silicon nitride membrane substrates. The coherent excitation reveals asymmetric surface plasmon resonance in the nano-structures. One of the most important issues in nano-scale science is to gain control over the shape, size, and assembly of nanoparticles. A novel method is developed to chemically synthesize ligand-passivated atomic noble metal clusters in solution phase. The method, named thermal decomposition method, enables facile yet robust synthesis of fluorescent atomic clusters. Thus synthesized atomic clusters are very stable, and show behaviors of quantum dots. A novel and versatile approach for creation of nanoparticle arrays is developed. This method is different from the

  1. Noble metal abundances in komatiite suites from Alexo, Ontario and Gorgona Island, Colombia

    Science.gov (United States)

    Brügmann, G. E.; Arndt, N. T.; Hofmann, A. W.; Tobschall, H. J.

    1987-08-01

    The distribution of the chalcophile and siderophile metals Cu, Ni, Au, Pd, Ir, Os and Ru in an Archaean komatiite flow from Alexo, Ontario and in a Phanerozoic komatiitic suite of Gorgona Island, Colombia, provides new information about the geochemical behaviour of these elements. Copper, Au and Pd behave as incompatible elements during the crystallization of these ultramafic magmas. In contrast, Ni, Ir, Os and Ru concentrations systematically decrease with decreasing MgO contents, a pattern characteristic of compatible elements. These trends are most probably controlled by olivine crystallization, which implies that Ir, Os and Ru are compatible in olivine. Calculated partition coefficients for Ir, Os and Ru between olivine and the melt are about 1.8. Compared to primitive mantle, parental komatiitic liquids are enriched in (incompatible) Cu, Au and Pd and depleted in (compatible) Ir, Os and Ru. Within both Archaean and Phanerozoic komatiites, noble metal ratios such as Au/Pd, Ir/Os, Os/Ru and Ru/Ir and ratios of lithophile and siderophile elements such as Ti/Pd, Ti/Au are constant and similar to primitive mantle values. This implies that Au and Pd are moderately incompatible elements and that there has been no significant fractionation of siderophile and lithophile elements since the Archaean. Platinum-group element abundances of normal MORB are highly variable and always much lower than in komatiites, because MORB magma is saturated with sulfur and a variable but minor amount of sulfide segregated during mantle melting or during the ascent of magma to the surface. Sulfide deposits associated with komatiites display similar chalcophile element patterns to those of komatiites. Noble metal ratios such as Pd/Ir, Au/Ir, Pd/Os and Pd/Ru can be used to determine the composition of the host komatiite at the time of sulfide segregation.

  2. Non-noble metal graphene oxide-copper (II) ions hybrid electrodes for electrocatalytic hydrogen evolution reaction

    KAUST Repository

    Muralikrishna, S.; Ravishankar, T.N.; Ramakrishnappa, T.; Nagaraju, Doddahalli H.; Krishna Pai, Ranjith

    2015-01-01

    Non-noble metal and inexpensive graphene oxide-copper (II) ions (GO-Cu2+) hybrid catalysts have been explored for the hydrogen evolution reaction (HER). We were able to tune the binding abilities of GO toward the Cu2+ ions and hence their catalytic

  3. Fabrication and magnetic-induced aggregation of Fe3O4–noble metal composites for superior SERS performances

    International Nuclear Information System (INIS)

    Gan, Zibao; Zhao, Aiwu; Zhang, Maofeng; Wang, Dapeng; Guo, Hongyan; Tao, Wenyu; Gao, Qian; Mao, Ranran; Liu, Erhu

    2013-01-01

    Fe 3 O 4 –noble metal composites were obtained by combining Au, Ag nanoparticles (NPs) with 3-aminopropyltrimethoxysilane-functionalized Fe 3 O 4 NPs. UV–Visible absorption spectroscopy demonstrates the obtained Fe 3 O 4 –noble metal composites inherit the typical surface plasmon resonance bands of Au, Ag at 533 and 453 nm, respectively. Magnetic measurements also indicated that the superparamagnetic Fe 3 O 4 –noble metal composites have excellent magnetic response behavior. A magnetic-induced idea was introduced to change their aggregated states and take full advantage of their surface-enhanced Raman scattering (SERS) performances. Under the induction of an external magnetic field, the bifunctional Fe 3 O 4 –noble metal aggregates exhibit the unique superiority in SERS detection of Rhodamine 6G (R6G), compared with the naturally dispersed Au, Ag NPs. Especially, the detection limit of the Fe 3 O 4 –Ag aggregates for R6G is as low as 10 −14  M, and the calculated EF reaches up to 1.2 × 10 6 , which meets the requirements for trace detection of analytes. Furthermore, the superiority could be extended to sensitive detection of other organic molecules, such as 4-mercaptopyridine. This work provides a new insight for active adjustment of the aggregated states of SERS substrates and the optimization of SERS performances

  4. Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

    KAUST Repository

    Al-ShaikhAli, Anaam H.

    2016-11-30

    Liquid organic chemical hydride is a promising candidate for hydrogen storage and transport. Methylcyclohexane (MCH) to toluene (TOL) cycle has been considered as one of the feasible hydrogen carrier systems, but selective dehydrogenation of MCH to TOL has only been achieved using the noble Pt-based catalysts. The aim of this study is to develop non-noble, cost-effective metal catalysts that can show excellent catalytic performance, mainly maintaining high TOL selectivity achievable by Pt based catalysts. Mono-metallic Ni based catalyst is a well-known dehydrogenation catalyst, but the major drawback with Ni is its hydrogenolysis activity to cleave C-C bonds, which leads to inferior selectivity towards dehydrogenation of MCH to TOL. This study elucidate addition of the second metal to Ni based catalyst to improve the TOL selectivity. Herein, ubiquitous bi-metallic nanoparticles catalysts were investigated including (Ni–M, M: Ag, Zn, Sn or In) based catalysts. Among the catalysts investigated, the high TOL selectivity (> 99%) at low conversions was achieved effectively using the supported NiZn catalyst under flow of excess H2. In this work, a combined study of experimental and computational approaches was conducted to determine the main role of Zn over Ni based catalyst in promoting the TOL selectivity. A kinetic study using mono- and bimetallic Ni based catalysts was conducted to elucidate reaction mechanism and site requirement for MCH dehydrogenation reaction. The impact of different reaction conditions (feed compositions, temperature, space velocity and stability) and catalyst properties were evaluated. This study elucidates a distinctive mechanism of MCH dehydrogenation to TOL reaction over the Ni-based catalysts. Distinctive from Pt catalyst, a nearly positive half order with respect to H2 pressure was obtained for mono- and bi-metallic Ni based catalysts. This kinetic data was consistent with rate determining step as (somewhat paradoxically) hydrogenation

  5. An effective hydrothermal route for the synthesis of multiple PDDA-protected noble-metal nanostructures.

    Science.gov (United States)

    Chen, Hongjun; Wang, Yuling; Dong, Shaojun

    2007-12-10

    In this article, we demonstrate an effective hydrothermal route for the synthesis of multiple PDDA-protected (PDDA = poly(diallyl dimethylammonium) chloride) noble-metal (including silver, platinum, palladium, and gold) nanostructures in the absence of any seeds and surfactants, in which PDDA, an ordinary and water-soluble polyelectrolyte, acts as both a reducing and a stabilizing agent. Under optimal experimental conditions, Ag nanocubes, Pt and Pd nanopolyhedrons, and Au nanoplates can be obtained, which were characterized by transmission electron microscopy , scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. More importantly, the nanostructures synthesized show potential applications in surface-enhanced Raman scattering and electrocatalysis, in which Ag nanocubes and Pt nanopolyhedrons were chosen as the examples, respectively.

  6. Interaction of noble-metal fission products with pyrolytic silicon carbide

    International Nuclear Information System (INIS)

    Lauf, R.J.; Braski, D.N.

    1982-01-01

    Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain layers of pyrolytic carbon and silicon carbide, which act as a miniature pressure vessel and form the primary fission product barrier. Of the many fission products formed during irradiation, the noble metals are of particular interest because they interact significantly with the SiC layer and their concentrations are somewhat higher in the low-enriched uranium fuels currently under consideration. To study fission product-SiC interactions, particles of UO 2 or UC 2 are doped with fission product elements before coating and are then held in a thermal gradient up to several thousand hours. Examination of the SiC coatings by TEM-AEM after annealing shows that silver behaves differently from the palladium group

  7. Porous Silicon Hydrogen Sensor at Room Temperature: The Effect of Surface Modification and Noble Metal Contacts

    Directory of Open Access Journals (Sweden)

    Jayita KANUNGO

    2009-04-01

    Full Text Available Porous silicon (PS was fabricated by anodization of p-type crystalline silicon of resistivity 2-5 Ω cm. After formation, the PS surface was modified by the solution containing noble metal like Pd. Pd-Ag catalytic contact electrodes were deposited on porous silicon and on p-Silicon to fabricate Pd-Ag/PS/p-Si/Pd-Ag sensor structure to carry out the hydrogen sensing experiments. The Sensor was exposed to 1% hydrogen in nitrogen as carrier gas at room temperature (270C. Pd modified sensor showed minimum fluctuations and consistent performance with 86% response, response time and recovery time of 24 sec and 264 sec respectively. The stability experiments were studied for both unmodified and Pd modified sensor structures for a period of about 24 hours and the modified sensors showed excellent durability with no drift in response behavior.

  8. Hot-Electron Intraband Luminescence from Single Hot Spots in Noble-Metal Nanoparticle Films

    Science.gov (United States)

    Haug, Tobias; Klemm, Philippe; Bange, Sebastian; Lupton, John M.

    2015-08-01

    Disordered noble-metal nanoparticle films exhibit highly localized and stable nonlinear light emission from subdiffraction regions upon illumination by near-infrared femtosecond pulses. Such hot spot emission spans a continuum in the visible and near-infrared spectral range. Strong plasmonic enhancement of light-matter interaction and the resulting complexity of experimental observations have prevented the development of a universal understanding of the origin of light emission. Here, we study the dependence of emission spectra on excitation irradiance and provide the most direct evidence yet that the continuum emission observed from both silver and gold nanoparticle aggregate surfaces is caused by recombination of hot electrons within the conduction band. The electron gas in the emitting particles, which is effectively decoupled from the lattice temperature for the duration of emission, reaches temperatures of several thousand Kelvin and acts as a subdiffraction incandescent light source on subpicosecond time scales.

  9. Synthesis of noble metal nanoparticles and their superstructures; Darstellung von Edelmetallnanopartikeln und deren Ueberstrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Bigall, Nadja-Carola

    2009-08-18

    A modified synthesis procedure for citrate-stabilized gold nanoparticles in aqueous solution is transferred under application of equal concentrations to the systems silver, platinum, and palladium. The nanoparticles are analyzed by means of absorption spectroscopy and electron microscopy. Ordered superstructures of the noble-metal nanoparticles can be synthesized by infiltration of templates of block-copolymer films with aqueous nanoparticle solution. In dependence on the pre-treatment of the polymer films either two-dimensional periodical arrangements with a periodicity of less than 30 nm or fingerprint-like arrangements with a groove distance in the same order of magnitude. By removal of the polymer one- respectively two-dimensional arrangements of platinum nanowires respectively nanoparticles on a silicon waver arise.

  10. A systematic chemical separation for thermal neutron activation analysis of seven noble metals in rock

    International Nuclear Information System (INIS)

    Ayabe, Muneo

    1980-01-01

    A method for the systematic activation analysis of seven noble metals - ruthenium, silver, rhenium, osmium, iridium, platinum and gold - in rocks were developed and examined with radiotracers and irradiated rock samples. After the fusion of the irradiated rock sample with sodium hydroxide and sodium peroxide, 10% sodium sulfide solution is added and rhenium is extracted with pyridine-benzene mixture from 6N sodium hydroxide solution. From the hydroxide-sulfide precipitate fraction, ruthenium and osmium are distilled as tetroxides, silver is precipitated as chloride, gold is extracted with ethyl acetate, and iridium and platinum are extracted with diantipyrylmethane. Each fraction is purified and subjected to the γ-ray spectrometry. Chemical yields for the elements are more than 60%. Determination limits are given for the seven elements. (author)

  11. New technique for the determination of trace noble metal content in geological and process materials

    Energy Technology Data Exchange (ETDEWEB)

    Mitkin, V.N. E-mail: mit@che.nsk.su; Zayakina, S.B.; Anoshin, G.N

    2003-02-03

    A new two-step sample preparation technique is proposed for the instrumental determination of trace quantities of noble metals (NM) in refractory geological and process materials. The decomposition procedure is based on the oxidizing fluorination of samples with subsequent sulfatization (OFS) of the sample melt or cake. Fluorination of samples is accomplished using a mixture of KHF{sub 2}+KBrF{sub 4} or KHF{sub 2}+BrF{sub 3} depending on the ratio of sample mass to oxidizing mixture. Both cakes and melts can result using this procedure. Sulfatization of resulting fluorides is completed using concentrated sulfuric acid heated to 550 deg. C. Validation studies using certified geostandard reference materials (GSO VP-2, ZH-3, Matte RTP, HO-1, SARM-7) have shown that the proposed method is fast, convenient and most often produces non-hygroscopic homogeneous residues suitable for analysis by atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES). Results obtained for NM concentrations in reference materials agreed with certified concentration ranges and results obtained using other methods of analysis. The OFS procedure combined with direct current plasma d.c. plasma AES achieved the following limits of detection (LOD) for the noble metals: Ag, Au, Pd, 1-2x10{sup -6}; Pt, 5x10{sup -6}; and Ru, Rh, Ir, Os, 1-3x10{sup -7} wt.%. Using graphite furnace AAS (GFAAS) combined extraction pre-concentration the following LODs for NMs were achieved: Pt, Ru, 1x10{sup -6}; Pd, Rh, 1x10{sup -7}; and Au, Ag, 1-2x10{sup -8} wt.%. The relative standard deviation for NM determinations (S{sub r}) was dependent on NM concentration and sample type, but commonly was in the range of 3-15% for d.c. plasma AES and 5-30% for GFAAS.

  12. Conversion of ion-exchange resins, catalysts and sludges to glass with optional noble metal recovery using the GMODS process

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Beahm, E.C.

    1996-01-01

    Chemical processing and cleanup of waste streams (air and water) typically result in products, clean air, clean water, and concentrated hazardous residues (ion exchange resins, catalysts, sludges, etc.). Typically, these streams contain significant quantities of complex organics. For disposal, it is desirable to destroy the organics and immobilize any heavy metals or radioactive components into stable waste forms. If there are noble metals in the residues, it is desirable to recover these for reuse. The Glass Material Oxidation and Dissolution System (GMODS) is a new process that directly converts radioactive and hazardous chemical wastes to borosilicate glass. GMODS oxidizes organics with the residue converted to glass; converts metals, ceramics, and amorphous solids to glass; converts halides (eg chlorides) to borosilicate glass and a secondary sodium halide stream; and recovers noble metals. GMODS has been demonstrated on a small laboratory scale (hundreds of grams), and the equipment needed for larger masses has been identified

  13. Transparent and conductive electrodes by large-scale nano-structuring of noble metal thin-films

    DEFF Research Database (Denmark)

    Linnet, Jes; Runge Walther, Anders; Wolff, Christian

    2018-01-01

    grid, and nano-wire thin-films. The indium and carbon films do not match the chemical stability nor the electrical performance of the noble metals, and many metal films are not uniform in material distribution leading to significant surface roughness and randomized transmission haze. We demonstrate...... solution-processed masks for physical vapor-deposited metal electrodes consisting of hexagonally ordered aperture arrays with scalable aperture-size and spacing in an otherwise homogeneous noble metal thin-film that may exhibit better electrical performance than carbon nanotube-based thin-films...... for equivalent optical transparency. The fabricated electrodes are characterized optically and electrically by measuring transmittance and sheet resistance. The presented methods yield large-scale reproducible results. Experimentally realized thin-films with very low sheet resistance, Rsh = 2.01 ± 0.14 Ω...

  14. Update on the use of dissolved oxygen addition to monitor the effectiveness of noble metal applications in external manifolds

    International Nuclear Information System (INIS)

    Varela, J.A.; Huie, H.H.; Seeman, R.A.; Bourne, C.M.; Odell, A.D.

    2014-01-01

    Electrochemical corrosion potential (ECP) measurements in a Mitigation Monitoring System (MMS) ECP manifold have historically been a primary indicator of the effectiveness of an On-Line NobleChem™ (OLNC) application, with the MMS ECP intended to measure the catalytic effect of noble metal deposited on the ECP manifold surface. In some plants ECP measurements made on untreated surfaces prior to an OLNC application were significantly lower than what would be expected for stainless steel under reactor bulk chemistry conditions. This is due to the consumption and depletion of bulk liquid dissolved oxygen (DO) in the lines supplying reactor water to these external ECP measurement locations. This phenomenon degrades the ability to use these external manifolds to confirm noble metal deposition. Previous papers have described how the injection of an oxygen-rich stream to the MMS supply stream (DO Addition) can be used to re-establish the capability of external ECP measurements to monitor the catalytic behavior of platinum deposited during an OLNC injection. This paper will provide an update of how this method is being successfully used in operating BWRs to monitor OLNC injections. The paper will outline the overall approach used to characterize the catalytic behavior of external ECP manifolds before and after the noble metal application and present plant data collected during DO Additions performed under various conditions. (author)

  15. The determination, by x-ray-fluorescence spectrometry, of noble and base metals in matte-leach residues

    International Nuclear Information System (INIS)

    Austen, C.E.

    1977-01-01

    An accurate and precise method is described for the determination of noble and base metals in matte-leach residues. Preparation of the samples essentially involves fusion with sodium peroxide in a zirconium crucible and leaching with hydrochloric and nitric acids. Matrix correction and calibration are achieved by use of the single-standard calibration method with reference solutions prepared from pure metals or from compounds of the element to be determined

  16. Characterisation and behaviour of Ti/TiO2/noble metal anodes

    International Nuclear Information System (INIS)

    Gueneau de Mussy, Jean-Paul; Macpherson, Julie V.; Delplancke, Jean-Luc

    2003-01-01

    The morphology, composition and the electrical and electrochemical behaviour of the anodic microporous layer, prepared by the galvanostatic anodisation of Ti after sparking, followed by galvanostatic deposition of Pt or Ir have been investigated. These electrodes are proposed to function as dimensionally stable anodes (DSAs). For Ti/TiO 2 /Pt electrodes, Pt is deposited within some of the micropores of the oxide film. In contrast, for Ti/TiO 2 /Ir, the metal is deposited preferentially on the top surface. This difference is thought to result from the position of the metal deposition potential with respect to the flat band potential of n-TiO 2 . Optical imaging of both types of DSA suggests that only a few sites on the surface are responsible for electron exchange at the DSA-electrolyte interface. C-AFM measurements of Ti/TiO 2 /Pt samples subjected to long-term anodic polarisation, suggest that the Ti-noble metal contact is progressively insulated by thickening of the TiO 2 barrier layer, promoting passivation of the DSA. For Ir coated anodes, catalytic activity is directly related to the presence of Ir and to the stability of the catalytic oxide layer. Under Cu electrowinning conditions, the electrochemically formed hydrated Ir oxide was found to be catalytically less stable, than the iridium oxide film subjected to a heat treatment

  17. Interactions of noble metal nanoparticles with their environment; Wechselwirkungen von Edelmetallnanopartikeln mit ihrer Umgebung

    Energy Technology Data Exchange (ETDEWEB)

    Reismann, Maximilian

    2009-12-08

    Upon irradiating noble metal nanoparticles with light, unique optical phenomena can occur, such as resonantly enhanced light-scattering and light-absorption, or a tremendous enhancement of the exciting optical field close to the surface of the nanoparticles. These phenomena rely on the excitations of collective oscillations of the conduction electrons within a nanoparticle. The optical properties of a nanoparticle are determined by the resonance frequency of these so-called plasmon oscillations. This resonance frequency and the light-scattering spectrum of a nanoparticle depend (among other effects) on the dielectric environment of the particle. Due to this effect, noble metal nanoparticles can be applied for local optical sensing of chemical substances. The large light-absorption properties of a nanoparticle also enable the usage of light-irradiation to deposit heat in the nanoparticle in a selective and highly localized manner. Therefore, a local temperature increase can be induced in the nanoparticle and its immediate environment. This temperature increase could be used to trigger chemical or biological reactions, or it could be used for a selective hyperthermia of biological material. These and further possible applications rely on the detection or the systematic excitation of interactions between the noble metal nanoparticle and its environment. These interactions are the central subject of this thesis. Particular attention is paid to photothermal interactions. An interesting question is to what extend a nanoparticle-supported, photothermally-induced temperature rise can be applied to trigger a biomolecular reaction in a spatially confined volume. By carefully adjusting the photothermal treatment, one aims at affecting the molecules without damaging their chemical functionality. The photothermal interaction is addressed in two projects: First, networks built up by gold nanoparticles are investigated. In these networks, double-stranded DNA-molecules are used to

  18. N-acyl thioureas - selective ligands for complexing of heavy metals and noble metals

    International Nuclear Information System (INIS)

    Schuster, M.

    1992-01-01

    Acyl thioureas are complexing agents for heavy metals that are easily produced and very stable. Their favourable toxicological data make them particularly suitable for industrial applications, e.g. detoxification of metallic process solutions or solvent extraction of metals. (orig.) [de

  19. Contributions to the determination of the noble metals gold, iridium, palladium, platinum, rhodium and application to environmentally relevant samples

    International Nuclear Information System (INIS)

    Zischka, M.

    1998-11-01

    The concentrations of noble metals in the environment are still very low (low ng/g and sub ng/g range), although they are emitted to an increasing extent as components of catalytic exhaust emission converters into the environment. The determination of these elements can be error prone even when the determinations are carried out by use of highly sensitive methods in combination with high performance sample preparation techniques. Accurate data with smallest possible measurement uncertainties are a prerequisite for the interpretation of the distribution of noble metals in the environment and their possible toxicological effects. Difficulties related to the determination of the noble metals could be the incomplete recovery after sample preparation, sample digestion and interferences arising in subsequent instrumental determination methods. For this reason two different sample decomposition methods in combination with powerful instrumental techniques are checked for suitability for the determination of the noble metals in environmentally relevant samples. Digestion methods under evaluation are the NiS fire assay and the leaching with aqua regia in closed vessels under high pressure and high temperature. The NiS fire assay provides pre-concentration of the noble-metals and matrix separation of most of the remaining matrix elements. Disadvantages of this method are the need for experienced analysts, the awkward handling and the time-consuming procedure. On the other hand leaching with aqua regia under high pressure at high temperatures is easy to handle and not time-consuming with the crucial disadvantage that neither a pre-concentration of the noble metals nor a matrix separation can be achieved. Investigated instrumental techniques are the ICP-AES (inductively coupled plasma atomic emission spectrometry) with an axially arranged plasma either with a cross-flow or with an ultrasonic nebulizer, the quadrupole ICP-MS (inductively coupled plasma mass spectrometry) and the

  20. Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dikovska, A.Og. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria); Atanasova, G.B. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Avdeev, G.V. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria)

    2016-06-30

    Highlights: • ZnO nanostructures were fabricated on Au–Ag alloy coated silicon substrates by applying pulsed laser deposition. • Morphology of the ZnO nanostructures was related to the Au–Ag alloy content in the catalyst layer. • Increasing the Ag content in Au–Ag catalyst layer changes the morphology of the ZnO nanostructures from nanorods to nanobelts. - Abstract: In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm{sup −2} – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au{sub 3}Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg{sub 2}) layer resulted in the growth of a dense structure of ZnO nanobelts.

  1. Intermetallic nickel silicide nanocatalyst-A non-noble metal-based general hydrogenation catalyst.

    Science.gov (United States)

    Ryabchuk, Pavel; Agostini, Giovanni; Pohl, Marga-Martina; Lund, Henrik; Agapova, Anastasiya; Junge, Henrik; Junge, Kathrin; Beller, Matthias

    2018-06-01

    Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO 2 as the silicon atom source. The process involves thermal reduction of Si-O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon-carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H 2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal-based catalysts.

  2. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    International Nuclear Information System (INIS)

    King, R.B.; Bhattacharyya, N.K.; Wiemers, K.D.

    1994-08-01

    Simulants for the Hanford Waste Vitrification Plant (HWVP) feed containing the major non-radioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO 3 2- , NO 3 -, and NO 2 - were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO 2 H → H 2 + CO 2 catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100 degree C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO 2 , H 2 , NO, and N 2 O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl 3 ·3H 2 O, was found to be the most active catalyst for hydrogen generation from formic acid above ∼80 degree C in the presence of nitrite ion in accord with earlier observations. The inherent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is suggested by the approximate pseudo first-order dependence of the hydrogen production rate on Rh concentration. Titration of the typical feed simulants containing carbonate and nitrite with formic acid in the presence of rhodium at the reaction temperature (∼90 degree C) indicates that the nitrite-promoted Rh-catalyzed decomposition of formic acid occurs only after formic acid has reacted with all of the carbonate and nitrite present to form CO 2 and NO/N 2 O, respectively. The catalytic activities of Ru and Pd towards hydrogen generation from formic acid are quite different than those of Rh in that they are inhibited rather than promoted by the presence of nitrite ion

  3. Noble metal based plasmonic nanomaterials and their application for bio-imaging and photothermal therapy

    Science.gov (United States)

    Zhu, Dewei

    During the past two decades, researchers have gained more and more insight into the manipulation of nanomaterials to create useful technologies. Numerous classes of nanomaterials have been produced and studied based upon their intriguing chemical and physical properties and their potential applications in diverse fields, ranging from electronics to renewable energy and biomedicine. In this dissertation, we describe the synthesis and potential biomedical applications of several types of noble metal-based nanomaterials in which we control size, shape, and coupling to other materials to tune their localized surface plasmon resonance (LSPR) interaction with light. We demonstrate the application of these novel nanostructures as contrast agents for photoacoustic imaging and as photosensitizers for photothermal therapy. Chapter one first presents protocols for producing monodisperse spherical nanoparticles of gold and silver. The diameter of the nanospheres can be adjusted from less than 2 nm to greater than 10 nm by controlling the reaction conditions, including ligands that cap the nanosphere surfaces, reaction time, and reaction temperature. Next, we describe the synthesis of multi-branched Au nanocrystals with predominantly tripodal, tetrapodal and star-shaped morphologies. We demonstrate tuning of the LSPR energy in these materials by changing the branch length. In the third part of this chapter, we present a novel method for coupling heavily-doped p-type copper selenide (Cu2-xSe) NPs with Au NPs by seeded nanocrystal growth to form a new type of semiconductor-metal heterogeneous nanostructure. This new class of plasmonic nanomaterials can simultaneously exhibit two types of LSPR in a single system, producing a broad optical absorbance that is nearly flat across the near infrared (NIR) spectral region (750-1150nm), along with a small shoulder at 566 nm that originates from the Au NP. We conclude this first chapter by demonstrating the use of self-doped copper sulfide

  4. Catalytic activity of polypyrrole nanotubes decorated with noble-metal nanoparticles and their conversion to carbonized analogues

    Czech Academy of Sciences Publication Activity Database

    Sapurina, Irina; Stejskal, Jaroslav; Šeděnková, Ivana; Trchová, Miroslava; Kovářová, Jana; Hromádková, Jiřina; Kopecká, J.; Cieslar, M.; Abu El-Nasr, A.; Ayad, M. M.

    2016-01-01

    Roč. 214, April (2016), s. 14-22 ISSN 0379-6779 R&D Projects: GA ČR(CZ) GA13-00270S; GA MŠk(CZ) LH14199; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : conducting polymer * polypyrrole nanotubes * noble metals Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.435, year: 2016

  5. Screening metal-organic frameworks for selective noble gas adsorption in air: effect of pore size and framework topology.

    Science.gov (United States)

    Parkes, Marie V; Staiger, Chad L; Perry, John J; Allendorf, Mark D; Greathouse, Jeffery A

    2013-06-21

    The adsorption of noble gases and nitrogen by sixteen metal-organic frameworks (MOFs) was investigated using grand canonical Monte Carlo simulation. The MOFs were chosen to represent a variety of net topologies, pore dimensions, and metal centers. Three commercially available MOFs (HKUST-1, AlMIL-53, and ZIF-8) and PCN-14 were also included for comparison. Experimental adsorption isotherms, obtained from volumetric and gravimetric methods, were used to compare krypton, argon, and nitrogen uptake with the simulation results. Simulated trends in gas adsorption and predicted selectivities among the commercially available MOFs are in good agreement with experiment. In the low pressure regime, the expected trend of increasing adsorption with increasing noble gas polarizabilty is seen. For each noble gas, low pressure adsorption correlates with several MOF properties, including free volume, topology, and metal center. Additionally, a strong correlation exists between the Henry's constant and the isosteric heat of adsorption for all gases and MOFs considered. Finally, we note that the simulated and experimental gas selectivities demonstrated by this small set of MOFs show improved performance compared to similar values reported for zeolites.

  6. Visible light active TiO{sub 2} films prepared by electron beam deposition of noble metals

    Energy Technology Data Exchange (ETDEWEB)

    Hou Xinggang, E-mail: hou226@163.co [Department of Physics, Tianjin Normal University, Tianjin 300387 (China); Ma Jun [Department of Physics, Tianjin Normal University, Tianjin 300387 (China); Liu Andong [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Beijing Normal University, Beijing 100875 (China); Li Dejun; Huang Meidong; Deng Xiangyun [Department of Physics, Tianjin Normal University, Tianjin 300387 (China)

    2010-03-15

    TiO{sub 2} films prepared by sol-gel method were modified by electron beam deposition of noble metals (Pt, Pd, and Ag). Effects of noble metals on the chemical and surface characteristics of the films were studied using XPS, TEM and UV-Vis spectroscopy techniques. Photocatalytic activity of modified TiO{sub 2} films was evaluated by studying the degradation of methyl orange dye solution under visible light UV irradiation. The result of TEM reveals that most of the surface area of TiO{sub 2} is covered by tiny particles of noble metals with diameter less than 1 nm. Broad red shift of UV-Visible absorption band of modified photocatalysts was observed. The catalytic degradation of methyl orange in aqueous solutions under visible light illumination demonstrates a significant enhancement of photocatalytic activity of these films compared with the un-loaded films. The photocatalytic efficiency of modified TiO{sub 2} films by this method is affected by the concentration of impregnating solution.

  7. Noble metal (NM) behavior during simulated HLLW vitrification in induction melter with cold crucible

    International Nuclear Information System (INIS)

    Demin, A.V.; Matyunin, Y.I.; Fedorova, M.I.

    1995-01-01

    The investigation of noble metal (Ru, Rh, Pd) properties in, glass melts are connected with their specific behaviors during HLLW vitrification. Ruthenium, rhodium and palladium volatilities and heterogeneous platinoid phases forming on melts are investigated in reasonable details conformably to Joule's heating ceramic melters. The vitrification conditions in melters with induction heating of melts are differ from the vitrification ones in ceramic melters on some numbers of parameters (the availability of significant temperature gradients and convection flows in melts, short time of molten mass updating in melter and probability of definite interaction between high-frequency field and melt inhomogeneities). The results of simulated HLLW solidification modelling of the vitrification process in induction melter with cold crucible to produce phosphate and boron-silicate materials are presented. The properties of received glasses and behavior of platinoids are shown to have analogies and distinctions in comparison with compounds, synthesized in ceramic melter. The structures of dispersed particles of NM heterogeneous phases forming in glass melts prepared in induction melter with cold crucible are identified. The results of investigations show, that the marked distinctions between two processes can influence (in definite degree) as on property of synthesized materials, as on behavior of platinoid during vitrifications

  8. An Amorphous Noble-Metal-Free Electrocatalyst that Enables Nitrogen Fixation under Ambient Conditions.

    Science.gov (United States)

    Lv, Chade; Yan, Chunshuang; Chen, Gang; Ding, Yu; Sun, Jingxue; Zhou, Yansong; Yu, Guihua

    2018-02-23

    N 2 fixation by the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is regarded as a potential approach to achieve NH 3 production, which still heavily relies on the Haber-Bosch process at the cost of huge energy and massive production of CO 2 . A noble-metal-free Bi 4 V 2 O 11 /CeO 2 hybrid with an amorphous phase (BVC-A) is used as the cathode for electrocatalytic NRR. The amorphous Bi 4 V 2 O 11 contains significant defects, which play a role as active sites. The CeO 2 not only serves as a trigger to induce the amorphous structure, but also establishes band alignment with Bi 4 V 2 O 11 for rapid interfacial charge transfer. Remarkably, BVC-A shows outstanding electrocatalytic NRR performance with high average yield (NH 3 : 23.21 μg h -1  mg -1 cat. , Faradaic efficiency: 10.16 %) under ambient conditions, which is superior to the Bi 4 V 2 O 11 /CeO 2 hybrid with crystalline phase (BVC-C) counterpart. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Study of Thermodynamics of Liquid Noble-Metals Alloys Through a Pseudopotential Theory

    International Nuclear Information System (INIS)

    Vora, Aditya M.

    2010-01-01

    The Gibbs-Bogoliubov (GB) inequality is applied to investigate the thermodynamic properties of some equiatomic noble metal alloys in liquid phase such as Au-Cu, Ag-Cu, and Ag-Au using well recognized pseudopotential formalism. For description of the structure, well known Percus-Yevick (PY) hard sphere model is used as a reference system. By applying a variation method the best hard core diameters have been found which correspond to minimum free energy. With this procedure the thermodynamic properties such as entropy and heat of mixing have been computed. The influence of local field correction function viz; Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F), and Sarkar et al. (S) is also investigated. The computed results of the excess entropy compares favourably in the case of liquid alloys while the agreement with experiment is poor in the case of heats of mixing. This may be due to the sensitivity of the heats of mixing with the potential parameters and the dielectric function. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Ab initio study of the trapping of polonium on noble metals

    Science.gov (United States)

    Rijpstra, Kim; Van Yperen-De Deyne, Andy; Maugeri, Emilio Andrea; Neuhausen, Jörg; Waroquier, Michel; Van Speybroeck, Veronique; Cottenier, Stefaan

    2016-04-01

    In the future MYRRHA reactor, lead bismuth eutectic (LBE) will be used both as coolant and as spallation target. Due to the high neutron flux a small fraction of the bismuth will transmute to radiotoxic 210Po. Part of this radiotoxic element will evaporate into the gas above the coolant. Extracting it from the gas phase is necessary to ensure a safe handling of the reactor. An issue in the development of suitable filters is the lack of accurate knowledge on the chemical interaction between a candidate filter material and either elemental polonium or polonium containing molecules. Experimental work on this topic is complicated by the high radiotoxicity of polonium. Therefore, we present in this paper a first-principles study on the adsorption of polonium on noble metals as filter materials. The adsorption of monoatomic Po is considered on the candidate filter materials palladium, platinum, silver and gold. The case of the gold filter is looked upon in more detail by examining how bismuth pollution affects its capability to capture polonium and by studying the adsorption of the heavy diatomic molecules Po2, PoBi and PoPb on this gold filter.

  11. Ab initio study of the trapping of polonium on noble metals

    Energy Technology Data Exchange (ETDEWEB)

    Rijpstra, Kim; Van Yperen-De Deyne, Andy [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Ghent (Belgium); Maugeri, Emilio Andrea; Neuhausen, Jörg [Laboratory for Radiochemistry, Paul Scherrer Institute (PSI), 5232 Villigen (Switzerland); Waroquier, Michel; Van Speybroeck, Veronique [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Ghent (Belgium); Cottenier, Stefaan, E-mail: stefaan.cottenier@ugent.be [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Ghent (Belgium); Department of Materials Science and Engineering, Ghent University, Technologiepark 903, 9052 Ghent (Belgium)

    2016-04-15

    In the future MYRRHA reactor, lead bismuth eutectic (LBE) will be used both as coolant and as spallation target. Due to the high neutron flux a small fraction of the bismuth will transmute to radiotoxic {sup 210}Po. Part of this radiotoxic element will evaporate into the gas above the coolant. Extracting it from the gas phase is necessary to ensure a safe handling of the reactor. An issue in the development of suitable filters is the lack of accurate knowledge on the chemical interaction between a candidate filter material and either elemental polonium or polonium containing molecules. Experimental work on this topic is complicated by the high radiotoxicity of polonium. Therefore, we present in this paper a first-principles study on the adsorption of polonium on noble metals as filter materials. The adsorption of monoatomic Po is considered on the candidate filter materials palladium, platinum, silver and gold. The case of the gold filter is looked upon in more detail by examining how bismuth pollution affects its capability to capture polonium and by studying the adsorption of the heavy diatomic molecules Po{sub 2}, PoBi and PoPb on this gold filter.

  12. Effect of noble metals on the corrosion of AISI 316L stainless steel in nitric acid

    International Nuclear Information System (INIS)

    Robin, R.; Andreoletti, G.; Fauvet, P.; Terlain, A.

    2004-01-01

    In the spent fuel treatment, the solutions of fission products contain dissolution fines, in particular platinoids. These solutions are stored into AISI 316L stainless steel tanks, and the contact of noble metallic particles such as platinoids with austenitic stainless steels may induce a shift of the steel corrosion potential towards the trans-passive domain by galvanic coupling. In that case, the steel may be polarized up to a potential value above the range of passive domain, that induces an increase of the corrosion current. The galvanic corrosion of AISI 316L stainless steel in contact with different platinoids has been investigated by electrochemical and gravimetric techniques. Two types of tests were conducted in 1 mol/L nitric acid media at 80 deg C: (1) polarization curves and (2) immersion tests with either platinoid powders (Ru, Rh, Pd) or true insoluble dissolution fines (radioactive laboratory test). The results of the study have shown that even if galvanic coupling enhances the corrosion rate by about a factor 10 in these conditions, the corrosion behavior of AISI 316L remains low (a corrosion rate below 6 μm/year, few small intergranular indentations). No specific effect of irradiation and of elements contained in radioactive fines (other than Ru, Rh and Pd) was observed on corrosion behavior. A platinoids-ranking has also been established according to their coupling potential: Ru > Pd > Rh. (authors)

  13. Non-enzymatic electrochemical immunoassay using noble metal nanoparticles: a review

    International Nuclear Information System (INIS)

    Tang, Juan; Tang, Dianping

    2015-01-01

    Electrochemical immunodetection has attracted considerable attention due to its high sensitivity, low cost and simplicity. Large efforts have recently made in order to design ultrasensitive assays. Noble metal nanoparticles (NM-NPs) offer advantages such as high conductivity and large surface-to-volume ratio. NM-NPs therefore are excellent candidates for developing electrochemical platforms for immunodetection and as signal tags. The use of biofunctionalized NM-NPs often results in amplified recognition via stronger loading of signal tags, and also in enhanced signal. This review (with 87 references) gives an overview on the current state in the use of NM-NPs in Non-enzymatic electrochemical immunosensing. We discuss the application of NM-NPs as electrode matrices and as electroactive labels (either as a carrier or as electrocatalytic labels), and compare the materials (mainly nanoparticles of gold, platinum, or of bimetallic materials) in terms of performance (for example by increasing sensitivity via label amplification or via high densities of capture molecules). A conclusion covers current challenges and gives an outlook. Rather than being exhaustive, the review focuses on representative examples that illustrate novel concepts and promising applications. NM-NPs based immunosensing opens a series of concepts for basic research and offers new tools for determination of trace amounts of protein-related analytes in environment and clinical applications. (author)

  14. Structural Stability and Performance of Noble Metal-Free SnO2-Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Antonio Tricoli

    2012-05-01

    Full Text Available The structural stability of pure SnO2 nanoparticles and highly sensitive SnO2-SiO2 nanocomposites (0–15 SiO2 wt% has been investigated for conditions relevant to their utilization as chemoresistive gas sensors. Thermal stabilization by SiO2 co-synthesis has been investigated at up to 600 °C determining regimes of crystal size stability as a function of SiO2-content. For operation up to 400 °C, thermally stable crystal sizes of ca. 24 and 11 nm were identified for SnO2 nanoparticles and 1.4 wt% SnO2-SiO2 nanocomposites, respectively. The effect of crystal growth during operation (TO = 320 °C on the sensor response to ethanol has been reported, revealing possible long-term destabilization mechanisms. In particular, crystal growth and sintering-neck formation were discussed with respect to their potential to change the sensor response and calibration. Furthermore, the effect of SiO2 cosynthesis on the cross-sensitivity to humidity of these noble metal-free SnO2-based gas sensors was assessed.

  15. Recent Advances in the Field of Bionanotechnology: An Insight into Optoelectric Bacteriorhodopsin, Quantum Dots, and Noble Metal Nanoclusters

    Directory of Open Access Journals (Sweden)

    Christopher Knoblauch

    2014-10-01

    Full Text Available Molecular sensors and molecular electronics are a major component of a recent research area known as bionanotechnology, which merges biology with nanotechnology. This new class of biosensors and bioelectronics has been a subject of intense research over the past decade and has found application in a wide variety of fields. The unique characteristics of these biomolecular transduction systems has been utilized in applications ranging from solar cells and single-electron transistors (SETs to fluorescent sensors capable of sensitive and selective detection of a wide variety of targets, both organic and inorganic. This review will discuss three major systems in the area of molecular sensors and electronics and their application in unique technological innovations. Firstly, the synthesis of optoelectric bacteriorhodopsin (bR and its application in the field of molecular sensors and electronics will be discussed. Next, this article will discuss recent advances in the synthesis and application of semiconductor quantum dots (QDs. Finally, this article will conclude with a review of the new and exciting field of noble metal nanoclusters and their application in the creation of a new class of fluorescent sensors.

  16. Characterization of the electrochemical behavior of coating by steel welding 308l and in presence of noble metals deposits; Caracterizacion del comportamiento electroquimico de recubrimiento por soldadura de acero 308L y en presencia de depositos de metales nobles

    Energy Technology Data Exchange (ETDEWEB)

    Piedras, P.; Arganis J, C. R., E-mail: pedro.piedras@hotmail.es [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    In this work the oxide deposits and noble metals deposit were characterized (Ag and Pt) on a coating of stainless steel 308l that were deposited by the shield metal arc welding (SMAW) on steel A36 by means of scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The extrapolation of Tafel technique was also used to obtain the corrosion potential (Ec) for the pre-rusty steel and for the samples with deposits of Pt and Ag under conditions of hydrogen water chemistry (HWC), demonstrating that this parameter diminishes with the presence of this deposits. (Author)

  17. Characterization of the electrochemical behavior of coating by steel welding 308l and in presence of noble metals deposits

    International Nuclear Information System (INIS)

    Piedras, P.; Arganis J, C. R.

    2014-10-01

    In this work the oxide deposits and noble metals deposit were characterized (Ag and Pt) on a coating of stainless steel 308l that were deposited by the shield metal arc welding (SMAW) on steel A36 by means of scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The extrapolation of Tafel technique was also used to obtain the corrosion potential (Ec) for the pre-rusty steel and for the samples with deposits of Pt and Ag under conditions of hydrogen water chemistry (HWC), demonstrating that this parameter diminishes with the presence of this deposits. (Author)

  18. Marginal discrepancy of noble metal-ceramic fixed dental prosthesis frameworks fabricated by conventional and digital technologies.

    Science.gov (United States)

    Afify, Ahmed; Haney, Stephan; Verrett, Ronald; Mansueto, Michael; Cray, James; Johnson, Russell

    2018-02-01

    Studies evaluating the marginal adaptation of available computer-aided design and computer-aided manufacturing (CAD-CAM) noble alloys for metal-ceramic prostheses are lacking. The purpose of this in vitro study was to evaluate the vertical marginal adaptation of cast, milled, and direct metal laser sintered (DMLS) noble metal-ceramic 3-unit fixed partial denture (FDP) frameworks before and after fit adjustments. Two typodont teeth were prepared for metal-ceramic FDP abutments. An acrylic resin pattern of the prepared teeth was fabricated and cast in nickel-chromium (Ni-Cr) alloy. Each specimen group (cast, milled, DMLS) was composed of 12 casts made from 12 impressions (n=12). A single design for the FDP substructure was created on a laboratory scanner and used for designing the specimens in the 3 groups. Each specimen was fitted to its corresponding cast by using up to 5 adjustment cycles, and marginal discrepancies were measured on the master Ni-Cr model before and after laboratory fit adjustments. The milled and DMLS groups had smaller marginal discrepancy measurements than those of the cast group (PDMLS and cast groups (F=30.643, P<.001). Metal-ceramic noble alloy frameworks fabricated by using a CAD-CAM workflow had significantly smaller marginal discrepancies compared with those with a traditional cast workflow, with the milled group demonstrating the best marginal fit among the 3 test groups. Manual refining significantly enhanced the marginal fit of all groups. All 3 groups demonstrated marginal discrepancies within the range of clinical acceptability. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. Wire gauze and cordierite supported noble metal catalysts for passive autocatalytic recombiner

    International Nuclear Information System (INIS)

    Sanap, Kiran K.; Varma, S.; Waghmode, S.B.; Bharadwaj, S.R.

    2015-01-01

    Highlights: • Synthesis by electroless deposition method and chemical reduction route. • Particle size of 0.1–0.5 μm & 3.5–5 nm for Pt–Pd/Wg & Pt–Pd/Cord catalysts. • Active for H_2 and O_2 reaction with initial H_2 concentration of 1.5 to 7% in air. • Active in presence of different contaminants like CO_2, CH_4, CO & relative humidity. • Enhanced resistance of Pt–Pd/Cord catalyst towards the poisoning of CO. - Abstract: Hydrogen released in nuclear reactor containment under severe accident scenario poses a threat to containment and hence needs to be regulated by catalytic recombination. Mixed noble metal catalysts with platinum–palladium supported on stainless steel wire gauze and cordierite support have been developed for this purpose. The developed catalysts have been found to be highly efficient for removal of hydrogen concentration in the range of 1.5 to 7.0% v/v in air. Though both the catalysts exhibit similar kinetics for lower hydrogen concentration, cordierite supported catalysts exhibits better kinetic rate at higher hydrogen concentration. The performances of these catalysts in presence of various probable catalytic poison like carbon monoxide and catalytic inhibitors like moisture, carbon dioxide, and hydrocarbons provide data for use of these catalysts under the actual scenario. Compared to stainless steel wire gauze supported catalyst, the cordierite based catalyst are found to exhibit enhanced resistance towards carbon monoxide and limited temperature rise for safer application at higher hydrogen concentrations.

  20. Mitigation of hydrogen by oxidation using nitrous oxide and noble metal catalysts

    International Nuclear Information System (INIS)

    Britton, M.D.

    1995-01-01

    This test studied the ability of a blend of nuclear-grade, noble-metal catalysts to catalyze a hydrogen/nitrous oxide reaction in an effort to mitigate a potential hydrogen (H 2 ) gas buildup in the Hanford Site Grout Disposal Facility. For gases having H 2 and a stoichiometric excess of either nitrous oxide or oxygen, the catalyst blend can effectively catalyze the H 2 oxidation reaction at a rate exceeding 380 μmoles of H 2 per hour per gram of catalyst (μmol/h/g) and leave the gas with less than a 0.15 residual H 2 Concentration. This holds true in gases with up to 2.25% water vapor and 0.1% methane. This should also hold true for gases with up to 0.1% carbon monoxide (CO) but only until the catalyst is exposed to enough CO to block the catalytic sites and stop the reaction. Gases with ammonia up to 1% may be slightly inhibited but can have reaction rates greater than 250 μmol/h/g with less than a 0.20% residual H 2 concentration. The mechanism for CO poisoning of the catalyst is the chemisorption of CO to the active catalyst sites. The CO sorption capacity (SC) of the catalyst is the total amount of CO that the catalyst will chemisorb. The average SC for virgin catalyst was determined to be 19.3 ± 2.0 μmoles of CO chemisorbed to each gram of catalyst (μmol/g). The average SC for catalyst regenerated with air was 17.3 ± 1.9 μmol/g

  1. A simple alkali-metal and noble gas ion source for SIMS equipments with mass separation of the primary ions

    International Nuclear Information System (INIS)

    Duesterhoeft, H.; Pippig, R.

    1986-01-01

    An alkali-metal ion source working without a store of alkali-metals is described. The alkali-metal ions are produced by evaporation of alkali salts and ionization in a low-voltage arc discharge stabilized with a noble gas plasma or in the case of small alkali-metal ion currents on the base of the well known thermic ionization at a hot tungsten wire. The source is very simple in construction and produces a stable ion current of 0.3 μA for more than 100 h. It is possible to change the ion species in a short time. This source is applicable to all SIMS equipments using mass separation for primary ions. (author)

  2. Synergistic effects of semiconductor substrate and noble metal nano-particles on SERS effect both theoretical and experimental aspects

    Science.gov (United States)

    Yang, Chen; Liang, Pei; Tang, Lisha; Zhou, Yongfeng; Cao, Yanting; Wu, Yanxiong; Zhang, De; Dong, Qianmin; Huang, Jie; He, Peng

    2018-04-01

    As a means of chemical identification and analysis, Surface enhanced Raman spectroscopy (SERS), with the advantages of high sensitivity and selectivity, non-destructive, high repeatability and in situ detection etc., has important significance in the field of composition detection, environmental science, biological medicine etc. Physical model of coupling effect between different semiconductor substrates and noble metal particles were investigated by using 3D-FDTD method. Mechanism and the effects of excitation wavelength, particle spacing and semiconductor substrate types on the SERS effect were discussed. The results showed that the optimal excitation wavelengths of three noble metals of Ag, Au, Cu, were located at 510, 600 and 630 nm, respectively; SERS effect of Ag, Au, Cu increases with the decreasing of the inter distance of particles, while the distance of the NPs reaches the critical value of 3 nm, the strength of SERS effect will be greatly enhanced. For the four different types of substrate of Ge, Si, SiO2 (glass) and Al2O3, the SERS effect of Ag on SiO2 > Ge > Al2O3 > Si. For Au and Cu nanoparticles, the SERS effect of them on oxide substrate is stronger than that on non-oxide substrate. In order to verify FDTD simulations, taking silver nanoparticles as an example, and silver nanoparticles prepared by chemical method were spinning coating on the four different substrates with R6G as probe molecules. The results show that the experimental results are consistent with FDTD theoretical simulations, and the SERS enhancement effect of Ag-SiO2 substrate is best. The results of this study have important theoretical significance to explain the variations of SERS enhancement on different noble metals, which is also an important guide for the preparation of SERS substrates, especially for the microfluidics. The better Raman effect can be realized by choosing proper substrate type, particle spacing and excitation wavelength, result in expanding the depth and width

  3. Experimental and computational approaches to evaluate the environmental mitigation effect in narrow spaces by noble metal chemical addition (NMCA)

    International Nuclear Information System (INIS)

    Shimizu, Ryosuke; Ota, Nobuyuki; Nagase, Makoto; Aizawa, Motohiro; Ishida, Kazushige; Wada, Yoichi

    2014-01-01

    The environmental mitigation effect of NMCA in a narrow space was evaluated by experimental and computational approaches. In the experiment at 8 MPa and 553K, T-tube whose branched line had a narrow space was prepared, and the Zr electrodes were set in the branched line at certain intervals, which were 1, 3, 5, 7, 9, 11, 15 and 29 cm from the opening section of the branched line. Electrochemical corrosion potential (ECP) at the tip of the branched narrow space varied in response to the water chemistry in the main line which was at right angle with the branched line. Computational fluid dynamics (CFD) analysis reproduced the experimental results. It was also confirmed by CFD analysis that the ingress of water from the main line into the narrow space was accelerated by cavity flow and thermal convection. By CFD analysis in a thermal sleeve of actual plant condition, which had a narrow space, the concentration of dissolved oxygen at a tip of the thermal sleeve reached at 250 ppb within 300 sec, which was the same concentration of the main line. Noble metal deposition on the surface of the thermal sleeve was evaluated by mass transfer model. Noble metal deposition was the largest near the opening section of the branched line, and gradually decreased toward the tip section. In light of the consumption of dissolved oxygen in the branched line, noble metal deposition in the thermal sleeve was sufficient to reduce the ECP. It was expected that NMCA could mitigate the corrosion environment in the thermal sleeve. (author)

  4. Performance evaluation of a biodiesel fuelled transportation engine retrofitted with a non-noble metal catalysed diesel oxidation catalyst for controlling unregulated emissions.

    Science.gov (United States)

    Shukla, Pravesh Chandra; Gupta, Tarun; Agarwal, Avinash Kumar

    2018-02-15

    In present study, engine exhaust was sampled for measurement and analysis of unregulated emissions from a four cylinder transportation diesel engine using a state-of-the-art FTIR (Fourier transform infrared spectroscopy) emission analyzer. Test fuels used were Karanja biodiesel blend (B20) and baseline mineral diesel. Real-time emission measurements were performed for raw exhaust as well as exhaust sampled downstream of the two in-house prepared non-noble metal based diesel oxidation catalysts (DOCs) and a baseline commercial DOC based on noble metals. Two prepared non-noble metal based DOCs were based on Co-Ce mixed oxide and Lanthanum based perovskite catalysts. Perovskite based DOC performed superior compared to Co-Ce mixed oxide catalyst based DOC. Commercial noble metal based DOC was found to be the most effective in reducing unregulated hydrocarbon emissions in the engine exhaust, followed by the two in-house prepared non-noble metal based DOCs. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Neutron activation determination of noble metals in samples of terrestrial and cosmic origin using microfire assay concentration

    International Nuclear Information System (INIS)

    Kolesov, G.M.; Sapozhnikov, D.Yu.

    1995-01-01

    The effects of various factors (composition of mixture, relationship between the mass of mixture and sample, value of the Ni:S ratio, fusion time, and temperature) on the conditions of the fire assay concentration of the noble metals with nickel sulfide were investigated, and a method proposed for their quantitative separation from different geological matrices with a neutron activation determination for up to 10 -1 -10 -3 ppb. The proposed method is used to analyse geological samples, i.e. ores, stones, iron meteorites, chromites, soil and lunar rocks. (author)

  6. The role of fission products (noble metal particles) in spent fuel corrosion process in a failed container

    Energy Technology Data Exchange (ETDEWEB)

    Wu, L., E-mail: lwu59@uwo.ca [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada); Shoesmith, D.W. [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada); Univ. of Western Ontario, Surface Science Western, London, Ontario (Canada)

    2013-07-01

    The corrosion/dissolution of simulated spent fuel has been studied electrochemically. Fission products within the UO{sub 2} matrix are found to have significant effect on the anodic dissolution behaviour of the fuel. It is observed that H{sub 2}O{sub 2}oxidation is accelerated on the surfaces of doped noble metal (ε) particles existing in the fuel matrix. It is concluded that H{sub 2}O{sub 2} decomposition rather than UO{sub 2} corrosion should be the dominant reaction under high H{sub 2}O{sub 2} concentrations. (author)

  7. Reaction pathways of biomass-derived oxygenates on noble metal surfaces

    Science.gov (United States)

    McManus, Jesse R.

    As the global demand for energy continues to rise, the environmental concerns associated with increased fossil fuel consumption have motivated the use of biomass as an alternative, carbon-renewable energy feedstock. Controlling reactive chemistry of the sugars that comprise biomass through the use of catalysis becomes essential in effectively producing green fuels and value-added chemicals. Recent work on biomass conversion catalysts have demonstrated the efficacy of noble metal catalyst systems for the reforming of biomass to hydrogen fuel, and the hydrodeoxygenation of biomass-derived compounds to value-added chemicals. In particular, Pt and Pd surfaces have shown considerable promise as reforming catalysts in preliminary aqueous phase reforming studies. It becomes important to understand the mechanisms by which these molecules react on the catalyst surfaces in order to determine structure-activity relationships and bond scission energetics as to provide a framework for engineering more active and selective catalysts. Fundamental surface science techniques provide the tools to do this; however, work in this field has been so far limited to simple model molecules like ethanol and ethylene glycol. Herein, temperature programmed desorption and high resolution electron energy loss spectroscopy are utilized in an ultra-high vacuum surface science study of the biomass-derived sugar glucose on Pt and Pd single crystal catalysts. Overall, it was determined that the aldehyde function of a ring-open glucose molecule plays an integral part in the initial bonding and reforming reaction pathway, pointing to the use of aldoses glycolaldehyde and glyceraldehyde as the most appropriate model compounds for future studies. Furthermore, the addition of adatom Zn to a Pt(111) surface was found to significantly decrease the C-H and C-C bond scission activity in aldehyde containing compounds, resulting in a preferred deoxygenation pathway in opposition to the decarbonylation pathway

  8. Potential Energy Curves and Associated Line Shape of Alkali-Metal and Noble-Gas Interactions

    Science.gov (United States)

    2014-10-20

    work. The ab initio calculations for M + Ng molecular combina- tions are reported and discussed in Chapter 3. Chapter 4 discusses both pedagogical ...mass of the noble-gas atom decreases. These barriers at R = rb are accompanied by shallow wells at R = rmin2 and, together with the shallow wells

  9. Expeditious synthesis of noble metal nanoparticles using Vitamin B12 under microwave irradiation

    Science.gov (United States)

    A greener synthesis protocol for noble nanometals is developed using vitamin B12 as a reducing and capping agent in conjunction with the use of microwaves. Successful assembly of nanoparticles or microparticles with varied shapes and sizes have been demonstrated. The synthesized ...

  10. Scattering of low energy noble gas ions from a metal surface

    International Nuclear Information System (INIS)

    Luitjens, S.B.

    1980-01-01

    Reflection of low energy (0.1-10 keV) noble gas ions can be used to analyse a solid surface. To study charge exchange processes, the ion fractions of neon and of argon, scattered from a Cu(100) surface, have been determined. (Auth.)

  11. Analysis of functional organic molecules at noble metal surfaces by means of vibrational spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Leyssner, Felix

    2011-10-24

    The goal of this work is to optimize the efficiency of photoinduced molecular switching processes on surfaces via controlled variations of the adsorption and electronic properties of the switch. We investigated the influence of external stimuli, i.e. photons and thermal activation, on surface bound molecular switches undergoing trans/cis-isomerizations and ring-opening/closing-reactions, respectively. High resolution electron energy loss spectroscopy (HREELS) and sum-frequency generation (SFG) spectroscopy have been used as the main tools to investigate the adsorption behavior and the molecular switching properties. Two basic concepts of coupling the molecular switch to the surface have been studied: (i) physisorbed or weakly chemisorbed systems deposited on noble metal surfaces under UHV conditions and (ii) molecular switches bound covalently via anchor groups. In the HREELS study following concept (i), we investigated the adsorption geometry and isomerization behavior of various molecular switches on metal substrates which are able to undergo a photoinduced trans/cis-isomerization in solution. We investigated three isoelectronic molecules on Au where we systematically changed the photochemically active group from the diazo-group in an azobenzene-derivative (on Cu(111)) to the imine-group, and the vinylene-group, respectively. Finding the photoisomerization quenched for all systems we observed considerable differences in their thermal isomerization behavior. Comparable we find the photoinduced ring-opening/closing-reaction of spiropyran quenched on Au(111) but a thermally induced ring-opening reaction resulting in the open form being strongly stabilized by the metal. SFG spectroscopy is employed to investigate the reversible, photoinduced trans/cis-isomerization of an azobenzene-functionalized self-assembled monolayer (SAM) on gold using a tripodal linker system. In consequence of the decoupling provided by the tripodal linker, the switching behavior of the

  12. [Studies on high temperature oxidation of noble metal alloys for dental use. (III) On high temperature oxidation resistance of noble metal alloys by adding small amounts of alloying elements. (author's transl)].

    Science.gov (United States)

    Ohno, H

    1976-11-01

    The previous report pointed out the undesirable effects of high temperature oxidation on the casting. The influence of small separate additions of Zn, Mg, Si, Be and Al on the high temperature oxidation of the noble metal alloys was examined. These alloying elements were chosen because their oxide have a high electrical resistivity and they have much higher affinity for oxygen than Cu. The casting were oxidized at 700 degrees C for 1 hour in air. The results obtained were as follows: 1. The Cu oxides are not observed on the as-cast surface of noble metal alloys containing small amounts of Zn, Mg, Si, Be, and Al. The castings have gold- or silver-colored surface. 2. After heating of the unpolished and polished castings, the additions of Si, Be and Al are effective in preventing oxidation of Cu in the 18 carats gold alloys. Especially the golden surface is obtained by adding Be and Al. But there is no oxidation-resistance on the polished castings in the alloys containing Zn and Mg. 3. The zinc oxide film formed on the as-cast specimen is effective in preventing of oxidation Cu in 18 carats gold alloys. 4. It seems that the addition of Al is most available in dental application.

  13. Control of radiation fields in BWRs after noble metal chemical addition

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, R.L.; Wood, C.J. [EPRI, Palo Alto, CA (United States)

    2002-07-01

    Hydrogen water chemistry (HWC) was developed to mitigate the intergranular stress corrosion cracking (IGSCC) that can occur in the welded piping and internal components of boiling water reactors (BWRs). HWC is practiced by adding hydrogen gas to the feedwater to reduce the electrochemical corrosion potential (ECP) of the component to be protected to below -0.230 V(SHE). Unfortunately, only a few BWR owners implemented HWC for internals component IGSCC protection because of the factor of 4 to 5 increase in operating dose rates that accompanies its use. Noble metal chemical addition (NMCA) was developed to address this shortcoming. NMCA is a process in which Pt and Rh chemicals are added to a shutdown Boiling Water Reactor while the reactor water temperature is maintained in the range of 120 C to 150 C for 48 hours. During that time, a target concentration of Pt and Rh is maintained in the reactor water. At the end of the 48 hour period the plant then either goes back to power or enters into a refueling outage. The end result of the NMCA process is a uniform deposit of Pt and Rh metal at very low concentrations, on the order of 0.5 to 1.0 mg/cm{sup 2}, on the reactor wetted surfaces. During subsequent operation, when a small amount of hydrogen is added to the feedwater (less than 0.4 ppm), very low ECPs will be developed on the wetted catalytic surfaces, on the order of -0.500 V(SHE), and intergranular stress corrosion cracking (IGSCC) of components will be mitigated. Since NMCA with hydrogen changes the surface chemistry and not the bulk chemistry, there is little or no increase in operating dose rate. See References 1 through 5 for a more complete discussion of HWC and NMCA fundamentals. To date, 26 BWRs worldwide have applied NMCA. As operating plants have completed their first full operating cycle after NMCA application, it has become apparent that NMCA can have a significant impact on shutdown dose rates, as can be seen in Table 1. (The shut down dose rates

  14. Noble metal-free RGO/TiO2 composite nanofiber with enhanced photocatalytic H2-production performance

    Science.gov (United States)

    Xu, Difa; Li, Lingling; He, Rongan; Qi, Lifang; Zhang, Liuyang; Cheng, Bei

    2018-03-01

    1D reduced graphene oxide (RGO)/TiO2 nanocomposite fibers were fabricated by a facile two-step method. These samples demonstrated high photocatalytic H2-production activity from methanol aqueous solution, even without the aid of noble metal. When the ratio of RGO is 0.25 wt%, the highest H2-production rate was achieved. It increased by 10 fold than bare TiO2, reaching 149 μmol h-1 g-1 with quantum efficiency (QE) of 0.75%. The reasons were as follows. Firstly, the RGO nanosheets acted as electron acceptors. Secondly, some shallow trap states at the surface or interface of TiO2 were created by the reduction of GO during calcination. Thirdly, the redox potential position of graphene/graphene- was suitable. Fourthly, RGO could efficiently promote the separation of photogenerated electron-hole pairs and significantly enhance the photocatalytic H2-production activity. This interpretation was corroborated by transient photocurrent response. The aforementioned marvelous results provided a probable solution to replace noble metals (such as Pt) by graphene as an effective cocatalyst.

  15. Crystal phase-based epitaxial growth of hybrid noble metal nanostructures on 4H/fcc Au nanowires

    Science.gov (United States)

    Lu, Qipeng; Wang, An-Liang; Gong, Yue; Hao, Wei; Cheng, Hongfei; Chen, Junze; Li, Bing; Yang, Nailiang; Niu, Wenxin; Wang, Jie; Yu, Yifu; Zhang, Xiao; Chen, Ye; Fan, Zhanxi; Wu, Xue-Jun; Chen, Jinping; Luo, Jun; Li, Shuzhou; Gu, Lin; Zhang, Hua

    2018-03-01

    Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au-Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.

  16. Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles

    Directory of Open Access Journals (Sweden)

    Rudolf Herrmann

    2014-12-01

    Full Text Available The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core–shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4–260 ± 40 nm diameter can be prepared and decorated with noble metal nanoparticles (2–5 nm diameter. Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation.

  17. Tailoring of the PS surface with low energy ions: Relevance to growth and adhesion of noble metals

    International Nuclear Information System (INIS)

    Zaporojtchenko, V.; Zekonyte, J.; Wille, S.; Schuermann, U.; Faupel, F.

    2005-01-01

    Ion-polymer interaction induces different phenomena in the near surface layer of polymers, and promotes its adhesion to metals. Using XPS, TEM and AFM, polystyrene surface was examined after 1 keV ion-beam treatments with oxygen, nitrogen and argon ions in the ion fluence range from 10 12 to 10 16 cm -2 to clarify the following points: chemical reaction after treatment in vacuum and after exposure to air, identification of adsorption-relevant species for metal atoms, formation of cross-links in the outermost polymer layer. The early stages of metal-polymer interface formation during metallization play a crucial role in the metal-polymer adhesion. Therefore, the influence of the ion fluence and ion chemistry on the condensation of noble metals, film growth and peel strength were measured. The peel strength showed a maximum at a certain fluence depending on ion chemistry. For example, the surface treatment with very low fluence of oxygen ions improved the adhesion between copper and polystyrene by two orders of magnitude without significantly increasing the surface roughness measured with AFM. The locus of failure changed at the same time from interfacial failure for untreated polymer surfaces to cohesive failure in the polymer for modified surfaces. A multilayer model of the metal-polymer interface after ion treatment is suggested

  18. Photoemission studies of zinc-noble metal alloys: Zn--Cu, Zn--Ag, and Zn--Au films on Ru(001)

    International Nuclear Information System (INIS)

    Rodriguez, J.A.; Hrbek, J.

    1993-01-01

    Zn and the noble metals alloy when coadsorbed on Ru(001). The properties of Zn--Cu, Zn--Ag, and Zn--Au alloys have been studied using core- and valence-level photoemission and temperature programmed desorption. Alloy formation induces only small shifts (-0.2 to -0.3 eV) in the position of the Zn 2p, 3s, and 3d levels. In contrast, the core and valence levels of the noble metals show large shifts toward higher binding energy. For small amounts of Cu, Ag, and Au dissolved in Zn multilayers, the shifts in the core levels of the nobel metals follow the sequence: Cu(2p 3/2 ), 0.8 eV∼Ag(3d 5/2 ), 0.8 eV 7/2 ), 1.4 eV. The magnitude of the shift increases as the Pauling electronegativity of the noble metal increases. However, the sign of the shifts for the Cu(2p 3/2 ), Ag(3d 5/2 ), or Au(4f 7/2 ) levels is not directly determined by the direction of charge transfer within the corresponding Zn-noble metal bond

  19. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    International Nuclear Information System (INIS)

    Li Siheng; Wang Enbo; Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying

    2008-01-01

    In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag(MFe 2 O 4 ) (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag(C) microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe 3+ and M 2+ on the surface of the Ag(C) spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core. - Graphical abstract: MFe 2 O 4 (M=Ni, Co, Mg, Zn) hollow spheres with a noble metal nanoparticle core were successfully prepared by using colloidal metal(C) core-shell spheres as templates with no need of surface modification. The shell thickness and magnetic properties of the ferrite hollow spheres could be controlled by varying the synthetic parameters

  20. Synthesis of metal-metal oxide catalysts and electrocatalysts using a metal cation adsorption/reduction and adatom replacement by more noble ones

    Science.gov (United States)

    Adzic, Radoslav; Vukmirovic, Miomir; Sasaki, Kotaro

    2010-04-27

    The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen. The invention also relates to methods of making the metal-metal oxide composites.

  1. Surface Functionalization of g-C 3 N 4 : Molecular-Level Design of Noble-Metal-Free Hydrogen Evolution Photocatalysts

    KAUST Repository

    Chen, Yin; Lin, Bin; Yu, Weili; Yang, Yong; Bashir, Shahid M.; Wang, Hong; Takanabe, Kazuhiro; Idriss, Hicham; Basset, Jean-Marie

    2015-01-01

    A stable noble-metal-free hydrogen evolution photocatalyst based on graphite carbon nitride (g-C3N4) was developed by a molecular-level design strategy. Surface functionalization was successfully conducted to introduce a single nickel active site

  2. Evaluation of HWVP feed preparation chemistry for an NCAW simulant -- Fiscal year 1993: Effect of noble metals concentration on offgas generation and ammonia formation

    International Nuclear Information System (INIS)

    Patello, G.K.; Wiemers, K.D.; Bell, R.D.; Smith, H.D.; Williford, R.E.; Clemmer, R.G.

    1995-03-01

    The High-Level Waste Vitrification Program is developing technology for the Department of Energy to immobilize high-level and transuranic wastes as glass for permanent disposal. Pacific Northwest Laboratory (PNL) is conducting laboratory-scale melter feed preparation studies using a HWVP simulated waste slurry, Neutralized Current Acid Waste (NCAW). A FY 1993 laboratory-scale study focused on the effects of noble metals (Pd, Rh, and Ru) on feed preparation offgas generation and NH 3 production. The noble metals catalyze H 2 and NH 3 production, which leads to safety concerns. The information gained from this study is intended to be used for technology development in pilot scale testing and design of the Hanford High-Level Waste Vitrification Facility. Six laboratory-scale feed preparation tests were performed as part of the FY 1993 testing activities using nonradioactive NCAW simulant. Tests were performed with 10%, 25%, 50% of nominal noble metals content. Also tested were 25% of the nominal Rh and a repeat of 25% nominal noble metals. The results of the test activities are described. 6 refs., 28 figs., 12 tabs

  3. Evaluation of HWVP feed preparation chemistry for an NCAW simulant -- Fiscal year 1993: Effect of noble metals concentration on offgas generation and ammonia formation

    Energy Technology Data Exchange (ETDEWEB)

    Patello, G.K.; Wiemers, K.D.; Bell, R.D.; Smith, H.D.; Williford, R.E.; Clemmer, R.G.

    1995-03-01

    The High-Level Waste Vitrification Program is developing technology for the Department of Energy to immobilize high-level and transuranic wastes as glass for permanent disposal. Pacific Northwest Laboratory (PNL) is conducting laboratory-scale melter feed preparation studies using a HWVP simulated waste slurry, Neutralized Current Acid Waste (NCAW). A FY 1993 laboratory-scale study focused on the effects of noble metals (Pd, Rh, and Ru) on feed preparation offgas generation and NH{sub 3} production. The noble metals catalyze H{sub 2} and NH{sub 3} production, which leads to safety concerns. The information gained from this study is intended to be used for technology development in pilot scale testing and design of the Hanford High-Level Waste Vitrification Facility. Six laboratory-scale feed preparation tests were performed as part of the FY 1993 testing activities using nonradioactive NCAW simulant. Tests were performed with 10%, 25%, 50% of nominal noble metals content. Also tested were 25% of the nominal Rh and a repeat of 25% nominal noble metals. The results of the test activities are described. 6 refs., 28 figs., 12 tabs.

  4. A first-principles study on the interaction of biogas with noble metal (Rh, Pt, Pd) decorated nitrogen doped graphene as a gas sensor: A DFT study

    Science.gov (United States)

    Zhao, Chunjiang; Wu, Huarui

    2018-03-01

    Density functional theory calculations are carried out to investigate the adsorption characteristics of methane (CH4), carbon dioxide (CO2), hydrogen (H2), hydrogen sulfide (H2S), nitrogen (N2), and oxygen (O2) on the surface of pyridine-like nitrogen doped graphene (PNG) as well as noble metal (Rh, Pt, Pd) decorated PNG to elaborate their potentials as gas sensors. The adsorption intensities of biogas on noble metal (Rh, Pt, Pd) decorated PNG are in the order of O2> H2S> N2> CH4> CO2> H2, which are corresponded to the order of their sensitivity on surface. Compared with biogas adsorption on pristine PNG, there exist higher adsorption ability, higher charge transfer and higher orbital hybridization upon adsorption on noble metal (Rh, Pt, Pd) decorated PNG. Consequently, the noble metal (Rh, Pt, Pd) decorated PNG can transform the existence of CH4, CO2, H2, H2S, N2, and O2 molecules into electrical signal and they could potentially be used as ideal sensors for detection of biogas in ambient situation.

  5. The effect of dielectric constants on noble metal/semiconductor SERS enhancement: FDTD simulation and experiment validation of Ag/Ge and Ag/Si substrates.

    Science.gov (United States)

    Wang, Tao; Zhang, Zhaoshun; Liao, Fan; Cai, Qian; Li, Yanqing; Lee, Shuit-Tong; Shao, Mingwang

    2014-02-11

    The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 10(9)) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 10(7) and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones.

  6. Radiological analysis by the addition of hydrogen and noble metals in the reactors of the Laguna Verde central

    International Nuclear Information System (INIS)

    Padilla C, I.

    2006-01-01

    During the operation of the nuclear power stations there are metals that are subject to condition and agents that cause that these they present indications of intergranular corrosion and for their importance they are subject to a continuous surveillance to assure their integrity. During the time of operation, for the level of indications, it can be necessary the substitution of these. The internal components of the vessel and particularly those of the structure of the reactor core are exposed during the operation to a neutron flow that causes that these they are activated and, in consequence, before an eventual repair it will be necessary to face high radiation levels. At the moment a technique that controls exists and it reduces the growth rate of the indications in the metals and it increases its useful life: the addition of hydrogen. The addition of hydrogen it is an ALARA measure from long term when protecting the internals of the vessel that requires to establish radiological controls in the stage of their application to avoid unnecessary dose to the personnel. The addition of hydrogen to the primary system has as objective to reduce the growth of indications taken place by intergranular corrosion in metals of the reactor core and this is achieved when the electrochemical thresholds are reached. Hydrogen to interacting with the metal surfaces it generates reductive reactions causing in consequence an increment in the concentration of soluble cobalt in the coolant one and an increment in the nitrogen concentration. To reduce the magnitude of the radiological impact that in some NC reach up to factors 10, its are injected to the system noble metals as the rhodium and the platinum, to reduce the concentration of hydrogen to the system and to be below the threshold electrochemical potential necessary to protect the internals of the reactor vessel. The external and internal operational experience generated on this protection technique to the internals of the vessel

  7. Noble metal catalyzed aqueous phase hydrogenation and hydrodeoxygenation of lignin-derived pyrolysis oil and related model compounds.

    Science.gov (United States)

    Mu, Wei; Ben, Haoxi; Du, Xiaotang; Zhang, Xiaodan; Hu, Fan; Liu, Wei; Ragauskas, Arthur J; Deng, Yulin

    2014-12-01

    Aqueous phase hydrodeoxygenation of lignin pyrolysis oil and related model compounds were investigated using four noble metals supported on activated carbon. The hydrodeoxygenation of guaiacol has three major reaction pathways and the demethylation reaction, mainly catalyzed by Pd, Pt and Rh, produces catechol as the products. The presence of catechol and guaiacol in the reaction is responsible for the coke formation and the catalysts deactivation. As expected, there was a significant decrease in the specific surface area of Pd, Pt and Rh catalysts during the catalytic reaction because of the coke deposition. In contrast, no catechol was produced from guaiacol when Ru was used so a completely hydrogenation was accomplished. The lignin pyrolysis oil upgrading with Pt and Ru catalysts further validated the reaction mechanism deduced from model compounds. Fully hydrogenated bio-oil was produced with Ru catalyst. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Non-noble metal Cu-loaded TiO2 for enhanced photocatalytic H2 production.

    Science.gov (United States)

    Foo, Wei Jian; Zhang, Chun; Ho, Ghim Wei

    2013-01-21

    Here we have demonstrated the preparation of high-quality, monodispersed and tunable phases of Cu nanoparticles. Structural and chemical composition studies depict the evolution of Cu-Cu(2)O-CuO nanoparticles at various process stages. The loading of Cu and Cu oxide nanoparticles on TiO(2) catalyst has enhanced the photocatalytic H(2) production. Comparatively, H(2) treatment produces well-dispersed Cu nanoparticles with thin oxide shells that show the highest H(2) production amongst the samples. The relatively higher photocatalytic performance is deemed to result from reduced structural defects, higher surface area and dispersivity as well as favorable charge transfer, which inhibits recombination. The Cu nanoparticles are shown to be a promising alternative to noble metal-loaded TiO(2) catalyst systems due to their low cost and high performance in photocatalytic applications.

  9. Tantalum oxide-based compounds as new non-noble cathodes for polymer electrolyte fuel cell

    International Nuclear Information System (INIS)

    Ishihara, Akimitsu; Tamura, Motoko; Matsuzawa, Koichi; Mitsushima, Shigenori; Ota, Ken-ichiro

    2010-01-01

    Tantalum oxide-based compounds were examined as new non-noble cathodes for polymer electrolyte fuel cell. Tantalum carbonitride powder was partially oxidized under a trace amount of oxygen gas at 900 o C for 4 or 8 h. Onset potential for oxygen reduction reaction (ORR) of the specimen heat-treated for 8 h was 0.94 V vs. reversible hydrogen electrode in 0.1 mol dm -3 sulfuric acid at 30 o C. The partial oxidation of tantalum carboniride was effective to enhance the catalytic activity for the ORR. The partially oxidized specimen with highest catalytic activity had ca. 5.25 eV of ionization potential, indicating that there was most suitable strength of the interaction of oxygen and tantalum on the catalyst surface.

  10. Substrate-Based Noble-Metal Nanomaterials: Shape Engineering and Applications

    Science.gov (United States)

    Hajfathalian, Maryam

    Nanostructures have potential for use in state-of-the-art applications such as sensing, imaging, therapeutics, drug delivery, and electronics. The ability to fabricate and engineer these nanoscale materials is essential for the continued development of such devices. Because the morphological features of nanomaterials play a key role in determining chemical and physical properties, there is great interest in developing and improving methods capable of controlling their size, shape, and composition. While noble nanoparticles have opened the door to promising applications in fields such as imaging, cancer targeting, photothermal treatment, drug delivery, catalysis and sensing, the synthetic processes required to form these nanoparticles on surfaces are not well-developed. Herein is a detailed account on efforts for adapting established solution-based seed-mediated synthetic protocols to structure in a substrate-based platform. These syntheses start by (i) defining heteroepitaxially oriented nanostructured seeds at site-specific locations using lithographic or directed-assembly techniques, and then (ii) transforming the seeds using either a solution or vapor phase processing route to activate kinetically- or thermodynamically-driven growth modes, to arrive at nanocrystals with complex and useful geometries. The first series of investigations highlight synthesis-routes based on heterogeneous nucleation, where templates serve as nucleation sites for metal atoms arriving in the vapor phase. In the first research direction, the vapor-phase heterogeneous nucleation of Ag on Au was carried out at high temperatures, where the Ag vapor was sourced from a sublimating foil onto adjacent Au templates. This process transformed both the composition and morphology of the initial Au Wulff-shaped nanocrystals to a homogeneous AuAg nanoprism. In the second case, the vapor-phase heterogeneous nucleation of Cu atoms on Au nanocrystal templates was investigated by placing a Cu foil next

  11. Phenomenological understanding of dewetting and embedding of noble metal nanoparticles in thin films induced by ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Jai, E-mail: jai.gupta1983@gmail.com [Department of Chemistry, MMH College (Ch. Charan Singh University Meerut), Ghaiziabad 201001 (India); Chemical Physics of Materials, Université Libre de Bruxelles, Campus de la Plaine, CP 243, B-1050 Bruxelles (Belgium); Tripathi, A. [Inter University Accelerator Centre, Aruna Asif Ali Marg, New Delhi 110067 (India); Gautam, Sanjeev; Chae, K.H.; Song, Jonghan [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136–791 (Korea, Republic of); Rigato, V. [INFN Laboratori Nazionali di Legnaro, Via Romea. 4, 35020 Legnaro, Padova (Italy); Tripathi, Jalaj [Department of Chemistry, MMH College (Ch. Charan Singh University Meerut), Ghaiziabad 201001 (India); Asokan, K. [Inter University Accelerator Centre, Aruna Asif Ali Marg, New Delhi 110067 (India)

    2014-10-15

    The present experimental work provides the phenomenological approach to understand the dewetting in thin noble metal films with subsequent formation of nanoparticles (NPs) and embedding of NPs induced by ion irradiation. Au/polyethyleneterepthlate (PET) bilayers were irradiated with 150 keV Ar ions at varying fluences and were studied using scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (X-TEM). Thin Au film begins to dewet from the substrate after irradiation and subsequent irradiation results in spherical nanoparticles on the surface that at a fluence of 5 × 10{sup 16} ions/cm{sup 2} become embedded into the substrate. In addition to dewetting in thin films, synthesis and embedding of metal NPs by ion irradiation, the present article explores fundamental thermodynamic principles that govern these events systematically under the effect of irradiation. The results are explained on the basis of ion induced sputtering, thermal spike inducing local melting and of thermodynamic driving forces by minimization of the system free energy where contributions of surface and interfacial energies are considered with subsequent ion induced viscous flow in substrate. - Highlights: • Phenomenological interpretation of dewetting and embedding of metal NPs in thin film. • Exploring fundamental thermodynamic principles under influence of ion irradiation. • Ion induced surface/interface microstructural changes using SEM/X-TEM. • Ion induced sputtering, thermal spike induced local melting. • Thermodynamic driving forces relate to surface and interfacial energies.

  12. Applications of UV/Vis Spectroscopy in Characterization and Catalytic Activity of Noble Metal Nanoparticles Fabricated in Responsive Polymer Microgels: A Review.

    Science.gov (United States)

    Begum, Robina; Farooqi, Zahoor H; Naseem, Khalida; Ali, Faisal; Batool, Madeeha; Xiao, Jianliang; Irfan, Ahmad

    2018-11-02

    Noble metal nanoparticles loaded smart polymer microgels have gained much attention due to fascinating combination of their properties in a single system. These hybrid systems have been extensively used in biomedicines, photonics, and catalysis. Hybrid microgels are characterized by using various techniques but UV/Vis spectroscopy is an easily available technique for characterization of noble metal nanoparticles loaded microgels. This technique is widely used for determination of size and shape of metal nanoparticles. The tuning of optical properties of noble metal nanoparticles under various stimuli can be studied using UV/Vis spectroscopic method. Time course UV/Vis spectroscopy can also be used to monitor the kinetics of swelling and deswelling of microgels and hybrid microgels. Growth of metal nanoparticles in polymeric network or growth of polymeric network around metal nanoparticle core can be studied by using UV/Vis spectroscopy. This technique can also be used for investigation of various applications of hybrid materials in catalysis, photonics, and sensing. This tutorial review describes the uses of UV/Vis spectroscopy in characterization and catalytic applications of responsive hybrid microgels with respect to recent research progress in this area.

  13. Formation of Self-assembled Nanostructure on Noble Metal Islands Based on Anodized Aluminum Oxide

    International Nuclear Information System (INIS)

    Park, Jong Bae; Kim, Young Sic; Kim, Seong Kyu; Lee, Hae Seong

    2004-01-01

    We have developed the methodology to produce nanoscale gold rods using an AAO template. Each gold rod was generated in every AAO pore. This nanoislands array of gold formed over the AAO pores can be used as corner stones for building nanostructures. We demonstrated this by forming a nanostructure on the Au/AAO by binding a self-assembly class of molecules onto the metal islands. Anodized aluminum oxide (AAO) has been considered an attractive template for simple fabrication of highly-ordered nanostructures. It provides a 2-dimensional array of hexagonal cells with pores of uniform diameter and inter-pore distance that are adjustable in the range of a few tens to hundreds of nanometers. It can be easily grown on an aluminum sheet with high purity by a sequence of several electrochemical steps; electro-polishing, the 1st anodization, etching, and the 2nd anodization. The pores are grown vertically with respect to the AAO surface. The regularity of the pore structure is usually limited by the inherent grain domain in the aluminum sheet to a few micrometers, but can be improved to cover many millimeters of monodomain by pre-indenting the aluminum sheet with SiC 7 or Si 3 N 4 molds. Although fabrication of such molds requires elaborate and costly processes with e-beam nanolithography, such potentially superb regularity can be practically applied to fabrication of nanoscale devices in electronics, optics, biosensors, etc

  14. Separation of the noble metals ruthenium and palladium from nitric acid solution of the nuclear fuel reprocessing containing complexing agents

    International Nuclear Information System (INIS)

    Ghafourian, H.

    1989-06-01

    Two extraction chromatographic techniques have been developed. N'N diethylthiourea (DETU), which forms complexes with ruthenium that can be retained on an AG50W-X2 ion exchanger, has proved to be a suitable reagent. The structures of these complexes were elucidated by electrophoresis, ion exchange and IR spectroscopy. Under the same conditions Pd forms an insoluble DETU-complex of the formula [Pd(DETU) 4 ] 2+ , which allows the separation of this metal quantitatively. With regard to the application of the developed technique for recovery of the mentioned noble metals from dissolver residues of the nuclear fuel reprocessing, comparative studies were carried out for accompanying fission product nuclides and actinides such as Mo, Tc, Zr, Ce, U and Pu. It was found out that no complex between diethylthiourea and the fission products zirconium, molybdenum and cerium and the actinides uranium, plutonium and americium were formed. Technetium, which was originally present as pertechnetate, is reduced to Tc(IV) and retained on the cation exchanger together with ruthenium. Ruthenium was eluted with 6 M HNO 3 . The efficiency of the developed process has been demonstrated with simulated solutions. The achieved decontamination factors ranged from 10 2 to 10 6 depending on the nuclide. (orig./RB) [de

  15. Synthesis, Characterization and Spectral Studies of Noble Heterobinuclear Complexes of Transition Metal Ions and their Biological Activity

    Directory of Open Access Journals (Sweden)

    Netra Pal Singh

    2011-01-01

    Full Text Available Some noble heterobinuclear complexes of transition metal ions with bis(salicylaldehydemalonyl-dihydrazone in the presence of 5-nitroindazole Cu(II / Ni(II- chloride of the type [ML1M‘L2Cl2] or [ML1FeL2Cl2]Cl, where M = Ni(II, Cu(II and M' = Mn(II, Co(II, have been prepared. All the complexes have been characterized by IR, UV vis and EPR spectroscopy, elemental analysis, magnetic moment and molar conductance measurement. Spectral studies and magnetic moment measurement in DMF suggest the covalent nature of the complexes, except the [ML1FeL2Cl2]Cl complex which is 1:1 electrolyte. An octahedral geometry is proposed for M‘ and square planer for M for the heterobinuclear complexes. The low value of magnetic moment and overlapping EPR signals are due to spin crossover since both of the metals have unpaired electrons with same molecular symmetry. The lowering of the magnetic moment has been discussed. The biological activity (antifungal and antibacterial of the represented compounds has been studied.

  16. Development of new generation of perovskite based noble metal/semiconductor photocatalysts for visible-light-driven hydrogen production

    Science.gov (United States)

    Shen, Peichuan

    described in this dissertation. Noble metal nanoparticles have been proved to be effective co-catalysts due to their unique physical and chemical properties. Au and Pt nanoparticles with different sizes were synthesized and deposited on CdS. Sub-nanometer Au and Pt were found to be promising co-catalysts for photocatalytic hydrogen production reaction. Specifically, sub-nm Au and sub-nm Pt nanoparticles were found to enhance the photocatalytic activity in hydrogen production of CdS by 35 and 15 times respectively. Other noble metal co-catalysts, such as Ru, Pd and Rh were also deposited on CdS and their photocatalytic activities were investigated. Additionally, a novel chamber for photocatalytic reactions was developed as a part of this dissertation. The reaction chamber has several unique features allowing different reactions and measurements. The reactor was proved to be suitable for future projects in photocatalysis such as photocatalytic CO2 conversion into hydrocarbons.

  17. GREENER PRODUCTION OF NOBLE METAL NANOSTRUCTURES AND NANOCOMPOSITES: RISK REDUCTION AND APPLICATIONS

    Science.gov (United States)

    The synthesis of nanometal/nano metal oxide/nanostructured polymer and their stabilization (through dispersant, biodegradable polymer) involves the use of natural renewable resources such plant material extract, biodegradable polymers, sugars, vitamins and finally efficient and s...

  18. Three-dimensional noble-metal nanostructure: A new kind of substrate for sensitive, uniform, and reproducible surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Tian Cui-Feng; You Hong-Jun; Fang Ji-Xiang

    2014-01-01

    Surface-enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique for highly sensitive structural detection of low concentration analyte. The SERS activities largely depend on the topography of the substrate. In this review, we summarize the recent progress in SERS substrate, especially focusing on the three-dimensional (3D) noble-metal substrate with hierarchical nanostructure. Firstly, we introduce the background and general mechanism of 3D hierarchical SERS nanostructures. Then, a systematic overview on the fabrication, growth mechanism, and SERS property of various noble-metal substrates with 3D hierarchical nanostructures is presented. Finally, the applications of 3D hierarchical nanostructures as SERS substrates in many fields are discussed. (invited review — international conference on nanoscience and technology, china 2013)

  19. Radiolytic model of Cofrentes NPP using the BWRVIA: analysis of the effectiveness of mitigation in localizations of the vessel with noble metal application on-line

    International Nuclear Information System (INIS)

    Sanchez Zapata, J. D.; Martin-Serrano, C.

    2013-01-01

    Chemistry is one of the principal factors that takes part in IGSCC materials susceptibility. BWR industry has been applying different mitigation techniques against IGSCC: hydrogen injection and noble metals. Mitigation effectiveness is checked by studying chemical parameters: ECP (for hydrogen injection) and Molar Ratio (for noble metal application). There is a software from EPRI called BWRVIA that allows to modelize radiolysis influence in parameters variation and obtain them at different points in the vessel. Recently, this kind of studies have become very relevant within BWR industry because it is the previous step to implement BWRVIP-62-A guidelines in order to get longer inspection intervals at vessel location where mitigation effectiveness is justified, with the cost savings for plants that this means. (Author)

  20. Structural changes of noble metal catalysts during ignition and extinction of the partial oxidation of methane studied by advanced QEXAFS techniques

    DEFF Research Database (Denmark)

    Grunwaldt, Jan-Dierk; Beier, M.; Kimmerle, B.

    2009-01-01

    The dynamics of the ignition and extinction of the catalytic partial oxidation (CPO) of methane to hydrogen and carbon monoxide over Pt-Rh/Al2O3 and Pt/Al2O3 were studied in the subsecond timescale using quick-EXAFS with a novel cam-driven X-ray monochromator employing Si(111) and Si(311) crystals...... to discuss the potential and limitation of this technique in catalysis and related areas. With respect to the noble metal catalysed partial oxidation of methane, several interesting observations were made: structural changes during ignition were-independent of the chosen reaction conditions......-significantly faster than during the extinction of the reaction. The dynamic behavior of the catalysts was dependent on the flow conditions and the respective noble metal component(s). Higher reaction gas flow led to a faster ignition process. While the ignition over Pt-Rh/Al2O3 occurred at lower temperature than over...

  1. Recycling of spent noble metal catalysts with emphasis on pyrometallurgical processing

    Energy Technology Data Exchange (ETDEWEB)

    Hagelueken, C. [Degussa Huels AG, Hanau (Germany)

    1999-09-01

    Precious metal catalysts for catalytic Naphta Reforming, Isomerization, Hydrogenation and other chemical and petrochemical processes are valuable assets for oil refineries and chemical companies. At the end of the service life of a reactor load of catalyst, the efficient and reliable recovery of the precious metals contained in the catalyst is of paramount importance. More than 150 years of technological advances at Degussa-Huels have resulted in refining methods for all kinds of precious metal containing materials which guarantee an optimum technical yield of the precious metals included. The refining of catalysts today is one of the important activities in the precious metals business unit. In the state-of-the-art precious metal refinery at Hanau in the centre of Germany, a wide variety of processes for the recovery of all precious metals is offered. These processes include accurate preparation, sampling and analysis as well as both wet-chemical and pyrometallurgical recovery techniques. Special emphasis in this presentation is laid on the advantages of pyrometallurgical processes for certain kinds of catalysts. To avoid any risks during transport, sampling and treatment of the spent catalyst, all parties involved in the recycling chain strictly have to follow the relevant safety regulations. Under its commitment to 'Responsible Care' standard procedures have been developed which include pre-shipment samples, safety data sheets/questionnaires and inspection of spent catalysts. These measures not only support a safe and environmentally sound catalyst recycling but also enable to determine the most suitable and economic recovery process - for the benefit of the customer. (orig.)

  2. Three dimensional nano-assemblies of noble metal nanoparticle-infinite coordination polymers as specific oxidase mimetics for degradation of methylene blue without adding any cosubstrate.

    Science.gov (United States)

    Wang, Lihua; Zeng, Yi; Shen, Aiguo; Zhou, Xiaodong; Hu, Jiming

    2015-02-07

    Novel three-dimensional (3D) nano-assemblies of noble metal nanoparticle (NP)-infinite coordination polymers (ICPs) are conveniently fabricated through the infiltration of HAuCl4 into hollow Au@Ag@ICPs core-shell nanostructures and its replacement reaction with Au@Ag NPs. The present 3D nano-assemblies exhibit highly efficient and specific intrinsic oxidase-like activity even without adding any cosubstrate.

  3. Fabrication and magnetic-induced aggregation of Fe{sub 3}O{sub 4}–noble metal composites for superior SERS performances

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Zibao; Zhao, Aiwu, E-mail: awzhao@iim.ac.cn; Zhang, Maofeng; Wang, Dapeng; Guo, Hongyan; Tao, Wenyu; Gao, Qian; Mao, Ranran; Liu, Erhu [Chinese Academy of Sciences, Institute of Intelligent Machines (China)

    2013-11-15

    Fe{sub 3}O{sub 4}–noble metal composites were obtained by combining Au, Ag nanoparticles (NPs) with 3-aminopropyltrimethoxysilane-functionalized Fe{sub 3}O{sub 4} NPs. UV–Visible absorption spectroscopy demonstrates the obtained Fe{sub 3}O{sub 4}–noble metal composites inherit the typical surface plasmon resonance bands of Au, Ag at 533 and 453 nm, respectively. Magnetic measurements also indicated that the superparamagnetic Fe{sub 3}O{sub 4}–noble metal composites have excellent magnetic response behavior. A magnetic-induced idea was introduced to change their aggregated states and take full advantage of their surface-enhanced Raman scattering (SERS) performances. Under the induction of an external magnetic field, the bifunctional Fe{sub 3}O{sub 4}–noble metal aggregates exhibit the unique superiority in SERS detection of Rhodamine 6G (R6G), compared with the naturally dispersed Au, Ag NPs. Especially, the detection limit of the Fe{sub 3}O{sub 4}–Ag aggregates for R6G is as low as 10{sup −14} M, and the calculated EF reaches up to 1.2 × 10{sup 6}, which meets the requirements for trace detection of analytes. Furthermore, the superiority could be extended to sensitive detection of other organic molecules, such as 4-mercaptopyridine. This work provides a new insight for active adjustment of the aggregated states of SERS substrates and the optimization of SERS performances.

  4. Method and electrochemical cell for synthesis and treatment of metal monolayer electrocatalysts metal, carbon, and oxide nanoparticles ion batch, or in continuous fashion

    Science.gov (United States)

    Adzic, Radoslav; Zhang, Junliang; Sasaki, Kotaro

    2015-04-28

    An apparatus and method for synthesis and treatment of electrocatalyst particles in batch or continuous fashion is provided. In one embodiment, the apparatus comprises a sonication bath and a two-compartment chamber submerged in the sonication bath. The upper and lower compartments are separated by a microporous material surface. The upper compartment comprises a cover and a working electrode (WE) connected to a Pt foil contact, with the foil contact connected to the microporous material. The upper chamber further comprises reference counter electrodes. The lower compartment comprises an electrochemical cell containing a solution of metal ions. In one embodiment, the method for synthesis of electrocatalysts comprises introducing a plurality of particles into the apparatus and applying sonication and an electrical potential to the microporous material connected to the WE. After the non-noble metal ions are deposited onto the particles, the non-noble metal ions are displaced by noble-metal ions by galvanic displacement.

  5. Radiolytic model of CN Cofrentes using BWRVIA: analysis of the effectiveness of mitigation in locations of the vessel with application of noble metal son-line; Modelo radiolitico de C. N: Cofrentes utilizando el BWRVIA: analisis de la efectividad de mitigacion en localizaciones de la vasija con aplicacion de metales nobles on-line

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Serrano Ledesma, C.; Sanchez Zapata, J. D.

    2012-07-01

    The effectiveness of mitigation is found from two chemical parameters: electrochemical potential (pm-a hydrogen injection) and Molar Ratio (for the application of noble metals). EPRI code exists, the BWRVIA (BWR Vessel Internals Application,) which enables setting model the impact radiolysis of water, the balance of liquid-vapor phase and recirculation have on the chemical variation of these parameters.

  6. Noble metal emissions. Final presentation, Hanover, October 17/18, 1996; Edelmetall - Emissionen. Abschlusspraesentation, Hannover, 17. und 18. Oktober 1996. Kurzfassung der Vortraege

    Energy Technology Data Exchange (ETDEWEB)

    Pohl, D [comp.

    1998-12-31

    The discussion concerning noble metal emissions, in particular platinum emissions, and their environmental effects, started with the introduction of catalytical cleaning of gasoline engine exhaust. The Research Association for Noble Metal Emissions (Forschungsverbund Edelmetallemissionen) ws founded for the purpose of investigating problems concerning the types and volumes of noble metal emissions as well as their toxicological and allergological potential. In order to make valid statements on physiological and toxicological effects, it was necessary to identify the chemical forms of platinum and to develop powerful methods of analysis. Investigations of platinum concentrations in environmental samples suggest a 10 percent bioavailability. [Deutsch] Mit der Einfuehrung der katalytischen Abgasreinigung von Ottomotoren begann gleichzeitig die Diskussion ueber moegliche Emissionen von Edelmetallen, insbesondere von Platin, sowie ueber ihre eventuell moeglichen negativen Wirkungen in der Umwelt. Zur Erforschung der Fragestellungen zur Art und Menge der emittierten Platinmetalle, ihrer Aufnahme und dem Uebergang in den Nahrungskreislauf, sowie zu ihrem toxikologischen und allergologischen Potential wurde der Forschungsverbund ``Edelmetallemissionen`` gegruendet. Um Aussagen ueber physiologische und toxikologische Einfluesse zu machen, war es notwendig, die chemischen Erscheinungsformen des Platins zu identifizieren und nachweisstarke Analysenmethoden zu entwickeln. Untersuchungen zu Platinkonzentrationen in Umweltproben deuten auf eine Bioverfuegbarkeit von ca. 10 % hin. (ABI)

  7. Catalytic pyrolysis of wheat bran for hydrocarbons production in the presence of zeolites and noble-metals by using TGA-FTIR method.

    Science.gov (United States)

    Lazdovica, K; Liepina, L; Kampars, V

    2016-05-01

    Pyrolysis of wheat bran with or without catalysts was investigated using TGA-FTIR method in order to determine the influence of zeolite and noble metal catalysts on the evolution profile and relative yield of the volatile compounds. The addition of all catalysts decreased the volatile matter of wheat bran from 76.3% to 75.9%, 73.9%, 73.5%, 69.7% and increased the solid residue from 18.0% to 18.4%, 20.4%, 20.8%, 24.6% under the catalyst of ZSM-5, 5% Pd/C, MCM-41, and 5% Pt/C. Noble-metal catalysts had higher activity for deoxygenation of compounds containing carbonyl, carboxyl, and hydroxyl groups than zeolites. Degradation of nitrogen containing compounds atom proceeded better in presence of zeolites. Noble-metal catalysts promoted formation of aromatics and changed the profiles of evolved compounds whereas zeolites advanced formation of aliphatics and olefins. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Noble metal emissions. Final presentation, Hanover, October 17/18, 1996; Edelmetall - Emissionen. Abschlusspraesentation, Hannover, 17. und 18. Oktober 1996. Kurzfassung der Vortraege

    Energy Technology Data Exchange (ETDEWEB)

    Pohl, D. [comp.

    1997-12-31

    The discussion concerning noble metal emissions, in particular platinum emissions, and their environmental effects, started with the introduction of catalytical cleaning of gasoline engine exhaust. The Research Association for Noble Metal Emissions (Forschungsverbund Edelmetallemissionen) ws founded for the purpose of investigating problems concerning the types and volumes of noble metal emissions as well as their toxicological and allergological potential. In order to make valid statements on physiological and toxicological effects, it was necessary to identify the chemical forms of platinum and to develop powerful methods of analysis. Investigations of platinum concentrations in environmental samples suggest a 10 percent bioavailability. [Deutsch] Mit der Einfuehrung der katalytischen Abgasreinigung von Ottomotoren begann gleichzeitig die Diskussion ueber moegliche Emissionen von Edelmetallen, insbesondere von Platin, sowie ueber ihre eventuell moeglichen negativen Wirkungen in der Umwelt. Zur Erforschung der Fragestellungen zur Art und Menge der emittierten Platinmetalle, ihrer Aufnahme und dem Uebergang in den Nahrungskreislauf, sowie zu ihrem toxikologischen und allergologischen Potential wurde der Forschungsverbund ``Edelmetallemissionen`` gegruendet. Um Aussagen ueber physiologische und toxikologische Einfluesse zu machen, war es notwendig, die chemischen Erscheinungsformen des Platins zu identifizieren und nachweisstarke Analysenmethoden zu entwickeln. Untersuchungen zu Platinkonzentrationen in Umweltproben deuten auf eine Bioverfuegbarkeit von ca. 10 % hin. (ABI)

  9. Fe2Ni2N nanosheet array: an efficient non-noble-metal electrocatalyst for non-enzymatic glucose sensing

    Science.gov (United States)

    You, Chao; Dai, Rui; Cao, Xiaoqin; Ji, Yuyao; Qu, Fengli; Liu, Zhiang; Du, Gu; Asiri, Abdullah M.; Xiong, Xiaoli; Sun, Xuping; Huang, Ke

    2017-09-01

    It is very important to develop enhanced electrochemical sensing platforms for molecular detection and non-noble-metal nanoarray architecture, as electrochemical catalyst electrodes have attracted great attention due to their large specific surface area and easy accessibility to target molecules. In this paper, we demonstrate that an Fe2Ni2N nanosheet array grown on Ti mesh (Fe2Ni2N NS/TM) shows high electrocatalytic activity toward glucose electrooxidation in alkaline medium. As an electrochemical glucose sensor, such an Fe2Ni2N NS/TM catalyst electrode demonstrates superior sensing performance with a short response time of less than 5 s, a wide linear range of 0.05 μM-1.5 mM, a low detection limit of 0.038 μM (S/N = 3), a high sensitivity of 6250 μA mM-1 cm-2, as well as high selectivity and long-term stability.

  10. TiO2 promoted by two different non-noble metal cocatalysts for enhanced photocatalytic H2 evolution

    International Nuclear Information System (INIS)

    Lin, Jing-Dong; Yan, Shi; Huang, Qin-Dong; Fan, Mei-Ting; Yuan, You-Zhu; Tan, Timothy Thatt-Yang; Liao, Dai-Wei

    2014-01-01

    TiO 2 photocatalysts modified by cobalt and nickel cocatalysts were prepared via polymerized complex method (PCM) and evaluated by photocatalytic hydrogen evolution. Hydrogen generation in 6 h for the TiO 2 promoted by cobalt and nickel (0.1%Co + 0.2%Ni/TiO 2 ) is about two times (2456 μmol H 2 ) compared to that of TiO 2 promoted only by cobalt (1180 μmol H 2 for 0.1%Co/TiO 2 ) or nickel (1127 μmol H 2 for 0.2%Ni/TiO 2 ), and mechanically mixed TiO 2 promoted by cobalt and TiO 2 promoted by nickel (0.1%Co/TiO 2 :0.2%Ni/TiO 2 = 1:1 (m/m), 1282 μmol H 2 ). The high photocatalytic H 2 evolution activity over TiO 2 promoted by cobalt and nickel is ascribed to enhanced photo response due to the presence of cobalt and nickel impurity level, and effective separation of photogenerated electrons and holes due to the synergistic effect of cobalt and nickel, which serve as active sites for H 2 evolution reaction (HER) and oxidation reaction (OR) respectively. This study demonstrates a viable strategy to design more active photocatalysts for photocatalytic H 2 evolution by substituting noble metals with more abundant elements using as HER and OR cocatalysts, respectively.

  11. Non-noble metal graphene oxide-copper (II) ions hybrid electrodes for electrocatalytic hydrogen evolution reaction

    KAUST Repository

    Muralikrishna, S.

    2015-08-25

    Non-noble metal and inexpensive graphene oxide-copper (II) ions (GO-Cu2+) hybrid catalysts have been explored for the hydrogen evolution reaction (HER). We were able to tune the binding abilities of GO toward the Cu2+ ions and hence their catalytic properties by altering the pH. We have utilized the oxygen functional moieties such as carboxylate, epoxide, and hydroxyl groups on the edge and basal planes of the GO for binding the Cu2+ ions through dative bonds. The GO-Cu2+ hybrid materials were characterized by cyclic voltammetry in sodium acetate buffer solution. The morphology of the hybrid GO-Cu2+ was characterized by atomic force microscopy. The GO-Cu2+ hybrid electrodes show good electrocatalytic activity for HER with low overpotential in acidic solution. The Tafel slope for the GO-Cu2+ hybrid electrode implies that the primary discharge step is the rate determining step and HER proceed with Volmer step. © 2015 American Institute of Chemical Engineers Environ Prog.

  12. Hemoglobin-carbon nanotube derived noble-metal-free Fe5C2-based catalyst for highly efficient oxygen reduction reaction

    Science.gov (United States)

    Vij, Varun; Tiwari, Jitendra N.; Lee, Wang-Geun; Yoon, Taeseung; Kim, Kwang S.

    2016-02-01

    High performance non-precious cathodic catalysts for oxygen reduction reaction (ORR) are vital for the development of energy materials and devices. Here, we report an noble metal free, Fe5C2 nanoparticles-studded sp2 carbon supported mesoporous material (CNTHb-700) as cathodic catalyst for ORR, which was prepared by pyrolizing the hybrid adduct of single walled carbon nanotubes (CNT) and lyophilized hemoglobin (Hb) at 700 °C. The catalyst shows onset potentials of 0.92 V in 0.1 M HClO4 and in 0.1 M KOH which are as good as commercial Pt/C catalyst, giving very high current density of 6.34 and 6.69 mA cm-2 at 0.55 V vs. reversible hydrogen electrode (RHE), respectively. This catalyst has been confirmed to follow 4-electron mechanism for ORR and shows high electrochemical stability in both acidic and basic media. Catalyst CNTHb-700 possesses much higher tolerance towards methanol than the commercial Pt/C catalyst. Highly efficient catalytic properties of CNTHb-700 could lead to fundamental understanding of utilization of biomolecules in ORR and materialization of proton exchange membrane fuel cells for clean energy production.

  13. Microwave assisted green synthesis and characterizations of noble metal nanoparticles and their roles as catalysts in organic reduction reactions and anticancer agent

    Science.gov (United States)

    Francis, Sijo; Koshy, Ebey P.; Mathew, Beena

    2018-04-01

    Nanomaterials are interesting chemicals that uncover the explorations and expectations of decades. The report suggests environmentally benevolent and easy route for the synthesis of noble metal nanoparticles. Personnel, laboratory and ecological benefits of the synthesized nanoparticles are demonstrated herein. The aqueous extract from the leaves of Litchi chinensis Sonn is performed as the alternative reducing agent. The microwave activated silver and gold nanoparticles have spherical geometries with crystalline essence. X-ray diffraction technique witnessed the face centered cubic lattice for the nano silver and gold particles that preferentially oriented towards the (111) plane. The reduction of nitro anilines is performed to elucidate the heterogeneous catalytic power of the nanoparticles. The nano catalyst is a potential candidate to meet the challenges raised from organic pollutant dye that cause environmental contamination. The chemical stability, low-cost factor and plant based origin of the new nanoparticles are admired. The multitudes of health hazards especially human carcinoma can be effectively inhibited by the silver and gold nanoparticles. The leaf extract, silver and gold nanoparticles showed IC50 values 66.56 ± 0.80, 23.55 ± 0.43 and 20.38 ± 0.41 μg ml‑1 respectively against the human lung adenocarcinoma cell lines A549 determined using the MTT dye conversion assay.

  14. Properties and modification of two-dimensional electronic states on noble metals; Eigenschaften und Modifikation zweidimensionaler Elektronenzustaende auf Edelmetallen

    Energy Technology Data Exchange (ETDEWEB)

    Forster, F.

    2007-07-06

    In this thesis investigations on two-dimensional electronic structures of (111)-noble metal surfaces and the influence of various adsorbates upon them is presented. It chiefly focuses on the surface-localized Shockley states of Cu, Ag and Au and their band dispersion (binding energy, band mass, and spin-orbit splitting) which turns out to be a sensitive probe for surface modifications induced by adsorption processes. Angular resolved photoelectron spectroscopy enables the observation of even subtle changes in the electronic band structure of these two dimensional systems. Different mechanisms taking place at surfaces and the substrate/adsorbate interfaces influence the Shockley state in a different manner and will be analyzed using suitable adsorbate model systems. The experimental results are matched with appropriate theoretical models like the phase accumulation model and the nearly-free electron model and - if possible - with ab initio calculations based on density functional theory. This allows for the integration of the results into a stringent overall picture. The influence of sub-monolayer adsorption of Na upon the surface state regarding the significant change in surface work function is determined. A systematic study of the physisorption of noble gases shows the effect of the repulsive adsorbate-substrate interaction upon the electrons of the surface state. A step-by-step coverage of the Cu and Au(111) surfaces by monolayers of Ag creates a gradual change in the surface potential and causes the surface state to become increasingly Ag-like. For N=7 ML thick and layer-by-layer growing Ag films on Au(111), new two-dimensional electronic structures can be observed, which are attributed to the quantum well states of the Ag adsorbate. The question whether they are localized within the Ag-layer or substantially within the substrate is resolved by the investigation of their energetic and spatial evolution with increasing Ag-film thicknesses N. For this, beside the

  15. Highly stable noble-metal nanoparticles in tetraalkylphosphonium ionic liquids for in situ catalysis.

    Science.gov (United States)

    Banerjee, Abhinandan; Theron, Robin; Scott, Robert W J

    2012-01-09

    Gold and palladium nanoparticles were prepared by lithium borohydride reduction of the metal salt precursors in tetraalkylphosphonium halide ionic liquids in the absence of any organic solvents or external nanoparticle stabilizers. These colloidal suspensions remained stable and showed no nanoparticle agglomeration over many months. A combination of electrostatic interactions between the coordinatively unsaturated metal nanoparticle surface and the ionic-liquid anions, bolstered by steric protection offered by the bulky alkylated phosphonium cations, is likely to be the reason behind such stabilization. The halide anion strongly absorbs to the nanoparticle surface, leading to exceptional nanoparticle stability in halide ionic liquids; other tetraalkylphosphonium ionic liquids with non-coordinating anions, such as tosylate and hexafluorophosphate, show considerably lower affinities towards the stabilization of nanoparticles. Palladium nanoparticles stabilized in the tetraalkylphosphonium halide ionic liquid were stable, efficient, and recyclable catalysts for a variety of hydrogenation reactions at ambient pressures with sustained activity. Aerial oxidation of the metal nanoparticles occurred over time and was readily reversed by re-reduction of oxidized metal salts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Oxygen permeation through oxygen ion oxide-noble metal dual phase composites

    NARCIS (Netherlands)

    Chen, C.S.; Chen, C.S.; Kruidhof, H.; Bouwmeester, Henricus J.M.; Verweij, H.; Burggraaf, Anthonie; Burggraaf, A.J.

    1996-01-01

    Oxygen permeation behaviour of three composites, yttria-stabilized zirconia-palladium, erbia-stabilized bismuth oxidenoble metal (silver, gold) was studied. Oxygen permeation measurements were performed under controlled oxygen pressure gradients at elevated temperatures. Air was supplied at one side

  17. Noble metal-catalyzed homogeneous and heterogeneous processes in treating simulated nuclear waste media with formic acid

    International Nuclear Information System (INIS)

    King, R.B.; Bhattacharyya, N.K.; Smith, H.D.

    1995-09-01

    Simulants for the Hanford Waste Vitrification Plant feed containing the major non-radioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO 3 2 -, NO 3 -, and NO 2 - were used to study reactions of formic acid at 90 degrees C catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Such reactions were monitored using gas chromatography to analyze the CO 2 , H 2 , NO, and N 2 O in the gas phase and a microammonia electrode to analyze the NH 4 +/NH 3 in the liquid phase as a function of time. The following reactions have been studied in these systems since they are undesirable side reactions in nuclear waste processing: (1) Decomposition of formic acid to CO 2 + H 2 is undesirable because of the potential fire and explosion hazard of H 2 . Rhodium, which was introduced as soluble RhCl 3 -3H 2 O, was found to be the most active catalyst for H 2 generation from formic acid above ∼ 80 degrees C in the presence of nitrite ion. The H 2 production rate has an approximate pseudo first-order dependence on the Rh concentration, (2) Generation of NH 3 from the formic acid reduction of nitrate and/or nitrite is undesirable because of a possible explosion hazard from NH 4 NO 3 accumulation in a waste processing plant off-gas system. The Rh-catalyzed reduction of nitrogen-oxygen compounds to ammonia by formic acid was found to exhibit the following features: (a) Nitrate rather than nitrite is the principal source of NH 3 . (b) Ammonia production occurs at the expense of hydrogen production. (c) Supported rhodium metal catalysts are more active than rhodium in any other form, suggesting that ammonia production involves heterogeneous rather than homogeneous catalysis

  18. Study of conditions of production and characterization of noble metal micro-particles suspensions

    International Nuclear Information System (INIS)

    Malabre, Catherine

    1983-01-01

    As the production and identification of metal micro-particle suspensions are some aspects of issues related to nuclear fuel reprocessing, this research thesis reports the use of ruthenium, molybdenum, niobium, palladium and rhodium (fission metals) to generate such micro-particles. They are produced by erosion of two electrodes between which occurs an electric arc discharge in aqueous media. Different analytic methods are developed to determine the characteristics of so-produced colloidal solutions. A granulometry study is performed by transmission electronic microscopy, light quasi-elastic scattering, and turbidimetry associated to centrifugation. This has lead to the production of steady micro-particle suspensions which have been used in a first set of industrial trials [fr

  19. Synthesis, characterization and photocatalytic activity of noble metal-modified TiO2 nanosheets with exposed {0 0 1} facets

    International Nuclear Information System (INIS)

    Diak, Magdalena; Grabowska, Ewelina; Zaleska, Adriana

    2015-01-01

    Graphical abstract: - Highlights: • TiO 2 nanosheets with exposed {0 0 1} facets were prepared by hydrothermal method. • Pd and Ag NPs-loaded enhanced the photocatalytic activity under visible irradiation. • Photodeposition is an effective method to obtain noble metal NPs on TiO 2 surface. - Abstract: Pt, Pd, Ag and Au nanoparticles were photodeposited on the {0 0 1} crystal facets of the TiO 2 anatase nanosheets. Morphological and surface characterization of the samples as well as photocatalytic activity were studied. The influence of metal precursor concentration used during photodeposition (0.05−0.5%) on size of formed metal nanoparticles together with UV and vis-mediated activity of Pt, Pd, Ag or Au−TiO 2 was investigated. Generally, samples obtained by photodeposition of noble metal nanoparticles using their 0.2% precursor solutions revealed highest activity in phenol degradation reaction under visible light (λ > 420 nm). The photoactivity of the as-prepared samples with respect to the modified metal species was ordered Ag≅Pd > Au > Pt. TEM analysis showed that photodeposited metal nanoparticles appeared only on {0 0 1} facets of TiO 2 . The average degradation rate of phenol in the presence of Pd and Ag−TiO 2 was 0.5 μmol dm −3 min −1 after 60 min of irradiation under visible light, and was five times higher than that of pure TiO 2 nanosheets

  20. Noble-metal nanoparticles produced with colloidal lithography: fabrication, optical properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Bocchio, Noelia Laura

    2008-08-15

    In this work, metal nanoparticles produced by nanosphere lithography were studied in terms of their optical properties (in connection to their plasmon resonances), their potential application in sensing platforms - for thin layer sensing and bio-recognition events -, and for a particular case (the nanocrescents), for enhanced spectroscopy studies. The general preparation procedures introduced early in 2005 by Shumaker-Parry et al. to produce metallic nanocrescents were extended to give rise to more complex (isolated) structures, and also, by combining colloidal monolayer fabrication and plasma etching techniques, to arrays of them. The fabrication methods presented in this work were extended not only to new shapes or arrangements of particles, but included also a targeted surface tailoring of the substrates and the structures, using different thiol and silane compounds as linkers for further attachment of, i.e. polyelectrolyte layers, which allow for a controlled tailoring of their nanoenvironment. The optical properties of the nanocrescents were studied with conventional transmission spectroscopy; a simple multipole model was adapted to explain their behaviour qualitatively. In terms of applications, the results on thin film sensing using these particles show that the crescents present an interesting mode-dependent sensitivity and spatial extension. Parallel to this, the penetrations depths were modeled with two simplified schemes, obtaining good agreement with theory. The multiple modes of the particles with their characteristic decay lengths and sensitivities represent a major improvement for particle-sensing platforms compared to previous single resonance systems. The nanocrescents were also used to alter the emission properties of fluorophores placed close to them. In this work, green emitting dyes were placed at controlled distances from the structures and excited using a pulsed laser emitting in the near infrared. The fluorescence signal obtained in this

  1. Noble Gases

    Science.gov (United States)

    Podosek, F. A.

    2003-12-01

    The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the

  2. Grains of Nonferrous and Noble Metals in Iron-Manganese Formations and Igneous Rocks of Submarine Elevations of the Sea of Japan

    Science.gov (United States)

    Kolesnik, O. N.; Astakhova, N. V.

    2018-01-01

    Iron-manganese formations and igneous rocks of submarine elevations in the Sea of Japan contain overlapping mineral phases (grains) with quite identical morphology, localization, and chemical composition. Most of the grains conform to oxides, intermetallic compounds, native elements, sulfides, and sulfates in terms of the set of nonferrous, noble, and certain other metals (Cu, Zn, Sn, Pb, Ni, Mo, Ag, Pd, and Pt). The main conclusion that postvolcanic hydrothermal fluids are the key sources of metals is based upon a comparison of the data of electron microprobe analysis of iron-manganese formations and igneous rocks dredged at the same submarine elevations in the Sea of Japan.

  3. Non-noble metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution

    International Nuclear Information System (INIS)

    Song, Jun-Ling; Zhang, Jian-Han; Mao, Jiang-Gao

    2016-01-01

    We reported the synthesis and crystal structures of alkali metal and alkali-earth metal phosphite, namely, CsV 2 (H 3 O)(HPO 3 ) 4 (1), and Ba 3 V 2 (HPO 3 ) 6 (2). Both compounds were prepared by hydrothermal reactions and feature unique new structures. They both exhibit 3D complicated frameworks based on VO 6 octahedra which are connected by HPO 3 tetrahedra via corner-sharing. Alkali or alkali earth metal cations are filled in the different channels of the frameworks. Topological analysis shows that the framework of CsV 2 (H 3 O) (HPO 3 ) 4 (1) is a new 3,3,3,4,5-connected network with the Schläfli symbol of {4.6 2 } 2 {4 2 .6 6 .8 2 }{6 3 }{6 5 .8}. The investigations of X-ray photoelectron spectroscopy (XPS) and magnetic measurement on CsV 2 (H 3 O)(HPO 3 ) 4 suggest a +3 oxidation state of the vanadium ions in compound 1. Photocatalytic performance was evaluated by photocatalytic H 2 evolution and degradation of methylene blue, which shows that both compounds exhibit activity under visible-light irradiation. IR spectrum, UV–vis-NIR spectrum and thermogravimetric analysis (TGA) of compounds were also investigated. - Graphical abstract: Metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution and the degradation of methylene blue aqueous solution. - Highlights: • Two new vanadium phosphites, CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 , are reported. • CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 feature complicated 3D framework structures with different channels. • CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 exhibit strong and broad absorptions in the visible and Near IR region. • Photocatalytic properties of CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 are investigated. • The magnetic measurement of CsV 2 (H 3 O)(HPO 3 ) 4 was performed in the temperature range of 2–300 K.

  4. Plasmonic colorimetric sensors based on etching and growth of noble metal nanoparticles: Strategies and applications.

    Science.gov (United States)

    Zhang, Zhiyang; Wang, Han; Chen, Zhaopeng; Wang, Xiaoyan; Choo, Jaebum; Chen, Lingxin

    2018-08-30

    Plasmonic colorimetric sensors have emerged as a powerful tool in chemical and biological sensing applications due to the localized surface plasmon resonance (LSPR) extinction in the visible range. Among the plasmonic sensors, the most famous sensing mode is the "aggregation" plasmonic colorimetric sensor which is based on plasmon coupling due to nanoparticle aggregation. Herein, this review focuses on the newly-developing plasmonic colorimetric sensing mode - the etching or the growth of metal nanoparticles induces plasmon changes, namely, "non-aggregation" plasmonic colorimetric sensor. This type of sensors has attracted increasing interest because of their exciting properties of high sensitivity, multi-color changes, and applicability to make a test strip. Of particular interest, the test strip by immobilization of nanoparticles on the substrate can avoid the influence of nanoparticle auto-aggregation and increase the simplicity in storage and use. Although there are many excellent reviews available that describe the advance of plasmonic sensors, limited attention has been paid to the plasmonic colorimetric sensors based on etching or growth of metal nanoparticles. This review highlights recent progress on strategies and application of "non-aggregation" plasmonic colorimetric sensors. We also provide some personal insights into current challenges associated with "non-aggregation" plasmonic colorimetric sensors and propose future research directions. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Electrocatalysis of the oxidations of some organic compounds on noble-metal electrodes by foreign-metal ad-atoms

    International Nuclear Information System (INIS)

    Tsang, R.W.

    1981-10-01

    Electrochemical oxidation of formic acid was studied on Pt electrodes in acid, and that of dextrose was studied on Pt and Au in alkali. Poisoning was observed on Pt but not on Au. Several heavy-metal ad-atoms (Pb, Bi, Tl) enhance greatly the anodic currents on Pt, while transition metals (Cu, Zn) inhibit the oxidation on Pt. The enhancement effect of the metal ad-atoms is correlated with electron structure. All metal ad-atoms showed an inhibitory effect on Au. Amperometry showed that Pt electrodes are completely deactivated within 10 s during dextrose oxidation without ad-atoms, while Au retains much of its activity even after 10 min. Ad-atoms maintains the Pt activity over much more than 10 s. 50 figures, 38 tables

  6. Platinum and palladium alloys suitable as fuel cell electrodes

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt and Pd alloyed with an alkaline earth metal....

  7. Platinum and palladium alloys suitable as fuel cell electrodes

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic5 efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt and Pd alloyed with a lanthanide metal....

  8. Effects of noble-metal ion implantation on corrosion inhibition and charge injection capability of surgical Ti and Ti-6Al-4V

    International Nuclear Information System (INIS)

    Lee, I.S.

    1989-01-01

    Studies are described involving effects of noble-metal ion implantation on corrosion inhibition and charge injection capabilities of surgical Ti and Ti-6Al-4V. With surgical alloys, harmful biological responses are principally due to the type and quantity of metal ions released by the corrosion process. One approach to improve long-term biological performance involves surface modifications to significantly reduce degradation rates. With regard to surface-modifications, one of the most effective methods is through ion implantation. Results are presented for ion-implanted Au, Rh, and Ir. For the static in vitro corrosion properties, the noble-metal ion implanted Ti-6Al-4V and commercially-pure (CP) Ti were investigated in non-passivating acid and passivating saline solutions. It was postulated that during the early stages of corrosion (or during a corrosion pretreatment) the implanted noble-metal would enrich at the surface and significantly reduce subsequent corrosion rates. The observed behavior for the Ir and Rh implanted materials appeared to follow the postulated mechanism, with both initial and time-dependent improvements in corrosion resistance. However, the Au implanted material yielded early benefits, but the enhanced corrosion resistance deteriorated with time. X-ray photoelectron spectroscopy (XPS) analysis indicated that the implanted Au atoms remained as pure metallic Au, while the Ir and Rh atoms were in some oxide state, which gave the good adhesion of the Ir or Rh enriched surface to the Ti substrate. For a stimulating neural electrode, the charge density should be as large as possible to provide adequate stimulation of the nervous system while allowing for miniaturization of the electrode. Activated Ir has been known as having the highest charge injection capability of any material known

  9. Tuning the Morphology of Li2O2 by Noble and 3d metals: A Planar Model Electrode Study for Li-O2 Battery.

    Science.gov (United States)

    Yang, Yao; Liu, Wei; Wu, Nian; Wang, Xiaochen; Zhang, Tao; Chen, Linfeng; Zeng, Rui; Wang, Yingming; Lu, Juntao; Fu, Lei; Xiao, Li; Zhuang, Lin

    2017-06-14

    In this work, a planar model electrode method has been used to investigate the structure-activity relationship of multiple noble and 3d metal catalysts for the cathode reaction of Li-O 2 battery. The result shows that the battery performance (discharge/charge overpotential) strongly depends not only on the type of catalysts but also on the morphology of the discharge product (Li 2 O 2 ). Specifically, according to electrochemical characterization and scanning electron microscopy (SEM) observation, noble metals (Pd, Pt, Ru, Ir, and Au) show excellent battery performance (smaller discharge/charge overpotential), with wormlike Li 2 O 2 particles with size less than 200 nm on their surfaces. On the other hand, 3d metals (Fe, Co, Ni, and Mn) offered poor battery performance (larger discharge/charge overpotential), with much larger Li 2 O 2 particles (1 μm to a few microns) on their surfaces after discharging. Further research shows that a "volcano plot" is found by correlating the discharging/charging plateau voltage with the adsorption energy of LiO 2 on different metals. The metals with better battery performance and worm-like-shaped Li 2 O 2 are closer to the top of the "volcano", indicating adsorption energy of LiO 2 is one of the key characters for the catalyst to reach a good performance for the oxygen electrode of Li-O 2 battery, and it has a strong influence on the morphology of the discharge product on the electrode surface.

  10. Rubber effect and stabilization of martensites in noble metal based alloys

    International Nuclear Information System (INIS)

    Marukawa, K.; Takezawa, K.; Hoshi, H.

    1999-01-01

    In a previous paper, it has been pointed out that the rubber effect and stabilization of the martensite phase are caused by short range reordering during aging [K. Marukawa, K. Tsuchiya, Scripta Metall. Mater. 32 (1995) 77]. This view was further examined by experimental and theoretical studies. It has been found that the change in electrical resistivity produced by aging is well correlated with magnitudes of these effects. The relation between the short range order parameters and the representative quantities of these effects was formulated on the basis of thermodynamics. Quantitative evaluation was performed by numerical calculations utilizing the Monte Carlo method. It was found that the rubber effect is prominent when the aging temperature is in the vicinity of the order-disorder transition temperature. It was also shown that in most cases disordering or lowering in the long range order causes the stabilization. (orig.)

  11. Noble metals nanoparticles on titanium dioxide nanostructured films and the influence of their photocatalytic activity

    International Nuclear Information System (INIS)

    Nakamura, Liana Key Okada

    2012-01-01

    Currently, nanoscience and nanotechnology are considered an emerging field and continuously breaking the barrier among various disciplines. The main focus of study involves controlling structures at molecular level, arranging the atoms in order to achieve an understanding and controlling the fundamental properties of matter. In this study, molecular changes on the basis of morphology, optical and crystalline properties of TiO 2 hin films in order to increase their photon efficiency were proposed. The TiO 2 thin films were prepared by sol gel process evaluating the influence of different acids and templates to obtain the nano structured arrangements. Then, metal nanoparticles like Au, Ag, Pd and Pt were incorporated on TiO 2 thin films. This incorporation might minimize the electron-hole recombination, so it could improve the photon efficiency. From the several routes studied, the TiO 2 thin films prepared with acetic acid showed the best performance by the reason of low agglomeration of TiO 2 grains, which favors the exposure of the photoactive sites. The presence of template in the formulation had a slightly effect on photon efficiency, possible due to the higher agglomeration of the grains on the TiO 2 thin films. The addition of Pt and Au nanoparticles on TiO 2 thin films showed superior photon efficiency. The TiO 2 thin films with hexamine and metallic nanoparticles did not show the improvement on photon efficiency except for Pt and Au nanoparticles. On these situations, the improvement on photon efficiency is might be due to a possible decrease at the electron-hole recombination's velocity. Thus, the present work demonstrates the great influence of preparation conditions on the optical, morphological properties and the photon efficiency. In the future, with greater understanding of the mechanism of this influence, the properties of TiO 2 thin films will be able tailoring depending on the application. (author)

  12. Intriguing structures and magic sizes of heavy noble metal nanoclusters around size 55 governed by relativistic effect and covalent bonding

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X. J.; Xue, X. L.; Jia, Yu [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Guo, Z. X. [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Department of Chemistry and London Centre for Nanotechnology, University College London, London WC1H (United Kingdom); Li, S. F., E-mail: sflizzu@zzu.edu.cn [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); ICQD, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhenyu, E-mail: zhangzy@ustc.edu.cn [ICQD, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Gao, Y. F., E-mail: ygao7@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2015-11-07

    Nanoclusters usually display exotic physical and chemical properties due to their intriguing geometric structures in contrast to their bulk counterparts. By means of first-principles calculations within density functional theory, we find that heavy noble metal Pt{sub N} nanoclusters around the size N = 55 begin to prefer an open configuration, rather than previously reported close-packed icosahedron or core-shell structures. Particularly, for Pt{sub N}, the widely supposed icosahedronal magic cluster is changed to a three-atomic-layered structure with D{sub 6h} symmetry, which can be well addressed by our recently established generalized Wulff construction principle (GWCP). However, the magic number of Pt{sub N} clusters around 55 is shifted to a new odd number of 57. The high symmetric three-layered Pt{sub 57} motif is mainly stabilized by the enhanced covalent bonding contributed by both spin-orbital coupling effect and the open d orbital (5d{sup 9}6s{sup 1}) of Pt, which result in a delicate balance between the enhanced Pt–Pt covalent bonding of the interlayers and negligible d dangling bonds on the cluster edges. These findings about Pt{sub N} clusters are also applicable to Ir{sub N} clusters, but qualitatively different from their earlier neighboring element Os and their later neighboring element Au. The magic numbers for Os and Au are even, being 56 and 58, respectively. The findings of the new odd magic number 57 are the important supplementary of the recently established GWCP.

  13. The effect of noble metals on catalytic methanation reaction over supported Mn/Ni oxide based catalysts

    Directory of Open Access Journals (Sweden)

    Wan Azelee Wan Abu Bakar

    2015-09-01

    Full Text Available Carbon dioxide (CO2 in sour natural gas can be removed using green technology via catalytic methanation reaction by converting CO2 to methane (CH4 gas. Using waste to wealth concept, production of CH4 would increase as well as creating environmental friendly approach for the purification of natural gas. In this research, a series of alumina supported manganese–nickel oxide based catalysts doped with noble metals such as ruthenium and palladium were prepared by wetness impregnation method. The prepared catalysts were run catalytic screening process using in-house built micro reactor coupled with Fourier Transform Infra Red (FTIR spectroscopy to study the percentage CO2 conversion and CH4 formation analyzed by GC. Ru/Mn/Ni(5:35:60/Al2O3 calcined at 1000 °C was found to be the potential catalyst which gave 99.74% of CO2 conversion and 72.36% of CH4 formation at 400 °C reaction temperature. XRD diffractogram illustrated that the supported catalyst was in polycrystalline with some amorphous state at 1000 °C calcination temperature with the presence of NiO as active site. According to FESEM micrographs, both fresh and used catalysts displayed spherical shape with small particle sizes in agglomerated and aggregated mixture. Nitrogen Adsorption analysis revealed that both catalysts were in mesoporous structures with BET surface area in the range of 46–60 m2/g. All the impurities have been removed at 1000 °C calcination temperature as presented by FTIR, TGA–DTA and EDX data.

  14. EFFECTS OF ALTERNATE ANTIFOAM AGENTS, NOBLE METALS, MIXING SYSTEMS AND MASS TRANSFER ON GAS HOLDUP AND RELEASE FROM NONNEWTONIAN SLURRIES

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, H; Mark Fowley, M; Charles Crawford, C; Michael Restivo, M; Robert Leishear, R

    2007-12-24

    Gas holdup tests performed in a small-scale mechanically-agitated mixing system at the Savannah River National Laboratory (SRNL) were reported in 2006. The tests were for a simulant of waste from the Hanford Tank 241-AZ-101 and featured additions of DOW Corning Q2-3183A Antifoam agent. Results indicated that this antifoam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter intuitively, that the holdup increased as the simulant shear strength decreased (apparent viscosity decreased). These results raised questions about how the AFA might affect gas holdup in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs). And whether the WTP air supply system being designed would have the capacity to handle a demand for increased airflow to operate the sparger-PJM mixing systems should the AFA increase retention of the radiochemically generated flammable gases in the waste by making the gas bubbles smaller and less mobile, or decrease the size of sparger bubbles making them mix less effectively for a given airflow rate. A new testing program was developed to assess the potential effects of adding the DOW Corning Q2-3183A AFA to WTP waste streams by first confirming the results of the work reported in 2006 by Stewart et al. and then determining if the AFA in fact causes such increased gas holdup in a prototypic sparger-PJM mixing system, or if the increased holdup is just a feature of the small-scale agitation system. Other elements of the new program include evaluating effects other variables could have on gas holdup in systems with AFA additions such as catalysis from trace noble metals in the waste, determining mass transfer coefficients for the AZ-101 waste simulant, and determining whether other AFA compositions such as Dow Corning 1520-US could also increase gas holdup in Hanford waste. This new testing program was split into two investigations, prototypic sparger

  15. Formation, Characteristics and Electrocatalytic Properties of Nanoporous Metals Formed by Dealloying of Ternary-Noble Alloys

    Science.gov (United States)

    Vega Zuniga, Adrian A.

    Nanoporous metals formed by electrochemical dealloying of silver from Ag-Au-Pt alloys, with 77 at.% silver and platinum contents of 1, 2 and 3 at.%, have been studied. The presence of platinum, which is immobile relative to gold, refine the ligament size and stabilized the nanostructure against coarsening, even under experimental conditions that would be expected to promote coarsening (e.g., exposure to high temperature, longer dealloying times). By adding only 1 at.% Pt to the alloy precursor, the ligament/pore size was reduced by 50% with respect to that in nanoporous gold (NPG), which was formed on a Ag-Au alloy with the same silver content as ternary alloys. A further decrease in the ligament size was observed by increasing the platinum content of the precursor; however, most of the improvement occurred with 1 at.% Pt. The adsorbate-induced surface segregation of platinum was also investigated for these nanoporous metals. By exposing freshly-dealloyed nanostructures to moderate temperatures in the presence of air, platinum segregated to the ligament surface; in contrast, in an inert atmosphere (Ar-H 2), platinum mostly reverted to the bulk of the ligaments. This thermally activated process was thermodynamically driven by the interaction between platinum and oxygen; however, at the desorption temperature of oxygen, platinum de-segregated from the surface. Moreover, the co-segregation of platinum and oxygen hindered the thermal coarsening of the ligaments. Finally, the electrocatalytic abilities of these nanostructures were studied towards methanol and ethanol electro-oxidation, in alkaline and acidic media, showing significantly improved response in comparison to that observed in NPG. The synergistic effect between gold and platinum atoms and the smaller feature size of the nanostructures were directly associated with this behaviour. In alkaline electrolyte, the nanostructure formed on the alloy with 1 at.% Pt showed higher catalytic response than the other two

  16. Sputter fabricated Nb-oxide-Nb josephson junctions incorporating post-oxidation noble metal layers

    International Nuclear Information System (INIS)

    Bain, R.J.P.; Donaldson, G.B.

    1985-01-01

    We present an extension, involving other metals, of the work of Hawkins and Clarke, who found that a thin layer of copper prevented the formation of the superconductive shorts which are an inevitable consequence of sputtering niobium counter-electrodes directly on top of niobium oxide. We find gold to be the most satisfactory, and that 0.3 nm is sufficient to guarantee short-free junctions of excellent electrical and mechanical stability, though high excess conductance means they are best suited to shunted-junction applications, as in SQUIDs. We present results for critical current dependence on oxide thickness and on gold thickness. Our data shows that thermal oxide growth is described by the Cabrera-Mott mechanism. We show that the protective effect of the gold layer can be understood in terms of the electro-chemistry of the Nb-oxide-Au structure, and that the reduced quasi-particle resistance of the junctions relative to goldfree junctions with evaporated counterelectrodes can be explained in terms of barrier shape modification, and not by proximity effect mechanisms. The performance of a DC SQUID based on these junctions is described

  17. An unsaturated metal site-promoted approach to construct strongly coupled noble metal/HNb3O8 nanosheets for efficient thermo/photo-catalytic reduction.

    Science.gov (United States)

    Shen, Lijuan; Xia, Yuzhou; Lin, Sen; Liang, Shijing; Wu, Ling

    2017-10-05

    Creating two-dimensional (2D) crystal-metal heterostructures with an ultrathin thickness has spurred increasing research endeavors in catalysis because of its fascinating opportunities in tuning the electronic state at the surface and enhancing the chemical reactivity. Here we report a novel and facile Nb 4+ -assisted strategy for the in situ growth of highly dispersed Pd nanoparticles (NPs) on monolayer HNb 3 O 8 nanosheets (HNb 3 O 8 NS) constituting a 2D Pd/HNb 3 O 8 NS heterostructure composite without using extra reducing agents and stabilizing agents. The Pd NP formation is directed via a redox reaction between an oxidative Pd salt precursor (H 2 PdCl 4 ) and reductive unsaturated surface metal (Nb 4+ ) sites induced by light irradiation on monolayer HNb 3 O 8 NS. The periodic arrangement of metal Nb nodes on HNb 3 O 8 NS leads to a homogeneous distribution of Pd NPs. Density functional theory (DFT) calculations reveal that the direct redox reaction between the Nb 4+ and Pd 2+ ions leads to a strong chemical interaction between the formed Pd metal NPs and the monolayer HNb 3 O 8 support. Consequently, the as-obtained Pd/HNb 3 O 8 composite serves as a highly efficient bifunctional catalyst in both heterogeneous thermocatalytic and photocatalytic selective reduction of aromatic nitro compounds in water under ambient conditions. The achieved high activity originates from the unique 2D nanosheet configuration and in situ Pd incorporation, which leads to a large active surface area, strong metal-support interaction and enhanced charge transport capability. Moreover, this facile Nb 4+ -assisted synthetic route has demonstrated to be general, which can be applied to load other metals such as Au and Pt on monolayer HNb 3 O 8 NS. It is anticipated that this work can extend the facile preparation of noble metal/nanosheet 2D heterostructures, as well as promote the simultaneous capture of duple renewable thermal and photon energy sources to drive an energy efficient

  18. Respondence Between Electrochemical Fluctuations and Phenomenon for Localized Corrosion of Less-Noble Metals

    International Nuclear Information System (INIS)

    Itoi, Yasuhiko; Take, Seisho; Tsuru, Tooru

    2008-01-01

    We have been studying application of electrochemical noise (Fluctuation) analysis for localized corrosion. Foils of Zinc, Aluminum and Magnesium were used as specimens for electrochemical cell simulating localized corrosion. These specimens were dipped in sodium chloride solutions adjusted to each exponent of hydrogen ion concentration (pH) condition of 5.5, 10, 12 respectively. Time variations of potential and current were measured in those solutions, and simultaneously the surfaces of specimens were observed using microscope with television monitor. Two types of electrochemical cells were arranged for experiments simulated localized corrosion. The fluctuations on trendy component of short-circuited potential and short-circuited current were appeared in synchronization. It was seemed that these fluctuations result from hydrogen evolution on the aluminum active site in the crevice from the microscopic observation. In the case of zinc and magnesium, fluctuations appeared on the trendy component of the corrosion potential. Two types fluctuation were detected. First one is the fluctuation varied periodically. The second one is the random fluctuation. It was seemed that these fluctuations result from generation of corrosion products and hydrogen evolution on the active site in the crevice of zinc and magnesium from the microscopic observation

  19. Stabilisation of late transition metal and noble metal films in hexagonal and body centred tetragonal phases by epitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Hueger, E.

    2005-08-26

    In this work ultrathin metallic films with a crystal phase different to their natural bulk structure were produced by hetero-epitaxial growth on metallic substrates. A further aim of this work was to understand the initiation, growth and stability of crystal phase modifications of these films. there exist cases where the films turn beyond the pseudomorphic-growth to a crystal phase different from their natural bulk structure. The present work presents and discusses such a case in addition to the general phenomenon of pseudomorphic-growth. In particular it is shown that metals whose natural phase is face centred cubic (fcc) can be grown in body centred tetragonal (bct) or hexagonal close packed (hcp) phases in the form of thin films on (001) surfaces of appropriate substrates. The growth behavior, electron diffraction analysis, appearance conditions, geometric fit considerations, examples and a discussion of the phase stability of non-covered films and superlattices is given reviewing all epitaxial-systems whose diffraction pattern can be explained by the hexagonal or pseudomorphic bct phase. (orig.)

  20. Metal Matrix Composite Solar Cell Metallization

    Directory of Open Access Journals (Sweden)

    Wilt David M.

    2017-01-01

    Full Text Available Advanced solar cells are moving to ever thinner formats in order to save mass and in some cases improve performance. As cells are thinned, the possibility that they may fracture or cleave due to mechanical stresses is increased. Fractures of the cell can degrade the overall device performance if the fracture propagates through the contact metallization, which frequently occurs. To address this problem, a novel semiconductor metallization system based on multi-walled carbon nanotube (CNT reinforcement, termed metal matrix composite (MMC metallization is under investigation. Electro-mechanical characterization of MMC films demonstrate their ability to provide electrical conductivity over >40 micron wide cracks in the underlying semiconductor, with the carbon nanotubes bridging the gap. In addition, these materials show a “self-healing” behaviour, electrically reconnecting at ~30 microns when strained past failure. Triple junction (TJ space cells with MMC metallization demonstrated no loss in Jsc after intentional fracture, whereas TJ cells with conventional metallization suffer up to 50% Jsc loss.

  1. Radiolytic model of Cofrentes NPP using the BWRVIA: analysis of the effectiveness of mitigation in localizations of the vessel with noble metal application on-line; Modelo Radiolitico de C.N. Cofrentes utilizando el BWRVIA: analisis de la efectividad de mitigacion en localizaciones de la vasija con aplicacion de metales nobles on-line

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Zapata, J. D.; Martin-Serrano, C.

    2013-03-01

    Chemistry is one of the principal factors that takes part in IGSCC materials susceptibility. BWR industry has been applying different mitigation techniques against IGSCC: hydrogen injection and noble metals. Mitigation effectiveness is checked by studying chemical parameters: ECP (for hydrogen injection) and Molar Ratio (for noble metal application). There is a software from EPRI called BWRVIA that allows to modelize radiolysis influence in parameters variation and obtain them at different points in the vessel. Recently, this kind of studies have become very relevant within BWR industry because it is the previous step to implement BWRVIP-62-A guidelines in order to get longer inspection intervals at vessel location where mitigation effectiveness is justified, with the cost savings for plants that this means. (Author)

  2. Noble metal nanoparticle-functionalized ZnO nanoflowers for photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide

    International Nuclear Information System (INIS)

    Hussain, Muhammad; Sun, Hongyu; Karim, Shafqat; Nisar, Amjad; Khan, Maaz; Ul Haq, Anwar; Iqbal, Munawar; Ahmad, Mashkoor

    2016-01-01

    Flower-like hierarchical Zinc oxide nanostructures synthesized by co-precipitation method have been hydrothermally functionalized with 8 nm Au NPs and 15 nm Ag nanoparticles. The photocatalytic and electrochemical performance of these structures are investigated. XPS studies show that the composite exhibits a strong interaction between noble metal nanoparticles (NPs) and Zinc oxide nanoflowers. The PL spectra exhibit UV emission arising due to near band edge transition and show that the reduced PL intensities of Au–ZnO and Ag–ZnO composites are responsible for improved photocatalytic activity arising due to increase in defects. Moreover, the presence of Au NPs on ZnO surface remarkably enhances photocatalytic activity as compared to Ag–ZnO and pure ZnO due to the higher catalytic activity and stability of Au NPs. On the other hand, Ag–ZnO-modified glassy carbon electrode shows good amperometric response to hydrogen peroxide (H_2O_2), with linear range from 1 to 20 µM, and detection limit of 2.5 µM (S/N = 3). The sensor shows high and reproducible sensitivity of 50.8 μA cm"−"2 μM"−"1 with a fast response less than 3 s and good stability as compared to pure ZnO and Au–ZnO-based sensors. All these results show that noble metal NPs-functionalized ZnO base nanocomposites exhibit great prospects for developing efficient non-enzymatic biosensor and environmental remediators.Graphical abstractZnO nanoflowers functionalized with noble metal nanoparticles enhance photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide.

  3. Noble metal nanoparticle-functionalized ZnO nanoflowers for photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Muhammad [PINSTECH, Nanomaterials Research Group, Physics Division (Pakistan); Sun, Hongyu [Tsinghua University, Laboratory of Advanced Materials and The State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering Beijing, National Center for Electron Microscopy (China); Karim, Shafqat; Nisar, Amjad; Khan, Maaz [PINSTECH, Nanomaterials Research Group, Physics Division (Pakistan); Ul Haq, Anwar [PINSTECH, Non-destructive testing Group (Pakistan); Iqbal, Munawar [University of the Punjab, Centre for High Energy Physics (Pakistan); Ahmad, Mashkoor, E-mail: mashkoorahmad2003@yahoo.com [PINSTECH, Nanomaterials Research Group, Physics Division (Pakistan)

    2016-04-15

    Flower-like hierarchical Zinc oxide nanostructures synthesized by co-precipitation method have been hydrothermally functionalized with 8 nm Au NPs and 15 nm Ag nanoparticles. The photocatalytic and electrochemical performance of these structures are investigated. XPS studies show that the composite exhibits a strong interaction between noble metal nanoparticles (NPs) and Zinc oxide nanoflowers. The PL spectra exhibit UV emission arising due to near band edge transition and show that the reduced PL intensities of Au–ZnO and Ag–ZnO composites are responsible for improved photocatalytic activity arising due to increase in defects. Moreover, the presence of Au NPs on ZnO surface remarkably enhances photocatalytic activity as compared to Ag–ZnO and pure ZnO due to the higher catalytic activity and stability of Au NPs. On the other hand, Ag–ZnO-modified glassy carbon electrode shows good amperometric response to hydrogen peroxide (H{sub 2}O{sub 2}), with linear range from 1 to 20 µM, and detection limit of 2.5 µM (S/N = 3). The sensor shows high and reproducible sensitivity of 50.8 μA cm{sup −2} μM{sup −1} with a fast response less than 3 s and good stability as compared to pure ZnO and Au–ZnO-based sensors. All these results show that noble metal NPs-functionalized ZnO base nanocomposites exhibit great prospects for developing efficient non-enzymatic biosensor and environmental remediators.Graphical abstractZnO nanoflowers functionalized with noble metal nanoparticles enhance photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide.

  4. In Situ Studies of Surface Mobility on Noble Metal Model Catalysts Using STM and XPS at Ambient Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Derek Robert [Univ. of California, Berkeley, CA (United States)

    2010-06-01

    High Pressure Scanning Tunneling Microscopy (HP-STM) and Ambient Pressure X-ray Photoelectron Spectroscopy were used to study the structural properties and catalytic behavior of noble metal surfaces at high pressure. HP-STM was used to study the structural rearrangement of the top most atomic surface layer of the metal surfaces in response to changes in gas pressure and reactive conditions. AP-XPS was applied to single crystal and nanoparticle systems to monitor changes in the chemical composition of the surface layer in response to changing gas conditions. STM studies on the Pt(100) crystal face showed the lifting of the Pt(100)-hex surface reconstruction in the presence of CO, H2, and Benzene. The gas adsorption and subsequent charge transfer relieves the surface strain caused by the low coordination number of the (100) surface atoms allowing the formation of a (1 x 1) surface structure commensurate with the bulk terminated crystal structure. The surface phase change causes a transformation of the surface layer from hexagonal packing geometry to a four-fold symmetric surface which is rich in atomic defects. Lifting the hex reconstruction at room temperature resulted in a surface structure decorated with 2-3 nm Pt adatom islands with a high density of step edge sites. Annealing the surface at a modest temperature (150 C) in the presence of a high pressure of CO or H2 increased the surface diffusion of the Pt atoms causing the adatom islands to aggregate reducing the surface concentration of low coordination defect sites. Ethylene hydrogenation was studied on the Pt(100) surface using HP-STM. At low pressure, the lifting of the hex reconstruction was observed in the STM images. Increasing the ethylene pressure to 1 Torr, was found to regenerate the hexagonally symmetric reconstructed phase. At room temperature ethylene undergoes a structural rearrangement to form ethylidyne. Ethylidyne preferentially binds at the three-fold hollow sites, which

  5. Hierarchical hybrid of Ni{sub 3}N/N-doped reduced graphene oxide nanocomposite as a noble metal free catalyst for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qi; Li, Yingjun; Li, Yetong [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Huang, Keke [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab. of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Zhang, Jun, E-mail: cejzhang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab. of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

    2017-04-01

    Highlights: • Hybrid of Ni{sub 3}N/N-RGO catalysts are synthesized by using a two-step method. • The catalysts manifest superior catalytic activity towards the ORR. • High activities are attributed to enhanced electron density and synergistic effects. - Abstract: Novel nickel nitride (Ni{sub 3}N) nanoparticles supported on nitrogen-doped reduced graphene oxide nanosheets (N-RGOs) are synthesized via a facile strategy including hydrothermal and subsequent calcination methods, in which the reduced graphene oxide nanosheets (RGOs) are simultaneously doped with nitrogen species. By varying the content of the RGOs, a series of Ni{sub 3}N/N-RGO nanocomposites are obtained. The Ni{sub 3}N/N-RGO-30% hybrid nanocomposite exhibits superior catalytic activity towards oxygen reduction reaction (ORR) under alkaline condition (0.1 M KOH). Furthermore, this hybrid catalyst also demonstrates high tolerance to methanol poisoning. The RGO containing rich N confers the nanocomposite with large specific surface area and high electronic conduction ability, which can enhance the catalytic efficiency of Ni{sub 3}N nanoparticles. The enhanced catalytic activity can be attributed to the synergistic effect between Ni{sub 3}N and nitrogen doped reduced graphene oxide. In addition, the sufficient contact between Ni{sub 3}N nanoparticles and the N-RGO nanosheets simultaneously promotes good nanoparticle dispersion and provides a consecutive activity sites to accelerate electron transport continuously, which further enhance the ORR performance. The Ni{sub 3}N/N-RGO may be further an ideal candidate as efficient and inexpensive noble metal-free ORR electrocatalyst in fuel cells.

  6. The growth of noble metals in (112-bar0)-oriented hexagonal close-packed nano-films by epitaxy on Nb(001)

    International Nuclear Information System (INIS)

    Hueger, E.; Osuch, K.

    2005-01-01

    The morphology and crystal structure of noble metal nano-films deposited on oxygen contaminated and oxygen-free Nb(001) surfaces have been studied with angle-resolved ultraviolet photoelectron spectroscopy, X-ray photo-electron diffraction, and reflection high energy electron diffraction. In the both cases a deposited noble metal film aligns its direction with the [110] direction of the Nb(001) surface. But, while a noble metal grows on an oxygen contaminated Nb(001) surface with the hexagonal close-packed (hcp) (111) planes parallel to the surface (i.e. in the (111)-oriented face centred cubic phase (fcc)), on a non-contaminated Nb(001) it grows with its hcp planes perpendicular to the surface. The latter happens because in the initial stages of the epitaxy the first two monolayers (MLs) of the noble metal grow pseudomorphically on a contamination-free Nb(001). The pseudomorphic layer is strongly extended parallel to the Nb(001) surface in comparison to its natural fcc (001) plane. As a consequence of the atomic volume conservation principle the out-of-plane lattice of the pseudomorphic layer is contracted. Thus, its body centred tetragonal (110) planes, which stay perpendicular to the surface, contract into denser-packed planes, i.e. in hcp ones. In the direction perpendicular to the surface, where the substrate does not have a direct influence on the film, the pseudomorphic layer relaxes into its natural close-packed phase, i.e. into hcp atomic planes. These planes appear as soon as the third pseudomorphic ML begins to grow. The stacking axis of the planes lies in the (100) surface of Nb and is locked by it. The fact that thick nano-films of Cu (up to 50 MLs), Ag and Au (up to 100 MLs) grow in the (112-bar0)-oriented hcp phase can be attributed to a much better fit of the hcp than of fcc stacking sequence to the four-fold symmetry of the Nb(001) surface

  7. Noble metal nanoparticle-functionalized ZnO nanoflowers for photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide

    DEFF Research Database (Denmark)

    Hussain, Muhammad; Sun, Hongyu; Karim, Shafqat

    2016-01-01

    Flower-like hierarchical Zinc oxide nanostructures synthesized by co-precipitation method have been hydrothermally functionalized with 8 nm Au NPs and 15 nm Ag nanoparticles. The photocatalytic and electrochemical performance of these structures are investigated. XPS studies show that the composite...... exhibits a strong interaction between noble metal nanoparticles (NPs) and Zinc oxide nanoflowers. The PL spectra exhibit UV emission arising due to near band edge transition and show that the reduced PL intensities of Au–ZnO and Ag–ZnO composites are responsible for improved photocatalytic activity arising...

  8. Self-consistent meta-generalized gradient approximation study of adsorption of aromatic molecules on noble metal surfaces

    DEFF Research Database (Denmark)

    Ferrighi, Lara; Madsen, Georg Kent Hellerup; Hammer, Bjørk

    2011-01-01

    aromatic molecules considered. The adsorption of pentacene is studied on Au, Ag, and Cu surfaces. In agreement with experiment, the adsorption energies are found to increase with decreasing nobleness, but the dependency is underestimated. We point out how the kinetic energy density can discriminate between...

  9. Study of metal specific interaction, F-LUMO and VL shift to understand interface of CuPc thin films and noble metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Sumona; Mukherjee, M., E-mail: manabendra.mukherjee@saha.ac.in

    2015-10-30

    Graphical abstract: - Highlights: • F-LUMO, a hybridized state near E{sub F} confirms partial charge transfer. • Non-significant role of partial charge transfer in VL shift over push back effect. • Pyrrole sites affected for partial charge transfer from Cu and Ag substrates. • Negligible effect on pyrrole cites for Pt and Au substrates. - Abstract: The performances of organic electronic devices are significantly associated with their energy level alignment at organic semiconductor/metal–electrode interfaces. The electronic character of an organic semiconducting molecular over-layer on a metal surface can vary from semiconducting to metallic, depending on the nature of the molecular orbitals with respect to the Fermi level of the electrode. The general tendency of extrapolating established models for single crystal substrates to ‘real’ device substrates is highly misleading. Hence, the importance of metal specific interaction, former lowest unoccupied molecular orbital (F-LUMO) and vacuum level (VL) shift have been investigated as a function of thickness of the deposited films by means of photoelectron spectroscopy (XPS and UPS) to understand the interface between CuPc and Cu, Ag, Pt and Au foils sequentially. The XPS data provides the signature of affectability of pyrrole sites of CuPc molecules for partial charge transfer from Cu and Ag substrates while a negligible effect on pyrrole cites resulted for Pt and Au substrates. Furthermore, the appearance of F-LUMO, a hybridized state close to the Fermi level gives confirmatory information about partial charge transfer. Contrary to the general belief that vacuum level shift caused by charge transfer can partially or totally cancel that for push back effect, our observation indicates that the partial charge transfer does not play significant role in the shift of vacuum level. The entire thickness dependent electronic energy level alignment of CuPc films on all noble metal substrates is explained in terms

  10. Study of metal specific interaction, F-LUMO and VL shift to understand interface of CuPc thin films and noble metal surfaces

    International Nuclear Information System (INIS)

    Sinha, Sumona; Mukherjee, M.

    2015-01-01

    Graphical abstract: - Highlights: • F-LUMO, a hybridized state near E_F confirms partial charge transfer. • Non-significant role of partial charge transfer in VL shift over push back effect. • Pyrrole sites affected for partial charge transfer from Cu and Ag substrates. • Negligible effect on pyrrole cites for Pt and Au substrates. - Abstract: The performances of organic electronic devices are significantly associated with their energy level alignment at organic semiconductor/metal–electrode interfaces. The electronic character of an organic semiconducting molecular over-layer on a metal surface can vary from semiconducting to metallic, depending on the nature of the molecular orbitals with respect to the Fermi level of the electrode. The general tendency of extrapolating established models for single crystal substrates to ‘real’ device substrates is highly misleading. Hence, the importance of metal specific interaction, former lowest unoccupied molecular orbital (F-LUMO) and vacuum level (VL) shift have been investigated as a function of thickness of the deposited films by means of photoelectron spectroscopy (XPS and UPS) to understand the interface between CuPc and Cu, Ag, Pt and Au foils sequentially. The XPS data provides the signature of affectability of pyrrole sites of CuPc molecules for partial charge transfer from Cu and Ag substrates while a negligible effect on pyrrole cites resulted for Pt and Au substrates. Furthermore, the appearance of F-LUMO, a hybridized state close to the Fermi level gives confirmatory information about partial charge transfer. Contrary to the general belief that vacuum level shift caused by charge transfer can partially or totally cancel that for push back effect, our observation indicates that the partial charge transfer does not play significant role in the shift of vacuum level. The entire thickness dependent electronic energy level alignment of CuPc films on all noble metal substrates is explained in terms of a

  11. Plasma-chemical production of metal-polypyrrole-catalysts for the reduction of oxygen in fuel cells. Precious-metal-free catalysts for fuel cells.; Plasmachemische Erzeugung von Metall-Polypyrrol-Katalysatoren fuer die Sauerstoffreduktion in Brennstoffzellen. Edelmetallfreie Katalysatoren fuer Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Christian

    2013-07-01

    This thesis is about the production of non noble metal catalysts for the oxygen reduction reaction in fuel cells. Therefore, a novel dual plasma process is developed, constructed and the so-produced films are analysed by various electrochemical (CV, RDE and RRDE) and structural methods (SEM, EDX, IR, XPS, conductivity, XRD, NEXAFS, EXAFS and TEM). It is shown, that by doing this, non noble metal catalysts could be produced without the need of a high temperature treatment. Furthermore, the catalytic activity obtained is superior to that of chemically produced metal-polypyrrole films.

  12. TLC-SERS Plates with a Built-In SERS Layer Consisting of Cap-Shaped Noble Metal Nanoparticles Intended for Environmental Monitoring and Food Safety Assurance

    Directory of Open Access Journals (Sweden)

    H. Takei

    2015-01-01

    Full Text Available We report on a thin layer chromatograph (TLC with a built-in surface enhanced Raman scattering (SERS layer for in-situ identification of chemical species separated by TLC. Our goal is to monitor mixture samples or diluted target molecules suspended in a host material, as happens often in environmental monitoring or detection of food additives. We demonstrate that the TLC-SERS can separate mixture samples and provide in-situ SERS spectra. One sample investigated was a mixture consisting of equal portions of Raman-active chemical species, rhodamine 6 G (R6G, crystal violet (CV, and 1,2-di(4-pyridylethylene (BPE. The three components could be separated and their SERS spectra were obtained from different locations. Another sample was skim milk with a trace amount of melamine. Without development, no characteristic peaks were observed, but after development, a peak was observed at 694 cm−1. Unlike previous TLC-SERS whereby noble metal nanoparticles are added after development of a sample, having a built-in SERS layer greatly facilitates analysis as well as maintaining high uniformity of noble metal nanoparticles.

  13. X-ray and magnetic studies on intermetallic phases of the type CaCu5 using noble metals and strontium

    International Nuclear Information System (INIS)

    Heumann, T.; Birnschein, R.R.

    1976-01-01

    The intermetallic phases SrAu 5 , SrAg 5 and SrPd 5 and their binary part systems with the specific noble metals as well as the pseudobinary series SrAu 5 -SrPd 5 and SrAg 5 -SrPd 5 are dealt with within the framework of this lecture. The noble metals gold, silver and palladium form AB 5 phases with strontium which cristallize in CaCu 5 structure. The atomic susceptibilities of the part systems Ag-SrAg 5 and Au-SrAu 5 as a function of the Sr concentration, of the part system Pd-SrPd 5 as a function of the temperature and the Sr concentration, of Au-Pd as a function of the Pd concentration, of the series SrAu 5 -SrPd 5 as a function of the SrPd 5 concentration, of the series SrAg 5 -SrPd 5 as function of the SrPd 5 concentration, the electrical resistance of Ag-SrAg 5 and Au-SrAu 5 as function of the Sr concentration, the lattice constants of the series SrAu 5 -SrPd 5 as a function of the SrPd 5 concentration, as well as the number of effective magnetones in the system Au-Pd as a function of the Pd concentration, were measured and evaluated. (orig./LH) [de

  14. Sources of metals in the Porgera gold deposit, Papua New Guinea: Evidence from alteration, isotope, and noble metal geochemistry

    Science.gov (United States)

    Richards, Jeremy P.; McCulloch, Malcolm T.; Chappell, Bruce W.; Kerrich, Robert

    1991-02-01

    The Porgera gold deposit is spatially and temporally associated with the Late Miocene, mafic, alkalic, epizonal Porgera Intrusive Complex (PIC), located in the highlands of Papua New Guinea (PNG). The highlands region marks the site of a Tertiary age continent-island-arc collision zone, located on the northeastern edge of the Australasian craton. The PIC was emplaced within continental crust near the Lagaip Fault Zone, which represents an Oligocene suture between the craton and volcano-sedimentary rocks of the Sepik terrane. Magmatism at Porgera probably occurred in response to the Late Miocene elimination of an oceanic microplate, and subsequent Early Pliocene collision between the craton margin and an arc system located on the Bismarck Sea plate. Gold mineralization occurred within 1 Ma of the time of magmatism. Metasomatism accompanying early disseminated Au mineralization in igneous host rocks resulted in additions of K, Rb, Mn, S, and CO 2, and depletions of Fe, Mg, Ca, Na, Ba, and Sr; rare-earth and high-field-strength elements remained largely immobile. Pervasive development of illite-K-feldspar-quartz-carbonate alteration assemblages suggests alteration by mildly acidic, 200 to 350°C fluids, at high water/ rock ratios. Strontium and lead isotopic compositions of minerals from early base-metal sulphide veins associated with K-metasomatism, and later quartz-roscoelite veins carrying abundant free gold and tellurides, are remarkably uniform (e.g., 87Sr /86Sr = 0.70745 ± 0.00044 [n = 10] , 207Pb /204Pb = 15.603 ± 0.004 [n = 15] ). These compositions fall between those of unaltered igneous and sedimentary host rocks, and specifically sedimentary rocks from the Jurassic Om Formation which underlies the deposit (igneous rocks: 87Sr /86Sr ≈ 0.7035 , 207Pb /204Pb ≈ 15.560 ; Om Formation: 87Sr /86Sr |t~ 0.7153 , 207Pb /204Pb ≈ 15.636 ). It is therefore suggested that the hydrothermal fluids acquired their Sr and Pb isotopic signatures by interaction with, or

  15. Proceedings of the 4th seminar of R and D on advanced ORIENT 'strategy and technical requirement for new resource of noble metals in advanced atomic energy science'

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Yuji; Koyama, Shinichi; Ozawa, Masaki [Japan Atomic Energy Agency, Nuclear Science and Engineering Directorate, Tokai, Ibaraki (Japan)

    2010-12-15

    The 4th Seminar of R and D on advanced ORIENT, 'Strategy and technical requirement for new resource of noble metals in advanced atomic energy science' was held in Swany hall, Rokkasho-Mura, on July 30th, 2010 organized by Japan Atomic Energy Agency. The first meeting of this seminar was held at Oarai, Ibaraki on May, 2007, the second seminar was held at Tokai, on November, 2008, and the third seminar was held at Sendai, on October, 2009. Spent nuclear fuel should be recognized as not only mass of radioactive elements but also potentially useful materials including platinum metals and rare earth elements. Taking the cooperation with universities related companies and research institutes, into consideration, we aimed at expanding and progressing the basic researches. In this seminar, there are many poster presentation included, and the useful discussion with many students are performed. This report records abstracts and figures submitted from the oral speakers in this seminar. (author)

  16. Metodologia para o crescimento de esferas monocristalinas de metais nobres A methodology for the growing of single crystal spheres of noble metals

    Directory of Open Access Journals (Sweden)

    Luiz H. Dall'Antonia

    1999-09-01

    Full Text Available This paper describes in detail a technique employed to grow quasi-spherical single crystals of noble metals for electrochemical applications, using platinum as an example. The metal beads were formed by melting the extremity of a wire in an oxygen / butane flame. X-ray techniques were used to check the crystallization and to determine the orientation of the crystals. Treatment with a pure hydrogen flame followed by a cooling procedure in a hydrogen / argon atmosphere were used for conditioning the well-defined platinum single crystal surfaces. Finally, electrochemical characterization of the Pt(111, Pt(110 and Pt(100 surfaces was done in diluted sulfuric acid solution in the hydrogen adsorption / desorption potential region.

  17. Proceedings of the 4th seminar of R and D on advanced ORIENT 'strategy and technical requirement for new resource of noble metals in advanced atomic energy science'

    International Nuclear Information System (INIS)

    Sasaki, Yuji; Koyama, Shinichi; Ozawa, Masaki

    2010-12-01

    The 4th Seminar of R and D on advanced ORIENT, 'Strategy and technical requirement for new resource of noble metals in advanced atomic energy science' was held in Swany hall, Rokkasho-Mura, on July 30th, 2010 organized by Japan Atomic Energy Agency. The first meeting of this seminar was held at Oarai, Ibaraki on May, 2007, the second seminar was held at Tokai, on November, 2008, and the third seminar was held at Sendai, on October, 2009. Spent nuclear fuel should be recognized as not only mass of radioactive elements but also potentially useful materials including platinum metals and rare earth elements. Taking the cooperation with universities related companies and research institutes, into consideration, we aimed at expanding and progressing the basic researches. In this seminar, there are many poster presentation included, and the useful discussion with many students are performed. This report records abstracts and figures submitted from the oral speakers in this seminar. (author)

  18. Electrochemistry of conductive polymers 39. Contacts between conducting polymers and noble metal nanoparticles studied by current-sensing atomic force microscopy.

    Science.gov (United States)

    Cho, Shin Hyo; Park, Su-Moon

    2006-12-28

    Electrical properties of contacts formed between conducting polymers and noble metal nanoparticles have been examined using current-sensing atomic force microscopy (CS-AFM). Contacts formed between electrochemically prepared pi-conjugated polymer films such as polypyrrole (PPy), poly(3-methylthiophene) (P3MeT), as well as poly(3,4-ethylenedioxythiophene) (PEDOT) and noble metal nanoparticles including platinum (Pt), gold (Au), and silver (Ag) have been examined. The Pt nanoparticles were electrochemically deposited on a pre-coated PPy film surface by reducing a platinum precursor (PtCl62-) at a constant potential. Both current and scanning electron microscopic images of the film showed the presence of Pt islands. The Au and Ag nanoparticles were dispersed on the P3MeT and PEDOT film surfaces simply by dipping the polymer films into colloid solutions containing Au or Ag particles for specified periods (5 to approximately 10 min). The deposition of Au or Ag particles resulted from either their physical adsorption or chemical bonding between particles and the polymer surface depending on the polymer. When compared with PPy, P3MeT and PEDOT showed a stronger binding to Au or Ag nanoparticles when dipped in their colloidal solutions for the same period. This indicates that Au and Ag particles are predominantly linked with the sulfur atoms via chemical bonding. Of the two, PEDOT was more conductive at the sites where the particles are connected to the polymer. It appears that PEDOT has better aligned sulfur atoms on the surface and is strongly bonded to Au and Ag nanoparticles due to their strong affinity to gold and silver. The current-voltage curves obtained at the metal islands demonstrate that the contacts between these metal islands and polymers are ohmic.

  19. Efficient hydrogenation of biomass-derived furfural and levulinic acid on the facilely synthesized noble-metal-free Cu–Cr catalyst

    International Nuclear Information System (INIS)

    Yan, Kai; Chen, Aicheng

    2013-01-01

    Biomass-derived platform intermediate furfural and levulinic acid were efficiently hydrogenated to the value-added furfuryl alcohol and promising biofuel γ-valerolactone, respectively, using a noble-metal-free Cu–Cr catalyst, which was facilely and successfully synthesized by a modified co-precipitation method using the cheap metal nitrates. In the first hydrogenation of furfural, 95% yield of furfuryl alcohol was highly selectively produced at 99% conversion of furfural under the mild conditions. For the hydrogenation of levulinic acid, 90% yield of γ-valerolactone was highly selectively produced at 97.8% conversion. Besides, the physical properties of the resulting Cu–Cr catalysts were studied by XRD (X-ray diffraction), EDX (Energy-dispersive X-ray), TEM (Transmission electron microscopy) and XPS (X-ray photoelectron spectroscopy) to reveal their influence on the catalytic performance. Subsequently, different reaction parameters were studied and it was found that Cu 2+ /Cr 3+ ratios (0.5, 1 and 2), reaction temperature (120–220 °C) and hydrogen pressure (35–70 bar) presented important influence on the catalytic activities. In the end, the stability of the Cu–Cr catalysts was also studied. - Highlights: • A noble-metal-free Cu–Cr catalyst was successfully synthesized using metal nitrates. • Cu–Cr catalysts were highly selective hydrogenation of biomass-derived furfural to FA. • Cu–Cr catalysts were efficient for hydrogenation of biomass-derived LA to biofuel GVL. • The physical properties of the resulting Cu–Cr catalysts were systematically studied. • Reaction parameters and stability in the hydrogenation of furfural were studied in details

  20. 4,6-Dimethyl-dibenzothiophene conversion over Al{sub 2}O{sub 3}-TiO{sub 2}-supported noble metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, Sara [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Vicentina, Iztapalapa, 09340, Mexico, D.F. (Mexico); Escobar, Jose, E-mail: jeaguila@imp.mx [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, San Bartolo Atepehuacan, Gustavo A. Madero, 07730, Mexico, D.F. (Mexico); Vazquez, Armando; Reyes, Jose Antonio de los [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Vicentina, Iztapalapa, 09340, Mexico, D.F. (Mexico); Hernandez-Barrera, Melissa [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, San Bartolo Atepehuacan, Gustavo A. Madero, 07730, Mexico, D.F. (Mexico)

    2011-03-15

    Research highlights: {yields} Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-TiO{sub 2} (molar ratio Al/Ti = 2, AT2) mixed oxides were pore-filling impregnated to obtain Pd, Pt and Pd-Pt catalysts with {approx}1 wt% nominal metal loading. {yields} Reduced catalysts were tested in the 4,6-dimethyl-dibenzothiophene hydrodesulfurization (HDS). {yields} In Pd-containing materials, TiO{sub 2} incorporation into the alumina support was favorable to the catalytic activity of noble metal catalysts. {yields} Enhanced intrinsic activity (per exposed metallic site) was obtained in Pt-containing catalysts supported on the AT2 mixed oxide. {yields} Yield to different products over various catalysts seemed to be strongly influenced by metallic particles dispersion. - Abstract: Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-TiO{sub 2} (molar ratio Al/Ti = 2, AT2) mixed oxides were synthesized using a low-temperature sol-gel method and were further pore-filling impregnated to obtain Pd and Pt catalysts with {approx}1 wt% nominal metal loading. Simultaneous impregnation was used to prepare bimetallic materials at Pd:Pt = 80:20. Solids characterization was carried out by N{sub 2}-physisorption, high-resolution transmission electron microscopy (HR-TEM and E-FTEM), X-ray diffraction, temperature-programmed reduction and CO-chemisorption. Reduced (350 deg. C, H{sub 2} flow) catalysts were tested in the 4,6-dimethyl-dibenzothiophene hydrodesulfurization (HDS) (in n-dodecane, at 300 deg. C and 5.5 MPa, batch reactor). In Pd-containing materials, TiO{sub 2} incorporation into the alumina support was favorable to the catalytic activity of noble metal catalysts, where bimetallic Pd-Pt with AT2 carrier had the highest organo-S compound conversion. Enhanced intrinsic activity (per exposed metallic site) was obtained in Pt-containing catalysts supported on the AT2 mixed oxide (as compared to alumina-supported ones). Yield to different products over various catalysts seemed to be strongly influenced by

  1. Surface modification of g-C3N4 by hydrazine: Simple way for noble-metal free hydrogen evolution catalysts

    KAUST Repository

    Chen, Yin

    2015-11-02

    The graphitic carbon nitride (g-C3N4) usually is thought to be an inert material and it’s difficult to have the surface terminated NH2 groups functionalized. By modifying the g-C3N4 surface with hydrazine, the diazanyl group was successfully introduced onto the g-C3N4 surface, which allows the introduction with many other function groups. Here we illustrated that by reaction of surface hydrazine group modified g-C3N4 with CS2 under basic condition, a water electrolysis active group C(=S)SNi can be implanted on the g-C3N4 surface, and leads to a noble metal free hydrogen evolution catalyst. This catalyst has 40% hydrogen evolution efficiency compare to the 3 wt% Pt photo precipitated g-C3N4, with only less than 0.2 wt% nickel.

  2. Surface modification of g-C3N4 by hydrazine: Simple way for noble-metal free hydrogen evolution catalysts

    KAUST Repository

    Chen, Yin; Lin, Bin; Wang, Hong; Yang, Yong; Zhu, Haibo; Yu, Weili; Basset, Jean-Marie

    2015-01-01

    The graphitic carbon nitride (g-C3N4) usually is thought to be an inert material and it’s difficult to have the surface terminated NH2 groups functionalized. By modifying the g-C3N4 surface with hydrazine, the diazanyl group was successfully introduced onto the g-C3N4 surface, which allows the introduction with many other function groups. Here we illustrated that by reaction of surface hydrazine group modified g-C3N4 with CS2 under basic condition, a water electrolysis active group C(=S)SNi can be implanted on the g-C3N4 surface, and leads to a noble metal free hydrogen evolution catalyst. This catalyst has 40% hydrogen evolution efficiency compare to the 3 wt% Pt photo precipitated g-C3N4, with only less than 0.2 wt% nickel.

  3. Surface Functionalization of g-C 3 N 4 : Molecular-Level Design of Noble-Metal-Free Hydrogen Evolution Photocatalysts

    KAUST Repository

    Chen, Yin

    2015-06-12

    A stable noble-metal-free hydrogen evolution photocatalyst based on graphite carbon nitride (g-C3N4) was developed by a molecular-level design strategy. Surface functionalization was successfully conducted to introduce a single nickel active site onto the surface of the semiconducting g-C3N4. This catalyst family (with less than 0.1 wt% of Ni) has been found to produce hydrogen with a rate near to the value obtained by using 3 wt% platinum as co-catalyst. This new catalyst also exhibits very good stability under hydrogen evolution conditions, without any evidence of deactivation after 24h. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Ni supported CdIn2S4 spongy-like spheres: a noble metal free high-performance sunlight driven photocatalyst for hydrogen production.

    Science.gov (United States)

    Vu, Manh-Hiep; Nguyen, Chinh-Chien; Sakar, M; Do, Trong-On

    2017-11-08

    Nickel supported CdIn 2 S 4 (Ni-CIS) spongy-like spheres have been developed using alcoholysis followed by a sulfidation process. The formation of nanocrystalline-single phase CdIn 2 S 4 was confirmed using X-ray diffraction studies. Electron microscopy images showed that the spongy-like spheres are composed of CdIn 2 S 4 nanoparticles with average sizes of around 25 nm. X-ray photoelectron spectra indicated the presence of elements with their respective stable oxidation states that led to the formation of single phase CdIn 2 S 4 with enhanced structural integrity and chemical composition. The absorption spectra indicated the visible light activity of the material and the band gap energy is deduced to be 2.23 eV. The photocatalytic efficiency of the synthesized Ni-CIS in relation to its ability to produce hydrogen under solar light irradiation is estimated to be 1060 μmol g -1 h -1 , which is around 5.5 and 3.6 fold higher than that of Pt-CIS (180 μmol g -1 h -1 ) and Pd-CIS (290 μmol g -1 h -1 ), respectively, as obtained in this study. Accordingly, the mechanism of the observed efficiency of the Ni-CIS nanoparticles is also proposed. The recyclability test showed consistent hydrogen evolution efficiency over 3 cycles (9 h), which essentially revealed the excellent photo- and chemical-stability of the photocatalyst. The strategy to utilize non-noble metals such as Ni, rather than noble-metals, as a co-catalyst opens up a new possibility to develop low cost and high-performance sunlight-driven photocatalysts as achieved in this study.

  5. Development of casting investment preventing blackening of noble metal alloys part 1. Application of developed investment for Ag-Pd-Cu-Au alloy.

    Science.gov (United States)

    Kakuta, Kiyoshi; Nakai, Akira; Goto, Shin-ichi; Wakamatsu, Yasushi; Yara, Atushi; Miyagawa, Yukio; Ogura, Hideo

    2003-03-01

    The objective of this study is to develop a casting investment that prevents the blackening of the cast surface of noble metal alloys. The experimental investments were prepared using a gypsum-bonded investment in which the metallic powders such as boron (B), silicon (Si), aluminum (Al) and titanium (Ti) were added as oxidizing agents. An Ag-Pd-Cu-Au alloy was cast into the mold made of the prepared investment. The effect of the addition of each metal powder was evaluated from the color difference between the as-cast surface and the polished surface of the cast specimen. The color of the as-cast surface approached that of the polished surface with increasing B and Al content. A lower mean value in the color difference was obtained at 0.25-1.00 mass% B content. B and Al are useful as an additive in a gypsum-bonded investment to prevent the blackening of an Ag-Pd-Cu-Au alloy. The effects of Si and Ti powder addition could not be found.

  6. Phenolic Fractions from Muscadine Grape "Noble" Pomace can Inhibit Breast Cancer Cell MDA-MB-231 Better than those from European Grape "Cabernet Sauvignon" and Induce S-Phase Arrest and Apoptosis.

    Science.gov (United States)

    Luo, Jianming; Wei, Zheng; Zhang, Shengyu; Peng, Xichun; Huang, Yu; Zhang, Yali; Lu, Jiang

    2017-05-01

    Tons of grape pomace which still contained a rich amount of plant polyphenols, is discarded after winemaking. Plant polyphenols have multi-functional activities for human body. In this study, polyphenols of pomaces from Muscadinia rotundifolia "Noble" and Vitis vinifera "Cabernet Sauvignon" were extracted and fractionated, and then they were analyzed with LC-MS and the inhibitory effects on breast cancer cells were compared. The inhibition on MDA-MB-231 cells of fractions from "Noble" was further evaluated. The results showed that polyphenols from 2 grape pomaces could be separated into 3 fractions, and ellagic acid and/or ellagitannins were only detected in fractions from "Noble" pomace. All 3 fractions from "Noble" pomace inhibited MDA-MB-231 better than MCF-7. But fraction 2 from "Cabernet Sauvignon" inhibited MCF-7 better while fraction 1 and fraction 3 inhibited both 2 cells similarly. Moreover, the fractions from "Noble" pomace rather than "Cabernet Sauvignon" can inhibit MDA-MB-231 better. Finally, fractions from "Noble" pomace can induce S-phase arrest and apoptosis on MDA-MB-231. These findings suggested the extracts from grape pomace especially those from "Noble," are potential to be utilized as health beneficial products or even anti-breast cancer agents. © 2017 Institute of Food Technologists®.

  7. Potential hazards of particulate noble metal emissions from car exhaust catalysts. Gefaehrdungspotential von partikulaeren Edelmetallemissionen aus Automobilabgas-Katalysatoren

    Energy Technology Data Exchange (ETDEWEB)

    Stoeber, W.

    1985-01-01

    The aim of the present bibliographical study is to investigate into the possibility of health impairment by emissions of eroded and particulate precious metals of catalytic converters for motor-car exhaust gas. Connected therewith is a survey of environmental pollution so far caused by platinum metals and of their biological impact. The risk estimation relates solely to the data on emission obtained during normal operation; research work is still needed with respect to the chemical composition, the size distribution and the particle forms of the precious metals emitted. Besides, only limited data are available as to the environmental behaviour of the precious metals.

  8. Disruption, segregation, and passivation for Pd and noble-metal overlayers on YBa2Cu3O/sub 6.9/

    International Nuclear Information System (INIS)

    Wagener, T.J.; Gao, Y.; Vitomirov, I.M.; Aldao, C.M.; Joyce, J.J.; Capasso, C.; Weaver, J.H.; Capone II, D.W.

    1988-01-01

    We have investigated interfaces formed when Pd and the noble metals Cu, Ag, and Au are deposited onto polycrystalline samples of YBa 2 Cu 3 O/sub 6.9/ fractured in ultrahigh vacuum. Synchrotron-radiation photoemission results show that Cu and Pd overlayers leach oxygen from the underlying YBa 2 Cu 3 O/sub 6.9/ substrate, disrupt the superconductor, and destroy electronic states near the Fermi level. Interface reactions become kinetically limited at room temperature after the deposition of ∼4 A of Cu or Pd, significantly sooner than for the reactive metals Fe, Al, Ti, and In. The presence of Ba near the surface after the deposition of more than 100 A of Cu and Pd reflects substrate disruption and subsequent surface segregation. In contrast, overlayers of Ag and Au do not disrupt the superconductor substrate, no segregation is observed, but the overlayers are nonuniform and the quality of passivation is in question for coverages <100 A

  9. Noble-metal-free NiO@Ni-ZnO/reduced graphene oxide/CdS heterostructure for efficient photocatalytic hydrogen generation

    Science.gov (United States)

    Chen, Fayun; Zhang, Laijun; Wang, Xuewen; Zhang, Rongbin

    2017-11-01

    Noble-metal-free semiconductor materials are widely used for photocatalytic hydrogen generation because of their low cost. ZnO-based heterostructures with synergistic effects exhibit an effective photocatalytic activity. In this work, NiO@Ni-ZnO/reduced graphene oxide (rGO)/CdS heterostructures are synthesized by a multi-step method. rGO nanosheets and CdS nanoparticles were introduced into the heterostructures via a redox reaction and light-assisted growth, respectively. A novel Ni-induced electrochemical growth method was developed to prepare ZnO rods from Zn powder. NiO@Ni-ZnO/rGO/CdS heterostructures with a wide visible-light absorption range exhibited highly photocatalytic hydrogen generation rates under UV-vis and visible light irradiation. The enhanced photocatalytic activity is attributed to the Ni nanoparticles that act as cocatalysts for capturing photoexcited electrons and the improved synergistic effect between ZnO and CdS due to the rGO nanosheets acting as photoexcited carrier transport channels.

  10. Noble Metal Decoration and Presulfation on TiO2: Increased Photocatalytic Activity and Efficient Esterification of n-Butanol with Citric Acid

    Directory of Open Access Journals (Sweden)

    Yu Niu

    2016-01-01

    Full Text Available TiO2 has been widely used as a key catalyst in photocatalytic reactions; it also shows good catalytic activity for esterification reactions. Different sulfated M-TiO2 nanoparticles (M = Ag, Au, Rh, and Pt were prepared by photodeposition and ultrasonic methods. The results show that the noble metal nanoparticles, which were loaded onto a TiO2 surface, slightly affected the crystal phase and particle size of TiO2. Among all the catalysts, SO42-/Au-TiO2 exhibited the best catalytic activity in the esterification reaction for the synthesis of citric acid n-butyl acetate and in the decomposition of methyl orange, as confirmed by a high conversion rate of up to 98.2% and 100% degradation rate, respectively. This can be attributed to an increase in the Lewis acidity of the catalyst and increased separation efficiency of electron-hole pairs. This superior catalyst has great potential applications in esterification reactions and wastewater treatments.

  11. WS2 as an Effective Noble-Metal Free Cocatalyst Modified TiSi2 for Enhanced Photocatalytic Hydrogen Evolution under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Dongmei Chu

    2016-09-01

    Full Text Available A noble-metal free photocatalyst consisting of WS2 and TiSi2 being used for hydrogen evolution under visible light irradiation, has been successfully prepared by in-situ formation of WS2 on the surface of TiSi2 in a thermal reaction. The obtained samples were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectrometry (EDX, transmission electron microscopy (TEM, and X-ray photoelectron spectroscopy (XPS. The results demonstrate that WS2 moiety has been successfully deposited on the surface of TiSi2 and some kind of chemical bonds, such as Ti-S-W and Si-S-W, might have formed on the interface of the TiSi2 and WS2 components. Optical and photoelectrochemical investigations reveal that WS2/TiSi2 composite possesses lower hydrogen evolution potential and enhanced photogenerated charge separation and transfer efficiency. Under 6 h of visible light (λ > 420 nm irradiation, the total amount of hydrogen evolved from the optimal WS2/TiSi2 catalyst is 596.4 μmol·g−1, which is around 1.5 times higher than that of pure TiSi2 under the same reaction conditions. This study shows a paradigm of developing the effective, scalable and inexpensive system for photocatalytic hydrogen generation.

  12. First-principles dynamics treatment of light emission in collisions between alkali-metal atom and noble-gas atom collisions at 10keV

    Science.gov (United States)

    Pacheco, Alexander B.; Reyes, Andrés; Micha, David A.

    2006-12-01

    Collision-induced light emission during the interaction of an alkali-metal atom and a noble-gas atom is treated within a first-principles, or direct, dynamics approach that calculates a time-dependent electric dipole for the whole system, and spectral emission cross sections from its Fourier transform. These cross sections are very sensitive to excited diatomic potentials and a source of information on their shape. The coupling between electronic transitions and nuclear motions is treated with atomic pseudopotentials and an electronic density matrix coupled to trajectories for the nuclei. A recently implemented pseudopotential parametrization scheme is used here for the ground and excited states of the LiHe system, and to calculate state-to-state dipole moments. To verify the accuracy of our new parameters, we recalculate the integral cross sections for the LiHe system in the keV energy regime and obtain agreement with other results from theory and experiment. We further present results for the emission spectrum from 10keV Li(2s)+He collisions, and compare them to experimental values available in the region of light emitted at 300-900nm .

  13. Barrierless growth of precursor-free, ultrafast laser-fragmented noble metal nanoparticles by colloidal atom clusters - A kinetic in situ study.

    Science.gov (United States)

    Jendrzej, Sandra; Gökce, Bilal; Amendola, Vincenzo; Barcikowski, Stephan

    2016-02-01

    Unintended post-synthesis growth of noble metal colloids caused by excess amounts of reactants or highly reactive atom clusters represents a fundamental problem in colloidal chemistry, affecting product stability or purity. Hence, quantified kinetics could allow defining nanoparticle size determination in dependence of the time. Here, we investigate in situ the growth kinetics of ps pulsed laser-fragmented platinum nanoparticles in presence of naked atom clusters in water without any influence of reducing agents or surfactants. The nanoparticle growth is investigated for platinum covering a time scale of minutes to 50days after nanoparticle generation, it is also supplemented by results obtained from gold and palladium. Since a minimum atom cluster concentration is exceeded, a significant growth is determined by time resolved UV/Vis spectroscopy, analytical disc centrifugation, zeta potential measurement and transmission electron microscopy. We suggest a decrease of atom cluster concentration over time, since nanoparticles grow at the expense of atom clusters. The growth mechanism during early phase (<1day) of laser-synthesized colloid is kinetically modeled by rapid barrierless coalescence. The prolonged slow nanoparticle growth is kinetically modeled by a combination of coalescence and Lifshitz-Slyozov-Wagner kinetic for Ostwald ripening, validated experimentally by the temperature dependence of Pt nanoparticle size and growth quenching by Iodide anions. Copyright © 2015. Published by Elsevier Inc.

  14. Redox potential monitoring as a method to control unwanted noble metal-catalyzed hydrogen generation from formic acid treatment of simulated nuclear waste media

    International Nuclear Information System (INIS)

    King, R.B.; Bhattacharyya, N.K.

    1998-01-01

    Simulants for the Hanford Waste Vitrification Plant feed containing the major nonradioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO 3 2- , NO 3 - , and NO 2 - were used to study redox potential changes in reactions of formic acid at 90 C catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Such reactions were monitored using gas chromatography to analyze the CO 2 , H 2 , NO, and N 2 O in the gas phase and a redox electrode to follow redox potential changes as a function of time. In the initial phase of formic acid addition to nitrite-containing feed simulants, the redox potential of the reaction mixture rises typically to +400 mV relative to the Al/AgCl electrode because of the generation of the moderately strongly oxidizing nitrous acid. No H 2 production occurs at this stage of the reaction as long as free nitrous acid is present. After all of the nitrous acid has been destroyed by reduction to N 2 O and NO and disproportionation to NO/NO 3 - , the redox potential of the reaction mixture becomes more negative than the Ag/AgCl electrode. The experiments outlined in this paper suggest the feasibility of controlling the production of H 2 by limiting the amount of formic acid used and monitoring the redox potential during formic acid treatment

  15. Noble metals can have different effects on photocatalysis over metal-organic frameworks (MOFs): a case study on M/NH₂-MIL-125(Ti) (M=Pt and Au).

    Science.gov (United States)

    Sun, Dengrong; Liu, Wenjun; Fu, Yanghe; Fang, Zhenxing; Sun, Fangxiang; Fu, Xianzhi; Zhang, Yongfan; Li, Zhaohui

    2014-04-14

    M-doped NH2-MIL-125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) analyses, N2-sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible-light irradiations showed that the noble metal-doping on NH2-MIL-125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2-MIL-125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt- and Au-loaded NH2-MIL-125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH2-MIL-125(Ti), Pt/NH2-MIL-125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2-MIL-125(Ti).The photocatalytic mechanisms over M/NH2-MIL-125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2-MIL-125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2-MIL-125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal-doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. The effect of noble metal additives on the optimum operating temperature of SnO2 gas sensors

    Science.gov (United States)

    Mohammad-Yousefi, S.; Rahbarpour, S.; Ghafoorifard, H.

    2017-12-01

    The effect of Pd and Au additives on gas sensing properties of SnO2 was investigated. SnO2 pallets were fabricated and sintered at 900 °C for 90 minutes. Several nanometer layers of Pd and Au were deposited on separate SnO2 pallets and were intentionally dispersed into the SnO2 pallets by long heat treatment (400 °C for 1 Day). All metal loaded samples showed significant enhancement in response level and optimum operating temperature compare to pure SnO2 gas sensors. The amount of enhancement was strongly dependent on the material and the thickness of deposited metal layer. Studying butanol response showed that increasing the thickness of metal causes the response level to increase. Further thickness increase caused contrary effect and decreased the performance of sensors. Best results were achieved at 10 nm-thick Au and 7 nm-thick Pd. Generally, Pd-SnO2 samples demonstrated better performance than Au-SnO2 ones, however, Au-SnO2 samples were proved to be good candidate to sense reducing gases with lower hydrogen atoms in their formula. Given experimental results were also good evidence of chemical activity of gold and simply confirms the relation between chemical activity and gold particle size. Results were qualitatively described by gas diffusion theory and surface reactions take place on metal particles.The first section in your paper

  17. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    Science.gov (United States)

    Li, Siheng; Wang, Enbo; Tian, Chungui; Mao, Baodong; Kang, Zhenhui; Li, Qiuyu; Sun, Guoying

    2008-07-01

    In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag@ MFe 2O 4 ( M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag@C microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe 3+ and M 2+ on the surface of the Ag@C spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core.

  18. Characterization and H2-O2 reactivity of noble nano-metal tailored single wall nano-carbons

    International Nuclear Information System (INIS)

    K Kaneko; T Itoh; E Bekyarova; H Kanoh; S Utsumi; H Tanaka; M Yudasaka; S Iijima; S Iijima

    2005-01-01

    Full text of publication follows: Single wall carbon nano-tube (SWNT) and single wall carbon nano-horn (SWNH) have nano-spaces in their particles and the nano-spaces become open by oxidation. In particular, SWNH forms a unique colloidal structure which has micropores and meso-pores between the SWNH particles. Although non-treated SWNH colloids have quasi-one dimensional nano-pores [1], oxidized SWNH colloids have both of interstitial and internal nano-pores [2-5]. SWNH colloids show excellent supercritical methane storage ability [6], molecular sieving effect [7], and unique hydrogen adsorption characteristic [8]. Selective adsorptivity of SWNH colloids for H 2 and D 2 due to uncertainty principle of those molecules was shown [9-10]. As SWNH has no metallic impurities, we can study the effect of tailoring of metallic nano-particles on the surface activities of SWNH [11]. We tailored Pd or Pt nano-particles on SWNH and SWNH oxidized at 823 K (ox-SWNH) using poly[(2-oxo-pyrrolidine-1-yl)ethylene]. The oxidation of SWNH donates nano-scale windows to the single wall. The tailored metal amount was determined by TG analysis. TEM showed uniform dispersion of nano-metal particles of 2-3 nm in the diameter on SWNH. The nitrogen adsorption amount of SWNH oxidized decreases by tailoring, indicating that nano-particles are attached to the nano-scale windows. The electronic states of tailored metals were characterized by X-ray photoelectron spectroscopy. The surface activities of Pd tailored SWNH and ox-SWNH were examined for the reaction of hydrogen and oxygen near room temperature. The catalytic reactivities of Pd tailored SWNH and ox-SWNH were 4 times greater than that of Pd-dispersed activated carbon. The temperature dependence of the surface activity will be discussed with the relevance to the tube porosity. References [1] T. Ohba et al, J. Phys. Chem. In press. [2] S. Utsumi et al, J. Phys. Chem. In press. [3] C.- Min Yang, et al. Adv. Mater. In press. [4]C.M. Yang, J

  19. Size characterisation of noble-metal nano-crystals formed in sapphire by ion irradiation and subsequent thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mota-Santiago, Pablo-Ernesto [Instituto de Fisica, Universidad Nacional Autonoma de Mexico A.P. 20-364 01000 Mexico D.F. (Mexico); Crespo-Sosa, Alejandro, E-mail: crespo@fisica.unam.mx [Instituto de Fisica, Universidad Nacional Autonoma de Mexico A.P. 20-364 01000 Mexico D.F. (Mexico); Jimenez-Hernandez, Jose-Luis; Silva-Pereyra, Hector-Gabriel; Reyes-Esqueda, Jorge-Alejandro; Oliver, Alicia [Instituto de Fisica, Universidad Nacional Autonoma de Mexico A.P. 20-364 01000 Mexico D.F. (Mexico)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Systematic study on the formation of Ag and Au nano-particles in Al{sub 2}O{sub 3}. Black-Right-Pointing-Pointer Annealing in a reducing atmosphere, below the metal melting point is more suitable. Black-Right-Pointing-Pointer Au nano-particles grow up to 15 nm and Ag nano-particles up to 45 nm in radius. Black-Right-Pointing-Pointer Ostwald ripening is the mechanism responsible for the formation of large nanoparticles. Black-Right-Pointing-Pointer Optical properties of metallic nano-particles in Al{sub 2}O{sub 3} can be related to their size. - Abstract: Metallic nano-particles embedded in transparent dielectrics are very important for new technological applications because of their unique optical properties. These properties depend strongly on the size and shape of the nano-particles. In order to achieve the synthesis of metallic nano-particles it has been used the technique of ion implantation. This is a very common technique because it allows the control of the depth and concentration of the metallic ions inside the sample, limited mostly by straggling, without introducing other contaminant agents. The purpose of this work was to measure the size of the nano-particles grown under different conditions in Sapphire and its size evolution during the growth process. To achieve this goal, {alpha}-Al{sub 2}O{sub 3} single crystals were implanted with Ag or Au ions at room temperature with different fluences (from 2 Multiplication-Sign 10{sup 16} ions/cm{sup 2} to 8 Multiplication-Sign 10{sup 16} ions/cm{sup 2}). Afterwards, the samples were annealed at different temperatures (from 600 Degree-Sign C to 1100 Degree-Sign C) in oxidising, reducing, Ar or N{sub 2} atmospheres. We measured the ion depth profile by Rutherford Backscattering Spectroscopy (RBS) and the nano-crystals size distribution by using two methods, the surface plasmon resonance in the optical extinction spectrum and the Transmission Electron Microscopy (TEM).

  20. Production of mono- and bimetallic nanoparticles of noble metals by pyrolysis of organic extracts on silicon dioxide

    International Nuclear Information System (INIS)

    Serga, V; Kulikova, L; Cvetkov, A; Krumina, A; Kodols, M; Chornaja, S; Dubencovs, K; Sproge, E

    2013-01-01

    In the present work the influence of the tri-n-octylammonium (Oct 3 NH + ) salt anion (PtCl 6 2- , PdCl 4 2- , AuCl 4 − ) nature on the phase composition and mean size of crystallites of the extract pyrolysis products on the SiO 2 nanopowder has been studied. The XRD phase analysis of the composites (metal loading 2.4 wt.%) made under the same conditions, at the pyrolysis of Pt- and Au-containing extracts has shown the formation of nanoparticles of Pt (d Pt = 15 nm) and Au (d Au = 33 nm), respectively. The end-product of the pyrolysis of the Pd-containing extract has an admixture phase of PdO along with the main metal phase (d Pd = 21 nm). At the preparation of bimetallic particles (Pt-Pd, Pt-Au, Pd-Au) on the SiO 2 nanopowder it has been found that the nanoparticles of the PtPd alloy, Pt and Au or Pd and Au nanoparticles are the products of the thermal decomposition of two-component mixtures of extracts. The investigation of catalytic properties of the produced composites in the reaction of glycerol oxidation by molecular oxygen in alkaline aqueous solutions has shown that all bimetallic composites exhibit catalytic activity in contrast to monometallic ones

  1. Noble gas magnetic resonator

    Science.gov (United States)

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  2. Highly porous nanocomposites based on TiO2-noble metal particles for sensitive detection of water pollutants by SERS

    International Nuclear Information System (INIS)

    Baia, M; Melinte, G; Iancu, V; Baia, L; Barbu-Tudoran, L; Diamandescu, L; Cosoveanu, V; Danciu, V

    2011-01-01

    Highly porous nanocomposites based on TiO2 aerogel and silver colloidal particles were prepared by different methods in order to study their capacity to detect pollutant species adsorbed on metallic nanoparticles surface from aqueous solution. The efficiency of the obtained composites to detect contaminants from water by means of SERS was evaluated using acrylamide and crystal violet as test molecules. It was found that the detection limits depend both on pollutant and composite type, and were determined to be in the range of 10 -1 -10 -4 M for acrylamide and around 10 -5 M for the dye molecule. These results prove the potential of the prepared porous composites for further use in the development of new SERS-based sensors devices.

  3. Highly porous nanocomposites based on TiO2-noble metal particles for sensitive detection of water pollutants by SERS

    Energy Technology Data Exchange (ETDEWEB)

    Baia, M; Melinte, G; Iancu, V; Baia, L [Faculty of Physics, Babes-Bolyai University, 400084, Cluj-Napoca (Romania); Barbu-Tudoran, L [Faculty of Biology and Geology, Babes-Bolyai University, 400015, Cluj-Napoca (Romania); Diamandescu, L [National Institute of Materials Physics, PO Box MG-7, 77125, Bucharest-Magurele (Romania); Cosoveanu, V; Danciu, V, E-mail: lucian.baia@phys.ubbcluj.ro [Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, 400028, Cluj-Napoca (Romania)

    2011-07-06

    Highly porous nanocomposites based on TiO2 aerogel and silver colloidal particles were prepared by different methods in order to study their capacity to detect pollutant species adsorbed on metallic nanoparticles surface from aqueous solution. The efficiency of the obtained composites to detect contaminants from water by means of SERS was evaluated using acrylamide and crystal violet as test molecules. It was found that the detection limits depend both on pollutant and composite type, and were determined to be in the range of 10{sup -1}-10{sup -4} M for acrylamide and around 10{sup -5} M for the dye molecule. These results prove the potential of the prepared porous composites for further use in the development of new SERS-based sensors devices.

  4. Faceted titania nanocrystals doped with indium oxide nanoclusters as a superior candidate for sacrificial hydrogen evolution without any noble-metal cocatalyst under solar irradiation.

    Science.gov (United States)

    Amoli, Vipin; Sibi, Malayil Gopalan; Banerjee, Biplab; Anand, Mohit; Maurya, Abhayankar; Farooqui, Saleem Akhtar; Bhaumik, Asim; Sinha, Anil Kumar

    2015-01-14

    Development of unique nanoheterostructures consisting of indium oxide nanoclusters like species doped on the TiO2 nanocrystals surfaces with {101} and {001} exposed facets, resulted in unprecedented sacrificial hydrogen production (5.3 mmol h(-1) g(-1)) from water using methanol as a sacrificial agent, under visible light LED source and AM 1.5G solar simulator (10.3 mmol h(-1) g(-1)), which is the highest H2 production rate ever reported for titania based photocatalysts, without using any noble metal cocatalyst. X-ray photoelectron spectroscopy (XPS) analysis of the nanostructures reveals the presence of Ti-O-In and In-O-In like species on the surface of nanostructures. Electron energy-loss spectroscopy (EELS) elemental mapping and EDX spectroscopy techniques combined with transmission electron microscope evidenced the existence of nanoheterostructures. XPS, EELS, EDX, and HAADF-STEM tools collectively suggest the presence of indium oxide nanoclusters like species on the surface of TiO2 nanostructures. These indium oxide nanocluster doped TiO2 (In2O3/T{001}) single crystals with {101} and {001} exposed facets exhibited 1.3 times higher visible light photocatalytic H2 production than indium oxide nanocluster doped TiO2 nanocrystals with only {101}facets (In2O3/T{101}) exposed. The remarkable photocatalytic activity of the obtained nanoheterostructures is attributed to the combined synergetic effect of indium oxide nanoclusters interacting with the titania surface, enhanced visible light response, high crystallinity, and unique structural features.

  5. Toward control of the metal-organic interfacial electronic structure in molecular electronics: a first-principles study on self-assembled monolayers of pi-conjugated molecules on noble metals.

    Science.gov (United States)

    Heimel, Georg; Romaner, Lorenz; Zojer, Egbert; Brédas, Jean-Luc

    2007-04-01

    Self-assembled monolayers (SAMs) of organic molecules provide an important tool to tune the work function of electrodes in plastic electronics and significantly improve device performance. Also, the energetic alignment of the frontier molecular orbitals in the SAM with the Fermi energy of a metal electrode dominates charge transport in single-molecule devices. On the basis of first-principles calculations on SAMs of pi-conjugated molecules on noble metals, we provide a detailed description of the mechanisms that give rise to and intrinsically link these interfacial phenomena at the atomic level. The docking chemistry on the metal side of the SAM determines the level alignment, while chemical modifications on the far side provide an additional, independent handle to modify the substrate work function; both aspects can be tuned over several eV. The comprehensive picture established in this work provides valuable guidelines for controlling charge-carrier injection in organic electronics and current-voltage characteristics in single-molecule devices.

  6. Determination of plasma frequency, damping constant, and size distribution from the complex dielectric function of noble metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Herrera, Luis J.; Arboleda, David Muñetón [Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina); Schinca, Daniel C.; Scaffardi, Lucía B., E-mail: lucias@ciop.unlp.edu.ar [Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina); Departamento de Ciencias Básicas, Facultad de Ingeniería, UNLP (Argentina)

    2014-12-21

    This paper develops a novel method for simultaneously determining the plasma frequency ω{sub P}   and the damping constant γ{sub free} in the bulk damped oscillator Drude model, based on experimentally measured real and imaginary parts of the metal refractive index in the IR wavelength range, lifting the usual approximation that restricts frequency values to the UV-deep UV region. Our method was applied to gold, silver, and copper, improving the relative uncertainties in the final values for ω{sub p} (0.5%–1.6%) and for γ{sub free} (3%–8%), which are smaller than those reported in the literature. These small uncertainties in ω{sub p} and γ{sub free} determination yield a much better fit of the experimental complex dielectric function. For the case of nanoparticles (Nps), a series expansion of the Drude expression (which includes ω{sub p} and γ{sub free} determined using our method) enables size-dependent dielectric function to be written as the sum of three terms: the experimental bulk dielectric function plus two size corrective terms, one for free electron, and the other for bound-electron contributions. Finally, size distribution of nanometric and subnanometric gold Nps in colloidal suspension was determined through fitting its experimental optical extinction spectrum using Mie theory based on the previously determined dielectric function. Results are compared with size histogram obtained from Transmission Electron Microscopy (TEM)

  7. Investigations on extraction separation of noble metals from secondary raw materials by means of tracer technique application

    International Nuclear Information System (INIS)

    Urban'ski, T.S.; Migdal, V.; Lada, V.

    1979-01-01

    In laboratory scale equilibrium and kinetics of the liquid extraction of gold, platinum and palladium from chloride and nitrate-chloride solutions were investigated. Experiments were done using model solutions and solutions, obtained in processing of secondary raw materials, for example: solutions in aqua regia of anode slurries after electrical refining of silver and jewelry wastes, as well as solutions after extraction of silver from nitrate mwdia. In investigations for determination of the extraction factor, the radioisotope indicators method have been used. Gold-198, platinum-197, palladium-109, silver-110 m and copper-64 were used. Radioisotope platinum-197 was refined from gold-199 on the ionite Dauex 50VX2 in the medium of hydrobromic acid. Gold was extracted by neutral extraction agents such as tributilphosphate; methylizobutylketone; amylacetate; amil alcohol; 2-ethylhexanol and dibutylcarbitol. In details extraction of palladium and platinum by tri-n-actylamine in different diluents with additions of modifiers, as well as their extraction by aliquat 336 in benzene and by some petroleum products. Influence was determined of the time of phases contact, of application of diluents, influence of extracting agents concentrations on the magnitude of extraction factor and on the separation factor for investigated metals [ru

  8. Photocatalysis-Based Nanoprobes Using Noble Metal-Semiconductor Heterostructure for Visible Light-Driven in Vivo Detection of Mercury.

    Science.gov (United States)

    Zhi, Lihua; Zeng, Xiaofan; Wang, Hao; Hai, Jun; Yang, Xiangliang; Wang, Baodui; Zhu, Yanhong

    2017-07-18

    The development of sensitive and reliable methods to monitor the presence of mercuric ions in cells and organisms is of great importance to biological research and biomedical applications. In this work, we propose a strategy to construct a solar-driven nanoprobe using a 3D Au@MoS 2 heterostructure as a photocatalyst and rhodamine B (RB) as a fluorescent and color change reporter molecule for monitoring Hg 2+ in living cells and animals. The sensing mechanism is based on the photoinduced electron formation of gold amalgam in the 3D Au@MoS 2 heterostructure under visible light illumination. This formation is able to remarkably inhibit the photocatalytic activity of the heterostructure toward RB decomposition. As a result, "OFF-ON" fluorescence and color change are produced. Such characteristics enable this new sensing platform to sensitively and selectively detect Hg 2+ in water by fluorescence and colorimetric methods. The detection limits of the fluorescence assay and colorimetric assay are 0.22 and 0.038 nM for Hg 2+ , respectively; these values are well below the acceptable limits in drinking water standards (10 nM). For the first time, such photocatalysis-based sensing platform is successfully used to monitor Hg 2+ in live cells and mice. Our work therefore opens a promising photocatalysis-based analysis methodology for highly sensitive and selective in vivo Hg 2+ bioimaging studies.

  9. Understanding how cells allocate metals using metal sensors and metallochaperones.

    Science.gov (United States)

    Tottey, Stephen; Harvie, Duncan R; Robinson, Nigel J

    2005-10-01

    Each metalloprotein must somehow acquire the correct metal. We review the insights into metal specificity in cells provided by studies of ArsR-SmtB DNA binding, metal-responsive transcriptional repressors, and a bacterial copper chaperone. Cyanobacteria are the one bacterial group that have known enzymatic demand for cytoplasmic copper import. The copper chaperone and ATPases that supply cyanobacterial plastocyanin and cytochrome oxidase are reviewed, along with related ATPases for cobalt and zinc. These studies highlight the contributions of protein-protein interactions to metal speciation. Metal sensors and metallochaperones, along with metal transporters and metal-storage proteins, act in concert not only to supply the correct metals but also to withhold the wrong ones.

  10. Bioinspired metal-cell wall-metal sandwich structure on an individual bacterial cell scaffold.

    Science.gov (United States)

    Zhang, Xiaoliang; Yu, Mei; Liu, Jianhua; Li, Songmei

    2012-08-25

    Pd nanoparticles were introduced to individual Bacillus cells and dispersedly anchored on both the inside and outside of the cell walls. The anchored nanoparticles served as "seeds" to drive the formation of double metallic layers forming a metal-cell wall-metal sandwich structure at the single-cell level.

  11. Down-conversion phosphors as noble-metal-free co-catalyst in ZnO for efficient visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Jiaqing [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Lei, Wenyan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Jinliang [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Wu, Tianyang [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Ping [Shanghai Nanotechnology Promotion Center, Shanghai 200237 (China); Li, Huili; Pan, Likun [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China)

    2017-01-01

    Graphical abstract: ZnO-Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} hybrid photocatalysts were synthesized via a fast microwave-assisted approach for visible light photocatalytic degradation of organic pollutions with a high degradation rate of 91%. - Highlights: • ZnO-Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} were synthesized via a facile microwave-assisted method. • Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} acts as co-catalyst to facilitates the self-sensitized degradation of MB. • ZnO-Lu{sub 3}(Al,Si){sub 5}(O,N){sub 12}:Ce{sup 3+} exhibited enhanced visible light photocatalytic activity. • A high MB degradation rate of 91% was achieved under visible light irradiation. - Abstract: Exploring novel visible light responsive photocatalysts is one of greatly significant issues from the viewpoint of using solar energy. Here we report the yellow-orange emitting α-Si{sub 3}N{sub 4}-doped Lu{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} (Lu{sub 3}Al{sub 5-x}Si{sub x}O{sub 12-x}N{sub x}:Ce{sup 3+}) phosphors as a noble-metal-free co-catalyst for enhanced visible light photocatalytic activity of ZnO. The results show that ZnO-Lu{sub 3}Al{sub 5-x}Si{sub x}O{sub 12-x}N{sub x}:Ce{sup 3+} hybrid photocatalysts using a fast microwave-assisted approach exhibits a 91% methylene blue (MB) degradation under visible light irradiation at 240 min, which evidence the synergistic effect of ZnO and Lu{sub 3}Al{sub 5-x}Si{sub x}O{sub 12-x}N{sub x}:Ce{sup 3+} that suppress the rate of charge recombination and increase the self-sensitized degradation of MB. ZnO-down conversion phosphors can be envisaged as potential candidate in environmental engineering and solar energy applications.

  12. Study and characterization of noble metal deposits on similar rusty surfaces to those of the reactor U-1 type BWR of nuclear power station of Laguna Verde

    International Nuclear Information System (INIS)

    Flores S, V. H.

    2011-01-01

    In the present investigation work, were determined the parameters to simulate the conditions of internal oxidation reactor circulation pipes of the nuclear power plant of Laguna Verde in Veracruz. We used 304l stainless steel cylinders with two faces prepared with abrasive paper of No. 600, with the finality to obtain similar surface to the internal circulation piping nuclear reactor. Oxides was formed within an autoclave (Autoclave MEX-02 unit B), which is a device that simulates the working conditions of the nuclear reactor, but without radiation generated by the fission reaction within the reactor. The oxidation conditions were a temperature of 280 C and pressure of 8 MPa, similar conditions to the reactor operating in nuclear power plant of Laguna Verde in Veracruz, Mexico (BWR conditions), with an average conductivity of 4.58 ms / cm and 2352 ppb oxygen to simulate normal water chemistry NWC. Were obtained deposits of noble metal oxides formed on 304l stainless steel samples, in a 250 ml autoclave at a temperature range of 180 to 200 C. The elements that were used to deposit platinum-rhodium (Pt-Rh) with aqueous Na 2 Pt (OH) 6 and Na 3 Rh (NO 2 ) 6 , Silver (Ag) with an aqueous solution of AgNO 3 , zirconium (Zr) with aqueous Zr O (NO 3 ) and ZrO 2 , and zinc (Zn) in aqueous solution of Zn (NO 3 ) 2 under conditions of normal water chemistry. Also there was the oxidation of 304l stainless steel specimens in normal water chemistry with a solution of Zinc (Zn) (NWC + Zn). Oxidation of the specimens in water chemistry with a solution of zinc (Zn + NWC) was prepared in two ways: within the MEX-02 autoclave unit A in a solution of zinc and a flask at constant temperature in zinc solution. The oxides formed and deposits were characterized by scanning electron microscopy, energy dispersive X-ray analysis, elemental field analysis and X-ray diffraction. By other hand was evaluated the electrochemical behavior of the oxides formed on the surface of 304l stainless steel

  13. The use of masking agents in the determination, by hydride generation and atomic-absorption spectrophotometry, of arsenic, antimony, selenium, tellurium, and bismuth in the presence of noble metals

    International Nuclear Information System (INIS)

    Kellerman, S.P.

    1982-01-01

    The effectiveness of thiosemicarbazide, tellurium, and potassium iodide as masking agents to eliminate interferences was assessed. Thiosemicarbazide was found to be effective in eliminating or reducing the interferences on arsenic, antimony, and bismuth, and tellurium reduced the interferences on selenium. The interferences on tellurium could not be eliminated. Arsenic, antimony, selenium, and bismuth were determined in metal sulphide concentrates that were spiked with the noble metals (defined here as gold plus all the platinum-group metals except osmium). The relative standard deviations for arsenic, antimony, bismuth, and selenium were 0,061, 0,017, 0,029, and 0,145 respectively. The values obtained for all the analytes agreed favourably with the preferred values for two in-house reference samples. The laboratory method is detailed in an appendix

  14. Muon diffusion in noble metals

    International Nuclear Information System (INIS)

    Schillaci, M.E.; Bokema, C.; Heffner, R.H.; Hutson, R.L.; Leon, M.; Olsen, C.E.; Dodds, S.A.; MacLaughlin, D.E.; Richards, P.M.

    1983-01-01

    Diffusion-induced muon depolarization in dilute AgGd and AgEr were measured in the temperature range 200-700 K and have thereby determined the muon diffusion parameters in Ag. The diffusion parameters for μ + in Cu, Ag, and Au are compared with those of hydrogen. For Ag and Au, the μ + parameters are similar to those of hydrogen, whereas for Cu, the μ + parameters are much smaller. Lattice-activated tunneling and over-barrier hopping are investigated with computational models. 15 references, 1 figure, 2 tables

  15. Muon diffusion in noble metals

    International Nuclear Information System (INIS)

    Schillaci, M.E.; Boekema, C.; Heffner, R.H.; Hutson, R.L.; Leon, M.; Olsen, C.E.; Dodds, S.A.; MacLaughlin, D.E.; Richards, P.M.

    1982-01-01

    Diffusion-induced muon depolarization was measured in dilute AgGd and AgEr in the temperature range 200 to 700 0 K and have thereby determined the muon diffusion parameters in Ag. The diffusion parameters for μ + in Cu, Ag, and Au are compared with those of hydrogen. For Ag and Au, the μ + parameters are similar to those of hydrogen, whereas for Cu, the μ + parameters are much smaller. Lattice-activated tunneling and over-barrier hopping are investigated with computational models

  16. Effect of electric arc, gas oxygen torch and induction melting techniques on the marginal accuracy of cast base-metal and noble metal-ceramic crowns.

    Science.gov (United States)

    Gómez-Cogolludo, Pablo; Castillo-Oyagüe, Raquel; Lynch, Christopher D; Suárez-García, María-Jesús

    2013-09-01

    The aim of this study was to identify the most appropriate alloy composition and melting technique by evaluating the marginal accuracy of cast metal-ceramic crowns. Seventy standardised stainless-steel abutments were prepared to receive metal-ceramic crowns and were randomly divided into four alloy groups: Group 1: palladium-gold (Pd-Au), Group 2: nickel-chromium-titanium (Ni-Cr-Ti), Group 3: nickel-chromium (Ni-Cr) and Group 4: titanium (Ti). Groups 1, 2 and 3 were in turn subdivided to be melted and cast using: (a) gas oxygen torch and centrifugal casting machine (TC) or (b) induction and centrifugal casting machine (IC). Group 4 was melted and cast using electric arc and vacuum/pressure machine (EV). All of the metal-ceramic crowns were luted with glass-ionomer cement. The marginal fit was measured under an optical microscope before and after cementation using image analysis software. All data was subjected to two-way analysis of variance (ANOVA). Duncan's multiple range test was run for post-hoc comparisons. The Student's t-test was used to investigate the influence of cementation (α=0.05). Uncemented Pd-Au/TC samples achieved the best marginal adaptation, while the worst fit corresponded to the luted Ti/EV crowns. Pd-Au/TC, Ni-Cr and Ti restorations demonstrated significantly increased misfit after cementation. The Ni-Cr-Ti alloy was the most predictable in terms of differences in misfit when either torch or induction was applied before or after cementation. Cemented titanium crowns exceeded the clinically acceptable limit of 120μm. The combination of alloy composition, melting technique, casting method and luting process influences the vertical seal of cast metal-ceramic crowns. An accurate use of the gas oxygen torch may overcome the results attained with the induction system concerning the marginal adaptation of fixed dental prostheses. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Platinum and Palladium Alloys Suitable as Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt, Pd and mixtures thereof alloyed with a further element selected from Sc, Y and La as well as any mixtures thereof, wherein said alloy is supported on a conductive...

  18. Noble gas absorption process

    International Nuclear Information System (INIS)

    Thomas, J.W.

    1975-01-01

    A method of removing a noble gas from air comprising the use of activated carbon filters in stages in which absorption and desorption steps in succession are conducted in order to increase the capacity of the filters is described. (U.S.)

  19. Bioelectrochemical metal recovery with microbial fuel cells

    NARCIS (Netherlands)

    Rodenas Motos, Pau

    2017-01-01

    This thesis aims to explain the metal recovery through the study of their components using Copper as a model compound of the heavy metals. Different electrochemical cells distribution and sizes were used to improve efficiency and current density. Two different electron donors were tested, acetate

  20. Rechargeable Lithium Metal Cell, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — PSI proposes to develop a rechargeable lithium metal cell with energy density >400Wh/kg. This represents a >70% increase as compared to similarly constructed...

  1. Excellent photocatalytic hydrogen production over CdS nanorods via using noble metal-free copper molybdenum sulfide (Cu{sub 2}MoS{sub 4}) nanosheets as co-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sangyeob; Kumar, D. Praveen; Reddy, D. Amaranatha; Choi, Jiha; Kim, Tae Kyu, E-mail: tkkim@pusan.ac.kr

    2017-02-28

    Highlights: • Developed Cu{sub 2}MoS{sub 4} nanosheets as co-catalysts. • Cu{sub 2}MoS{sub 4} as active replacements for precious noble metal. • Controlled charge recombination for use in photocatalytic H{sub 2} evolution. • Obtained superior rate of H{sub 2} production by using Cu{sub 2}MoS{sub 4} loaded CdS nanorods. - Abstract: Charge carrier recombination and durability issues are major problems in photocatalytic hydrogen (H{sub 2}) evolution processes. Thus, there is a very important necessitate to extend an efficient photocatalyst to control charge-carrier dynamics in the photocatalytic system. We have developed copper molybdenum sulfide (Cu{sub 2}MoS{sub 4}) nanosheets as co-catalysts with CdS nanorods for controlling charge carriers without recombination for use in photocatalytic H{sub 2} evolution under simulated solar light irradiation. Effective control and utilization of charge carriers are possible by loading Cu{sub 2}MoS{sub 4} nanosheets onto the CdS nanorods. The loading compensates for the restrictions of CdS, and stimulated synergistic effects, such as efficient photoexcited charge separation, lead to an improvement in photostability because of the layered structure of the Cu{sub 2}MoS{sub 4}nanosheets. These layered Cu{sub 2}MoS{sub 4} nanosheets have emerged as novel and active replacements for precious noble metal co-catalysts in photocatalytic H{sub 2} production by water splitting. We have obtained superior H{sub 2} production rates by using Cu{sub 2}MoS{sub 4} loaded CdS nanorods. The physicochemical properties of the composites are analyzed by diverse characterization techniques.

  2. Study and characterization of noble metal deposits on similar rusty surfaces to those of the reactor U-1 type BWR of nuclear power station of Laguna Verde; Estudio y caracterizacion de depositos de metales nobles sobre superficies oxidadas similares a las del reactor de la Central de Laguna Verde (CNLV) U1 del tipo BWR

    Energy Technology Data Exchange (ETDEWEB)

    Flores S, V. H.

    2011-07-01

    In the present investigation work, were determined the parameters to simulate the conditions of internal oxidation reactor circulation pipes of the nuclear power plant of Laguna Verde in Veracruz. We used 304l stainless steel cylinders with two faces prepared with abrasive paper of No. 600, with the finality to obtain similar surface to the internal circulation piping nuclear reactor. Oxides was formed within an autoclave (Autoclave MEX-02 unit B), which is a device that simulates the working conditions of the nuclear reactor, but without radiation generated by the fission reaction within the reactor. The oxidation conditions were a temperature of 280 C and pressure of 8 MPa, similar conditions to the reactor operating in nuclear power plant of Laguna Verde in Veracruz, Mexico (BWR conditions), with an average conductivity of 4.58 ms / cm and 2352 ppb oxygen to simulate normal water chemistry NWC. Were obtained deposits of noble metal oxides formed on 304l stainless steel samples, in a 250 ml autoclave at a temperature range of 180 to 200 C. The elements that were used to deposit platinum-rhodium (Pt-Rh) with aqueous Na{sub 2}Pt (OH){sub 6} and Na{sub 3}Rh (NO{sub 2}){sub 6}, Silver (Ag) with an aqueous solution of AgNO{sub 3}, zirconium (Zr) with aqueous Zr O (NO{sub 3}) and ZrO{sub 2}, and zinc (Zn) in aqueous solution of Zn (NO{sub 3}){sub 2} under conditions of normal water chemistry. Also there was the oxidation of 304l stainless steel specimens in normal water chemistry with a solution of Zinc (Zn) (NWC + Zn). Oxidation of the specimens in water chemistry with a solution of zinc (Zn + NWC) was prepared in two ways: within the MEX-02 autoclave unit A in a solution of zinc and a flask at constant temperature in zinc solution. The oxides formed and deposits were characterized by scanning electron microscopy, energy dispersive X-ray analysis, elemental field analysis and X-ray diffraction. By other hand was evaluated the electrochemical behavior of the oxides

  3. Noble Gas Detectors

    CERN Document Server

    Aprile, Elena; Bolozdynya, Alexander I; Doke, Tadayoshi

    2006-01-01

    This book discusses the physical properties of noble fluids, operational principles of detectors based on these media, and the best technical solutions to the design of these detectors. Essential attention is given to detector technology: purification methods and monitoring of purity, information readout methods, electronics, detection of hard ultra-violet light emission, selection of materials, cryogenics etc.The book is mostly addressed to physicists and graduate students involved in the preparation of fundamental next generation experiments, nuclear engineers developing instrumentation

  4. Significance of a Noble Metal Nanolayer on the UV and Visible Light Photocatalytic Activity of Anatase TiO2 Thin Films Grown from a Scalable PECVD/PVD Approach.

    Science.gov (United States)

    Baba, Kamal; Bulou, Simon; Quesada-Gonzalez, Miguel; Bonot, Sébastien; Collard, Delphine; Boscher, Nicolas D; Choquet, Patrick

    2017-11-29

    UV and visible light photocatalytic composite Pt and Au-TiO 2 coatings have been deposited on silicon and glass substrates at low temperature using a hybrid ECWR-PECVD/MS-PVD process. Methylene blue, stearic acid, and sulfamethoxazole were used as dye, organic, and antibiotic model pollutants, respectively, to demonstrate the efficiency of these nanocomposite coatings for water decontamination or self-cleaning surfaces applications. Raman investigations revealed the formation of anatase polymorph of TiO 2 in all synthesized coatings with a shifting of the main vibrational mode peak to higher wavenumber in the case of Au-TiO 2 coating, indicating an increase number of crystalline defects within this coating. Because of the difference of the chemical potentials of each of the investigated noble metals, the sputtered metal layers exhibit different morphology. Pt sputtered atoms, with high surface adhesion, promote formation of a smooth 2D layer. On the other hand, Au sputtered atoms with higher cohesive forces promote the formation of 5-10 nm nanoparticles. As a result, the surface plasmon resonance phenomenon was observed in the Au-TiO 2 coatings. UV photoactivity of the nanocomposite coatings was enhanced 1.5-3 times and 1.3 times for methylene blue and stearic acid, respectively, thanks to the enhancement of electron trapping in the noble metal layer. This electron trapping phenomenon is higher in the Pt-TiO 2 coating because of its larger work function. On the other hand, the enhancement of the visible photoactivity was more pronounced (3 and 7 times for methylene blue and stearic acid, respectively) in the case of Au-TiO 2 thanks to the surface plasmon resonance. Finally, these nanocomposite TiO 2 coatings exhibited also a good ability for the degradation of antibiotics usually found in wastewater such as sulfamethoxazole. However, a complementary test have showed an increase of the toxicity of the liquid medium after photocatalysis, which could be due the

  5. Noble Gases in Lakes and Ground Waters

    OpenAIRE

    Kipfer, Rolf; Aeschbach-Hertig, Werner; Peeters, Frank; Stute, Marvin

    2002-01-01

    In contrast to most other fields of noble gas geochemistry that mostly regard atmospheric noble gases as 'contamination,' air-derived noble gases make up the far largest and hence most important contribution to the noble gas abundance in meteoric waters, such as lakes and ground waters. Atmospheric noble gases enter the meteoric water cycle by gas partitioning during air / water exchange with the atmosphere. In lakes and oceans noble gases are exchanged with the free atmosphere at the surface...

  6. Selective noble gases monitoring

    International Nuclear Information System (INIS)

    Janecka, S.; Jancik, O.; Kapisovsky, V.; Kubik, I.; Sevecka, S.

    1995-01-01

    The monitoring of leak releases from ventilation stack of NPP requires a system by several orders more sensitive then currently used radiometer Kalina, designed to cover the range up to a design-based accident. To reach this goal a noble gases monitor with a germanium detector (MPVG) has been developed. It enables nuclide selective monitoring of current value of volume activity of particular nuclides in ventilation stack and daily releases of noble gases (balancing). MPVG can be viewed as a system build of three levels of subsystem: measuring level; control level; presentation level. Measuring level consists of gamma-spectroscopy system and operational parameters monitoring unit (flow rate, temperature, humidity). Control level provides communication between presentation and measuring level, acquisition of operational parameters and power supply. The presentation level of MPVG enables: 1) the measured data storage in predetermined time intervals; 2) the presentation of measured and evaluated values of radiation characteristics. The monitored radionuclides - default set: argon-41, krypton-85m, krypton-87, krypton-88, krypton-89, xenon-131m, xenon-133, xenon-133m, xenon-135, xenon-135m, xenon-137 and xenon-138. The values of volume activities observed at maximum releases have been approximately ten times higher. In that case in balancing some other nuclides exceed corresponding detection limits: 88 Kr(67; 22) Bq/m 3 ; 85m Kr(17; 7) Bq/m 3 ; 135m Xe(7.1; 0.5) Bq/m 3 ; 138 Xe(5.9; 0.9) Bq/m 3 . (J.K.)

  7. Selective noble gases monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Janecka, S; Jancik, O; Kapisovsky, V; Kubik, I; Sevecka, S [Nuclear Power Plants Research Institute, a.s., Trnava (Slovakia)

    1996-12-31

    The monitoring of leak releases from ventilation stack of NPP requires a system by several orders more sensitive then currently used radiometer Kalina, designed to cover the range up to a design-based accident. To reach this goal a noble gases monitor with a germanium detector (MPVG) has been developed. It enables nuclide selective monitoring of current value of volume activity of particular nuclides in ventilation stack and daily releases of noble gases (balancing). MPVG can be viewed as a system build of three levels of subsystem: measuring level; control level; presentation level. Measuring level consists of gamma-spectroscopy system and operational parameters monitoring unit (flow rate, temperature, humidity). Control level provides communication between presentation and measuring level, acquisition of operational parameters and power supply. The presentation level of MPVG enables: 1) the measured data storage in predetermined time intervals; 2) the presentation of measured and evaluated values of radiation characteristics. The monitored radionuclides - default set: argon-41, krypton-85m, krypton-87, krypton-88, krypton-89, xenon-131m, xenon-133, xenon-133m, xenon-135, xenon-135m, xenon-137 and xenon-138. The values of volume activities observed at maximum releases have been approximately ten times higher. In that case in balancing some other nuclides exceed corresponding detection limits: {sup 88}Kr(67; 22) Bq/m{sup 3}; {sup 85m}Kr(17; 7) Bq/m{sup 3}; {sup 135m}Xe(7.1; 0.5) Bq/m{sup 3}; {sup 138}Xe(5.9; 0.9) Bq/m{sup 3}. (J.K.).

  8. Noble gases solubility in water

    International Nuclear Information System (INIS)

    Crovetto, Rosa; Fernandez Prini, Roberto.

    1980-07-01

    The available experimental data of solubility of noble gases in water for temperatures smaller than 330 0 C have been critically surveyed. Due to the unique structure of the solvent, the solubility of noble gases in water decreases with temperature passing through a temperature of minimum solubility which is different for each gas, and then increases at higher temperatures. As aresult of the analysis of the experimental data and of the features of the solute-solvent interaction, a generalized equation is proposed which enables thecalculation of Henry's coefficient at different temperatures for all noble gases. (author) [es

  9. Positron scattering from noble gases future prospects

    Energy Technology Data Exchange (ETDEWEB)

    Jones, A C L; Caradonna, P; Makochekanwa, C; Slaughter, D S; Sullivan, J P; Buckman, S J [Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University, Canberra, ACT (Australia); Mitroy, J, E-mail: acj107@rsphysse.anu.edu.a [Faculty of Education Health and Science, Charles Darwin University, NT (Australia)

    2009-11-01

    Recent results for positron scattering from noble gases over an energy range from 0.5 to 60eV are presented. Measurements include the grand total ({sigma}{sub GT}), Ps formation ({sigma}{sub Ps}) and Grand total - Ps formation (({sigma}{sub GT}-P{sub s}) cross sections. Some preliminary DCS results will also be presented. Work on a formulation of modified effective range theory (MERT) is being undertaken to determine the value of the scattering length which may be useful for identifying a bound state. Plans for experiments on metal atoms will be outlined.

  10. Formation and Diffusion of Metal Impurities in Perovskite Solar Cell Material CH3NH3PbI3: Implications on Solar Cell Degradation and Choice of Electrode.

    Science.gov (United States)

    Ming, Wenmei; Yang, Dongwen; Li, Tianshu; Zhang, Lijun; Du, Mao-Hua

    2018-02-01

    Solar cells based on methylammonium lead triiodide (MAPbI 3 ) have shown remarkable progress in recent years and have demonstrated efficiencies greater than 20%. However, the long-term stability of MAPbI 3 -based solar cells has yet to be achieved. Besides the well-known chemical and thermal instabilities, significant native ion migration in lead halide perovskites leads to current-voltage hysteresis and photoinduced phase segregation. Recently, it is further revealed that, despite having excellent chemical stability, the Au electrode can cause serious solar cell degradation due to Au diffusion into MAPbI 3 . In addition to Au, many other metals have been used as electrodes in MAPbI 3 solar cells. However, how the external metal impurities introduced by electrodes affect the long-term stability of MAPbI 3 solar cells has rarely been studied. A comprehensive study of formation energetics and diffusion dynamics of a number of noble and transition metal impurities (Au, Ag, Cu, Cr, Mo, W, Co, Ni, Pd) in MAPbI 3 based on first-principles calculations is reported herein. The results uncover important general trends of impurity formation and diffusion in MAPbI 3 and provide useful guidance for identifying the optimal metal electrodes that do not introduce electrically active impurity defects in MAPbI 3 while having low resistivities and suitable work functions for carrier extraction.

  11. Excellent photocatalytic hydrogen production over CdS nanorods via using noble metal-free copper molybdenum sulfide (Cu2MoS4) nanosheets as co-catalysts

    Science.gov (United States)

    Hong, Sangyeob; Kumar, D. Praveen; Reddy, D. Amaranatha; Choi, Jiha; Kim, Tae Kyu

    2017-02-01

    Charge carrier recombination and durability issues are major problems in photocatalytic hydrogen (H2) evolution processes. Thus, there is a very important necessitate to extend an efficient photocatalyst to control charge-carrier dynamics in the photocatalytic system. We have developed copper molybdenum sulfide (Cu2MoS4) nanosheets as co-catalysts with CdS nanorods for controlling charge carriers without recombination for use in photocatalytic H2 evolution under simulated solar light irradiation. Effective control and utilization of charge carriers are possible by loading Cu2MoS4 nanosheets onto the CdS nanorods. The loading compensates for the restrictions of CdS, and stimulated synergistic effects, such as efficient photoexcited charge separation, lead to an improvement in photostability because of the layered structure of the Cu2MoS4nanosheets. These layered Cu2MoS4 nanosheets have emerged as novel and active replacements for precious noble metal co-catalysts in photocatalytic H2 production by water splitting. We have obtained superior H2 production rates by using Cu2MoS4 loaded CdS nanorods. The physicochemical properties of the composites are analyzed by diverse characterization techniques.

  12. Mixed valent perovskites Ba/sub 3/B/sup 3 +/Ru/sub 2/sup(4. 5+)O/sub 9/. Catalytic activity of perovskite oxides with noble metals

    Energy Technology Data Exchange (ETDEWEB)

    Treiber, U; Kemmler-Sack, S; Ehmann, A; Schaller, H U; Duerrschmidt, E; Thumm, I; Bader, H [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-10-01

    The black compounds Ba/sub 3/B/sup 3 +/Ru/sub 2/O/sub 9/ crystallize with B/sup 3 +/ = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y in a hexagonal BaTiO/sub 3/ structure (6L, sequence (hcc)/sub 2/) with an ordered distribution (1:2 order) of B/sup 3 +/ and ruthenium (BO/sub 6/ single octahedra; Ru/sub 2/O/sub 9/ double groups). The mean oxidation state of ruthenium is about +4.5. The properties are compared with those of other isotypic stacking polytypes Ba/sub 3/B/sup 3 +/M/sub 2/sup(4.5)O/sub 9/ (M/sub 2/ = IrRu, Ir/sub 2/, PtRu) and Ba/sub 3/B/sup 2 +/M/sub 2//sup 5 +/O/sub 9/ (M = Ru, Ir). The results of activity tests concerning the efficiency of perovskite oxides with noble metals in respect of the oxidation of CO or CHsub(x) and the reduction of NOsub(x) are reported.

  13. Noble metal (Pt or Au)-doped monolayer MoS2 as a promising adsorbent and gas-sensing material to SO2, SOF2 and SO2F2: a DFT study

    Science.gov (United States)

    Chen, Dachang; Zhang, Xiaoxing; Tang, Ju; Cui, Hao; Li, Yi

    2018-02-01

    We explored the adsorption of SO2, SOF2, and SO2F2 on Pt- or Au-doped MoS2 monolayer based on density functional theory. The adsorption energy, adsorption distance, charge transfer as well as density of states were discussed. SO2 and SOF2 exhibit strong chemical interactions with Pt-doped MoS2 based on large adsorption energy, charge transfer, and changes of electron orbitals in gas molecule. SO2 also shows obvious chemisorption on Au-doped MoS2 with apparent magnetism transfer from Au to gas molecules. The adsorption of SO2F2 on Pt-MoS2 and SOF2 on Au-MoS2 exhibits weaker chemical interactions and SO2F2 losses electrons when adsorbed on Pt-MoS2 which is different from other gas adsorption. The adsorption of SO2F2 on Au-MoS2 represents no obvious chemical interaction but physisorption. The gas-sensing properties are also evaluated based on DFT results. This work could provide prospects and application value for typical noble metal-doped MoS2 as gas-sensing materials.

  14. Comparing Ullmann Coupling on Noble Metal Surfaces: On-Surface Polymerization of 1,3,6,8-Tetrabromopyrene on Cu(111) and Au(111)

    DEFF Research Database (Denmark)

    Pham, Tuan Anh; Song, Fei; Nguyen, Manh-Thuong

    2016-01-01

    to a dissociation of the C−Br bonds and the formation of disordered metal-coordinated molecular networks. Further annealing at 573 K resulted in the formation of covalently linked disordered networks. Importantly, we found that the chosen substrate not only plays an important role as catalyst for the Ullmann...

  15. Understanding the adsorption of CuPc and ZnPc on noble metal surfaces by combining quantum-mechanical modelling and photoelectron spectroscopy.

    Science.gov (United States)

    Huang, Yu Li; Wruss, Elisabeth; Egger, David A; Kera, Satoshi; Ueno, Nobuo; Saidi, Wissam A; Bucko, Tomas; Wee, Andrew T S; Zojer, Egbert

    2014-03-07

    Phthalocyanines are an important class of organic semiconductors and, thus, their interfaces with metals are both of fundamental and practical relevance. In the present contribution we provide a combined theoretical and experimental study, in which we show that state-of-the-art quantum-mechanical simulations are nowadays capable of treating most properties of such interfaces in a quantitatively reliable manner. This is shown for Cu-phthalocyanine (CuPc) and Zn-phthalocyanine (ZnPc) on Au(111) and Ag(111) surfaces. Using a recently developed approach for efficiently treating van der Waals (vdW) interactions at metal/organic interfaces, we calculate adsorption geometries in excellent agreement with experiments. With these geometries available, we are then able to accurately describe the interfacial electronic structure arising from molecular adsorption. We find that bonding is dominated by vdW forces for all studied interfaces. Concomitantly, charge rearrangements on Au(111) are exclusively due to Pauli pushback. On Ag(111), we additionally observe charge transfer from the metal to one of the spin-channels associated with the lowest unoccupied π-states of the molecules. Comparing the interfacial density of states with our ultraviolet photoelectron spectroscopy (UPS) experiments, we find that the use of a hybrid functionals is necessary to obtain the correct order of the electronic states.

  16. Understanding the Adsorption of CuPc and ZnPc on Noble Metal Surfaces by Combining Quantum-Mechanical Modelling and Photoelectron Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yu Li Huang

    2014-03-01

    Full Text Available Phthalocyanines are an important class of organic semiconductors and, thus, their interfaces with metals are both of fundamental and practical relevance. In the present contribution we provide a combined theoretical and experimental study, in which we show that state-of-the-art quantum-mechanical simulations are nowadays capable of treating most properties of such interfaces in a quantitatively reliable manner. This is shown for Cu-phthalocyanine (CuPc and Zn-phthalocyanine (ZnPc on Au(111 and Ag(111 surfaces. Using a recently developed approach for efficiently treating van der Waals (vdW interactions at metal/organic interfaces, we calculate adsorption geometries in excellent agreement with experiments. With these geometries available, we are then able to accurately describe the interfacial electronic structure arising from molecular adsorption. We find that bonding is dominated by vdW forces for all studied interfaces. Concomitantly, charge rearrangements on Au(111 are exclusively due to Pauli pushback. On Ag(111, we additionally observe charge transfer from the metal to one of the spin-channels associated with the lowest unoccupied π-states of the molecules. Comparing the interfacial density of states with our ultraviolet photoelectron spectroscopy (UPS experiments, we find that the use of a hybrid functionals is necessary to obtain the correct order of the electronic states.

  17. Effect of Ni and noble metals (Ru, Pd and Pt) on performance of bifunctional MoP/SiO2 for hydroconversion of methyl laurate

    Science.gov (United States)

    Nie, Ziyang; Zhang, Zhena; Chen, Jixiang

    2017-10-01

    SiO2 supported bifunctional MoP catalysts modified with different metal promoters (Ni, Ru, Pd, Pt), where Mo/Ni and Mo/M(M = Ru, Pd and Pt) atomic ratios was respectively 10 and 40, were prepared by TPR method from the phosphate precursors. It was found that the introduction of metal promoters facilitated the reduction of phosphate precursor and enhanced the dispersion of MoP. However, the MoP catalyst acidity was scarcely influenced by the small amount of metal promoters. In the hydroconversion of methyl laurate, the promoters enhanced the MoP catalyst activity for conversion of methyl laurate and hydrogenation of alkenes (intermediate), but reduced isomerization ability. Among the promoters, Ru was an optimum to decrease selectivity to alkenes while maintain high selectivity to iso-alkanes, and Mo40RuP showed better stability than MoP. At 380 °C and 3.0 MPa, the conversion of methyl laurate, the total selectivity to C11 and C12 hydrocarbons and the selectivity to iso-alkanes maintained at 100%, ∼94% and ∼30% on Mo40RuP during 102 h, respectively. The good stability of Mo40RuP is ascribed to that the presence of Ru prevented the sintering of MoP particles and suppressed carbon deposition.

  18. Process for recycling components of a PEM fuel cell membrane electrode assembly

    Science.gov (United States)

    Shore, Lawrence [Edison, NJ

    2012-02-28

    The membrane electrode assembly (MEA) of a PEM fuel cell can be recycled by contacting the MEA with a lower alkyl alcohol solvent which separates the membrane from the anode and cathode layers of the assembly. The resulting solution containing both the polymer membrane and supported noble metal catalysts can be heated under mild conditions to disperse the polymer membrane as particles and the supported noble metal catalysts and polymer membrane particles separated by known filtration means.

  19. Metal nanoparticles for thin film solar cells

    DEFF Research Database (Denmark)

    Gritti, Claudia

    and intensity depends on the nanoparticle’s size, shape, and local dielectric environment, thus absorption enhancement in a defined wavelength range can be achieved varying these properties (tuning the LSP resonance). Even though scattering enhancement of photons above the gap of the semiconductor is useful...... to increase light trapping and can come along regardless, we aim, as first target, to absorb forbidden (for the semiconductor) photons by the NPs which can excite hot electrons inside the metal NP and emit them directly into the conduction band of the solar cell semiconductor, without going through...... the promotion of electrons from the valence band of the semiconductor. The photoemission would extend the spectral response of the photovoltaic device. Thus, NPs are placed at the metal/semiconductor interface (in order to exploit the localization characteristic of the LSP enhancement) and are used as active...

  20. Non-noble metal Bi deposition by utilizing Bi2WO6 as the self-sacrificing template for enhancing visible light photocatalytic activity

    Science.gov (United States)

    Yu, Shixin; Zhang, Yihe; Li, Min; Du, Xin; Huang, Hongwei

    2017-01-01

    Bi metal deposited on Bi2WO6 composite photocatalysts have been successfully synthesized via a simple in-situ reduction method at room temperature with using Bi2WO6 as self-sacrificing template and NaBH4 as reducing agent. The reduction extent can be easily modulated by controlling the concentration of NaBH4 solution. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectra, N2 adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), diffuse reflection spectroscopy (DRS) and photoelectrochemical measurements were carried out to analyze the phase, morphology, optical property and photoelectrochemical property of the as-prepared samples. The photocatalytic activity is surveyed by degradation of phenol under visible light (λ > 420 nm), which showed that the BWO-0.2 photocatalyst exhibited the highest efficiency, which was over 3 times as high as pure Bi2WO6. The enhanced photocatalytic activity should be attributed to strengthened photoabsorption and charge separation efficiency derived from the surface plasmon resonance (SPR) of Bi metal.

  1. Application of chitosan and its N-heterocyclic derivatives for preconcentration of noble metal ions and their determination using atomic absorption spectrometry.

    Science.gov (United States)

    Azarova, Yu A; Pestov, A V; Ustinov, A Yu; Bratskaya, S Yu

    2015-12-10

    Chitosan and its N-heterocyclic derivatives N-2-(2-pyridyl)ethylchitosan (2-PEC), N-2-(4-pyridyl) ethylchitosan (4-PEC), and N-(5-methyl-4-imidazolyl) methylchitosan (IMC) have been applied in group preconcentration of gold, platinum, and palladium for subsequent determination by atomic absorption spectroscopy (AAS) in solutions with high background concentrations of iron and sodium ions. It has been shown that the sorption mechanism, which was elucidated by XPS, significantly influences the sorption capacity of materials, the efficiency of metal ions elution after preconcentration, and, as a result, the accuracy of metal determination by AAS. We have shown that native chitosan was not suitable for preconcentration of Au(III), if the elution step was used as a part of the analysis scheme. The group preconcentration of Au(III), Pd(II), and Pt(IV) with subsequent quantitative elution using 0.1M HCl/1M thiourea solution was possible only on IMC and 4-PEC. Application of IMC for analysis of the national standard quartz ore sample proved that gold could be accurately determined after preconcentration/elution with the recovery above 80%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Influence of the noble metals (Pd, Au, Ag) in the thermoluminescent signal induced by radiation in the ZrO2

    International Nuclear Information System (INIS)

    Villa S, G.

    2006-01-01

    When increasing the use of the ionizing and non ionizing radiations (for example, gamma and ultraviolet radiation) in different areas of the science and technology, there is necessary to apply more accurate safety measures and to avoid over-exposures that could put in risk the life of workers that manipulate radiation sources, patient that are exposed to this under some medical treatment, as well as materials that undergo intentionally to radiation. Also, the UV radiation that arrives to the earth can cause some damages, to the one to weaken the protector layer of ozone the UV radiation increases that arrives to the earth surface being able to affect the alive beings and the materials. By this so much the development of new materials able to take a census of in a more accurate way, fields of gamma and UV radiation is becoming necessary. In this sense, this work presents the obtained results when quantifying radiation fields, through the analysis in the thermoluminescent behavior (TL) induced by the gamma and UV radiation in the zirconium dioxide synthesized by the sol gel method and doped with nanoparticles of Pd, Au and Ag. It is necessary to mention that in reported works in this respect its mention that the zircon has good thermoluminescent sensitivity induced by these radiation types, however it has shown high thermoluminescent instability that is translated in an important lost of the information after the irradiation. For that through the incorporation of the metallic nanoparticles it was intended to stabilize the TL behavior of zircon. The results showed that the doped zircon has a high sensitivity to the gamma and UV radiation. These also show that the ionizing and non ionizing radiation induce a thermoluminescent curve consisting of two TL peaks with maxima located around 65 C and 145 C and that the intensity is increased with the dose, following a lineal behavior in certain interval of dose exposure that is influenced by the presence of the nanoparticles

  3. Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Ruohao Xing

    2018-02-01

    Full Text Available Transition metal (Fe, Co, Ni complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR. In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows that the hollow carbon spheres possess an average diameter of ~150 nm with a narrow size distribution and a shell thickness of ~14.5 nm. The content of N doping ranges from 2.1 to 6.6 at.% depending on the calcination temperature from 900 to 1050 °C. Compared with commercial Pt/C, the Co-containing nitrogen-doped hollow carbon spheres prepared at 900 °C (CoNHCS-900 as an ORR electrocatalyst shows a half-wave potential shift of only ∆E1/2 = 55 mV, but a superior stability of about 90.2% maintenance after 20,000 s in the O2-saturated 0.1 M KOH at a rotating speed of 1600 rpm. This could be ascribed to the synergistic effects of N-containing moieties, Co-Nx species, and Co nanoparticles, which significantly increase the density of active sites and promote the charge transfer during the ORR process.

  4. Noble metal recycling. Project 2: Optimization of discontinuous thermal processes (emission reduction). Final report; Edelmetallrecycling. Teilvorhaben 2: Weiterentwicklung der Verfahrenstechnik bei diskontinuierlichen thermischen Prozessen (Emissionsminderung). Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Baumbach, G.; Berger, R.

    2000-10-01

    A batch operated incineration process, used for the recycling of precious metals is described in the report. The development of a new combined pyrolysis/oxidation Process is the main focus of the work. This new process has several remarkable advantages compared to traditionally used techniques. The optimisation of the process with a modern fuzzy based control technique is described in detail. The emissions of the process were reduced considerably applying the new process and the innovative control technique. Furthermore the layout of several components of the new process can be reduced in the future. The developed techniques can also be applied in other thermal processes, especially batch processes. Additionally the application of catalysts for PCDD/PCDF reduction in the flue gas upstream and downstream of the filter was investigated. Whereas the catalyst performed well, as expected, downstream of the filter, no acceptable operation was possible upstream of the filter. As the reheating downstream the filter is economically not feasible the application of catalysts is not applicable for the describe process. (orig.) [German] Die Arbeit beschreibt einen diskontinuierlichen thermischen Prozess, der zur Rueckgewinnung von Edelmetallen eingesetzt wird. Der Schwerpunkt der Arbeit liegt auf der Entwicklung eines neuartigen kombinierten Pyrolyse/Oxidations-Prozesses, der gegenueber den traditionell eingesetzten Anlagen grosse Vorteile aufweist. Die Optimierung dieses Prozesses mit Hilfe modernster Fuzzy-Regelungstechnik wird detailliert beschrieben. Mit dem neuen Verfahren und den innovativen Regelungstechniken konnten die Emissionen des Prozesses merklich gesenkt werden, ohne den Energiebedarf negativ zu beeinflussen. Ausserdem koennen zukuenftige Anlagen kleiner ausgelegt werden. Die entwickelten Verfahren koennen auch auf andere thermische Prozesse uebertragen werden. Weiterhin wurde der Einsatz von Katalysatoren zur PCDD/PCDF-Minderung im Rein- und Rohgas untersucht

  5. Muonium formation in noble gases and noble gas mixtures

    International Nuclear Information System (INIS)

    Stambaugh, R.D.; Casperson, D.E.; Crane, T.W.; Hughes, V.W.; Kaspar, H.F.; Souder, P.; Thompson, P.A.; Orth, H.; zu Putlitz, G.; Denison, A.B.

    1974-01-01

    An experiment is reported to study the behavior of positive muons stopped in He, Ne, and Xe in order to provide a more complete understanding of muonium formation in the noble gases. Free muon and muonium precession are plotted. (U.S.)

  6. The Fundamental Role of Nano-Scale Oxide Films in the Oxidation of Hydrogen and the Reduction of Oxygen on Noble Metal Electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Digby Macdonald

    2005-04-15

    The derivation of successful fuel cell technologies requires the development of more effective, cheaper, and poison-resistant electrocatalysts for both the anode (H{sub 2} oxidation in the presence of small amounts of CO from the reforming of carbonaceous fuels) and the cathode (reduction of oxygen in the presence of carried-over fuel). The proposed work is tightly focused on one specific aspect of electrocatalysis; the fundamental role(s) played by nanoscale (1-2 nm thick) oxide (''passive'') films that form on the electrocatalyst surfaces above substrate-dependent, critical potentials, on charge transfer reactions, particularly at elevated temperatures (25 C < T < 200 C). Once the role(s) of these films is (are) adequately understood, we will then use this information to specify, at the molecular level, optimal properties of the passive layer for the efficient electrocatalysis of the oxygen reduction reaction.

  7. Design of metallic bipolar plates for PEM fuel cells.

    Science.gov (United States)

    2012-01-01

    This project focused on the design and production of metallic bipolar plates for use in PEM fuel cells. Different metals were explored : and stainless steel was found out to be best suited to our purpose. Following the selection of metal, it was calc...

  8. The Inert and the Noble

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 3. The Inert and the Noble. A G Samuelson. Article-in-a-Box Volume 4 Issue 3 March 1999 pp 3-5 ... Author Affiliations. A G Samuelson1. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India.

  9. Cell complexes of transition metals in biochemistry and medicine

    International Nuclear Information System (INIS)

    Voloshin, Ya.Z.; Varzatskij, O.A.; Bubnov, Yu.N.

    2007-01-01

    Basic directions and prospects of use of cell complexes of transition metals in medicine and biochemistry are considered: incapsulation of radioactive metal ions for radiotherapy and diagnostics; preparation of contrast compounds for magnetic resonance tomography, antidotes and pharmaceutical preparation of prolonged effect, preparations for boron-neutron-capture therapy of neoplasms, antioxidants; membrane transport of metal ions; study of interaction of cell metal complexes with nucleic acids; possibility of use of self-assembly of cell complexes for imitation of ligases and use of clathrochelates as linkers; design of inhibitors of viruses for AIDS therapy [ru

  10. Metal accumulation in Nitellopsis obtusa cells from the laboratory solution

    International Nuclear Information System (INIS)

    Marciulioniene, D.; Montvydiene, D.; Ceburnis, D.

    2001-01-01

    The ability of Nitellopsis obtusa to accumulate heavy metals from the laboratory solution containing ions of Cd2+, Cr6+, Cu2+, Mn2+, Ni2+, Pb2+ and Zn2+ was investigated. Concentrations of heavy metals in the algae cells were determined, and the accumulation coefficient (AC) of heavy metals in the live cells (in the wall and the protoplast), in the dead cells (in the wall), and in the cells which have lost turgor were estimated. It was found that, according to the accumulation coefficient values in the cell wall of N. obtusa, the studied metals followed the order: Cr6+ < Pb2+ < Ni2+ < Cd2+ < Cu2+ < Zn2+ < Mn2+, while according to the accumulation coefficient values in the protoplast, the order was: Pb2+ < Cr6+ < Ni2+ < Zn2+ < Cd2+ < Cu2+ < Mn2+ . It was demonstrated that in both media metals were accumulated very similarly. The difference between AC in the cell walls of the live and dead cells was negligible. The obtained data allowed to conclude that all investigated metals were not only absorbed in the algae cell wall but they were intensively up taken into the cell. Data showed that among all investigated metals Cr6+ was the least absorbed in the cell wall, while Pb was predominantly absorbed in the cell wall, as well as Cd2+ and Cu2+ were more intensively up taken into the cell than other metals It was established that Mn2+ was Intensively adsorbed in the cell wall, and its uptake into the cell was intensive, too. (author)

  11. Highly efficient transition metal and nitrogen co-doped carbide-derived carbon electrocatalysts for anion exchange membrane fuel cells

    Science.gov (United States)

    Ratso, Sander; Kruusenberg, Ivar; Käärik, Maike; Kook, Mati; Puust, Laurits; Saar, Rando; Leis, Jaan; Tammeveski, Kaido

    2018-01-01

    The search for an efficient electrocatalyst for oxygen reduction reaction (ORR) to replace platinum in fuel cell cathode materials is one of the hottest topics in electrocatalysis. Among the many non-noble metal catalysts, metal/nitrogen/carbon composites made by pyrolysis of cheap materials are the most promising with control over the porosity and final structure of the catalyst a crucial point. In this work we show a method of producing a highly active ORR catalyst in alkaline media with a controllable porous structure using titanium carbide derived carbon as a base structure and dicyandiamide along with FeCl3 or CoCl2 as the dopants. The resulting transition metal-nitrogen co-doped carbide derived carbon (M/N/CDC) catalyst is highly efficient for ORR electrocatalysis with the activity in 0.1 M KOH approaching that of commercial 46.1 wt.% Pt/C. The catalyst materials are also investigated by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to characterise the changes in morphology and composition causing the raise in electrochemical activity. MEA performance of M/N/CDC cathode materials in H2/O2 alkaline membrane fuel cell is tested with the highest power density reached being 80 mW cm-2 compared to 90 mW cm-2 for Pt/C.

  12. Molybdenum-tin as a solar cell metallization system

    Science.gov (United States)

    Boyd, D. W.; Radics, C.

    1981-01-01

    The operations of solar cell manufacture are briefly examined. The formation of reliable, ohmic, low-loss, and low-cost metal contacts on solar cells is a critical process step in cell manufacturing. In a commonly used process, low-cost metallization is achieved by screen printing a metal powder-glass frit ink on the surface of the Si surface and the conductive metal powder. A technique utilizing a molybdenum-tin alloy for the metal contacts appears to lower the cost of materials and to reduce process complexity. The ink used in this system is formulated from MoO3 with Sn powder and a trace amount of titanium resonate. Resistive losses of the resulting contacts are low because the ink contains no frit. The MoO3 is finally melted and reduced in forming gas (N2+H2) to Mo metal. The resulting Mo is highly reactive which facilitates the Mo-Si bonding.

  13. Cell surface engineering of microorganisms towards adsorption of heavy metals.

    Science.gov (United States)

    Li, Peng-Song; Tao, Hu-Chun

    2015-06-01

    Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed.

  14. Electrical resistivity of liquid noble metal alloys

    International Nuclear Information System (INIS)

    Anis Alam, M.; Tomak, M.

    1983-08-01

    Calculations of the dependence of the electrical resistivity in liquid Ag-Au, Cu-Ag, Cu-Au binary alloys on composition are reported. The structure of the binary alloy is described as a hard sphere system. A one-parameter local pseudopotential, which incorporates s-d hybridization effects phenomenologically, is employed in the resistivity calculation. A reasonable agreement with experimental trends is observed in cases where experimental information is available. (author)

  15. Platinum Group Metal-free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells.

    Science.gov (United States)

    Yuan, Heyang; He, Zhen

    2017-07-01

    Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost-effective. A variety of noble-metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS 2 , carbon-based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Noble Gas Concept Of Operation

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-01-20

    The intent of this document is to provide the reader with an understanding of a general approach to performing the noble gas component of an On Site Inspection or OSI. The authors of this document recognize that owing to the wide range of scenarios that are possible for carrying out an underground nuclear explosion, the diverse sets of information that might be available to the inspection team initially and the potential range of political and physical constraints imposed during the inspection, a satisfactory prescriptive approach to carrying out the noble gas component of an OSI is unlikely. Rather, the authors intend only to aid the reader in understanding what a reasonable course of actions or responses may be as performed by an inspection team (IT) during a general OSI. If this document helps to inform the intuition of the reader about addressing the challenges resulting from the inevitable deviations from this general scenario, it will have achieved its intent.

  17. Determination of natural in vivo noble-gas concentrations in human blood.

    Directory of Open Access Journals (Sweden)

    Yama Tomonaga

    Full Text Available Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry.

  18. Ni/CeO{sub 2}-Al{sub 2}O{sub 3} catalysts promoted with noble metals for the hydrogen production by ethanol vapor reforming; Catalisadores de Ni/CeO{sub 2}-Al{sub 2}O{sub 3} promovidos com metais nobres para a producao de hidrogenio por reforma a vapor de etanol

    Energy Technology Data Exchange (ETDEWEB)

    Profeti, Luciene P.R.; Ticianelli, Edson Antonio; Assaf, Elisabete Moreira [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: eassaf@iqsc.usp.br

    2008-07-01

    The catalytic activity of Ni/CeO{sub 2}-Al{sub 2}O{sub 3} catalysts modified with noble metals (Ru, Ir, Pt and Pd) was investigated in the steam reforming of ethanol. The catalysts were characterized by energy dispersive spectroscopy, X-ray diffraction, UV-Vis diffuse reflectance spectroscopy and H{sub 2} temperature-programmed reduction-X-ray absorption fine structure (XANES). The results showed that the formation of inactive nickel aluminate was avoided due to the presence of a CeO{sub 2} dispersed on the alumina. The promoting effect of noble metals included a decrease of the reduction temperatures of NiO species interacting with the support due to the hydrogen spillover effect, leading to an increase of the reducibilities of the promoted catalysts The better catalytic performance for the ethanol steam reforming was obtained for the NiPd/CeAl catalyst, which presented an effluent gaseous mixture with the highest H{sub 2} yield. (author)

  19. Heavy metal biosorption by bacterial cells

    NARCIS (Netherlands)

    Vecchio, A; Finoli, C; Di Simine, D; Andreoni, [No Value

    Microbial biomass provides available ligand groups on which metal ions bind by different mechanisms. Biosorption of these elements from aqueous solutions represents a remediation technology suitable for the treatment of metal-contaminated effluents. The purpose of the present investigation was the

  20. Electrocatalyst advances for hydrogen oxidation in phosphoric acid fuel cells

    Science.gov (United States)

    Stonehart, P.

    1984-01-01

    The important considerations that presently exist for achieving commercial acceptance of fuel cells are centered on cost (which translates to efficiency) and lifetime. This paper addresses the questions of electrocatalyst utilization within porous electrode structures and the preparation of low-cost noble metal electrocatalyst combinations with extreme dispersions of the metal. Now that electrocatalyst particles can be prepared with dimensions of 10 A, either singly or in alloy combinations, a very large percentage of the noble metal atoms in a crystallite are available for reaction. The cost savings for such electrocatalysts in the present commercially driven environment are considerable.

  1. Back contact to film silicon on metal for photovoltaic cells

    Science.gov (United States)

    Branz, Howard M.; Teplin, Charles; Stradins, Pauls

    2013-06-18

    A crystal oriented metal back contact for solar cells is disclosed herein. In one embodiment, a photovoltaic device and methods for making the photovoltaic device are disclosed. The photovoltaic device includes a metal substrate with a crystalline orientation and a heteroepitaxial crystal silicon layer having the same crystal orientation of the metal substrate. A heteroepitaxial buffer layer having the crystal orientation of the metal substrate is positioned between the substrate and the crystal silicon layer to reduce diffusion of metal from the metal foil into the crystal silicon layer and provide chemical compatibility with the heteroepitaxial crystal silicon layer. Additionally, the buffer layer includes one or more electrically conductive pathways to electrically couple the crystal silicon layer and the metal substrate.

  2. Environmental tests of metallization systems for terrestrial photovoltaic cells

    Science.gov (United States)

    Alexander, P., Jr.

    1985-01-01

    Seven different solar cell metallization systems were subjected to temperature cycling tests and humidity tests. Temperature cycling excursions were -50 deg C to 150 deg C per cycle. Humidity conditions were 70 deg C at 98% relative humidity. The seven metallization systems were: Ti/Ag, Ti/Pd/Ag, Ti/Pd/Cu, Ni/Cu, Pd/Ni/Solder, Cr/Pd/Ag, and thick film Ag. All metallization systems showed a slight to moderate decrease in cell efficiencies after subjection to 1000 temperature cycles. Six of the seven metallization systems also evidenced slight increases in cell efficiencies after moderate numbers of cycles, generally less than 100 cycles. The copper based systems showed the largest decrease in cell efficiencies after temperature cycling. All metallization systems showed moderate to large decreases in cell efficiencies after 123 days of humidity exposure. The copper based systems again showed the largest decrease in cell efficiencies after humidity exposure. Graphs of the environmental exposures versus cell efficiencies are presented for each metallization system, as well as environmental exposures versus fill factors or series resistance.

  3. CIGS cells with metallized front contact: Longer cells and higher efficiency

    NARCIS (Netherlands)

    Deelen, J. van; Frijters, C.

    2017-01-01

    We have investigated the benefit of a patterned metallization on top of a transparent conductive oxide in CIGS thin-film solar panels. It was found that cells with a grid have a higher efficiency compared to cells with only a TCO. This was observed for all cell lengths used. Furthermore, metallic

  4. Heavy metals in the cell nucleus - role in pathogenesis.

    Science.gov (United States)

    Sas-Nowosielska, Hanna; Pawlas, Natalia

    2015-01-01

    People are exposed to heavy metals both in an occupational and natural environment. The most pronounced effects of heavy metals result from their interaction with cellular genetic material packed in form of chromatin. Heavy metals influence chromatin, mimicking and substituting natural microelements in various processes taking place in the cell, or interacting chemically with nuclear components: nucleic acids, proteins and lipids. This paper is a review of current knowledge on the effects of heavy metals on chromatin, exerted at the level of various nuclear components.

  5. Influence of the noble metals (Pd, Au, Ag) in the thermoluminescent signal induced by radiation in the ZrO{sub 2}; Influencia de los metales nobles (Pd, Au, Ag) en la senal termoluminiscente inducida por la radiacion en la ZrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Villa S, G

    2006-07-01

    When increasing the use of the ionizing and non ionizing radiations (for example, gamma and ultraviolet radiation) in different areas of the science and technology, there is necessary to apply more accurate safety measures and to avoid over-exposures that could put in risk the life of workers that manipulate radiation sources, patient that are exposed to this under some medical treatment, as well as materials that undergo intentionally to radiation. Also, the UV radiation that arrives to the earth can cause some damages, to the one to weaken the protector layer of ozone the UV radiation increases that arrives to the earth surface being able to affect the alive beings and the materials. By this so much the development of new materials able to take a census of in a more accurate way, fields of gamma and UV radiation is becoming necessary. In this sense, this work presents the obtained results when quantifying radiation fields, through the analysis in the thermoluminescent behavior (TL) induced by the gamma and UV radiation in the zirconium dioxide synthesized by the sol gel method and doped with nanoparticles of Pd, Au and Ag. It is necessary to mention that in reported works in this respect its mention that the zircon has good thermoluminescent sensitivity induced by these radiation types, however it has shown high thermoluminescent instability that is translated in an important lost of the information after the irradiation. For that through the incorporation of the metallic nanoparticles it was intended to stabilize the TL behavior of zircon. The results showed that the doped zircon has a high sensitivity to the gamma and UV radiation. These also show that the ionizing and non ionizing radiation induce a thermoluminescent curve consisting of two TL peaks with maxima located around 65 C and 145 C and that the intensity is increased with the dose, following a lineal behavior in certain interval of dose exposure that is influenced by the presence of the nanoparticles

  6. Recycled Cell Phones - A Treasure Trove of Valuable Metals

    Science.gov (United States)

    Sullivan, Daniel E.

    2006-01-01

    This U.S. Geological Survey (USGS) Fact Sheet examines the potential value of recycling the metals found in obsolete cell phones. Cell phones seem ubiquitous in the United States and commonplace throughout most of the world. There were approximately 1 billion cell phones in use worldwide in 2002. In the United States, the number of cell phone subscribers increased from 340,000 in 1985 to 180 million in 2004. Worldwide, cell phone sales have increased from slightly more than 100 million units per year in 1997 to an estimated 779 million units per year in 2005. Cell phone sales are projected to exceed 1 billion units per year in 2009, with an estimated 2.6 billion cell phones in use by the end of that year. The U.S. Environmental Protection Agency estimated that, by 2005, as many as 130 million cell phones would be retired annually in the United States. The nonprofit organization INFORM, Inc., anticipated that, by 2005, a total of 500 million obsolete cell phones would have accumulated in consumers' desk drawers, store rooms, or other storage, awaiting disposal. Typically, cell phones are used for only 1 1/2 years before being replaced. Less than 1 percent of the millions of cell phones retired and discarded annually are recycled. When large numbers of cell phones become obsolete, large quantities of valuable metals end up either in storage or in landfills. The amount of metals potentially recoverable would make a significant addition to total metals recovered from recycling in the United States and would supplement virgin metals derived from mining.

  7. The use of metal hydrides in fuel cell applications

    Directory of Open Access Journals (Sweden)

    Mykhaylo V. Lototskyy

    2017-02-01

    Full Text Available This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field, as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally, the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.

  8. Metal binding proteins, recombinant host cells and methods

    Science.gov (United States)

    Summers, Anne O.; Caguiat, Jonathan J.

    2004-06-15

    The present disclosure provides artificial heavy metal binding proteins termed chelons by the inventors. These chelons bind cadmium and/or mercuric ions with relatively high affinity. Also disclosed are coding sequences, recombinant DNA molecules and recombinant host cells comprising those recombinant DNA molecules for expression of the chelon proteins. In the recombinant host cells or transgenic plants, the chelons can be used to bind heavy metals taken up from contaminated soil, groundwater or irrigation water and to concentrate and sequester those ions. Recombinant enteric bacteria can be used within the gastrointestinal tracts of animals or humans exposed to toxic metal ions such as mercury and/or cadmium, where the chelon recombinantly expressed in chosen in accordance with the ion to be rededicated. Alternatively, the chelons can be immobilized to solid supports to bind and concentrate heavy metals from a contaminated aqueous medium including biological fluids.

  9. Parasitic corrosion-resistant anode for use in metal/air or metal/O/sub 2/ cells

    Science.gov (United States)

    Joy, R.W.; Smith, D.F.

    1982-09-20

    A consumable metal anode is described which is used in refuelable electrochemical cells and wherein at least a peripheral edge portion of the anode is protected against a corrosive alkaline environment of the cell by the application of a thin metal coating, the coating being formed of metals such as nickel, silver, and gold.

  10. Parasitic corrosion resistant anode for use in metal/air or metal/O.sub.2 cells

    Science.gov (United States)

    Joy, Richard W.; Smith, David F.

    1983-01-01

    A consumable metal anode which is used in refuelable electrochemical cells and wherein at least a peripheral edge portion of the anode is protected against a corrosive alkaline environment of the cell by the application of a thin metal coating, the coating being formed of metals such as nickel, silver, and gold.

  11. Heavy metals effect in Drosophila melanogaster germinal cells

    International Nuclear Information System (INIS)

    Rosa Duque de la, M.E.

    1984-01-01

    Heavy metals occur naturally and some of them are very important in cellular metabolism. Industrial development has increased metal concentration in the environment and in the living organisms tissues. This increase promotes the human risk to suffer teratogenesis, carcinogenesis and mutagenesis. Different biological systems have been used to proof the genetic effect of heavy metals including Drosophila. In the present work chromium, cadmium, lead, zinc and arsenic salts were administered to Drosophila females and males adults in order to determine the genetic effect produced by these compounds, in both femenine and masculine germinal cells. The mating system used (''Oster males'' and y 2 wsup(a)/y 2 wsup(a); e/e females) permited to determine among two succesive generations, the mutagenic effects produced by heavy metals in Drosophila. The salts administration to adult flies was made by injection. Non-disjunction, X-chromosome loss, and sex linked recessive lethals frequency was increased by heavy metals. It was observed a fertility disminution between F 1 descendants from individuals treated with the metalic salts. It was demonstrated that heavy metals can interact with genetic material at different levels in the two types of gametic cells to produce genetic damage. (author)

  12. Noble gases in nuclear medicine

    International Nuclear Information System (INIS)

    Calderon, M.; Burdine, J.A.

    1973-01-01

    Radioactive noble gases have made a significant contribution to diagnostic nuclear medicine. In the area of regional assessment of pulmonary function, 133 Xe has had its greatest clinical impact. Following a breath of 133 Xe gas, pulmonary ventilation can be measured using a scintillation camera or other appropriate radiation detector. If 133 Xe dissolved in saline is injected intravenously, both pulmonary capillary perfusion and ventilation can be measured since 90 percent of the highly insoluble xenon escapes into the alveoli during the first passage through the lungs. Radionuclide pulmonary function tests provide the first qualitative means of assessing lung ventilation and blood flow on a regional basis, and have recently been extended to include quantification of various parameters of lung function by means of a small computer interfaced to the scintillation camera. 133 Xe is also used in the measurement of organ blood flow following injection into a vessel leading into an organ such as the brain, heart kidneys, or muscles

  13. Subsurface Noble Gas Sampling Manual

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sun, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-09-18

    The intent of this document is to provide information about best available approaches for performing subsurface soil gas sampling during an On Site Inspection or OSI. This information is based on field sampling experiments, computer simulations and data from the NA-22 Noble Gas Signature Experiment Test Bed at the Nevada Nuclear Security Site (NNSS). The approaches should optimize the gas concentration from the subsurface cavity or chimney regime while simultaneously minimizing the potential for atmospheric radioxenon and near-surface Argon-37 contamination. Where possible, we quantitatively assess differences in sampling practices for the same sets of environmental conditions. We recognize that all sampling scenarios cannot be addressed. However, if this document helps to inform the intuition of the reader about addressing the challenges resulting from the inevitable deviations from the scenario assumed here, it will have achieved its goal.

  14. Modification of cell volume and proliferative capacity of Pseudokirchneriella subcapitata cells exposed to metal stress

    International Nuclear Information System (INIS)

    Machado, Manuela D.; Soares, Eduardo V.

    2014-01-01

    Highlights: •Metals induce morphological alterations on P. subcapitata. •Algal cell cycle consists: mother cell growth; cell division, with two nucleus divisions; release of four autospores. •Cu(II) and Cr(VI) arrest cell growth before the first nuclear division. •Cd(II) arrests cell growth after the second nuclear division but before the cytokinesis. •The approach used can be useful in the elucidation of different modes of action of pollutants. -- Abstract: The impact of metals (Cd, Cr, Cu and Zn) on growth, cell volume and cell division of the freshwater alga Pseudokirchneriella subcapitata exposed over a period of 72 h was investigated. The algal cells were exposed to three nominal concentrations of each metal: low (closed to 72 h-EC 10 values), intermediate (closed to 72 h-EC 50 values) and high (upper than 72 h-EC 90 values). The exposure to low metal concentrations resulted in a decrease of cell volume. On the contrary, for the highest metal concentrations an increase of cell volume was observed; this effect was particularly notorious for Cd and less pronounced for Zn. Two behaviours were found when algal cells were exposed to intermediate concentrations of metals: Cu(II) and Cr(VI) induced a reduction of cell volume, while Cd(II) and Zn(II) provoked an opposite effect. The simultaneous nucleus staining and cell image analysis, allowed distinguishing three phases in P. subcapitata cell cycle: growth of mother cell; cell division, which includes two divisions of the nucleus; and, release of four autospores. The exposure of P. subcapitata cells to the highest metal concentrations resulted in the arrest of cell growth before the first nucleus division [for Cr(VI) and Cu(II)] or after the second nucleus division but before the cytokinesis (release of autospores) when exposed to Cd(II). The different impact of metals on algal cell volume and cell-cycle progression, suggests that different toxicity mechanisms underlie the action of different metals

  15. Metal supplementation to UASB bioreactors: from cell-metal interactions to full-scale application

    International Nuclear Information System (INIS)

    Fermoso, Fernando G.; Bartacek, Jan; Jansen, Stefan; Lens, Piet N.L.

    2009-01-01

    Upflow anaerobic sludge bed (UASB) bioreactors are commonly used for anaerobic wastewater treatment. Trace metals need to be dosed to these bioreactors to maintain microbial metabolism and growth. The dosing needs to balance the supply of a minimum amount of micronutrients to support a desired microbial activity or growth rate with a maximum level of micronutrient supply above which the trace metals become inhibitory or toxic. In studies on granular sludge reactors, the required micronutrients are undefined and different metal formulations with differences in composition, concentration and species are used. Moreover, an appropriate quantification of the required nutrient dosing and suitable ranges during the entire operational period has been given little attention. This review summarizes the state-of-the-art knowledge of the interactions between trace metals and cells growing in anaerobic granules, which is the main type of biomass retention in anaerobic wastewater treatment reactors. The impact of trace metal limitation as well as overdosing (toxicity) on the biomass is overviewed and the consequences for reactor performance are detailed. Special attention is given to the influence of metal speciation in the liquid and solid phase on bioavailability. The currently used methods for trace metal dosing into wastewater treatment reactors are overviewed and ways of optimization are suggested.

  16. Metal supplementation to UASB bioreactors: from cell-metal interactions to full-scale application

    Energy Technology Data Exchange (ETDEWEB)

    Fermoso, Fernando G. [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' -Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Bartacek, Jan [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' -Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Pollution Prevention and Control core, UNESCO-IHE, P.O. Box 3015, 2601 DA Delft (Netherlands); Jansen, Stefan [Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen (Netherlands); Lens, Piet N.L., E-mail: Piet.Lens@wur.nl [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' -Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Pollution Prevention and Control core, UNESCO-IHE, P.O. Box 3015, 2601 DA Delft (Netherlands)

    2009-06-01

    Upflow anaerobic sludge bed (UASB) bioreactors are commonly used for anaerobic wastewater treatment. Trace metals need to be dosed to these bioreactors to maintain microbial metabolism and growth. The dosing needs to balance the supply of a minimum amount of micronutrients to support a desired microbial activity or growth rate with a maximum level of micronutrient supply above which the trace metals become inhibitory or toxic. In studies on granular sludge reactors, the required micronutrients are undefined and different metal formulations with differences in composition, concentration and species are used. Moreover, an appropriate quantification of the required nutrient dosing and suitable ranges during the entire operational period has been given little attention. This review summarizes the state-of-the-art knowledge of the interactions between trace metals and cells growing in anaerobic granules, which is the main type of biomass retention in anaerobic wastewater treatment reactors. The impact of trace metal limitation as well as overdosing (toxicity) on the biomass is overviewed and the consequences for reactor performance are detailed. Special attention is given to the influence of metal speciation in the liquid and solid phase on bioavailability. The currently used methods for trace metal dosing into wastewater treatment reactors are overviewed and ways of optimization are suggested.

  17. Cell-metal interactions: A comparison of natural uranium to other common metals in renal cells and bone osteoblasts

    International Nuclear Information System (INIS)

    Milgram, S.; Carriere, M.; Thiebault, C.; Berger, P.; Khodja, H.; Gouget, B.

    2007-01-01

    Uranium acute intoxication has been documented to induce nephrotoxicity. Kidneys are the main target organs after short term exposures to high concentrations of the toxic, while chronic exposures lead to its accumulation in the skeleton. In this paper, chemical toxicity of uranium is investigated for rat osteoblastic bone cells and compared to results previously obtained on renal cells. We show that bone cells are less sensitive to uranium than renal cells. The influence of the chemical form on U cytotoxicity is demonstrated. For both cell types, a comparison of uranium toxicity with other metals or metalloids toxicities (Mn, Ni, Co, Cu, Zn, Se and Cd) permits classification of Cd, Zn, Se IV and Cu as the most toxic and Ni, Se VI , Mn and U as the least toxic. Chemical toxicity of natural uranium proves to be far less than that of cadmium. To try to explain the differences in sensitivities observed between metals and different cell types, cellular accumulations in cell monolayers are quantified by inductively coupled plasma-mass spectroscopy (ICP-MS), function of time or function of dose: lethal doses which simulate acute intoxications and sub-lethal doses which are more realistic with regard to environmentally metals concentrations. In addition to being more resistant, bone cells accumulated much more uranium than did renal cells. Moreover, for both cell models, Mn, U-citrate and U-bicarbonate are strongly accumulated whereas Cu, Zn and Ni are weakly accumulated. On the other hand, a strong difference in Cd behaviour between the two cell types is shown: whereas Cd is very weakly accumulated in bone cells, it is very strongly accumulated in renal cells. Finally, elemental distribution of the toxics is determined on a cellular scale using nuclear microprobe analysis. For both renal and osteoblastic cells, uranium was accumulated in as intracellular precipitates similar to those observed previously by SEM/EDS

  18. Cell-metal interactions: A comparison of natural uranium to other common metals in renal cells and bone osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Milgram, S. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Carriere, M. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Thiebault, C. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Berger, P. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Khodja, H. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France); Gouget, B. [Laboratoire Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, 91191 Gif-sur-Yvette (France)]. E-mail: barbara.gouget@cea.fr

    2007-07-15

    Uranium acute intoxication has been documented to induce nephrotoxicity. Kidneys are the main target organs after short term exposures to high concentrations of the toxic, while chronic exposures lead to its accumulation in the skeleton. In this paper, chemical toxicity of uranium is investigated for rat osteoblastic bone cells and compared to results previously obtained on renal cells. We show that bone cells are less sensitive to uranium than renal cells. The influence of the chemical form on U cytotoxicity is demonstrated. For both cell types, a comparison of uranium toxicity with other metals or metalloids toxicities (Mn, Ni, Co, Cu, Zn, Se and Cd) permits classification of Cd, Zn, Se{sup IV} and Cu as the most toxic and Ni, Se{sup VI}, Mn and U as the least toxic. Chemical toxicity of natural uranium proves to be far less than that of cadmium. To try to explain the differences in sensitivities observed between metals and different cell types, cellular accumulations in cell monolayers are quantified by inductively coupled plasma-mass spectroscopy (ICP-MS), function of time or function of dose: lethal doses which simulate acute intoxications and sub-lethal doses which are more realistic with regard to environmentally metals concentrations. In addition to being more resistant, bone cells accumulated much more uranium than did renal cells. Moreover, for both cell models, Mn, U-citrate and U-bicarbonate are strongly accumulated whereas Cu, Zn and Ni are weakly accumulated. On the other hand, a strong difference in Cd behaviour between the two cell types is shown: whereas Cd is very weakly accumulated in bone cells, it is very strongly accumulated in renal cells. Finally, elemental distribution of the toxics is determined on a cellular scale using nuclear microprobe analysis. For both renal and osteoblastic cells, uranium was accumulated in as intracellular precipitates similar to those observed previously by SEM/EDS.

  19. Invited: A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar

    2014-01-01

    Alkaline fuel cells and electrolyzers are attracting increasing interest. This is to a large extent due to the broad selection of catalyst materials not based on resource limited and expensive noble metals. The first fuel cells in practical use were Francis Thomas Bacon’s based on an alkaline...

  20. A flow-through cell with integrated coulometric pH actuator

    NARCIS (Netherlands)

    Bohm, S.; Olthuis, Wouter; Bergveld, Piet

    1998-01-01

    A flow-through cell with integrated coulometric actuator capable of controlling the pH of a flowing liquid is presented. The cell, consisting of a rectangular channel with a noble metal actuator electrode deposited on the bottom, enables the titration of a moving liquid without the need for pumps

  1. Leaching of metals from end-of-life solar cells.

    Science.gov (United States)

    Chakankar, Mital; Su, Chun Hui; Hocheng, Hong

    2018-04-10

    The issue of recycling waste solar cells is critical with regard to the expanded use of these cells, which increases waste production. Technology establishment for this recycling process is essential with respect to the valuable and hazardous metals present therein. In the present study, the leaching potentials of Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans, Penicillium chrysogenum, and Penicillium simplicissimum were assessed for the recovery of metals from spent solar cells, with a focus on retrieval of the valuable metal Te. Batch experiments were performed to explore and compare the metal removal efficiencies of the aforementioned microorganisms using spent media. P. chrysogenum spent medium was found to be most effective, recovering 100% of B, Mg, Si, V, Ni, Zn, and Sr along with 93% of Te at 30 °C, 150 rpm and 1% (w/v) pulp density. Further optimization of the process parameters increased the leaching efficiency, and 100% of Te was recovered at the optimum conditions of 20 °C, 200 rpm shaking speed and 1% (w/v) pulp density. In addition, the recovery of aluminum increased from 31 to 89% upon process optimization. Thus, the process has considerable potential for metal recovery and is environmentally beneficial.

  2. Metal stress induces programmed cell death in aquatic fungi

    International Nuclear Information System (INIS)

    Azevedo, Maria-Manuel; Almeida, Bruno; Ludovico, Paula; Cassio, Fernanda

    2009-01-01

    Aquatic hyphomycetes are a group of fungi that play a key role in organic matter turnover in both clean and metal-polluted streams. We examined the ability of Cu or Zn to induce programmed cell death (PCD) in three aquatic hyphomycete species through the evaluation of typical apoptotic markers, namely reactive oxygen species (ROS) accumulation, caspase-like activity, nuclear morphological alterations, and the occurrence of DNA strand breaks assessed by TUNEL assay. The exposure to both metals induced apoptotic events in all tested aquatic fungi. The most tolerant fungi either to Zn (Varicosporium elodeae) or Cu (Heliscussubmersus) exhibited higher levels of PCD markers, suggesting that PCD processes might be linked to fungal resistance/tolerance to metal stress. Moreover, different patterns of apoptotic markers were found, namely a PCD process independent of ROS accumulation in V. elodeae exposed to Cu, or independent of caspase-like activity in Flagellospora curta exposed to Zn, or even without the occurrence of DNA strand breaks in F. curta exposed to Cu. This suggests that a multiplicity of PCD pathways might be operating in aquatic hyphomycetes. The occurrence of a tightly regulated cell death pathway, such as PCD, in aquatic hyphomycetes under metal stress might be a part of the mechanisms underlying fungal acclimation in metal-polluted streams, because it would allow the rapid removal of unwanted or damaged cells sparing nutrients and space for the fittest ones.

  3. Aluminum low temperature smelting cell metal collection

    Science.gov (United States)

    Beck, Theodore R.; Brown, Craig W.

    2002-07-16

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten salt electrolyte in an electrolytic cell having an anodic liner for containing the electrolyte, the liner having an anodic bottom and walls including at least one end wall extending upwardly from the anodic bottom, the anodic liner being substantially inert with respect to the molten electrolyte. A plurality of non-consumable anodes is provided and disposed vertically in the electrolyte. A plurality of cathodes is disposed vertically in the electrolyte in alternating relationship with the anodes. The anodes are electrically connected to the anodic liner. An electric current is passed through the anodic liner to the anodes, through the electrolyte to the cathodes, and aluminum is deposited on said cathodes. Oxygen bubbles are generated at the anodes and the anodic liner, the bubbles stirring the electrolyte. Molten aluminum is collected from the cathodes into a tubular member positioned underneath the cathodes. The tubular member is in liquid communication with each cathode to collect the molten aluminum therefrom while excluding electrolyte. Molten aluminum is delivered through the tubular member to a molten aluminum reservoir located substantially opposite the anodes and cathodes. The molten aluminum is collected from the cathodes and delivered to the reservoir while avoiding contact of the molten aluminum with the anodic bottom.

  4. Recovering metal values hydrometallurgically from spent dry battery cells

    Science.gov (United States)

    Rabah, M. A.; Barakat, M. A.; Mahrous, Y. Sh.

    1999-12-01

    A hydro-pyrometallurgical method was used to recover metal values from spent dry battery cells. Water-soluble ingredients were filtered, and solid residue was sorted by magnetic separation and water flotation. Parameters affecting the recovery efficiency were also studied. Results revealed that metallic parts, carbon rods, and paper were safely recovered; pure NH4Cl, MnO2, and ZnCl2 salts were obtained. Maximum recovery efficiencies reached 93 percent for manganese and 99.5 percent for zinc and NH4.

  5. Fuel cell research: Towards efficient energy

    CSIR Research Space (South Africa)

    Rohwer, MB

    2008-11-01

    Full Text Available fuel cells by optimising the loading of catalyst (being expensive noble metals) and ionomer; 2) Improving conventional acidic direct alcohol fuel cells by developing more efficient catalysts and by investigating other fuels than methanol; 3... these components add significantly to the overall cost of a PEMFC. 1 We focused our research activities on: 1) The effect of the loading of catalytic ink on cell performance; 2) The effect of the ionomer content in the catalytic ink; 3) Testing...

  6. Manufacturing of Cast Metal Foams with Irregular Cell Structure

    Directory of Open Access Journals (Sweden)

    Kroupová I.

    2015-06-01

    Full Text Available Metallic foams are materials of which the research is still on-going, with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.. These metallic materials have specific properties, such as large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting technology (infiltration method, which ensures rapid and economically feasible method for production of shaped components. In the experimental part we studied conditions of casting of metallic foams with open pores and irregular cell structure made of ferrous and nonferrous alloys by use of various types of filler material (precursors.

  7. Platinum redispersion on metal oxides in low temperature fuel cells

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Cerri, Isotta; Nagami, Tetsuo

    2013-01-01

    We have analyzed the aptitude of several metal oxide supports (TiO2, SnO2, NbO2, ZrO2, SiO2, Ta2O5 and Nb2O5) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in ...

  8. Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Jared; Bosco, Nick; Dauskardt, Reinhold

    2017-11-01

    Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of ethylene vinyl acetate (EVA) encapsulant to screen-printed silver metallization was evaluated. At room temperature, the fracture energy Gc [J/m2] of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/antireflective (AR) coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 h of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2 while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and chemical byproducts at elevated temperature, which in part accounts for the propensity of metalized surfaces to delaminate in the field.

  9. Synthesis and characterization of noble metal–titania core–shell nanostructures with tunable shell thickness

    Directory of Open Access Journals (Sweden)

    Bartosz Bartosewicz

    2017-10-01

    Full Text Available Core–shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired. A sol–gel based titania coating method, which allows control over the shell thickness, was developed and applied to the synthesis of Ag@TiO2 and Au@TiO2 with various shell thicknesses. The morphology of the synthesized structures was investigated using scanning electron microscopy (SEM. Their sizes and shell thicknesses were determined using tunable resistive pulse sensing (TRPS technique. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag@TiO2 and Au@TiO2 structures with shell thickness in the range of ≈40–70 nm and 90 nm, for the Ag and Au nanostructures respectively, were prepared using a method we developed and adapted, consisting of a change in the titania precursor concentration. The synthesized nanostructures exhibited significant absorption in the UV–vis range. The TRPS technique was shown to be a very useful tool for the characterization of metal–metal oxide core–shell nanostructures.

  10. Noble gases in common rocks and their bearing on noble gas occurrences in the hydrological cycle

    International Nuclear Information System (INIS)

    Mazor, E.

    1978-10-01

    The comparison of the noble gases contents in different rocks and in thermal and cold water sources in the French Massif Central was aimed to define the amounts and nature of noble gases contributed by country rocks as opposed to atmospheric noble gases brought in by recharged water. No difference in the noble gas contents was found between waters coming in igneous rocks to those issuing in sedimentary rocks. In both, significant variations in the contents of atmospheric and radiogenic noble gases were found. Radiogenic helium has been found to reveal a positive correlation to the contents of atmospheric Ne, Ar, Kr. This indicates water recharge into the deep part of the systems, mixing with radiogenic He and Ar flushed from igneous and sedimentary rocks and subsequent partial gas loss. Loss of gas is evident from the observed low noble gas contents. These losses have been accompanied by a reversed retention pattern of Ne, Ar, Xc. This reversed retention pattern cannot be an artifact of sampling as well as cannot result by partial steam loss. A similar interpretation for the observed noble gas depletions that agrees with the fact that the observed fractionation patterns are not ''normal'' is given by deuterium and oxygen-18. The stable isotope data seem to exclude partial steam losses

  11. Noble Gas signatures of Enhanced Oil Recovery

    Science.gov (United States)

    Barry, P. H.; Kulongoski, J. T.; Tyne, R. L.; Hillegonds, D.; Byrne, D. J.; Landon, M. K.; Ballentine, C. J.

    2017-12-01

    Noble gases are powerful tracers of fluids from various oil and gas production activities in hydrocarbon reservoirs and nearby groundwater. Non-radiogenic noble gases are introduced into undisturbed oil and natural gas reservoirs through exchange with formation waters [1-3]. Reservoirs with extensive hydraulic fracturing, injection for enhanced oil recovery (EOR), and/or waste disposal also show evidence for a component of noble gases introduced from air [4]. Isotopic and elemental ratios of noble gases can be used to 1) assess the migration history of the injected and formation fluids, and 2) determine the extent of exchange between multiphase fluids in different reservoirs. We present noble gas isotope and abundance data from casing, separator and injectate gases of the Lost Hills and Fruitvale oil fields in the San Joaquin basin, California. Samples were collected as part of the California State Water Resource Control Board's Oil and Gas Regional Groundwater Monitoring Program. Lost Hills (n=7) and Fruitvale (n=2) gases are geochemically distinct and duplicate samples are highly reproducible. Lost Hills casing gas samples were collected from areas where EOR and hydraulic fracturing has occurred in the past several years, and from areas where EOR is absent. The Fruitvale samples were collected from a re-injection port. All samples are radiogenic in their He isotopes, typical of a crustal environment, and show enrichments in heavy noble gases, resulting from preferential adsorption on sediments. Fruitvale samples reflect air-like surface conditions, with higher air-derived noble gas concentrations. Lost Hills gases show a gradation from pristine crustal signatures - indicative of closed-system exchange with formation fluids - to strongly air-contaminated signatures in the EOR region. Pristine samples can be used to determine the extent of hydrocarbon exchange with fluids, whereas samples with excess air can be used to quantify the extent of EOR. Determining noble

  12. Metal Oxides as Efficient Charge Transporters in Perovskite Solar Cells

    KAUST Repository

    Haque, Mohammed

    2017-07-10

    Over the past few years, hybrid halide perovskites have emerged as a highly promising class of materials for photovoltaic technology, and the power conversion efficiency of perovskite solar cells (PSCs) has accelerated at an unprecedented pace, reaching a record value of over 22%. In the context of PSC research, wide-bandgap semiconducting metal oxides have been extensively studied because of their exceptional performance for injection and extraction of photo-generated carriers. In this comprehensive review, we focus on the synthesis and applications of metal oxides as electron and hole transporters in efficient PSCs with both mesoporous and planar architectures. Metal oxides and their doped variants with proper energy band alignment with halide perovskites, in the form of nanostructured layers and compact thin films, can not only assist with charge transport but also improve the stability of PSCs under ambient conditions. Strategies for the implementation of metal oxides with tailored compositions and structures, and for the engineering of their interfaces with perovskites will be critical for the future development and commercialization of PSCs.

  13. Advances in Metal Supported Cells in the METSOFC EU Consortium

    DEFF Research Database (Denmark)

    McKenna, Brandon J.; Christiansen, Niels; Schauperl, Richard

    2012-01-01

    Employing a mechanically robust metal support as the structural element in SOFC has been the objective of various development efforts. The EU-sponsored project “METSOFC”, completed at the end of 2011, resulted in a number of advancements towards implementing this strategy. These include robust me...... outcomes of the METSOFC consortium are covered, along with associated work supported by the Danish National Advanced Technology Foundation.......Employing a mechanically robust metal support as the structural element in SOFC has been the objective of various development efforts. The EU-sponsored project “METSOFC”, completed at the end of 2011, resulted in a number of advancements towards implementing this strategy. These include robust...... metal supported cells (MSCs) having low ASR at low temperature, incorporation into small stacks of powers approaching ½kW, and stack tolerance to various operation cycles. DTU Energy Conversion's (formerly Risø DTU) research into planar MSCs has produced an advanced cell design with high performance...

  14. 77 FR 70159 - Marble River, LLC v. Noble Clinton Windpark I, LLC, Noble Ellenburg Windpark, LLC, Noble...

    Science.gov (United States)

    2012-11-23

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL13-20-000] Marble River... Commission's (Commission) Rules of Practice and Procedure, Marble River, LLC (Marble River or Complainant.... (NYISO or Respondent), alleging that Noble failed to pay Marble River for headroom created by common...

  15. Effects of metal salt catalysts on yeast cell growth in ethanol conversion

    Science.gov (United States)

    Chung-Yun Hse; Yin Lin

    2009-01-01

    The effects of the addition of metal salts and metal salt-catalyzed hydrolyzates on yeast cell growth in ethanol fermentation were investigated. Four yeast strains (Saccharomyces cerevisiae WT1, Saccharomyces cerevisiae MT81, Candida sp. 1779, and Klumaromyces fragilis), four metal salts (CuCl2, FeCl3, AgNO3, and I2), two metal salt-catalyzed hydrolyzates (...

  16. Multi-metallic anodes for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    Restivo, T.A. Guisard; Mello-Castanho, S.R.H.; Leite, D. Will

    2009-01-01

    A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

  17. Hydrometallurgical Recovery of Metal Values From Spent Dry Battery Cells

    International Nuclear Information System (INIS)

    Rabah, M.A.; Barakat, M.A.; Mahrous, Y.Sh.

    1999-01-01

    This study focuses on the recovery of metal values from spent dry battery cells (DBC) applying a hydro-pyrometallurgical method. A process flow sheet was followed up starting with cutting the DBC with toothed cutter disc followed by water soaking and rinsing. Water soluble ingredients were filtered. Solid residue was assorted with the help of magnetic separation and water flotation.The method utilizes hydrogen peroxide to enhance dissolution of these metals in acidic or alkaline leachants. Parameters affecting the recovery efficiency such as stoichiometric ratio, solid: liquid ratio, temperature, time and ph of the system were investigated. In this concern, experiments were executed with a battery sample weighing up to 15 kg. Atomic absorption analysis showed that the input DBC contain appreciable amounts of metal zinc, zinc chloride and manganese that are recoverable.Results obtained revealed that metallic parts, carbon rods and paper were safely separated for recycling. From the water-soluble salts, pure NH 4 CI, MnO 2 and ZnCI 2 salts are obtained meeting the standard specifications. Temperature up to 55 degree enhances the recovery process. Under the optimum conditions, maximum recovery efficiency obtained amounts to 93% for Mn, and 99.5% for Zn and NH 4 CI. A model for explaining the obtained results was also given. Dissolution of metals concerned increases in the order nitric> hydrochloric acid. Results were explained in the premise of the kinetic and thermodynamic properties of the reactions involved. Cost estimate of the products shows that the prices of the products are competitive to those of the market prices

  18. Natural Death and the Noble Savage.

    Science.gov (United States)

    Walter, Tony

    1995-01-01

    The belief that dying and grieving are natural processes is widely held in modern bereavement care. Examines four assumption often made in this connection: (1) most primitive cultures deal with death in an accepting way; (2) this way is different than our own; (3) it is a good and noble way; and (4) traditional societies see death as natural. (JBJ)

  19. The end of a noble narrative?

    DEFF Research Database (Denmark)

    Manners, Ian James; Murray, Philomena

    2015-01-01

    of the forerunner to the current EU we ask if this noble narrative of war and peace, which is at the heart of European integration, at an end. We argue that this principled account is likely to remain just one of several narratives of European integration, but with its reputation somewhat tarnished. Fresh...

  20. Noble gases as cardioprotectants - translatability and mechanism

    NARCIS (Netherlands)

    Smit, Kirsten F.; Weber, Nina C.; Hollmann, Markus W.; Preckel, Benedikt

    2015-01-01

    Several noble gases, although classified as inert substances, exert a tissue-protective effect in different experimental models when applied before organ ischaemia as an early or late preconditioning stimulus, after ischaemia as a post-conditioning stimulus or when given in combination before,

  1. Organ protection by the noble gas helium

    NARCIS (Netherlands)

    Smit, K.F.

    2017-01-01

    The aims of this thesis were to investigate whether helium induces preconditioning in humans, and to elucidate the mechanisms behind this possible protection. First, we collected data regarding organ protective effects of noble gases in general, and of helium in particular (chapters 1-3). In chapter

  2. Carbon composites with metal nanoparticles for Alcohol fuel cells

    Science.gov (United States)

    Ventrapragada, Lakshman; Siddhardha, R. S.; Podilla, Ramakrishna; Muthukumar, V. S.; Creager, Stephen; Rao, A. M.; Ramamurthy, Sai Sathish

    2015-03-01

    Graphene due to its high surface area and superior conductivity has attracted wide attention from both industrial and scientific communities. We chose graphene as a substrate for metal nanoparticle deposition for fuel cell applications. There are many chemical routes for fabrication of metal-graphene composites, but they have an inherent disadvantage of low performance due to the usage of surfactants, that adsorb on their surface. Here we present a design for one pot synthesis of gold nanoparticles and simultaneous deposition on graphene with laser ablation of gold strip and functionalized graphene. In this process there are two natural advantages, the nanoparticles are synthesized without any surfactants, therefore they are pristine and subsequent impregnation on graphene is linker free. These materials are well characterized with electron microscopy to find their morphology and spectroscopic techniques like Raman, UV-Vis. for functionality. This gold nanoparticle decorated graphene composite has been tested for its electrocatalytic oxidation of alcohols for alkaline fuel cell applications. An electrode made of this composite showed good stability for more than 200 cycles of operation and reported a low onset potential of 100 mV more negative, an important factor for direct ethanol fuel cells.

  3. Mass spectrometric production of heterogeneous metal clusters using Knudsen cell

    Directory of Open Access Journals (Sweden)

    Veljković Filip M.

    2016-01-01

    Full Text Available Knudsen effusion mass spectrometry or high-temperature method of mass spectrometry for decades gives new information about saturated vapor of hardly volatile compounds and it is an important method in the discovery of many new molecules, radicals, ions and clusters present in the gas phase. Since pioneering works until now, this method has been successfully applied to a large number of systems (ores, oxides, ceramics, glass materials, borides, carbides, sulfides, nitrates, metals, fullerenes, etc which led to the establishment of various research branches such as chemistry of clusters. This paper describes the basic principles of Knudsen cell use for both identification of chemical species created in the process of evaporation and determination of their ionization energies. Depending on detected ions intensities and the partial pressure of each gaseous component, as well as on changes in partial pressure with temperature, Knudsen cell mass spectrometry enables the determination of thermodynamic parameters of the tested system. A special attention is paid to its application in the field of small heterogeneous and homogeneous clusters of alkali metals. Furthermore, experimental results for thermodynamic parameters of some clusters, as well as capabilities of non-standard ways of using Knudsen cells in the process of synthesis of new clusters are presented herein. [Projekat Ministarstva nauke Republike Srbije, br. 172019

  4. Primordial Noble Gases from Earth's Core

    Science.gov (United States)

    Wang, K.; Lu, X.; Brodholt, J. P.

    2016-12-01

    Recent partitioning experiment suggests helium is more compatible in iron melt than in molten silicates at high pressures (> 10 GPa) (1), thus provide the possibility of the core as being the primordial noble gases warehouse that is responsible for the high primordial/radiogenic noble gas isotopic ratios observed in plume-related basalts. However, the possible transportation mechanism of the noble gases from the core to the overlying mantle is still ambiguous, understanding how this process would affect the noble gas isotopic characteristics of the mantle is critical to validate this core reservoir model. As diffusion is a dominant mass transport process that plays an important role in chemical exchange at the core-mantle boundary (CMB), we have determined the diffusion coefficients of helium, neon and argon in major lower mantle minerals, i.e. periclase (MgO), bridgemanite (MgSiO3-Pv) and post-perovskite (MgSiO3-PPv), by first-principles calculation based on density functional theory (DFT). As expected, the diffusion rate of helium is the fastest at the CMB, which is in the range of 3 × 10-10 to 1 × 10-8 m2/s. The neon diffusion is slightly slower, from 5 × 10-10 to 5 × 10-9 m2/s. Argon diffuses slowest at the rate from 1 × 10-10 to 2 × 10-10 m2/s. We have further simulated the evolution of noble gas isotopic ratios in the mantle near the CMB. Considering its close relationship with the mantle plumes and very likely to be the direct source of "hot-spot" basalts, we took a close investigation on the large low-shear-velocity provinces (LLSVPs). Under reasonable assumptions based on our diffusion parameters, the modelling results indicate that LLSVP is capable of generating all the noble gas isotope signals, e.g., 3He/4He = 55 Ra, 3He/22Ne = 3.1, 3He/36Ar = 0.82, 40Ar/36Ar = 9500, that are in good agreement with the observed values in "hot-spot" basalts (2). Therefore, this core-reservior hypothesis is a self-consistent model that can fits in multiple noble gas

  5. Platinum redispersion on metal oxides in low temperature fuel cells.

    Science.gov (United States)

    Tripković, Vladimir; Cerri, Isotta; Nagami, Tetsuo; Bligaard, Thomas; Rossmeisl, Jan

    2013-03-07

    We have analyzed the aptitude of several metal oxide supports (TiO(2), SnO(2), NbO(2), ZrO(2), SiO(2), Ta(2)O(5) and Nb(2)O(5)) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in detail; however, due to different operating conditions it is not straightforward to link the chemical and the electrochemical environment. The largest differences reflect in (1) the oxidation state of the surface (the oxygen species coverage), (2) temperature and (3) the possibility of platinum dissolution at high potentials and the interference of redispersion with normal working potential of the PEMFC cathode. We have calculated the PtO(x) (x = 0, 1, 2) adsorption energies on different metal oxides' surface terminations as well as inside the metal oxides' bulk, and we have concluded that NbO(2) might be a good support for platinum redispersion at PEMFC cathodes.

  6. Optical Pumping Spin Exchange 3He Gas Cells for Magnetic Resonance Imaging

    Science.gov (United States)

    Kim, W.; Stepanyan, S. S.; Kim, A.; Jung, Y.; Woo, S.; Yurov, M.; Jang, J.

    2009-08-01

    We present a device for spin-exchange optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin exchange optical pumping is used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized gas. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the 3He-N2 mixture. The cells could be refilled. The 3He reaches around 50% polarization in 5-15 hours.

  7. The Biomechanisms of Metal and Metal-Oxide Nanoparticles’ Interactions with Cells

    Directory of Open Access Journals (Sweden)

    Sondra S. Teske

    2015-01-01

    Full Text Available Humans are increasingly exposed to nanoparticles (NPs in medicine and in industrial settings, where significant concentrations of NPs are common. However, NP interactions with and effects on biomolecules and organisms have only recently been addressed. Within we review the literature regarding proposed modes of action for metal and metal-oxide NPs, two of the most prevalent types manufactured. Iron-oxide NPs, for instance, are used as tracers for magnetic resonance imaging of oncological tumors and as vehicles for therapeutic drug delivery. Factors and theories that determine the physicochemical and biokinetic behaviors of NPs are discussed, along with the observed toxicological effects of NPs on cells. Key thermodynamic and kinetic models that explain the sources of energy transfer from NPs to biological targets are summarized, in addition to quantitative structural activity relationship (QSAR modeling efforts. Future challenges for nanotoxicological research are discussed. We conclude that NP studies based on cell culture are often inconsistent and underestimate the toxicity of NPs. Thus, the effect of NPs needs to be examined in whole animal systems.

  8. A fast cost-assessment method for boiler equipment made of noble materials

    International Nuclear Information System (INIS)

    Perreard, J.C.

    1994-01-01

    The method is aimed at assessing equipment costs for preliminary technical-economic studies or succinct project evaluation. Advantages and disadvantages of nobles metals such as nickel, tantalum, titanium, zirconium ... are reviewed. The economic evaluation method is based on a combination of parametric techniques and statistical results, and allows for the assessment of the various cost components as a function of mass, design and manufacturing complexity in the context of industrial specific operating constraints. 3 figs., 6 tabs., 2 refs

  9. Theoretical study of noble gases diffraction from Ru(0001) using van der Waals DFT-based potentials

    International Nuclear Information System (INIS)

    Del Cueto, M; Muzas, A S; Martín, F; Díaz, C

    2015-01-01

    This study aims to analyze the role of van der Waals forces in the diffraction process of noble gases from a metal surface. We made use of different vdW implementations to rationalize the effect of dispersion forces on the corrugation of the system, the resulting scattering patterns and on the eventual diffraction results. (paper)

  10. Noble gas enrichment studies at JET

    International Nuclear Information System (INIS)

    Groth, M.; Andrew, P.; Fundamenski, W.; Guo, H.Y.; Hillis, D.L.; Hogan, J.T.; Horton, L.D.; Matthews, G.F.; Meigs, A.G.; Morgan, P.M.; Stamp, M.F.; Hellermann, M. von

    2001-01-01

    Adequate helium exhaust has been achieved in reactor-relevant ELMy H-mode plasmas in JET performed in the MKII AP and MKII GB divertor geometry. The divertor-characteristic quantities of noble gas compression and enrichment have been experimentally inferred from Charge Exchange Recombination Spectroscopy measurements in the core plasma, and from spectroscopic analysis of a Penning gauge discharge in the exhaust gas. The retention of helium was found to be satisfactory for a next-step device, with enrichment factors exceeding 0.1. The helium enrichment decreases with increasing core plasma density, while the neon enrichment has the opposite behaviour. Analytic and numerical analyses of these plasmas using the divertor impurity code package DIVIMP/NIMBUS support the explanation that the enrichment of noble gases depends significantly on the penetration depth of the impurity neutrals with respect to the fuel atoms. Changes of the divertor plasma configuration and divertor geometry have no effect on the enrichment

  11. Pathway to low-cost metallization of silicon solar cell through understanding of the silicon metal interface and plating chemistry

    International Nuclear Information System (INIS)

    Ebong, Abasifreke

    2014-01-01

    Metallization is crucial to silicon solar cell performance. It is the second most expensive process step in the fabrication of a solar cell. In order to reduce the cost of solar cell, the metallization cost has to be cut down by using less metal without compromising the efficiency. Screen-printing has been used in metallizing the commercial solar cell because of the high throughput and low cost at the expense of performance. However, because of the variability in the screen-printed gridlines, the amount of Ag metal used cannot be controlled. More so, the dependence of the contact resistance on doping necessitates the use of low sheet resistance emitters, which exacerbates losses in the blue response and hence the efficiency. To balance the contact resistance and improve blue response, several approaches have been undertaken including, use of Ag pastes incorporating nanoparticle glass frits that will not diffuse excessively into a lightly doped emitter, Ni plating on lightly doped emitter through SiNx dielectric plus NiSi formation followed by Cu and/or Ag plating, light induced plating (LIP) of Ag or Cu on fired through dielectric metal seed layers formed by aerosol or inkjet or screen-printing. All these approaches require excellent adhesion and gridline conductivity to minimize the total series resistance, which impedes the collection of electrons. This paper presents the issues and the pathway to achieving high efficiency using low cost metallization technology involving inkjet-printed Ag fine gridline having 38 μm width and 3 μm height fired through the SiNx followed by Ni and Cu plating. A comprehensive analysis of silicon/metal interface, using high precision microscopy, has shown that the investigated metallization technology is appropriate for the longevity of the device

  12. Noble metals nanoparticles on titanium dioxide nanostructured films and the influence of their photocatalytic activity; Atividade fotocatalitica de filmes nanoestruturados de dioxido de titanio incorporados com nanoparticulas de metais nobres

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Liana Key Okada

    2012-07-01

    Currently, nanoscience and nanotechnology are considered an emerging field and continuously breaking the barrier among various disciplines. The main focus of study involves controlling structures at molecular level, arranging the atoms in order to achieve an understanding and controlling the fundamental properties of matter. In this study, molecular changes on the basis of morphology, optical and crystalline properties of TiO{sub 2}hin films in order to increase their photon efficiency were proposed. The TiO{sub 2} thin films were prepared by sol gel process evaluating the influence of different acids and templates to obtain the nano structured arrangements. Then, metal nanoparticles like Au, Ag, Pd and Pt were incorporated on TiO{sub 2} thin films. This incorporation might minimize the electron-hole recombination, so it could improve the photon efficiency. From the several routes studied, the TiO{sub 2} thin films prepared with acetic acid showed the best performance by the reason of low agglomeration of TiO{sub 2} grains, which favors the exposure of the photoactive sites. The presence of template in the formulation had a slightly effect on photon efficiency, possible due to the higher agglomeration of the grains on the TiO{sub 2} thin films. The addition of Pt and Au nanoparticles on TiO{sub 2} thin films showed superior photon efficiency. The TiO{sub 2} thin films with hexamine and metallic nanoparticles did not show the improvement on photon efficiency except for Pt and Au nanoparticles. On these situations, the improvement on photon efficiency is might be due to a possible decrease at the electron-hole recombination's velocity. Thus, the present work demonstrates the great influence of preparation conditions on the optical, morphological properties and the photon efficiency. In the future, with greater understanding of the mechanism of this influence, the properties of TiO{sub 2} thin films will be able tailoring depending on the application. (author)

  13. On-chip fabrication of alkali-metal vapor cells utilizing an alkali-metal source tablet

    International Nuclear Information System (INIS)

    Tsujimoto, K; Hirai, Y; Sugano, K; Tsuchiya, T; Tabata, O; Ban, K; Mizutani, N

    2013-01-01

    We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN 6 ), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460–490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches. (paper)

  14. Carbon Nanotube Thread Electrochemical Cell: Detection of Heavy Metals.

    Science.gov (United States)

    Zhao, Daoli; Siebold, David; Alvarez, Noe T; Shanov, Vesselin N; Heineman, William R

    2017-09-19

    In this work, all three electrodes in an electrochemical cell were fabricated based on carbon nanotube (CNT) thread. CNT thread partially insulated with a thin polystyrene coating to define the microelectrode area was used as the working electrode; bare CNT thread was used as the auxiliary electrode; and a micro quasi-reference electrode was fabricated by electroplating CNT thread with Ag and then anodizing it in chloride solution to form a layer of AgCl. The Ag|AgCl coated CNT thread electrode provided a stable potential comparable to the conventional liquid-junction type Ag|AgCl reference electrode. The CNT thread auxiliary electrode provided a stable current, which is comparable to a Pt wire auxiliary electrode. This all-CNT thread three electrode cell has been evaluated as a microsensor for the simultaneous determination of trace levels of heavy metal ions by anodic stripping voltammetry (ASV). Hg 2+ , Cu 2+ , and Pb 2+ were used as a representative system for this study. The calculated detection limits (based on the 3σ method) with a 120 s deposition time are 1.05, 0.53, and 0.57 nM for Hg 2+ , Cu 2+ , and Pb 2+ , respectively. These electrodes significantly reduce the dimensions of the conventional three electrode electrochemical cell to the microscale.

  15. Brown algae overproduce cell wall polysaccharides as a protection mechanism against the heavy metal toxicity

    International Nuclear Information System (INIS)

    Andrade, Leonardo R.; Leal, Raquel N.; Noseda, Miguel; Duarte, Maria Eugenia R.; Pereira, Mariana S.; Mourao, Paulo A.S.; Farina, Marcos; Amado Filho, Gilberto M.

    2010-01-01

    Brown algae are often used as heavy metal biomonitors and biosorbents because they can accumulate high concentrations of metals. Cation-exchange performed by cell wall polysaccharides is pointed out as the main chemical mechanism for the metal sequestration. Here, we biochemically investigated if the brown alga Padina gymnospora living in a heavy metal contaminated area would modify their polysaccharidic content. We exposed non-living biomass to Cd and Pb and studied the metals adsorption and localization. We found that raw dried polysaccharides, sulfate groups, uronic acids, fucose, mannose, and galactose were significantly higher in contaminated algae compared with the control ones. Metal concentrations adsorbed by non-living biomass were rising comparatively to the tested concentrations. Electron microscopy showed numerous granules in the cell walls and X-ray microanalysis revealed Cd as the main element. We concluded that P. gymnospora overproduces cell wall polysaccharides when exposed to high metal concentrations as a defense mechanism.

  16. Noble metals nanoparticles on titanium dioxide nanostructured films and the influence of their photocatalytic activity; Atividade fotocatalitica de filmes nanoestruturados de dioxido de titanio incorporados com nanoparticulas de metais nobres

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Liana Key Okada

    2012-07-01

    Currently, nanoscience and nanotechnology are considered an emerging field and continuously breaking the barrier among various disciplines. The main focus of study involves controlling structures at molecular level, arranging the atoms in order to achieve an understanding and controlling the fundamental properties of matter. In this study, molecular changes on the basis of morphology, optical and crystalline properties of TiO{sub 2}hin films in order to increase their photon efficiency were proposed. The TiO{sub 2} thin films were prepared by sol gel process evaluating the influence of different acids and templates to obtain the nano structured arrangements. Then, metal nanoparticles like Au, Ag, Pd and Pt were incorporated on TiO{sub 2} thin films. This incorporation might minimize the electron-hole recombination, so it could improve the photon efficiency. From the several routes studied, the TiO{sub 2} thin films prepared with acetic acid showed the best performance by the reason of low agglomeration of TiO{sub 2} grains, which favors the exposure of the photoactive sites. The presence of template in the formulation had a slightly effect on photon efficiency, possible due to the higher agglomeration of the grains on the TiO{sub 2} thin films. The addition of Pt and Au nanoparticles on TiO{sub 2} thin films showed superior photon efficiency. The TiO{sub 2} thin films with hexamine and metallic nanoparticles did not show the improvement on photon efficiency except for Pt and Au nanoparticles. On these situations, the improvement on photon efficiency is might be due to a possible decrease at the electron-hole recombination's velocity. Thus, the present work demonstrates the great influence of preparation conditions on the optical, morphological properties and the photon efficiency. In the future, with greater understanding of the mechanism of this influence, the properties of TiO{sub 2} thin films will be able tailoring depending on the application. (author)

  17. Fully solution-processed organic solar cells on metal foil substrates

    KAUST Repository

    Gaynor, Whitney; Lee, Jung-Yong; Peumans, Peter

    2009-01-01

    We demonstrate fully solution-processed organic photovoltaic cells on metal foil substrates with power conversion efficiencies similar to those obtained in devices on transparent substrates. The cells are based on the regioregular poly- (3

  18. Facilitation of trace metal uptake in cells by inulin coating of metallic nanoparticles

    Science.gov (United States)

    Santillán-Urquiza, Esmeralda; Arteaga-Cardona, Fernando; Torres-Duarte, Cristina; Cole, Bryan; Wu, Bing; Méndez-Rojas, Miguel A.; Cherr, Gary N.

    2017-09-01

    Trace elements such as zinc and iron are essential for the proper function of biochemical processes, and their uptake and bioavailability are dependent on their chemical form. Supplementation of trace metals through nanostructured materials is a new field, but its application raises concerns regarding their toxicity. Here, we compared the intracellular zinc uptake of different sources of zinc: zinc sulfate, and ZnO and core-shell α-Fe2O3@ZnO nanoparticles, coated or uncoated with inulin, an edible and biocompatible polysaccharide. Using mussel haemocytes, a well-known model system to assess nanomaterial toxicity, we simultaneously assessed zinc accumulation and multiple cellular response endpoints. We found that intracellular zinc uptake was strongly enhanced by inulin coating, in comparison to the uncoated nanoparticles, while no significant effects on cell death, cell viability, mitochondrial membrane integrity, production of reactive oxygen species or lysosome abundance were observed at concentrations up to 20 ppm. Since no significant increments in toxicity were observed, the coated nanomaterials may be useful to increase in vivo zinc uptake for nutritional applications.

  19. Fluorescent metal nanoshell and CK19 detection on single cell image

    International Nuclear Information System (INIS)

    Zhang, Jian; Fu, Yi; Li, Ge; Lakowicz, Joseph R.; Zhao, Richard Y.

    2011-01-01

    Highlights: → Novel metal nanoshell as fluorescence imaging agent. → Fluorescent mAb-metal complex with enhanced intensity and shortened lifetime. → Immuno-interactions of mAb-metal complexes with CK19 molecules on CNCAP and HeLa cell surfaces. → Isolation of conjugated mAb-metal complexes from cellular autofluorescence on cell image. -- Abstract: In this article, we report the synthesis strategy and optical properties of a novel type of fluorescence metal nanoshell when it was used as imaging agent for fluorescence cell imaging. The metal nanoshells were made with 40 nm silica cores and 10 nm silver shells. Unlike typical fluorescence metal nanoshells which contain the organic dyes in the cores, novel metal nanoshells were composed of Cy5-labelled monoclonal anti-CK19 antibodies (mAbs) on the external surfaces of shells. Optical measurements to the single nanoparticles showed that in comparison with the metal free labelled mAbs, the mAb-Ag complexes displayed significantly enhanced emission intensity and dramatically shortened lifetime due to near-field interactions of fluorophores with metal. These metal nanoshells were found to be able to immunoreact with target cytokeratin 19 (CK19) molecules on the surfaces of LNCAP and HeLa cells. Fluorescence cell images were recorded on a time-resolved confocal microscope. The emissions from the metal nanoprobes could be clearly isolated from the cellular autofluorescence backgrounds on the cell images as either individuals or small clusters due to their stronger emission intensities and shorter lifetimes. These emission signals could also be precisely counted on single cell images. The count number may provide an approach for quantifying the target molecules in the cells.

  20. Doped Graphene as Non-Metallic Catalyst for Fuel Cells

    Directory of Open Access Journals (Sweden)

    Adriana MARINOIU

    2017-08-01

    Full Text Available Aiming a commercial development of proton exchange membrane fuel cells (PEMFC, a low cost, sustainable and high performance electrocatalyst for oxygen reduction reaction (ORR with capability to replace/reduce rare metals, are high desirable. In this paper, we present a class of doped graphene, namely iodinated graphene with highly ORR electrochemical performances, synthesized by using the electrophilic substitution method. The prepared samples were characterized by different techniques, including Scanning Electron Microscopy SEM, X-ray photoelectron spectroscopy XPS, Raman spectroscopy, surface area measurement by BET method, that revealed the structure and morphology. The most highly iodinated graphene was tested in a single cell by measuring the cyclic voltammetry. The electrochemical performances were evaluated and compared with a typical PEMFC configuration, when a single cathodic peak at 0.2 V with a current density of – 3.67 mA cm-2 for the Pt/C electrode was obtained. The best electrochemical performances in terms of electrochemical active area, was obtained for a new concept of cathode composed from Pt/C – iodine doped graphene, when a well-defined peak centred at 0.23 V with a current density of approx. – 9.1 mA cm-2 was obtained, indicating a high catalytic activity for ORR.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.16216

  1. Mixed noble gas effect on cut green peppers

    Science.gov (United States)

    Raymond, L. V.; Zhang, M.; Karangwa, E.; Chesereka, M. J.

    2013-01-01

    Increasing attempts at using gas which leads to hydrate formation as a preservative tool in fresh-cut fruits and vegetables have been reported. In this study, changes in some physical and biochemical properties of fresh-cut green peppers under compressed noble gas treatments were examined. Mixed argonkrypton and argon treatments were performed before cold storage at 5°C for 15 days. Mass loss and cell membrane permeability were found to be the lowest in mixed argon-krypton samples. Besides, a lower CO2 concentration and vitamin C loss were detected in gastreated samples compared to untreated samples (control). While the total phenol degradation was moderately reduced, the effect of the treatment on polyphenoloxidase activity was better at the beginning of the storage period. The minimum changes in quality observed in cut peppers resulted from both mixed and gas treatment alone.

  2. Metal Oxides as Efficient Charge Transporters in Perovskite Solar Cells

    KAUST Repository

    Haque, Mohammed; Sheikh, Arif D.; Guan, Xinwei; Wu, Tao

    2017-01-01

    . In this comprehensive review, we focus on the synthesis and applications of metal oxides as electron and hole transporters in efficient PSCs with both mesoporous and planar architectures. Metal oxides and their doped variants with proper energy band alignment

  3. The effects of heavy metal ions on the chlorophyll content and cell membrane permeability of charophytes

    International Nuclear Information System (INIS)

    Fu Hualong; Chen Hao; Dong Bin; Qing Renwei

    2001-01-01

    The authors studied the effects of several heavy metal ions in different concentrations (Cd 2+ , Hg 2+ , Pb 2+ , Cr 6+ ) on the chlorophyll content and cell membrane permeability of Chara vulgaris L. It was discovered that the effects of heavy metal ions on the chlorophyll content and cell membrane permeability of Chara vulgaris L. changed with their different concentration. The trend was that the chlorophyll content and cell membrane permeability were decreased with the increase of the heavy metal ions. The degree of chlorophyll content affected was Cr 6+ , Cd 2+ , Hg 2+ , Pb 2+ , and that of cell membrane permeability affected was Cd 2+ , Cr 6+ , Hg 2+ , Pb 2+

  4. From 1 Sun to 10 Suns c-Si Cells by Optimizing Metal Grid, Metal Resistance, and Junction Depth

    International Nuclear Information System (INIS)

    Chaudhari, V.A.; Solanki, C.S.

    2009-01-01

    Use of a solar cell in concentrator PV technology requires reduction in its series resistance in order to minimize the resistive power losses. The present paper discusses a methodology of reducing the series resistance of a commercial c-Si solar cell for concentrator applications, in the range of 2 to 10 suns. Step by step optimization of commercial cell in terms of grid geometry, junction depth, and electroplating of the front metal contacts is proposed. A model of resistance network of solar cell is developed and used for the optimization. Efficiency of un optimized commercial cell at 10 suns drops by 30% of its 1 sun value corresponding to resistive power loss of about 42%. The optimized cell with grid optimization, junction optimization, electroplating, and junction optimized with electroplated contacts cell gives resistive power loss of 20%, 16%, 11%, and 8%, respectively. An efficiency gain of 3% at 10 suns for fully optimized cell is estimated

  5. Resonance ionization spectroscopy: Counting noble gas atoms

    International Nuclear Information System (INIS)

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-01-01

    The purpose of this paper is to describe new work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions). When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. We show that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective. (orig./FKS)

  6. MRP proteins as potential mediators of heavy metal resistance in zebrafish cells.

    Science.gov (United States)

    Long, Yong; Li, Qing; Wang, Youhui; Cui, Zongbin

    2011-04-01

    Acquired resistance of mammalian cells to heavy metals is closely relevant to enhanced expression of several multidrug resistance-associated proteins (MRP), but it remains unclear whether MRP proteins confer resistance to heavy metals in zebrafish. In this study, we obtained zebrafish (Danio rerio) fibroblast-like ZF4 cells with resistance to toxic heavy metals after chronic cadmium exposure and selection for 6months. These cadmium-resistant cells (ZF4-Cd) were maintained in 5μM cadmium and displayed cross-resistance to cadmium, mercury, arsenite and arsenate. ZF4-Cd cells remained the resistance to heavy metals after protracted culture in cadmium-free medium. In comparison with ZF4-WT cells, ZF4-Cd cells exhibited accelerated rate of cadmium excretion, enhanced activity of MRP-like transport, elevated expression of abcc2, abcc4 and mt2 genes, and increased content of cellular GSH. Inhibition of MRP-like transport activity, GSH biosynthesis and GST activity significantly attenuated the resistance of ZF4-Cd cells to heavy metals. The results indicate that some of MRP transporters are involved in the efflux of heavy metals conjugated with cellular GSH and thus play crucial roles in heavy metal detoxification of zebrafish cells. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. Influence of hole transport material/metal contact interface on perovskite solar cells

    Science.gov (United States)

    Lei, Lei; Zhang, Shude; Yang, Songwang; Li, Xiaomin; Yu, Yu; Wei, Qingzhu; Ni, Zhichun; Li, Ming

    2018-06-01

    Interfaces have a significant impact on the performance of perovskite solar cells. This work investigated the influence of hole transport material/metal contact interface on photovoltaic behaviours of perovskite solar devices. Different hole material/metal contact interfaces were obtained by depositing the metal under different conditions. High incident kinetic energy metal particles were proved to penetrate and embed into the hole transport material. These isolated metal particles in hole transport materials capture holes and increase the apparent carrier transport resistance of the hole transport layer. Sample temperature was found to be of great significance in metal deposition. Since metal vapour has a high temperature, the deposition process accumulated a large amount of heat. The heat evaporated the additives in the hole transport layer and decreased the hole conductivity. On the other hand, high temperature may cause iodization of the metal contact.

  8. Metal ion transport quantified by ICP-MS in intact cells

    Science.gov (United States)

    Figueroa, Julio A. Landero; Stiner, Cory A.; Radzyukevich, Tatiana L.; Heiny, Judith A.

    2016-01-01

    The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions. PMID:26838181

  9. Constructal Optimization of Top Contact Metallization of a Photovoltaic Solar Cell

    OpenAIRE

    Bhakta, Aditya; Bandyopadhyay, Santanu

    2010-01-01

    A top contact metallization of a photovoltaic solar cell collects the current generated by incident solar radiation. Several power-loss mechanisms are associated with the current flow through the front contact grid. The design of the top metal contact grid is one of the most important areas of efficient photovoltaic solar cell design. In this paper, an approach based on the constructal theory is proposed to design the grid pattern in a photovoltaic solar cell, minimizing total resistive losse...

  10. Measurements of the diffusion and reflection coefficients of Cd(1S0) in noble gases

    International Nuclear Information System (INIS)

    Rudecki, P.; Domyslawska, J.

    2003-01-01

    A new method of simultaneous determining of the diffusion coefficient and the reflection coefficient of atoms from the reservoir walls is presented. The diffusion coefficient of cadmium atoms in the ground state in buffer noble gas atoms such as Ne, Ar, Kr and Xe and reflection coefficient of Cd atoms from the quartz cell wall in the temperature range 350-550 K were determined. Experimental values diffusion coefficient are compared with theoretical ones calculated from a available potentials. (author)

  11. Spinel-based coatings for metal supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Stefan, Elena; Neagu, Dragos; Blennow Tullmar, Peter

    2017-01-01

    Metal supports and metal supported half cells developed at DTU are used for the study of a solution infiltration approach to form protective coatings on porous metal scaffolds. The metal particles in the anode layer, and sometimes even in the support may undergo oxidation in realistic operating...... conditions leading to severe cell degradation. Here, a controlled oxidation of the porous metal substrate and infiltration of Mn and/or Ce nitrate solutions are applied for in situ formation of protective coatings. Our approach consists of scavenging the FeCr oxides formed during the controlled oxidation...... into a continuous and well adhered coating. The effectiveness of coatings is the result of composition and structure, but also of the microstructure and surface characteristics of the metal scaffolds....

  12. Enhanced Toxic Metal Accumulation in Engineered Bacterial Cells Expressing Arabidopsis thaliana Phytochelatin Synthase

    Science.gov (United States)

    Sauge-Merle, Sandrine; Cuiné, Stéphan; Carrier, Patrick; Lecomte-Pradines, Catherine; Luu, Doan-Trung; Peltier, Gilles

    2003-01-01

    Phytochelatins (PCs) are metal-binding cysteine-rich peptides, enzymatically synthesized in plants and yeasts from glutathione in response to heavy metal stress by PC synthase (EC 2.3.2.15). In an attempt to increase the ability of bacterial cells to accumulate heavy metals, the Arabidopsis thaliana gene encoding PC synthase (AtPCS) was expressed in Escherichia coli. A marked accumulation of PCs was observed in vivo together with a decrease in the glutathione cellular content. When bacterial cells expressing AtPCS were placed in the presence of heavy metals such as cadmium or the metalloid arsenic, cellular metal contents were increased 20- and 50-fold, respectively. We discuss the possibility of using genes of the PC biosynthetic pathway to design bacterial strains or higher plants with increased abilities to accumulate toxic metals, and also arsenic, for use in bioremediation and/or phytoremediation processes. PMID:12514032

  13. Composite nanomaterials of semiconductors and noble metals as plasmonic photocatalysts

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Law, Matt; Zhang, Jingdong

    behavior, and can be more stable under operating conditions. Composite photocatalysts of semiconductor nanoparticles (SNPs) and PNPs exploit broadly the solar spectrum, provide new catalytic routes and expand the scope of solar photocatalysis. The newly initiated project aims at developing composite...

  14. Selective extraction and detection of noble metal based on ionic ...

    Indian Academy of Sciences (India)

    ClPrNTf2) was developed for selective detection of gold(III) by use of inductively coupled ... The importance to develop pre- ... attention. Ionic liquids (ILs) immobilized onto SG have been successfully applied as solid phase adsorbents for.

  15. Noble metal nanostructures for double plasmon resonance with tunable properties

    Science.gov (United States)

    Petr, M.; Kylián, O.; Kuzminova, A.; Kratochvíl, J.; Khalakhan, I.; Hanuš, J.; Biederman, H.

    2017-02-01

    We report and compare two vacuum-based strategies to produce Ag/Au materials characterized by double plasmon resonance peaks: magnetron sputtering and method based on the use of gas aggregation sources (GAS) of nanoparticles. It was observed that the double plasmon resonance peaks may be achieved by both of these methods and that the intensities of individual localized surface plasmon resonance peaks may be tuned by deposition conditions. However, in the case of sputter deposition it was necessary to introduce a separation dielectric interlayer in between individual Ag and Au nanoparticle films which was not the case of films prepared by GAS systems. The differences in the optical properties of sputter deposited bimetallic Ag/Au films and coatings consisted of individual Ag and Au nanoparticles produced by GAS is ascribed to the divers mechanisms of nanoparticles formation.

  16. Carbon Nanofibers as Catalyst Support for Noble Metals

    NARCIS (Netherlands)

    Toebes, M.L.

    2004-01-01

    In the quest for new and well-defined support materials for heterogeneous catalysts we explored the potential of carbon nanofibers (CNF). CNF belongs to the by now extensive family of synthetic graphite-like carbon materials with advantageous and tunable physico-chemical properties. Aim of the work

  17. Plasmon resonances in large noble-metal clusters

    International Nuclear Information System (INIS)

    Soennichsen, C; Franzl, T; Wilk, T; Plessen, G von; Feldmann, J

    2002-01-01

    We investigate the optical properties of spherical gold and silver clusters with diameters of 20 nm and larger. The light scattering spectra of individual clusters are measured using dark-field microscopy, thus avoiding inhomogeneous broadening effects. The dipolar plasmon resonances of the clusters are found to have nearly Lorentzian line shapes. With increasing size we observe polaritonic red-shifts of the plasmon line and increased radiation damping for both gold and silver clusters. Apart from some cluster-to-cluster variations of the plasmon lines, agreement with Mie theory is reasonably good for the gold clusters. However, it is less satisfactory for the silver clusters, possibly due to cluster faceting or chemical effects

  18. Selective extraction and detection of noble metal based on ionic

    Indian Academy of Sciences (India)

    The kinetics study indicated that Au(III) adsorption kinetics data were well fit with the pseudo-second-order kinetic model on the basis of correlation coefficient fitting (0.996) and adsorption capacity agreement (62.26 mg g − 1 ). Furthermore, SG–ClPrNTf 2 phase was effectively performed for the determination of Au(III) in real ...

  19. Interaction of Graphene and Arenes with Noble Metals

    Czech Academy of Sciences Publication Activity Database

    Granatier, Jaroslav; Lazar, P.; Prucek, R.; Šafářová, K.; Zbořil, R.; Otyepka, M.; Hobza, Pavel

    2012-01-01

    Roč. 116, č. 26 (2012), s. 14151-14162 ISSN 1932-7447 R&D Projects: GA ČR GBP208/12/G016 Grant - others:GA MŠk(CZ) EE2.3.20.0017; European Regional Development Fund(XE) CZ.1.05/2.1.00/03.0058; GA ČR(CZ) GAP208/10/1742 Program:EE; GA Institutional research plan: CEZ:AV0Z40550506 Keywords : density-functional theory * effective core potentials * augmented-wave method * active catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.814, year: 2012

  20. Noble Metal Catalysts in the Production of Biofuels

    OpenAIRE

    Gutiérrez, Andrea

    2013-01-01

    The energy demand is increasing in the world together with the need to ensure energy security and the desire to decrease greenhouse gas emissions. While several renewable alternatives are available for the production of electricity, e.g. solar energy, wind power, and hydrogen, biomass is the only renewable source that can meet the demand for carbon-based liquid fuels and chemicals. The technology applied in the conversion of biomass depends on the type and complexity of the biomass, and the d...

  1. Catalytic Ammonia Oxidation on Noble Metal Surfaces: A Theoretical Study

    OpenAIRE

    Novell Leruth, Gerard

    2008-01-01

    Esta tesis se basa en el estudio de la oxidación de amoniaco sobre el grupo del platino. El objetivo de esta tesis es descartar o aceptar los diversos mecanismos propuestos. Incluso proponer el más correcto según los datos obtenidos. Para llevar a cabo esta acometida es necesario conocer cada geometría de las diferentes especies que pueden existir sobre la superficie del catalizador, así como los estados de transición entre las reacciones que lleven de una especie (o combinación de especies)...

  2. Metal-organic frameworks at interfaces of hybrid perovskite solar cells for enhanced photovoltaic properties.

    Science.gov (United States)

    Shen, Deli; Pang, Aiying; Li, Yafeng; Dou, Jie; Wei, Mingdeng

    2018-01-31

    In this study, metal-organic frameworks, as an interfacial layer, were introduced into perovskite solar cells (PSCs) for the first time. An interface modified with the metal-organic framework ZIF-8 efficiently enhanced perovskite crystallinity and grain sizes, and the photovoltaic performance of the PSCs was significantly improved, resulting in a maximum PCE of 16.99%.

  3. Simplified process for leaching precious metals from fuel cell membrane electrode assemblies

    Science.gov (United States)

    Shore, Lawrence [Edison, NJ; Matlin, Ramail [Berkeley Heights, NJ

    2009-12-22

    The membrane electrode assemblies of fuel cells are recycled to recover the catalyst precious metals from the assemblies. The assemblies are cryogenically embrittled and pulverized to form a powder. The pulverized assemblies are then mixed with a surfactant to form a paste which is contacted with an acid solution to leach precious metals from the pulverized membranes.

  4. Magnetron sputtered gadolinia-doped ceria diffusion barriers for metal-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Sønderby, Steffen; Klemensø, Trine; Christensen, Bjarke H.

    2014-01-01

    Gadolinia-doped ceria (GDC) thin films are deposited by reactive magnetron sputtering in an industrial-scale setup and implemented as barrier layers between the cathode and electrolyte in metal-based solid oxide fuel cells consisting of a metal support, an electrolyte of ZrO2 co-doped with Sc2O3...

  5. Neuromast hair cells retain the capacity of regeneration during heavy metal exposure.

    Science.gov (United States)

    Montalbano, G; Capillo, G; Laurà, R; Abbate, F; Levanti, M; Guerrera, M C; Ciriaco, E; Germanà, A

    2018-07-01

    The neuromast is the morphological unit of the lateral line of fishes and is composed of a cluster of central sensory cells (hair cells) surrounded by support and mantle cells. Heavy metals exposure leads to disruption of hair cells within the neuromast. It is well known that the zebrafish has the ability to regenerate the hair cells after damage caused by toxicants. The process of regeneration depends on proliferation, differentiation and cellular migration of sensory and non-sensory progenitor cells. Therefore, our study was made in order to identify which cellular types are involved in the complex process of regeneration during heavy metals exposure. For this purpose, adult zebrafish were exposed to various heavy metals (Arsenic, cadmium and zinc) for 72h. After acute (24h) exposure, immunohistochemical localization of S100 (a specific marker for hair cells) in the neuromasts highlighted the hair cells loss. The immunoreaction for Sox2 (a specific marker for stem cells), at the same time, was observed in the support and mantle cells, after exposure to arsenic and cadmium, while only in the support cells after exposure to zinc. After chronic (72h) exposure the hair cells were regenerated, showing an immunoreaction for S100 protein. At the same exposure time to the three metals, a Sox2 immunoreaction was expressed in support and mantle cells. Our results showed for the first time the regenerative capacity of hair cells, not only after, but also during exposure to heavy metals, demonstrated by the presence of different stem cells that can diversify in hair cells. Copyright © 2018 Elsevier GmbH. All rights reserved.

  6. All-Carbon Electrodes for Flexible Solar Cells

    OpenAIRE

    Zexia Zhang; Ruitao Lv; Yi Jia; Xin Gan; Hongwei Zhu; Feiyu Kang

    2018-01-01

    Transparent electrodes based on carbon nanomaterials have recently emerged as new alternatives to indium tin oxide (ITO) or noble metal in organic photovoltaics (OPVs) due to their attractive advantages, such as long-term stability, environmental friendliness, high conductivity, and low cost. However, it is still a challenge to apply all-carbon electrodes in OPVs. Here, we report our efforts to develop all-carbon electrodes in organic solar cells fabricated with different carbon-based materia...

  7. Metal octacarboxy phthalocyanines / Multiwalled carbon nanotubes hybrid for the development of dye solar cells

    CSIR Research Space (South Africa)

    Mphahlele, N

    2011-05-01

    Full Text Available photovoltaic cells. In these devices, photosensitisers are one of the main components for light-driven processes. Metallophthalocyanine (MPc) complexes, especially those containing diamagnetic metal centres (M = Zn, Ga, Si), are well established as efficient...

  8. Wide range noble gas radiation monitor

    International Nuclear Information System (INIS)

    Kuhlman, H.S. III; Wyvill, J.R.

    1984-01-01

    The present invention contemplates providing a sample system for effluent from a nuclear process wherein the effluent in a first mode passes through a sample chamber whose noble gases are quantitatively detected. The sample of the first mode is continued until the detector count rate reaches a predetermined maximum. The detector establishes a control signal which is applied to terminate the first mode effluent flow to the chamber, evacuate the chamber to a predetermined value of vacuum and connect the effluent into the sample chamber with a predetermined mode of flow rate different from the rate of the first mode to establish a sample concentration in the chamber within the range of the detector. A subsequent predetermined minimum rate will generate a signal to reconnect the sample chamber to the first mode connection and thereby cycle the system back to its first mode of operation

  9. Noble gases recycled into the mantle through cold subduction zones

    Science.gov (United States)

    Smye, Andrew J.; Jackson, Colin R. M.; Konrad-Schmolke, Matthias; Hesse, Marc A.; Parman, Steve W.; Shuster, David L.; Ballentine, Chris J.

    2017-08-01

    Subduction of hydrous and carbonated oceanic lithosphere replenishes the mantle volatile inventory. Substantial uncertainties exist on the magnitudes of the recycled volatile fluxes and it is unclear whether Earth surface reservoirs are undergoing net-loss or net-gain of H2O and CO2. Here, we use noble gases as tracers for deep volatile cycling. Specifically, we construct and apply a kinetic model to estimate the effect of subduction zone metamorphism on the elemental composition of noble gases in amphibole - a common constituent of altered oceanic crust. We show that progressive dehydration of the slab leads to the extraction of noble gases, linking noble gas recycling to H2O. Noble gases are strongly fractionated within hot subduction zones, whereas minimal fractionation occurs along colder subduction geotherms. In the context of our modelling, this implies that the mantle heavy noble gas inventory is dominated by the injection of noble gases through cold subduction zones. For cold subduction zones, we estimate a present-day bulk recycling efficiency, past the depth of amphibole breakdown, of 5-35% and 60-80% for 36Ar and H2O bound within oceanic crust, respectively. Given that hotter subduction dominates over geologic history, this result highlights the importance of cooler subduction zones in regassing the mantle and in affecting the modern volatile budget of Earth's interior.

  10. Development of Novel Non-Pt Group Metal Electrocatalysts for PEM Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Mukerjee, Sanjeev [Northeastern Univ., Boston, MA (United States). Dept. of Chemistry and Chemical Biology; Atanassov, Plamen [Univ. of New Mexico, Albuquerque, NM (United States); Barton, Scott [Michigan State Univ., East Lansing, MI (United States); Dale, Nilesh [Nissan Technical Center North America (NTCNA), Farmington Hills, MI (United States); Halevi, Bar [Pajarito Powder LLC, Albuquerque, NM (United States)

    2016-01-04

    The objective of this multi-institutional effort was to comprehensively pursue the goal of eliminating noble metal (Pt group metals, PGM) from the cathodic oxygen reduction reaction (ORR) electrode thereby providing a quantum leap in lowering the overall PGM loading in a polymer electrolyte fuel cell (PEMFC). The overall project scope encompassed (a) comprehensive materials discovery effort, (b) a concomitant effort to scale up these materials with very high ( ±5%) reproducibility, both intra and inter, (c) understanding mass transport in porous medium both in gas diffusion and micro-porous layers for enhanced areal activity, (d) understanding mechanistic aspects of active site structure and ORR electrocatalytic pathway. Overall project milestones and metrics were (a) first phase effort based on performance in oxygen where the project’s Go/No-Go decision point milestone of 100 mA/cm2 at 0.8 V (internal resistance-free, iR-free) at 80°C, pure H2/O2, with 1.5 bar total pressure was met. Subsequently, the principle objectives were to (a) transition the project from H2/O2 to H2/Air with slated target of exceeding 30 mA/cm2 @ 0.8 V, 2.5 bar total pressure and an end of the project target of 1 A/cm2 @ 0.4 V (same total pressure), both under 100% relative humidity. The target for catalyst material scale up was to achieve 100 g batch size at the end of the program. This scale up target had a quality control milestone of less than 5% variation of activity measured with H2/Air (2.5 bar total pressure) at 0.8 V. In addition, the project also aimed at arriving at a unified understanding of the nature of active sites in these catalysts as well as some preliminary understanding of the mechanistic pathway. Also addressed is the development of an integrated method for determination of mass transport parameters using a combination of Helox experiments and modeling of the gas

  11. Inorganic and Metallic Nanotubular Materials Recent Technologies and Applications

    CERN Document Server

    Kijima, Tsuyoshi

    2010-01-01

    This book describes the synthesis, characterization and applications of inorganic and metallic nanotubular materials. It cover a wide variety of nanotubular materials excluding carbon nanotubes, ranging from metal oxides, sulfides and nitrides such as titanium oxide, tungsten sulfide, and boron nitride, as well as platinum and other noble-metals to unique nanotubes consisting of water, graphene or fullerene. Based on their structural and compositional characteristics, these nanotubular materials are of importance for their potential applications in electronic devices, photocatalysts, dye-sensitized solar cells, nanothermometers, electrodes for fuel cells and batteries, sensors, and reinforcing fillers for plastics, among others. Such materials are also having a great impact on future developments, including renewable-energy sources as well as highly efficient energy-conversion and energy-saving technologies. This book will be of particular interest to experts in the fields of nanotechnology, material science ...

  12. Cytochemical characterization of gill and hepatopancreatic cells of the crab Ucides cordatus (Crustacea, Brachyura validated by cell metal transport

    Directory of Open Access Journals (Sweden)

    Priscila Ortega

    2014-09-01

    Full Text Available Ucides cordatus (Linnaeus, 1763 is a hypo-hyper-regulating mangrove crab possessing gills for respiratory and osmoregulatory processes, separated in anterior and posterior sections. They also have hepatopancreas, which is responsible for digestion and absorption of nutrients and detoxification of toxic metals. Each of these organs has specific cells that are important for in vitro studies in cell biology, ion and toxic metals transport. In order to study and characterize cells from gills and hepatopancreas, both were separated using a Sucrose Gradient (SG from 10 to 40% and cells in each gradient were characterized using the vital mitochondrial dye DASPEI (2-(4-dimethylaminostyryl-N- ethylpyridinium iodide and Trichrome Mallory's stain. Both in 20 and 40% SG for gill cells and 30% SG for hepatopancreatic cells, a greater number of cells were colored with DASPEI, indicating a larger number of mitochondria in these cells. It is concluded that the gill cells present in 20% and 40% SG are Thin cells, responsible for respiratory processes and Ionocytes responsible for ion transport, respectively. For hepatopancreatic cells, the 30% SG is composed of Fibrillar cells that possess larger number of membrane ion and nutrient transporters. Moreover, the transport of toxic metal cadmium (Cd by isolated hepatopancreatic cells was performed as a way of following cell physiological integrity after cell separation and to study differences in transport among the cells. All hepatopancreatic cells were able to transport Cd. These findings are the first step for further work on isolated cells of these important exchange epithelia of crabs, using a simple separation method and to further develop successful in vitro cell culture in crabs.

  13. Study of Plant Cell Wall Polymers Affected by Metal Accumulation Using Stimulated Raman Scattering Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shi-You [Harvard Univ., Cambridge, MA (United States)

    2015-03-02

    This project aims to employ newly-developed chemical imaging techniques to measure, in real-time, the concentration, dynamics and spatial distribution of plant cell wall polymers during biomass growth with inoculation of transgenic symbiotic fungi, and to explore a new pathway of delivering detoxified metal to plant apoplast using transgenic symbiotic fungi, which will enhance metal accumulation from soil, and potentially these metals may in turn be used as catalysts to improve the efficiency of biomass conversion to biofuels. The proposed new pathway of biomass production will: 1) benefit metal and radionuclide contaminant mobility in subsurface environments, and 2) potentially improve biomass production and process for bioenergy

  14. Industrial sheet metals for nanocrystalline dye-sensitized solar cell structures

    Energy Technology Data Exchange (ETDEWEB)

    Toivola, Minna; Ahlskog, Fredrik; Lund, Peter [Laboratory of Advanced Energy Systems, Department of Engineering Physics and Mathematics, Helsinki University of Technology, P.O. Box 4100, FIN-02015 TKK (Finland)

    2006-11-06

    Direct integration of dye-sensitized solar cells (DSSC) onto industrial sheet metals has been studied. The stability of the metals, including zinc-coated and plain carbon steel, stainless steel and copper in a standard iodine electrolyte was investigated with soaking and encapsulation tests. Stainless and carbon steel showed sufficient stability and were used as the cell counter-electrodes, yielding cells with energy conversion efficiencies of 3.6% and 3.1%, respectively. A DSSC built on flexible steel substrates is a promising approach especially from the viewpoint of large-scale, cost-effective industrial manufacturing of the cells. (author)

  15. Corrosion of metal bipolar plates for PEM fuel cells: A review

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, Renato A. [Engenharia de Materiais, Universidade Federal do ABC (UFABC), 09210-170 Santo Andre, SP (Brazil); Oliveira, Mara Cristina L.; Ett, Gerhard; Ett, Volkmar [Electrocell Ind. Com. Equip. Elet. LTDA, Centro de Inovacao, Empreendedorismo e Tecnologia (CIETEC), 05508-000 Sao Paulo, SP (Brazil)

    2010-04-15

    PEM fuel cells are of prime interest in transportation applications due to their relatively high efficiency and low pollutant emissions. Bipolar plates are the key components of these devices as they account for significant fractions of their weight and cost. Metallic materials have advantages over graphite-based ones because of their higher mechanical strength and better electrical conductivity. However, corrosion resistance is a major concern that remains to be solved as metals may develop oxide layers that increase electrical resistivity, thus lowering the fuel cell efficiency. This paper aims to present the main results found in recent literature about the corrosion performance of metallic bipolar plates. (author)

  16. Genotoxicity of 11 heavy metals detected as food contaminants in two human cell lines.

    Science.gov (United States)

    Kopp, B; Zalko, D; Audebert, M

    2018-04-01

    Heavy metals, such as arsenic (As), antimony (Sb), barium (Ba), cadmium (Cd), cobalt (Co), germanium (Ge), lead (Pb), nickel (Ni), tellurium (Te), and vanadium (V) are widely distributed in the environment and in the food chain. Human exposure to heavy metals through water and food has been reported by different international agencies. Although some of these heavy metals are essential elements for human growth and development, they may also be toxic at low concentrations due to indirect mechanisms. In this study, the genotoxic and cytotoxic properties of 15 different oxidation statuses of 11 different heavy metals were investigated using high-throughput screening (γH2AX assay) in two human cell lines (HepG2 and LS-174T) representative of target organs (liver and colon) for food contaminants. Base on their lowest observed adverse effect concentration, the genotoxic potency of each heavy metal in each cell line was ranked in decreasing order, NaAsO 2  > CdCl 2  > PbCl 2 (only in LS-174T cells) > As 2 O 5  > SbCl 3  > K 2 TeO 3  > As 2 O 3 . No significant genotoxicity was observed with the other heavy metals tested. Cell viability data indicate that several heavy metals (As, Cd, Co, Ni, Sb, and Te) induce cytotoxicity at high concentrations, whereas an increase in the number of cells was observed for lead concentrations >100 µM in both cell lines tested, suggesting that lead stimulates cell growth. All these results highlight the possible human health hazards associated with the presence of heavy metals present in food. Environ. Mol. Mutagen. 59:202-210, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  17. A simplistic analytical unit cell based model for the effective thermal conductivity of high porosity open-cell metal foams

    International Nuclear Information System (INIS)

    Yang, X H; Kuang, J J; Lu, T J; Han, F S; Kim, T

    2013-01-01

    We present a simplistic yet accurate analytical model for the effective thermal conductivity of high porosity open-cell metal foams saturated in a low conducting fluid (air). The model is derived analytically based on a realistic representative unit cell (a tetrakaidecahedron) under the assumption of one-dimensional heat conduction along highly tortuous-conducting ligaments at high porosity ranges (ε ⩾ 0.9). Good agreement with existing experimental data suggests that heat conduction along highly conducting and tortuous ligaments predominantly defines the effective thermal conductivity of open-cell metal foams with negligible conduction in parallel through the fluid phase. (paper)

  18. Cyborg cells: functionalisation of living cells with polymers and nanomaterials.

    Science.gov (United States)

    Fakhrullin, Rawil F; Zamaleeva, Alsu I; Minullina, Renata T; Konnova, Svetlana A; Paunov, Vesselin N

    2012-06-07

    Living cells interfaced with a range of polyelectrolyte coatings, magnetic and noble metal nanoparticles, hard mineral shells and other complex nanomaterials can perform functions often completely different from their original specialisation. Such "cyborg cells" are already finding a range of novel applications in areas like whole cell biosensors, bioelectronics, toxicity microscreening, tissue engineering, cell implant protection and bioanalytical chemistry. In this tutorial review, we describe the development of novel methods for functionalisation of cells with polymers and nanoparticles and comment on future advances in this technology in the light of other literature approaches. We review recent studies on the cell viability and function upon direct deposition of nanoparticles, coating with polyelectrolytes, polymer assisted assembly of nanomaterials and hard shells on the cell surface. The cell toxicity issues are considered for many practical applications in terms of possible adverse effects of the deposited polymers, polyelectrolytes and nanoparticles on the cell surface.

  19. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

    Science.gov (United States)

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-02-18

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  20. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

    Science.gov (United States)

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-02-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  1. Noble gas atoms as chemical impurities in silicon

    International Nuclear Information System (INIS)

    Tkachev, V.D.; Mudryi, A.V.; Minaev, N.S.

    1984-01-01

    The behaviour of noble gas atoms implanted in silicon is studied by the luminescence method. The energy position of Moessbauer-type luminescence bands with zero-phonon lines 1.0148, 1.0120, 1.0097, 1.0048 eV and others connected with implanted atoms of neon, helium, argon, krypton, respectively, indicates the formation of deep energy levels in the forbidden gap of silicon. Implantation of the noble gas isotopes confirms their participation in formation processes of the luminescence centers in silicon. The temperature range of existence and the symmetry of defects incorporating the noble gas atoms are found. It is noted that noble gas atoms form impurity complexes with deep energy levels and their behaviour in crystals does not differ from that of main doped or residual technological impurity atoms. (author)

  2. Topotactic Conversion of Copper(I) Phosphide Nanowires for Sensitive Electrochemical Detection of H2O2 Release from Living Cells.

    Science.gov (United States)

    Li, Zhenzhen; Xin, Yanmei; Wu, Wenlong; Fu, Baihe; Zhang, Zhonghai

    2016-08-02

    In this work, we clearly demonstrate for the first time the use of transition-metal phosphides to set up a new cathodic analysis platform for sensitive and selective electrochemical nonenzymatic detection of H2O2. With the help of a facile topotactic conversion method, the noble metal-free electrocatalyst of copper(I) phosphide nanowires on three-dimensional porous copper foam (Cu3P NWs/CF) is fabricated with electrochemical anodized Cu(OH)2 NWs as precursor. The Cu3P NWs/CF-based sensor presents excellent electrocatalytic activity for H2O2 reduction with a detection limit of 2 nM, the lowest detection limit achieved by noble-metal free electrocatalyst, which guarantees the possibility of sensitive and reliable detection of H2O2 release from living tumorigenic cells, thus showing the potential application as a sensitive cancer cell detection probe.

  3. High Voltage in Noble Liquids for High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Rebel, B. [Fermilab; Bernard, E. [Yale U.; Faham, C. H. [LBL, Berkeley; Ito, T. M. [Los Alamos; Lundberg, B. [Maryland U.; Messina, M. [Columbia U.; Monrabal, F. [Valencia U., IFIC; Pereverzev, S. P. [LLNL, Livermore; Resnati, F. [Zurich, ETH; Rowson, P. C. [SLAC; Soderberg, M. [Fermilab; Strauss, T. [Bern U.; Tomas, A. [Imperial Coll., London; Va' vra, J. [SLAC; Wang, H. [UCLA

    2014-08-22

    A workshop was held at Fermilab November 8-9, 2013 to discuss the challenges of using high voltage in noble liquids. The participants spanned the fields of neutrino, dark matter, and electric dipole moment physics. All presentations at the workshop were made in plenary sessions. This document summarizes the experiences and lessons learned from experiments in these fields at developing high voltage systems in noble liquids.

  4. The metal wrap through solar cell. Developement and characterisation; Die metal wrap through Solarzelle. Entwicklung und Charakterisierung

    Energy Technology Data Exchange (ETDEWEB)

    Clement, Florian

    2009-03-20

    This work focuses on the development and the optimization of the metal wrap through (MWT) solar cell. Primary goal of this work has been the development of an appropriate process flow for MWT solar cells, which generates only insignificant extra costs compared to the conventional process flow, however, achieves a significant efficiency increase for MWT cells compared to conventionally processed cells. The latter was one of the main challenges of this work. For this purpose MWT solar cells have been studied and characterized in detail. Loss mechanisms have been detected and improvements evaluated as well as transferred to the cell process. Furthermore, the assembling process for MWT solar cells in the module has been optimized focusing on less series resistance losses. A comparison with the conventional module assembling process is presented. A process flow similar to the one for the conventional process has been developed for MWT solar cells. Merely two additional laser process steps for hole drilling and rear contact isolation as well as one screen printing step for the through connection turn out to be necessary. It is shown that the additional screen printing process can be omitted without significant efficiency losses, if the through connection and solder pad metallization is done in a single process step. Furthermore, a fast and reliable through connection process has been developed and characterized in detail. Moreover, a gauge mounting block for MWT solar cells has been constructed, analyzed and calibrated for current-voltage-characteristic measurements. With multi crystalline MWT silicon solar cells an efficiency gain up to 0.5% absolute has been achieved compared to conventionally processed solar cells - thereby reaching a maximum cell efficiency of more than 16.7%. Due to a novel MWT module technology developed in this work the efficiency compared to the conventional technology could be improved further by another 0.3% absolute. The primary loss

  5. N-myc oncogene amplification is correlated to trace metal concentrations in neuroblastoma cultured cells

    International Nuclear Information System (INIS)

    Gouget, B.; Sergeant, C.; Benard, J.; Llabador, Y.; Simonoff, M.

    2000-01-01

    N-myc oncogene amplification is a powerful predictor of aggressive behavior of neuroblastoma (NB), the most common solid tumor of the early childhood. Since N-myc overexpression - subsequent to amplification - determines a phenotype of invasiveness and metastatic spreading, it is assumed that N-myc amplified neuroblasts synthesize zinc metalloenzymes leading to tumor invasion and formation of metastases. In order to test a possible relation between N-myc oncogene amplification and trace metal contents in human NB cells, Fe, Cu and Zn concentrations have been measured by nuclear microprobe analysis in three human neuroblastoma cell lines with various degrees of N-myc amplification. Elemental determinations show uniform distribution of trace metals within the cells, but variations of intracellular trace metal concentrations with respect to the degree of N-myc amplification are highly dependent on the nature of the element. Zinc concentration is higher in both N-myc amplified cell lines (IMR-32 and IGR-N-91) than in the non-amplified cells (SK-N-SH). In contrast, intracellular iron content is particularly low in N-myc amplified cell lines. Moreover, copper concentrations showed an increase with the degree of N-myc amplification. These results indicate that a relationship exists between intracellular trace metals and N-myc oncogene amplification. They further suggest that trace metals very probably play a determinant role in mechanisms of the neuroblastoma invasiveness

  6. Compact reaction cell for homogenizing and down-blending highly enriched uranium metal

    Science.gov (United States)

    McLean, W. II; Miller, P.E.; Horton, J.A.

    1995-05-02

    The invention is a specialized reaction cell for converting uranium metal to uranium oxide. In a preferred form, the reaction cell comprises a reaction chamber with increasing diameter along its length (e.g. a cylindrical chamber having a diameter of about 2 inches in a lower portion and having a diameter of from about 4 to about 12 inches in an upper portion). Such dimensions are important to achieve the necessary conversion while at the same time affording criticality control and transportability of the cell and product. The reaction chamber further comprises an upper port and a lower port, the lower port allowing for the entry of reactant gases into the reaction chamber, the upper port allowing for the exit of gases from the reaction chamber. A diffuser plate is attached to the lower port of the reaction chamber and serves to shape the flow of gas into the reaction chamber. The reaction cell further comprises means for introducing gases into the reaction chamber and a heating means capable of heating the contents of the reaction chamber. The present invention also relates to a method for converting uranium metal to uranium oxide in the reaction cell of the present invention. The invention is useful for down-blending highly enriched uranium metal by the simultaneous conversion of highly enriched uranium metal and natural or depleted uranium metal to uranium oxide within the reaction cell. 4 figs.

  7. Compact reaction cell for homogenizing and down-blanding highly enriched uranium metal

    Science.gov (United States)

    McLean, II, William; Miller, Philip E.; Horton, James A.

    1995-01-01

    The invention is a specialized reaction cell for converting uranium metal to uranium oxide. In a preferred form, the reaction cell comprises a reaction chamber with increasing diameter along its length (e.g. a cylindrical chamber having a diameter of about 2 inches in a lower portion and having a diameter of from about 4 to about 12 inches in an upper portion). Such dimensions are important to achieve the necessary conversion while at the same time affording criticality control and transportability of the cell and product. The reaction chamber further comprises an upper port and a lower port, the lower port allowing for the entry of reactant gasses into the reaction chamber, the upper port allowing for the exit of gasses from the reaction chamber. A diffuser plate is attached to the lower port of the reaction chamber and serves to shape the flow of gas into the reaction chamber. The reaction cell further comprises means for introducing gasses into the reaction chamber and a heating means capable of heating the contents of the reaction chamber. The present invention also relates to a method for converting uranium metal to uranium oxide in the reaction cell of the present invention. The invention is useful for down-blending highly enriched uranium metal by the simultaneous conversion of highly enriched uranium metal and natural or depleted uranium metal to uranium oxide within the reaction cell.

  8. Assessment of a 42 metal salts chemical library in mouse embryonic stem cells

    Science.gov (United States)

    The developmental effects of xenobiotics on differentiation can be profiled using mouse embryonic stem cells (mESCs). The adherent cell differentiation and cytotoxicity (ACDC) technique was used to evaluate a library of 42 metal and metaloid salts. Jl mESCs were allowed to prolif...

  9. Monitoring of noble gas radioisotopes in nuclear power plant effluents

    International Nuclear Information System (INIS)

    Kabat, M.J.

    1985-01-01

    Monitoring of gaseous radionuclides in the effluents of nuclear facilities is an essential requirement in effluent management programs. Since there is no practical way of removing noble gas radioisotopes from air at release pathways, their accurate monitoring is essential for providing appropriate environmental protection. Emitted γ dose-rate is the limiting factor for concentration-time integral of noble gas in gaseous effluents of reactor facilities. The external exposure to the public from a semi-infinite cloud is directly proportional to both the noble gas isotope concentration and the integrated γ energy per disintegration. Both can be directly measured in gaseous effluent pathways with a suitable detector. The capability of NaI(T1), CaF 2 (Eu) and plastic scintillation detectors to measure the γ-Ci.MeV content of noble gas releases was experimentally evaluated. The combination of CaF 2 (Eu) detector in a pressurized through-flow chamber, with a charge integrating scaler well complied with both γ energy response and detection sensitivity requirements. Noble gas source terms and effluent monitoring criteria are discussed, theoretical and experimental results are presented and a practical, on-line noble gas monitoring system is described

  10. Noble gas atmospheric monitoring at reprocessing facilities

    International Nuclear Information System (INIS)

    Nakhleh, C.W.; Perry, R.T. Jr.; Poths, J.; Stanbro, W.D.; Wilson, W.B.; Fearey, B.L.

    1997-01-01

    The discovery in Iraq after the Gulf War of the existence of a large clandestine nuclear-weapon program has led to an across-the-board international effort, dubbed Programme 93+2, to improve the effectiveness and efficiency of International Atomic Energy Agency (IAEA) safeguards. One particularly significant potential change is the introduction of environmental monitoring (EM) techniques as an adjunct to traditional safeguards methods. Monitoring of stable noble gas (Kr, Xe) isotopic abundances at reprocessing plant stacks appears to be able to yield information on the burnup and type of the fuel being processed. To estimate the size of these signals, model calculations of the production of stable Kr, Xe nuclides in reactor fuel and the subsequent dilution of these nuclides in the plant stack are carried out for two case studies: reprocessing of PWR fuel with a burnup of 35 GWd/tU, and reprocessing of CAND fuel with a burnup of 1 GWd/tU. For each case, a maximum-likelihood analysis is used to determine the fuel burnup and type from the isotopic data

  11. Effects of accelerated degradation on metal supported thin film-based solid oxide fuel cell

    DEFF Research Database (Denmark)

    Reolon, R. P.; Sanna, S.; Xu, Yu

    2018-01-01

    A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte and nanostruct......A thin film-based solid oxide fuel cell is deposited on a Ni-based metal porous support by pulsed laser deposition with a multi-scale-graded microstructure design. The fuel cell, around 1 μm in thickness, is composed of a stabilized-zirconia/doped-ceria bi-layered dense electrolyte......, electrochemical performances are steady, indicating the stability of the cell. Under electrical load, a progressive degradation is activated. Post-test analysis reveals both mechanical and chemical degradation of the cell. Cracks and delamination of the thin films promote a significant nickel diffusion and new...

  12. Heavy metals toxicity after acute exposure of cultured renal cells. Intracellular accumulation and repartition

    International Nuclear Information System (INIS)

    Khodja, Hicham; Carriere, Marie; Avoscan, Laure; Gouget, Barbara

    2005-01-01

    Lead (Pb), cadmium (Cd) and uranium (U) present no known biological function but are toxic in various concentration ranges. Pb and Cd lead generally to nephrotoxicity consisting in proximal renal tubular dysfunction and accumulation while U has been reported to induce chemical kidney toxicity, functional and histological damages being as well mainly observed in proximal tubule cells. This work address the question of Cd, Pb, and U cytotoxicity, intracellular accumulation and repartition after acute intoxication of renal proximal tubule epithelial cells. After cells exposure to different concentrations of metals for various times, morphological changes were observed and intracellular concentrations and distributions of toxic metals were specified by PIXE coupled to RBS. Cell viability, measured by biochemical tests, was used as toxicity indicator. A direct correlation between cytotoxicity and intracellular accumulation in renal epithelial cells have been established. Finally, intracellular Pb and U localizations were detected while Cd was found to be uniformly distributed in renal cells. (author)

  13. Improved contact metallization for high efficiency EFG polycrystalline silicon solar cells

    International Nuclear Information System (INIS)

    Dube, C.E.; Gonsiorawski, R.C.

    1990-01-01

    Improvements in the performance of polycrystalline silicon solar cells based on a novel, laser patterned contact process are described. Small lots of cells having an average conversion efficiency of 14 + %, with several cells approaching 15%, are reported for cells of 45 cm 2 area. The high efficiency contact design is based on YAG laser patterning of the silicon nitride anti-reflection coating. The Cu metallization is done using light-induced plating, with the cell providing the driving voltage for the plating process. The Cu electrodeposits into the laser defined windows in the AR coating for reduced contact area, following which the Cu bridges on top of the Ar coating to form a continuous finger pattern. The higher cell conversion efficiency is attributed to reduced shadow loss, higher junction quality, and reduced metal-semiconductor interfacial area

  14. Increasing the solar cell power output by coating with transition metal-oxide nanorods

    International Nuclear Information System (INIS)

    Kuznetsov, I.A.; Greenfield, M.J.; Mehta, Y.U.; Merchan-Merchan, W.; Salkar, G.; Saveliev, A.V.

    2011-01-01

    Highlights: → Nanoparticles enhance solar cell efficiency. → Solar cell power increase by nanorod coating. → Metal-oxide nanorods are prepared in flames. → Molybdenum oxide nanorods effectively scatter light on solar cell surface. → Scattering efficiency depends on coating density. -- Abstract: Photovoltaic cells produce electric current through interactions among photons from an ambient light source and electrons in the semiconductor layer of the cell. However, much of the light incident on the panel is reflected or absorbed without inducing the photovoltaic effect. Transition metal-oxide nanoparticles, an inexpensive product of a process called flame synthesis, can cause scattering of light. Scattering can redirect photon flux, increasing the fraction of light absorbed in the thin active layer of silicon solar cells. This research aims to demonstrate that the application of transition metal-oxide nanorods to the surface of silicon solar panels can enhance the power output of the panels. Several solar panels were coated with a nanoparticle-methanol suspension, and the power outputs of the panels before and after the treatment were compared. The results demonstrate an increase in power output of up to 5% after the treatment. The presence of metal-oxide nanorods on the surface of the coated solar cells is confirmed by electron microscopy.

  15. Small cell experiments for electrolytic reduction of uranium oxides to uranium metal using fluoride salts

    International Nuclear Information System (INIS)

    Haas, P.A.; Adcock, P.W.; Coroneos, A.C.; Hendrix, D.E.

    1994-01-01

    Electrolytic reduction of uranium oxide was proposed for the preparation of uranium metal feed for the atomic vapor laser isotope separation (AVLIS) process. A laboratory cell of 25-cm ID was operated to obtain additional information in areas important to design and operation of a pilot plant cell. Reproducible test results and useful operating and control procedures were demonstrated. About 20 kg of uranium metal of acceptable purity were prepared. A good supply of dissolved UO 2 feed at the anode is the most important controlling requirement for efficient cell operation. A large fraction of the cell current is nonproductive in that it does not produce a metal product nor consume carbon anodes. All useful test conditions gave some reduction of UF 4 to produce CF 4 in addition to the reduction of UO 2 , but the fraction of metal from the reduction of UF 4 can be decreased by increasing the concentration of dissolved UO 2 . Operation of large continuous cells would probably be limited to current efficiencies of less than 60 pct, and more than 20 pct of the metal would result from the reduction of UF 4

  16. Applications of noble gas radiation detectors to counter-terrorism

    International Nuclear Information System (INIS)

    Vanier, Peter E.; Forman, Leon

    2002-01-01

    Radiation detectors are essential tools in the detection, analysis and disposition of potential terrorist devices containing hazardous radioactive and/or fissionable materials. For applications where stand-off distance and source shielding are limiting factors, large detectors have advantages over small ones. The ability to distinguish between Special Nuclear Materials and false-positive signals from natural or man-made benign sources is also important. Ionization chambers containing compressed noble gases, notably xenon and helium-3, can be scaled up to very large sizes, improving the solid angle for acceptance of radiation from a distant source. Gamma spectrometers using Xe have a factor of three better energy resolution than NaI scintillators, allowing better discrimination between radioisotopes. Xenon detectors can be constructed so as to have extremely low leakage currents, enabling them to operate for long periods of time on batteries or solar cells. They are not sensitive to fluctuations in ambient temperature, and are therefore suitable for deployment in outdoor locations. Position-sensitive 3He chambers have been built as large as 3000 cm2, and with spatial resolution of less than 1 mm. Combined with coded apertures made of cadmium, they can be used to create images of thermal neutron sources. The natural background of spallation neutrons from cosmic rays generates a very low count rate, so this instrument could be quite effective at identifying a man-made source, such as a spontaneous fission source (Pu) in contact with a moderator (high explosive)

  17. High temperature corrosion of metallic interconnects in solid oxide fuel cells

    International Nuclear Information System (INIS)

    Bastidas, D. M.

    2006-01-01

    Research and development has made it possible to use metallic interconnects in solid oxide fuel cells (SOFC) instead of ceramic materials. The use of metallic interconnects was formerly hindered by the high operating temperature, which made the interconnect degrade too much and too fast to be an efficient alternative. When the operating temperature was lowered, the use of metallic interconnects proved to be favourable since they are easier and cheaper to produce than ceramic interconnects. However, metallic interconnects continue to be degraded despite the lowered temperature, and their corrosion products contribute to electrical degradation in the fuel cell. coatings of nickel, chromium, aluminium, zinc, manganese, yttrium or lanthanum between the interconnect and the electrodes reduce this degradation during operation. (Author) 66 refs

  18. Investigation of metal/carbon-related materials for fuel cell applications by electronic structure calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Ki-jeong [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of)]. E-mail: kong@krict.re.kr; Choi, Youngmin [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of); Ryu, Beyong-Hwan [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of); Lee, Jeong-O [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of); Chang, Hyunju [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of)

    2006-07-15

    The potential of carbon-related materials, such as carbon nanotubes (CNTs) and graphite nanofibers (GNFs), supported metal catalysts as an electrode for fuel cell application was investigated using the first-principle electronic structure calculations. The stable binding geometries and energies of metal catalysts are determined on the CNT surface and the GNF edge. The catalyst metal is more tightly bound to the GNF edge than to the CNT surface because of the existence of active dangling bonds of edge carbon atoms. The diffusion barrier of metal atoms on the surface and edge is also obtained. From our calculation results, we have found that high dispersity is achievable for GNF due to high barrier against the diffusion of metal atoms, while CNT appears less suitable. The GNF with a large edge-to-wall ratio is more suitable for the high-performance electrode than perfect crystalline graphite or CNT.

  19. Investigation of metal/carbon-related materials for fuel cell applications by electronic structure calculations

    International Nuclear Information System (INIS)

    Kong, Ki-jeong; Choi, Youngmin; Ryu, Beyong-Hwan; Lee, Jeong-O; Chang, Hyunju

    2006-01-01

    The potential of carbon-related materials, such as carbon nanotubes (CNTs) and graphite nanofibers (GNFs), supported metal catalysts as an electrode for fuel cell application was investigated using the first-principle electronic structure calculations. The stable binding geometries and energies of metal catalysts are determined on the CNT surface and the GNF edge. The catalyst metal is more tightly bound to the GNF edge than to the CNT surface because of the existence of active dangling bonds of edge carbon atoms. The diffusion barrier of metal atoms on the surface and edge is also obtained. From our calculation results, we have found that high dispersity is achievable for GNF due to high barrier against the diffusion of metal atoms, while CNT appears less suitable. The GNF with a large edge-to-wall ratio is more suitable for the high-performance electrode than perfect crystalline graphite or CNT

  20. Noble magnetic barriers in the ASDEX UG tokamak

    Science.gov (United States)

    Ali, Halima; Punjabi, Alkesh; Vazquez, Justin

    2010-02-01

    The second-order perturbation method of creating invariant tori inside chaos in Hamiltonian systems (Ali, H.; Punjabi, A. Plasma Phys. Contr. F. 2007, 49, 1565-1582) is applied to the axially symmetric divertor experiment upgrade (ASDEX UG) tokamak to build noble irrational magnetic barriers inside chaos created by resonant magnetic perturbations (m, n)=(3, 2)+(4, 3), with m and n the poloidal and toroidal mode numbers of the Fourier expansion of the magnetic perturbation. The radial dependence of the Fourier modes is ignored. The modes are considered to be locked and have the same amplitude δ. A symplectic mathematical mapping in magnetic coordinates is used to integrate magnetic field line trajectories in the ASDEX UG. Tori with noble irrational rotational transform are the last ones to be destroyed by perturbation in Hamiltonian systems. For this reason, noble irrational magnetic barriers are built inside chaos, and the strongest noble irrational barrier is identified. Three candidate locations for the strongest noble barrier in ASDEX UG are selected. All three candidate locations are chosen to be roughly midway between the resonant rational surfaces ψ32 and ψ43. ψ is the magnetic coordinate of the flux surface. The three candidate surfaces are the noble irrational surfaces close to the surface with q value that is a mediant of q=3/2 and 4/3, q value of the physical midpoint of the two resonant surfaces, and the q value of the surface where the islands of the two perturbing modes just overlap. These q values of the candidate surfaces are denoted by q MED, q MID, and q OVERLAP. The strongest noble barrier close to q MED has the continued fraction representation (CFR) [1;2,2,1∞] and exists for δ≤2.6599×10-4; the strongest noble barrier close to q MID has CFR [1;2,2,2,1∞] and exists for δ≤4.6311×10-4; and the strongest noble barrier close to q OVERLAP has CFR [1;2,2,6,2,1∞] and exists for δ≤1.367770×10-4. From these results, the strongest

  1. Cell overcharge testing inside sodium metal halide battery

    Science.gov (United States)

    Frutschy, Kris; Chatwin, Troy; Bull, Roger

    2015-09-01

    Testing was conducted to measure electrical performance and safety of the General Electric Durathon™ E620 battery module (600 V class 20 kWh) during cell overcharge. Data gathered from this test was consistent with SAE Electric Vehicle Battery Abuse Testing specification J2464 [1]. After cell overcharge failure and 24 A current flow for additional 60 minutes, battery was then discharged at 7.5 KW average power to 12% state of charge (SOC) and recharged back to 100% SOC. This overcharging test was performed on two cells. No hydrogen chloride (HCl) gas was detected during front cell (B1) test, and small amount (6.2 ppm peak) was measured outside the battery after center cell (F13) overcharge. An additional overcharge test was performed per UL Standard 1973 - Batteries for Use in Light Electric Rail (LER) Applications and Stationary Applications[2]. With the battery at 11% SOC and 280 °C float temperature, an individual cell near the front (D1) was deliberately imbalanced by charging it to 62% SOC. The battery was then recharged to 100% SOC. In all three tests, the battery cell pack was stable and individual cell failure did not propagate to other cells. Battery discharge performance, charge performance, and electrical isolation were normal after all three tests.

  2. Impact of sensor metal thickness on microwave spectroscopy sensitivity for individual particles and biological cells analysis

    OpenAIRE

    Chen , Wenli; Dubuc , David; Grenier , Katia

    2016-01-01

    International audience; This paper focuses on evaluating the impact of metal thickness of a microwave coplanar based sensor dedicated to the microwave dielectric spectroscopy of single particles and individual biological cells. A sensitivity study has therefore been achieved for metal thicknesses comprised between 0.3 and 20 µm. After the validation of electromagnetic simulations with measurements of 10 μm-diameter polystyrene bead, both capacitive and conductive contrasts have been defined f...

  3. Metal Carbides for Biomass Valorization

    Directory of Open Access Journals (Sweden)

    Carine E. Chan-Thaw

    2018-02-01

    Full Text Available Transition metal carbides have been utilized as an alternative catalyst to expensive noble metals for the conversion of biomass. Tungsten and molybdenum carbides have been shown to be effective catalysts for hydrogenation, hydrodeoxygenation and isomerization reactions. The satisfactory activities of these metal carbides and their low costs, compared with noble metals, make them appealing alternatives and worthy of further investigation. In this review, we succinctly describe common synthesis techniques, including temperature-programmed reaction and carbothermal hydrogen reduction, utilized to prepare metal carbides used for biomass transformation. Attention will be focused, successively, on the application of transition metal carbide catalysts in the transformation of first-generation (oils and second-generation (lignocellulose biomass to biofuels and fine chemicals.

  4. Novel Rear Side Metallization Route for Si Solar Cells Using a Transparent Conducting Adhesive: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lee, Benjamin G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nemeth, William M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); LaSalvia, Vincenzo A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-03-14

    The rear side metallization of Si solar cells comes with a number of inherent losses and trade-offs: a larger metallized area fraction improves fill factor at the expense of open-circuit voltage, depositing directly on textured Si leads to low contact resistivity at the expense of short-circuit current, and some metallization processes create defects in Si. To mitigate many of these losses we have developed a novel approach for rear side metallization of Si solar cells, utilizing a transparent conducting adhesive (TCA) to metallize Si without exposing the wafer to the metal deposition process. The TCA consists of an insulating adhesive loaded with conductive microspheres. This approach leads to virtually no loss in implied open-circuit voltage upon metallization. Electrical measurements showed that contact resistivities of 3-9 ..omega.. cm2 were achieved, and an analysis of the transit resistance per microsphere showed that less than 1 ..omega.. cm2 should be achievable with higher microsphere loading of the TCA.

  5. Topology optimization of front metallization patterns for solar cells

    NARCIS (Netherlands)

    Gupta, D.K.; Langelaar, M.; Barink, M.; Keulen, F. van

    2015-01-01

    This paper presents the application of topology optimization (TO) for designing the front electrode patterns for solar cells. Improving the front electrode design is one of the approaches to improve the performance of the solar cells. It serves to produce the voltage distribution for the front

  6. Application of liquid metals for the extraction of solid metals

    International Nuclear Information System (INIS)

    Borgstedt, H.U.

    1996-01-01

    Liquid metals dissolve several solid metals in considerable amounts at moderate temperatures. The dissolution processes may be based upon simple physical solubility, formation of intermetallic phases. Even chemical reactions are often observed in which non-metallic elements might be involved. Thus, the capacity to dissolve metals and chemical properties of the liquid metals play a role in these processes. Besides the solubility also chemical properties and thermochemical data are of importance. The dissolution of metals in liquid metals can be applied to separate the solutes from other metals or non-metallic phases. Relatively noble metals can be chemically reduced by the liquid phases. Such solution processes can be applied in the extractive metallurgy, for instance to extract metals from metallic waste. The recycling of metals is of high economical and ecological importance. Examples of possible processes are discussed. (author)

  7. Enhanced resveratrol production in Vitis vinifera cell suspension cultures by heavy metals without loss of cell viability.

    Science.gov (United States)

    Cai, Zhenzhen; Kastell, Anja; Speiser, Claire; Smetanska, Iryna

    2013-09-01

    The effects of heavy metal ions (Co(2+), Ag(+), Cd(2+)) on cell viability and secondary metabolite production, particularly anthocyanins and phenolic acids in Vitis vinifera cell suspension cultures, were investigated. Of these, Co at all three used concentrations (5.0, 25, and 50 μM), Ag, and Cd at low concentration (5.0 μM) were most effective to stimulate the phenolic acid production, increasing the 3-O-glucosyl-resveratrol up to 1.6-fold of the control level (250.5 versus 152.4 μmol/g), 4 h after the treatments. Meanwhile, the elicitors at effective concentrations did not suppress cell growth, while the cell viability maintained. In contrast, Ag and Cd at high concentrations (25 and 50 μM) remarkably reduced the cell viability, decreasing the cell viability up to about 15 % of the control level, 24 h after the treatments. The heavy metal ions did not affect the anthocyanin production. These observations show how, in a single system, different groups of secondary products can show distinct differences in their responses to potential elicitors. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, peroxidase activity, medium pH value, and conductivity were only slightly elevated by the heavy metal ions. The results suggest that some of the secondary metabolites production was stimulated by the used elicitors, but there was not a stress response of the cells.

  8. Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells.

    Science.gov (United States)

    Trost, S; Becker, T; Zilberberg, K; Behrendt, A; Polywka, A; Heiderhoff, R; Görrn, P; Riedl, T

    2015-01-16

    ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1-20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated.

  9. Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

    Science.gov (United States)

    Doeff, Marca M.; Peng, Marcus Y.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard C.

    1996-01-01

    An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M.sub.x Z.sub.y Mn.sub.(1-y) O.sub.2, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell.

  10. Ink jet assisted metallization for low cost flat plate solar cells

    Science.gov (United States)

    Teng, K. F.; Vest, R. W.

    1987-01-01

    Computer-controlled ink-jet-assisted metallization of the front surface of solar cells with metalorganic silver inks offers a maskless alternative method to conventional photolithography and screen printing. This method can provide low cost, fine resolution, reduced process complexity, avoidance of degradation of the p-n junction by firing at lower temperature, and uniform line film on rough surface of solar cells. The metallization process involves belt furnace firing and thermal spiking. With multilayer ink jet printing and firing, solar cells of about 5-6 percent efficiency without antireflection (AR) coating can be produced. With a titanium thin-film underlayer as an adhesion promoter, solar cells of average efficiency 8.08 percent without AR coating can be obtained. This efficiency value is approximately equal to that of thin-film solar cells of the same lot. Problems with regard to lower inorganic content of the inks and contact resistance are noted.

  11. Fluorescence lifetime microscopy for monitoring cell adhesion using metal induced energy transfer

    Science.gov (United States)

    Hwang, Wonsang; Seo, JinWon; Song, Jun ho; Kim, DongEun; Won, YoungJae; Choi, In-Hong; Yoo, Kyung-Hwa; Kim, Dug Young

    2018-02-01

    A precise control and a reliable monitoring tool for the adhesion properties of a cell are very important in atherosclerosis studies. If endothelial cells in contact with the intracellular membrane are not attached securely, low-density lipoprotein (LDL) particles can enter into the inner membrane. It is therefore necessary to measure conditions under which endothelial cell detachment occurs. When a cell is attached to a metal thin film, the lifetime of a fluorescence probe attached to the membrane of the cell is reduced by the metal-induced energy transfer (MIET). Fluorescence lifetime imaging microscopy (FLIM) is used to monitor the attachment condition of a cell to a metal surface using FRET. However, this requires high numerical aperture (NA) objective lens because axial confocal resolution must be smaller than the cell thickness. This requirement limits the field of view of the measurement specimen. In this study we provides a new method which can measure adhesion properties of endothelial cells even with a low NA objective lens by resolving two lifetime components in FLIM.

  12. Fabrication of ultrahigh density metal-cell-metal crossbar memory devices with only two cycles of lithography and dry-etch procedures

    KAUST Repository

    Zong, Baoyu; Goh, J. Y.; Guo, Zaibing; Luo, Ping; Wang, Chenchen; Qiu, Jinjun; Ho, Pin; Chen, Yunjie; Zhang, Mingsheng; Han, Guchang

    2013-01-01

    A novel approach to the fabrication of metal-cell-metal trilayer memory devices was demonstrated by using only two cycles of lithography and dry-etch procedures. The fabricated ultrahigh density crossbar devices can be scaled down to ≤70 nm in half

  13. Metal Complex Dyes for Dye-Sensitized Solar Cells: Recent ...

    Indian Academy of Sciences (India)

    interests are in coding theory, error-correction in networks and wireless communication.“ Ruthenium ..... Calculate power conversion efficiency by using the formula: 100 ... Molar Extinction Coefficient Charge-Transfer Sensitizers for Solar Cell.

  14. Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

    Science.gov (United States)

    Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

    1988-01-01

    The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  15. Solar cell metals and their hosts: A tale of oversupply and undersupply

    International Nuclear Information System (INIS)

    Elshkaki, Ayman; Graedel, T.E.

    2015-01-01

    discourage end of life recycling of those metals; (4) the greenhouse gases produced by mining oversupplies of the host metals zinc and copper will, in some case, exceed the greenhouse gases savings produced by a fossil fuel to solar cell transition; (5) these challenges can be minimized, but probably not avoided, by increasing the recovery rates of Se, Te, In, and Ge from the host metal ores, and by more efficient end of life recycling.

  16. Autophagy as an ultrastructural marker of heavy metal toxicity in human cord blood hematopoietic stem cells

    International Nuclear Information System (INIS)

    Di Gioacchino, Mario; Petrarca, Claudia; Perrone, Angela; Farina, Massimo; Sabbioni, Enrico; Hartung, Thomas; Martino, Simone; Esposito, Diana L.; Lotti, Lavinia Vittoria; Mariani-Costantini, Renato

    2008-01-01

    Stem cells are a key target of environmental toxicants, but little is known about their toxicological responses. We aimed at developing an in-vitro model based on adult human stem cells to identify biomarkers of heavy metal exposure. To this end we investigated the responses of human CD34+ hematopoietic progenitor cells to hexavalent chromium (Cr[VI]) and cadmium (Cd). Parallel cultures of CD34+ cells isolated from umbilical cord blood were exposed for 48 h to 0.1 μM and 10 μM Cr(VI) or Cd. Cultures treated with 10 μM Cr(VI) or Cd showed marked cell loss. Ultrastructural analysis of surviving cells revealed prominent autophagosomes/autophagolysosomes, which is diagnostic of autophagy, associated with mitochondrial damage and replication, dilatation of the rough endoplasmic reticulum and Golgi complex, cytoplasmic lipid droplets and chromatin condensation. Treated cells did not show the morphologic hallmarks of apoptosis. Treatment with 0.1 μM Cr(VI) or Cd did not result in cell loss, but at the ultrastructural level cells showed dilated endoplasmic reticulum and evidence of mitochondrial damage. We conclude that autophagy is implicated in the response of human hematopoietic stem cells to toxic concentrations of Cr(VI) and Cd. Autophagy, which mediates cell survival and death under stress, deserves further evaluation to be established as biomarker of metal exposure

  17. Autophagy as an ultrastructural marker of heavy metal toxicity in human cord blood hematopoietic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Di Gioacchino, Mario [Aging Research Center, ' G. d' Annunzio' University Foundation, Via Colle dell' Ara, 66100 Chieti (Italy); Medicine and Science of Ageing University of Chieti-Pescara, Via dei Vestini 1, 66100 Chieti (Italy)], E-mail: m.digioacchino@unich.it; Petrarca, Claudia; Perrone, Angela [Aging Research Center, ' G. d' Annunzio' University Foundation, Via Colle dell' Ara, 66100 Chieti (Italy); Medicine and Science of Ageing University of Chieti-Pescara, Via dei Vestini 1, 66100 Chieti (Italy); Farina, Massimo; Sabbioni, Enrico; Hartung, Thomas [Oncology and Neurosciences University of Chieti-Pescara, Via dei Vestini 1, 66100 Chieti (Italy); Martino, Simone [Department of Experimental Medicine, University La Sapienza, Viale Regina Elena 324, 00161 Rome (Italy); Esposito, Diana L. [Aging Research Center, ' G. d' Annunzio' University Foundation, Via Colle dell' Ara, 66100 Chieti (Italy); Oncology and Neurosciences University of Chieti-Pescara, Via dei Vestini 1, 66100 Chieti (Italy); Lotti, Lavinia Vittoria [Department of Experimental Medicine, University La Sapienza, Viale Regina Elena 324, 00161 Rome (Italy); Mariani-Costantini, Renato [Aging Research Center, ' G. d' Annunzio' University Foundation, Via Colle dell' Ara, 66100 Chieti (Italy); Oncology and Neurosciences University of Chieti-Pescara, Via dei Vestini 1, 66100 Chieti (Italy)

    2008-03-15

    Stem cells are a key target of environmental toxicants, but little is known about their toxicological responses. We aimed at developing an in-vitro model based on adult human stem cells to identify biomarkers of heavy metal exposure. To this end we investigated the responses of human CD34+ hematopoietic progenitor cells to hexavalent chromium (Cr[VI]) and cadmium (Cd). Parallel cultures of CD34+ cells isolated from umbilical cord blood were exposed for 48 h to 0.1 {mu}M and 10 {mu}M Cr(VI) or Cd. Cultures treated with 10 {mu}M Cr(VI) or Cd showed marked cell loss. Ultrastructural analysis of surviving cells revealed prominent autophagosomes/autophagolysosomes, which is diagnostic of autophagy, associated with mitochondrial damage and replication, dilatation of the rough endoplasmic reticulum and Golgi complex, cytoplasmic lipid droplets and chromatin condensation. Treated cells did not show the morphologic hallmarks of apoptosis. Treatment with 0.1 {mu}M Cr(VI) or Cd did not result in cell loss, but at the ultrastructural level cells showed dilated endoplasmic reticulum and evidence of mitochondrial damage. We conclude that autophagy is implicated in the response of human hematopoietic stem cells to toxic concentrations of Cr(VI) and Cd. Autophagy, which mediates cell survival and death under stress, deserves further evaluation to be established as biomarker of metal exposure.

  18. Solubility investigations in support of ultrasensitive noble gas detector development

    International Nuclear Information System (INIS)

    Gross, K.C.; Andersen, A.; Russ, W.R.; Stuenkel, D.; Valentine, J.D.

    1998-01-01

    Argonne National Laboratory (ANL) and the University of Cincinnati (UC) have been developing a new class of ultrasensitive noble gas detectors that are based upon the ANL discovery that corn oil has a high affinity for heavy noble gas absorption at room temperature but releases the noble gases with warming or by other low-energy-input means. Environmental applications for this new class of fluid-based detectors include ultrahigh sensitivity radioxenon detectors for comprehensive test ban treaty surveillance, improved fission gas detectors for enhanced environmental surveillance in the vicinity of US Department of Energy, US Department of Defense, and US Nuclear Regulatory Commission licensed facilities, and improved integrating Rn detectors for earthquake prediction. They present the results of theoretical and experimental investigations into the solubility phenomena of heavy noble gases (Rn, Xe, and Kr) in triglyceride oils. They intend for the findings presented herein to be used to guide future selection, development, and refinement of vegetable and other hydrocarbon oils to bring further enhancements to noble gas detection efficiencies

  19. Solubility investigations in support of ultrasensitive noble gas detector development

    International Nuclear Information System (INIS)

    Gross, K. C.

    1998-01-01

    Argonne National Laboratory (ANL) and the University of Cincinnati (UC) have been developing a new class of ultrasensitive noble gas detectors that are based upon the ANL discovery that corn oil has a high affinity for heavy noble gas absorption at room temperature, but releases the noble gases with warming or by other low-energy-input means. Environmental applications for this new class of fluid-based detectors include ultrahigh sensitivity radioxenon detectors for Comprehensive Test Ban Treaty Surveillance, improved fission gas detectors for enhanced environmental surveillance in the vicinity of DOE, DOD, and NRC-licensed facilities, and improved integrating Rn detectors for earthquake prediction. The purpose of the present paper is to present the results of theoretical and experimental investigations into the solubility phenomena of heavy noble gases (Rn, Xe, and Kr) in triglyceride oils. It is the authors' intention that the findings presented herein may be used to guide future selection, development, and refinement of vegetable and other hydrocarbon oils to bring further enhancements to noble gas detection efficiencies

  20. Study of metal bioaccumulation by nuclear microprobe analysis of algae fossils and living algae cells

    International Nuclear Information System (INIS)

    Guo, P.; Wang, J.; Li, X.; Zhu, J.; Reinert, T.; Heitmann, J.; Spemann, D.; Vogt, J.; Flagmeyer, R.-H.; Butz, T.

    2000-01-01

    Microscopic ion-beam analysis of palaeo-algae fossils and living green algae cells have been performed to study the metal bioaccumulation processes. The algae fossils, both single cellular and multicellular, are from the late Neoproterozonic (570 million years ago) ocean and perfectly preserved within a phosphorite formation. The biosorption of the rare earth element ions Nd 3+ by the green algae species euglena gracilis was investigated with a comparison between the normal cells and immobilized ones. The new Leipzig Nanoprobe, LIPSION, was used to produce a proton beam with 2 μm size and 0.5 nA beam current for this study. PIXE and RBS techniques were used for analysis and imaging. The observation of small metal rich spores (<10 μm) surrounding both of the fossils and the living cells proved the existence of some specific receptor sites which bind metal carrier ligands at the microbic surface. The bioaccumulation efficiency of neodymium by the algae cells was 10 times higher for immobilized algae cells. It confirms the fact that the algae immobilization is an useful technique to improve its metal bioaccumulation