Adsorption of heavy metal ion from aqueous solution by nickel oxide nano catalyst prepared by different methods

Directory of Open Access Journals (Sweden)

Amira M. Mahmoud

2015-03-01

Full Text Available Environmental pollution by heavy metal is arising as the most endangering tasks to both water sources and atmosphere quality today. The treatment of heavy metals is of special concern due to their recalcitrance and persistence in the environment. To limit the spread of the heavy metals within water sources, nickel oxide nanoparticles adsorbents were synthesized and characterized with the aim of removal of one of the aggressive heavy elements, namely; lead ions. Nano nickel oxide adsorbents were prepared using NaOH and oxalic acid dissolved in ethanol as precursors. The results indicated that adsorption capacity of Pb(II ion by NiO-org catalyst is favored than that prepared using NaOH as a precipitant. Nickel oxide nanoparticles prepared by the two methods were characterized structurally and chemically through XRD, DTA, TGA, BET and FT-IR. Affinity and efficiency sorption parameters of the solid nano NiO particles, such as; contact time, initial concentration of lead ions and the dosage of NiO nano catalyst and competitive adsorption behaviors were studied. The results showed that the first-order reaction law fit the reduction of lead ion, also showed good linear relationship with a correlation coefficient (R2 larger than 0.9.

Method and apparatus for the production of metal oxide powder

Science.gov (United States)

Harris, M.T.; Scott, T.C.; Byers, C.H.

1992-06-16

The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed. 2 figs.

Application of a mixed metal oxide catalyst to a metallic substrate

Science.gov (United States)

Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

2009-01-01

A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

Heavy metal removal from water/wastewater by nanosized metal oxides: A review

International Nuclear Information System (INIS)

Hua, Ming; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming; Lv, Lu; Zhang, Quanxing

2012-01-01

Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs’ preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance.

Formulation and method for preparing gels comprising hydrous aluminum oxide

Science.gov (United States)

Collins, Jack L.

2014-06-17

Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

Science.gov (United States)

Carnes, Corrie Leigh

The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3/MgO and ZnO/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR, BET, and TEM. The NC samples were all accompanied by a significant increase in surface area and decrease in crystallite size. Several chemical reactions were studied to compare the NC samples to the CM samples. One of the reactions involved a high temperature reaction between carbon tetrachloride and the oxide to form carbon dioxide and the corresponding metal chloride. A similar high temperature reaction was conducted between the metal oxide and hydrogen sulfide to form water and the corresponding metal sulfide. A room temperature gas phase adsorption was studied where SO2 was adsorbed onto the oxide. A liquid phase adsorption conducted at room temperature was the destructive adsorption of paraoxon (a toxic insecticide). In all reactions the NC samples exhibited greater activity, destroying or adsorbing a larger amount of the toxins compared to the CM samples. To better study surface area effects catalytic reactions were also studied. The catalysis of methanol was studied over the nanocrystalline ZnO, CuO, NiO, and ZnO/CuO samples in comparison to their commercial counterparts. In most cases the NC samples proved to be more active catalysts, having higher percent conversions and turnover numbers. A second catalytic reaction was also studied, this reaction was investigated to look at the support effects. The catalysis of cyclopropane to propane was studied over Pt and Co catalysts. These catalysts were supported onto NC and CM alumina by impregnation. By observing differences in the catalytic behavior, support effects have become apparent.

Preparation of titanium oxide and metal titanates as powders, thin films, and microspheres by complex sol-gel process

International Nuclear Information System (INIS)

Deptula, A.; Olczak, T.; Lada, W.; Chmielewski, A.G.; Jakubaszek, U.; Sartowska, B.; Goretta, K.C.; Alvani, C.; Casadio, S.; Contini, V.

2006-01-01

Titanium oxide, for many years an important pigment, has recently been applied widely as a photocatalyst or as supports for metallic catalysts, gas sensors, photovoltaic solar cells, and water and air purification devices. Titanium oxide (TiO 2 ) and titanates based on Ba, Sr and Ca were prepared from commercial solutions of TiCl 4 and HNO 3 . The main preparation steps for the sols consisted of elimination of Cl - by distillation with HNO 3 and addition of metal hydroxides for the titanates. Resulting sols were gelled and used to: (a) prepare irregularly shaped powders by evaporation; (b) produce by a dipping technique thin films on glass, Ag or Ti supports; (c) produce spherical powders (diameters <100 μm) by solvent extraction. Results of thermal and X-ray-diffraction analyses indicated that the temperatures required to form the various compounds were lower than those necessary to form the compounds by conventional solid-state reactions and comparable to those required with use of organometallic based sol-gel methods. Temperatures of formation could be further reduced by addition of ascorbic acid (ASC) to the sols

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.

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.

Method of producing homogeneous mixed metal oxides and metal--metal oxide mixtures

International Nuclear Information System (INIS)

Quinby, T.C.

1978-01-01

Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution to leave a molten urea solution containing the metal values. The molten urea solution is heated to above about 180 0 C, whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles

Preparation of the pur uranium-metal; La preparation de l'uranium-metal pur

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, B; Vertes, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

A detailed description of the chemical processes used to prepare in the factory of Bouchet of the CEA (Seine-Et-Oise) pur metal uranium with either relatively rich ores, or extracts coming of physical or chemical treatment of poor ores. The nitric treatment of ores succeeds to the production of uranate of impure sodium carbonate. This last last product is dissolved in nitric acid and the uranyl nitrate is extracted by tributyl-phosphate diluted in an inert solvent. The uranyl nitrate pure is re-extracted and successively transformed in uranium peroxide, in orange oxide then in brown oxide which is transformed in fluoride by the anhydrous hydrofluoric acid. Uranate fluoride is then reduced in metal by the pure calcium with an yield superior to 99%. (authors) [French] Description detaillee des procedes chimiques mis en jeu pour preparer a l'Usine du Bouchet du Commissariat a l'Energie Atomique (Seine-et-Oise) l'uranium metal pur a partir soit de minerais relativement riches, soit de concentres provenant de traitement physique ou chimique de minerais pauvres. Le traitement nitrique des minerais aboutit a la production d'uranate de soude impur. Ce dernier est a son tour dissous dans l'acide nitrique et le nitrate d'uranyle est extrait par du tributyl-phosphate dilue par un solvant inerte. Le nitrate d'uranyle pur reextrait est transforme successivement en peroxyde d'uranium, en oxyde orange puis en oxyde brun qui est transforme en fluorure par l'acide fluorhydrique anhydre. Le fluorure uraneux est reduit en metal par le calcium pur avec un rendement superieur a 99 %. (auteurs)

Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents.

Science.gov (United States)

Štengl, Václav; Henych, Jiří; Janoš, Pavel; Skoumal, Miroslav

2016-01-01

Metal oxides have very important applications in many areas of chemistry, physics and materials science; their properties are dependent on the method of preparation, the morphology and texture. Nanostructured metal oxides can exhibit unique characteristics unlike those of the bulk form depending on their morphology, with a high density of edges, corners and defect surfaces. In recent years, methods have been developed for the preparation of metal oxide powders with tunable control of the primary particle size as well as of a secondary particle size: the size of agglomerates of crystallites. One of the many ways to take advantage of unique properties of nanostructured oxide materials is stoichiometric degradation of chemical warfare agents (CWAs) and volatile organic compounds (VOC) pollutants on their surfaces.

Sample preparation and study by electronic diffraction of oxidations and fluorinations of some metals and alloys

International Nuclear Information System (INIS)

Auguin, B.

1963-06-01

After having recalled that electron diffraction is particularly adapted to the study of thin films and surface layers, notably those forming during corrosions, and recalled some characteristics of this technique (wavelength, interactions with substances, parasite reactions, observation by transmission or reflection, obtained diagrams for polycrystalline and mono-crystalline substances), the author describes how samples are prepared in the case of examinations performed by transmission and by reflection. As fluorination agents are used for the separation of uranium 235 and 238, the second part discusses some works related to the fluorination of metals and alloys, some of them being used in these separation installations. Chlorine trifluoride is generally used and materials are generally oxidised. Thus, the author reports the study of the action of ClF 3 on different oxides. Oxidations of iron, nickel and Monel are addressed, as well as the behaviour of stainless steel. The study of fluorinations of metals (nickel, chromium, copper), alloys (stainless steel, Monel) and oxides is reported. The author finally addresses treatments performed after fluorinations: vacuum heating, action of humid air

Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

Science.gov (United States)

Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

2017-06-01

Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

Field-induced resistance switching at metal/perovskite manganese oxide interface

International Nuclear Information System (INIS)

Ohkubo, I.; Tsubouchi, K.; Harada, T.; Kumigashira, H.; Itaka, K.; Matsumoto, Y.; Ohnishi, T.; Lippmaa, M.; Koinuma, H.; Oshima, M.

2008-01-01

Planar type metal/insulator/metal structures composed of an epitaxial perovskite manganese oxide layer and various metal electrodes were prepared for electric-field-induced resistance switching. Only the electrode pairs including Al show good resistance switching and the switching ratio reaches its maximum of 1000. This resistance switching occurs around the interface between Al electrodes and epitaxial perovskite manganese oxide thin films

Multi-metal oxide ceramic nanomaterial

Science.gov (United States)

O'Brien, Stephen; Liu, Shuangyi; Huang, Limin

2016-06-07

A convenient and versatile method for preparing complex metal oxides is disclosed. The method uses a low temperature, environmentally friendly gel-collection method to form a single phase nanomaterial. In one embodiment, the nanomaterial consists of Ba.sub.AMn.sub.BTi.sub.CO.sub.D in a controlled stoichiometry.

Preparation of the pur uranium-metal; La preparation de l'uranium-metal pur

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, B.; Vertes, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

A detailed description of the chemical processes used to prepare in the factory of Bouchet of the CEA (Seine-Et-Oise) pur metal uranium with either relatively rich ores, or extracts coming of physical or chemical treatment of poor ores. The nitric treatment of ores succeeds to the production of uranate of impure sodium carbonate. This last last product is dissolved in nitric acid and the uranyl nitrate is extracted by tributyl-phosphate diluted in an inert solvent. The uranyl nitrate pure is re-extracted and successively transformed in uranium peroxide, in orange oxide then in brown oxide which is transformed in fluoride by the anhydrous hydrofluoric acid. Uranate fluoride is then reduced in metal by the pure calcium with an yield superior to 99%. (authors) [French] Description detaillee des procedes chimiques mis en jeu pour preparer a l'Usine du Bouchet du Commissariat a l'Energie Atomique (Seine-et-Oise) l'uranium metal pur a partir soit de minerais relativement riches, soit de concentres provenant de traitement physique ou chimique de minerais pauvres. Le traitement nitrique des minerais aboutit a la production d'uranate de soude impur. Ce dernier est a son tour dissous dans l'acide nitrique et le nitrate d'uranyle est extrait par du tributyl-phosphate dilue par un solvant inerte. Le nitrate d'uranyle pur reextrait est transforme successivement en peroxyde d'uranium, en oxyde orange puis en oxyde brun qui est transforme en fluorure par l'acide fluorhydrique anhydre. Le fluorure uraneux est reduit en metal par le calcium pur avec un rendement superieur a 99 %. (auteurs)

Preparation of the pur uranium-metal

International Nuclear Information System (INIS)

Goldschmidt, B.; Vertes, P.

1955-01-01

A detailed description of the chemical processes used to prepare in the factory of Bouchet of the CEA (Seine-Et-Oise) pur metal uranium with either relatively rich ores, or extracts coming of physical or chemical treatment of poor ores. The nitric treatment of ores succeeds to the production of uranate of impure sodium carbonate. This last last product is dissolved in nitric acid and the uranyl nitrate is extracted by tributyl-phosphate diluted in an inert solvent. The uranyl nitrate pure is re-extracted and successively transformed in uranium peroxide, in orange oxide then in brown oxide which is transformed in fluoride by the anhydrous hydrofluoric acid. Uranate fluoride is then reduced in metal by the pure calcium with an yield superior to 99%. (authors) [fr

High index of refraction films for dielectric mirrors prepared by metal-organic chemical vapor deposition

International Nuclear Information System (INIS)

Brusasco, R.M.

1989-01-01

A wide variety of metal oxides with high index of refraction can be prepared by Metal-Organic Chemical Vapor Deposition. We present some recent optical and laser damage results on oxide films prepared by MOCVD which could be used in a multilayer structure for highly reflecting (HR) dielectric mirror applications. The method of preparation affects both optical properties and laser damage threshold. 10 refs., 8 figs., 4 tabs

Ionic liquid-modified metal sulfides/graphene oxide nanocomposites for photoelectric conversion

International Nuclear Information System (INIS)

Zhang, Yu; Zhang, Yù; Pei, Qi; Feng, Ting; Mao, Hui; Zhang, Wei; Wu, Shuyao; Liu, Daliang; Wang, Hongyu; Song, Xi-Ming

2015-01-01

Graphical abstract: - Highlights: • Metal sulfide (CdS, ZnS, Ag 2 S)/GO nanocomposites were prepared by electrostatic adherence. • Ionic liquid was used to link the metal sulfide and GO in the electrostatic adherence process. • The as-prepared samples showed enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation. - Abstract: Ionic liquid-modified metal sulfides/graphene oxide nanocomposites are prepared via a facile electrostatic adsorption. Ionic liquid (IL) is firstly used as surface modifier and structure-directing agent of metal sulfide (MS) crystallization process, obtaining ionic liquid modified-MS (IL-MS) nanoparticles with positive charges on surface. IL-MS/GO is obtained by electrostatic adherence between positively charged IL-MS and negatively charged graphene oxide (GO). The as-prepared sample shows enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation, indicating IL-MS/GO nanocomposites greatly promoted the separation of photogenerated electron–hole pairs

The use of metal alkoxides in the preparation of ceramic powders

International Nuclear Information System (INIS)

Chetcuti, A.M.; Woolfrey, J.L.

1982-01-01

The production of fine, chemically homogeneous and highly reactive powder is particularly desirable where the synthesis and fabrication of multicomponent ceramic systems, such as SYNROC, are concerned. To produce good sinterable material, a preparation technique that allows intimate mixing of all reacting species is desirable. Traditional routes for preparing fine powders have involved ball-milling metal oxides and spray-drying or flash-drying the resulting oxide slurries. The hydrolysis of metal alkoxides has been investigated as a technique to produce fine powders. The preparation of SYNROC B powder from alkoxides involves hydrolysing a mixture of titanium and zirconium alkoxides. The precipitated product is then blended with Al 3 + , Ba 2 + and Ca 2 + nitrate solution

Process for the preparation of fine grain metal carbide powders

International Nuclear Information System (INIS)

Gortsema, F.P.

1976-01-01

Fine grain metal carbide powders are conveniently prepared from the corresponding metal oxide by heating in an atmosphere of methane in hydrogen. Sintered articles having a density approaching the theoretical density of the metal carbide itself can be fabricated from the powders by cold pressing, hot pressing or other techniques. 8 claims, no drawings

Polymer derived non-oxide ceramics modified with late transition metals.

Science.gov (United States)

Zaheer, Muhammad; Schmalz, Thomas; Motz, Günter; Kempe, Rhett

2012-08-07

This tutorial review highlights the methods for the preparation of metal modified precursor derived ceramics (PDCs) and concentrates on the rare non-oxide systems enhanced with late transition metals. In addition to the main synthetic strategies for modified SiC and SiCN ceramics, an overview of the morphologies, structures and compositions of both, ceramic materials and metal (nano) particles, is presented. Potential magnetic and catalytic applications have been discussed for the so manufactured metal containing non-oxide ceramics.

GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

KAUST Repository

Khan, Mujeeb; Tahir, Muhammad Nawaz; Adil, Syed F; Khan, Hadayat Ullah; Siddiqui, Rafiq H; Al-Warthan, Abdulrahman Abdullah; Tremel, Wolfgang

2015-01-01

Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

KAUST Repository

Khan, Mujeeb

2015-06-11

Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

Metal Phosphate-Supported Pt Catalysts for CO Oxidation

Directory of Open Access Journals (Sweden)

Xiaoshuang Qian

2014-12-01

Full Text Available Oxides (such as SiO2, TiO2, ZrO2, Al2O3, Fe2O3, CeO2 have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported Pt catalysts for CO oxidation were rarely reported. Metal phosphates are a family of metal salts with high thermal stability and acid-base properties. Hydroxyapatite (Ca10(PO46(OH2, denoted as Ca-P-O here also has rich hydroxyls. Here we report a series of metal phosphate-supported Pt (Pt/M-P-O, M = Mg, Al, Ca, Fe, Co, Zn, La catalysts for CO oxidation. Pt/Ca-P-O shows the highest activity. Relevant characterization was conducted using N2 adsorption-desorption, inductively coupled plasma (ICP atomic emission spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, CO2 temperature-programmed desorption (CO2-TPD, X-ray photoelectron spectroscopy (XPS, and H2 temperature-programmed reduction (H2-TPR. This work furnishes a new catalyst system for CO oxidation and other possible reactions.

Charge transport in metal oxide nanocrystal-based materials

Science.gov (United States)

Runnerstrom, Evan Lars

structure. Charge transport can obviously be taken to mean the conduction of electrons, but it also refers to the motion of ions, such as lithium ions and protons. In many cases, the transport of ions is married to the motion of electrons as well, either through an external electrical circuit, or within the same material in the case of mixed ionic electronic conductors. The collective motion of electrons over short length scales, that is, within single nanocrystals, is also a subject of study as it pertains to plasmonic nanocrystals. Finally, charge transport can also be coupled to or result from the formation of defects in metal oxides. All of these modes of charge transport in metal oxides gain further complexity when considered in nanocrystalline systems, where the introduction of numerous surfaces can change the character of charge transport relative to bulk systems, providing opportunities to exploit new physical phenomena. Part I of this dissertation explores the combination of electronic and ionic transport in electrochromic devices based on nanocrystals. Colloidal chemistry and solution processing are used to fabricate nanocomposites based on electrochromic tin-doped indium oxide (ITO) nanocrystals. The nanocomposites, which are completely synthesized using solution processing, consist of ITO nanocrystals and lithium bis(trifluoromethylsulfonyl)amide (LiTFSI) salt dispersed in a lithium ion-conducting polymer matrix of either poly(ethylene oxide) (PEO) or poly(methyl methacrylate) (PMMA). ITO nanocrystals are prepared by colloidal synthetic methods and the nanocrystal surface chemistry is modified to achieve favorable nanocrystal-polymer interactions. Homogeneous solutions containing polymer, ITO nanocrystals, and lithium salt are thus prepared and deposited by spin casting. Characterization by DC electronic measurements, microscopy, and x-ray scattering techniques show that the ITO nanocrystals form a complete, connected electrode within a polymer electrolyte

Oxide-supported metal clusters: models for heterogeneous catalysts

International Nuclear Information System (INIS)

Santra, A K; Goodman, D W

2003-01-01

Understanding the size-dependent electronic, structural and chemical properties of metal clusters on oxide supports is an important aspect of heterogeneous catalysis. Recently model oxide-supported metal catalysts have been prepared by vapour deposition of catalytically relevant metals onto ultra-thin oxide films grown on a refractory metal substrate. Reactivity and spectroscopic/microscopic studies have shown that these ultra-thin oxide films are excellent models for the corresponding bulk oxides, yet are sufficiently electrically conductive for use with various modern surface probes including scanning tunnelling microscopy (STM). Measurements on metal clusters have revealed a metal to nonmetal transition as well as changes in the crystal and electronic structures (including lattice parameters, band width, band splitting and core-level binding energy shifts) as a function of cluster size. Size-dependent catalytic reactivity studies have been carried out for several important reactions, and time-dependent catalytic deactivation has been shown to arise from sintering of metal particles under elevated gas pressures and/or reactor temperatures. In situ STM methodologies have been developed to follow the growth and sintering kinetics on a cluster-by-cluster basis. Although several critical issues have been addressed by several groups worldwide, much more remains to be done. This article highlights some of these accomplishments and summarizes the challenges that lie ahead. (topical review)

Extracting metals directly from metal oxides

International Nuclear Information System (INIS)

Wai, C.M.; Smart, N.G.; Phelps, C.

1997-01-01

A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of β-diketones, halogenated β-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process. 4 figs

Characteristics and possibilities of software tool for metal-oxide surge arresters selection

Directory of Open Access Journals (Sweden)

Đorđević Dragan

2012-01-01

Full Text Available This paper presents a procedure for the selection of metal-oxide surge arresters based on the instructions given in the Siemens and ABB catalogues, respecting their differences and the characteristics and possibilities of the software tool. The software tool was developed during the preparation of a Master's thesis titled, 'Automation of Metal-Oxide Surge Arresters Selection'. An example is presented of the selection of metal-oxide surge arresters using the developed software tool.

Flame spray synthesis under a non-oxidizing atmosphere: Preparation of metallic bismuth nanoparticles and nanocrystalline bulk bismuth metal

Energy Technology Data Exchange (ETDEWEB)

Grass, Robert N.; Stark, Wendelin J. [Institute for Chemical and Bioengineering, ETH Zuerich (Switzerland)], E-mail: wendelin.stark@chem.ethz.ch

2006-10-15

Metallic bismuth nanoparticles of over 98% purity were prepared by a modified flame spray synthesis method in an inert atmosphere by oxygen-deficient combustion of a bismuth-carboxylate based precursor. The samples were characterized by X-ray diffraction, thermal analysis and scanning electron microscopy confirming the formation of pure, crystalline metallic bismuth nanoparticles. Compression of the as-prepared powder resulted in highly dense, nanocrystalline pills with strong electrical conductivity and bright metallic gloss.

Metal Oxide Nanostructures in Food Applications: Quality Control and Packaging

Directory of Open Access Journals (Sweden)

Vardan Galstyan

2018-04-01

Full Text Available Metal oxide materials have been applied in different fields due to their excellent functional properties. Metal oxides nanostructuration, preparation with the various morphologies, and their coupling with other structures enhance the unique properties of the materials and open new perspectives for their application in the food industry. Chemical gas sensors that are based on semiconducting metal oxide materials can detect the presence of toxins and volatile organic compounds that are produced in food products due to their spoilage and hazardous processes that may take place during the food aging and transportation. Metal oxide nanomaterials can be used in food processing, packaging, and the preservation industry as well. Moreover, the metal oxide-based nanocomposite structures can provide many advantageous features to the final food packaging material, such as antimicrobial activity, enzyme immobilization, oxygen scavenging, mechanical strength, increasing the stability and the shelf life of food, and securing the food against humidity, temperature, and other physiological factors. In this paper, we review the most recent achievements on the synthesis of metal oxide-based nanostructures and their applications in food quality monitoring and active and intelligent packaging.

Comparative evaluation of different nanostructured metal oxides for preparation of clinically useful 99Mo/99mTc generators

International Nuclear Information System (INIS)

Ram, Ramu; Chakravarty, Rubel; Dash, Ashutosh

2015-01-01

The potential of nanostructured metal oxides such as nanotitania, nanozirconia, nanoalumina and mesoporous alumina, as new generation sorbent materials for preparation of 99 Mo/ 99m Tc generator has recently been demonstrated. A comparative assessment of such materials is essential for determination of their suitability for preparation of clinically useful generators using (n,γ) 99 Mo. Characteristics which were compared included the sorption capacity, shelf-life of the generator, radioactive concentration and purity of 99m Tc for radiopharmaceutical applications. Mesoporous alumina was identified as the most suitable sorbent for ensuring sustainable production of clinical grade 99 Mo/ 99m Tc generators using low specific activity 99 Mo. (author)

Preparation of reactive and refractory metal powders (Paper No. 25)

International Nuclear Information System (INIS)

Sundaram, C.V.; Sharma, B.P.; Krishnan, T.S.

1979-01-01

In devising processes for the preparation of refractory and reactive metal powders, one has to reckon with many relevant factors. The choice of specific flowsheets is governed by the characteristics of the metal compounds and the reducing agents, the purity required and achievable in the as-reduced powder, the need for further refining of the metal, the possibilities of chemical/physical/mechanical comminution of the purified metal without contamination, and the end application of the powder metal. Micron size zirconium powder used as trigger material in photo-flash bulbs and detonator compositions, tantalum powder of controlled particle size and high purity for the production of electrolytic capacitors, and beryllium metal powder for the preparation of hot pressed powder metallurgy components are illustrative of the variety of reactive metal powders for industrial applications. The work carried out at the Bhabha Atomic Research Centre, Bombay, on the preparation of special metal powders, with particular emphasis on Group IV and V metals and also beryllium is presented. Reduction of metal oxides with alkaline earth metals/hydrides, reduction of metal halides with sodium/magnesium, vacuum arc and electron beam melt purification followed by comminution by hydrogen embrittlement/mechanical comminution are among the processes discussed. (auth.)

Magnesium oxide prepared via metal-chitosan complexation method: Application as catalyst for transesterification of soybean oil and catalyst deactivation studies

Science.gov (United States)

Almerindo, Gizelle I.; Probst, Luiz F. D.; Campos, Carlos E. M.; de Almeida, Rusiene M.; Meneghetti, Simoni M. P.; Meneghetti, Mario R.; Clacens, Jean-Marc; Fajardo, Humberto V.

2011-10-01

A simple method to prepare magnesium oxide catalysts for biodiesel production by transesterification reaction of soybean oil with ethanol is proposed. The method was developed using a metal-chitosan complex. Compared to the commercial oxide, the proposed catalysts displayed higher surface area and basicity values, leading to higher yield in terms of fatty acid ethyl esters (biodiesel). The deactivation of the catalyst due to contact with CO2 and H2O present in the ambient air was verified. It was confirmed that the active catalytic site is a hydrogenocarbonate adsorption site.

Surface Preparation and Deposited Gate Oxides for Gallium Nitride Based Metal Oxide Semiconductor Devices

Directory of Open Access Journals (Sweden)

Paul C. McIntyre

2012-07-01

Full Text Available The literature on polar Gallium Nitride (GaN surfaces, surface treatments and gate dielectrics relevant to metal oxide semiconductor devices is reviewed. The significance of the GaN growth technique and growth parameters on the properties of GaN epilayers, the ability to modify GaN surface properties using in situ and ex situ processes and progress on the understanding and performance of GaN metal oxide semiconductor (MOS devices are presented and discussed. Although a reasonably consistent picture is emerging from focused studies on issues covered in each of these topics, future research can achieve a better understanding of the critical oxide-semiconductor interface by probing the connections between these topics. The challenges in analyzing defect concentrations and energies in GaN MOS gate stacks are discussed. Promising gate dielectric deposition techniques such as atomic layer deposition, which is already accepted by the semiconductor industry for silicon CMOS device fabrication, coupled with more advanced physical and electrical characterization methods will likely accelerate the pace of learning required to develop future GaN-based MOS technology.

Metal oxide targets produced by the polymer-assisted deposition method

Energy Technology Data Exchange (ETDEWEB)

Garcia, Mitch A., E-mail: mitch@berkeley.ed [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, T. [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ashby, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gates, Jacklyn M. [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Stavsetra, Liv [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gregorich, Kenneth E.; Nitsche, Heino [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2010-02-11

The polymer-assisted deposition (PAD) method was used to create crack-free homogenous metal oxide films for use as targets in nuclear science applications. Metal oxide films of europium, thulium, and hafnium were prepared as models for actinide oxides. Films produced by a single application of PAD were homogenous and uniform and ranged in thickness from 30 to 320 nm. Reapplication of the PAD method (six times) with a 10% by weight hafnium(IV) solution resulted in an equally homogeneous and uniform film with a total thickness of 600 nm.

Metal oxide targets produced by the polymer-assisted deposition method

International Nuclear Information System (INIS)

Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, T.; Ashby, Paul D.; Gates, Jacklyn M.; Stavsetra, Liv; Gregorich, Kenneth E.; Nitsche, Heino

2010-01-01

The polymer-assisted deposition (PAD) method was used to create crack-free homogenous metal oxide films for use as targets in nuclear science applications. Metal oxide films of europium, thulium, and hafnium were prepared as models for actinide oxides. Films produced by a single application of PAD were homogenous and uniform and ranged in thickness from 30 to 320 nm. Reapplication of the PAD method (six times) with a 10% by weight hafnium(IV) solution resulted in an equally homogeneous and uniform film with a total thickness of 600 nm.

Methods of preparing deposits containing iron oxides for recycling

Directory of Open Access Journals (Sweden)

T. Lis

2013-04-01

Full Text Available The metallurgical industry is one of the largest sources of wastes. Some of them, however, owing to their content of metals such as zinc or iron, may become valuable secondary raw materials. In order to achieve that purpose, they require appropriate preparation. This article provides a discussion on the methods of preparation of scrap from steelworks, namely deposits containing iron oxides, enabling their recycling.

Benzyl Alcohol-Mediated Versatile Method to Fabricate Nonstoichiometric Metal Oxide Nanostructures.

Science.gov (United States)

Qamar, Mohammad; Adam, Alaaldin; Azad, Abdul-Majeed; Kim, Yong-Wah

2017-11-22

Nanostructured metal oxides with cationic or anionic deficiency find applications in a wide range of technological areas including the energy sector and environment. However, a facile route to prepare such materials in bulk with acceptable reproducibility is still lacking; many synthesis techniques are still only bench-top and cannot be easily scaled-up. Here, we report that the benzyl alcohol (BA)-mediated method is capable of producing a host of nanostructured metal oxides (MO x , where M = Ti, Zn, Ce, Sn, In, Ga, or Fe) with inherent nonstoichiometry. It employs multifunctional BA as a solvent, a reducing agent, and a structure-directing agent. Depending on the oxidation states of metal, elemental or nonstoichiometric oxide forms are obtained. Augmented photoelectrochemical oxidation of water under visible light by some of these nonstoichiometric oxides highlights the versatility of the BA-mediated synthesis protocol.

Mesoporous CuO–ZnO binary metal oxide nanocomposite for decontamination of sulfur mustard

International Nuclear Information System (INIS)

Praveen Kumar, J.; Prasad, G.K.; Ramacharyulu, P.V.R.K.; Garg, P.; Ganesan, K.

2013-01-01

Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. They were prepared by precipitation pyrolysis method and characterized by means of X-ray diffraction, transmission electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy techniques. Obtained data indicated the presence of mesopores with diameter ranging from 2 to 80 nm and the materials exhibited relatively high surface area 86 m 2 g −1 when compared to the individual metal oxide nanoparticles. Reactive sites of mesoporous CuO–ZnO binary metal oxide nanocomposites were studied by infrared spectroscopy technique using pyridine as a probe molecule. These materials demonstrated superior decontamination properties against sulfur mustard when compared to single component metal oxides and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Graphical abstract: Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. These materials demonstrated superior decontamination properties against sulfur mustard and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Highlights: • Preparation of mesoporous CuO–ZnO binary metal oxide nanocomposite. • CuO–ZnO with better surface area was synthesized by precipitation pyrolysis. • Decontamination of HD using mesoporous CuO–ZnO binary metal oxide nanocomposite. • HD decontaminated by elimination and hydrolysis reactions

Mesoporous CuO–ZnO binary metal oxide nanocomposite for decontamination of sulfur mustard

Energy Technology Data Exchange (ETDEWEB)

Praveen Kumar, J.; Prasad, G.K., E-mail: gkprasad2001@yahoo.com; Ramacharyulu, P.V.R.K.; Garg, P.; Ganesan, K.

2013-11-01

Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. They were prepared by precipitation pyrolysis method and characterized by means of X-ray diffraction, transmission electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy techniques. Obtained data indicated the presence of mesopores with diameter ranging from 2 to 80 nm and the materials exhibited relatively high surface area 86 m{sup 2} g{sup −1} when compared to the individual metal oxide nanoparticles. Reactive sites of mesoporous CuO–ZnO binary metal oxide nanocomposites were studied by infrared spectroscopy technique using pyridine as a probe molecule. These materials demonstrated superior decontamination properties against sulfur mustard when compared to single component metal oxides and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Graphical abstract: Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. These materials demonstrated superior decontamination properties against sulfur mustard and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Highlights: • Preparation of mesoporous CuO–ZnO binary metal oxide nanocomposite. • CuO–ZnO with better surface area was synthesized by precipitation pyrolysis. • Decontamination of HD using mesoporous CuO–ZnO binary metal oxide nanocomposite. • HD decontaminated by elimination and hydrolysis reactions.

Reduction of titanium dioxide and other metal oxides by electro-deoxidation

International Nuclear Information System (INIS)

Fray, Derek J.

2003-01-01

Titanium dioxide and other reactive metal compounds are reduced by more reactive metals to form pure metals. These, are expensive and time consuming processes which makes these metals very expensive. Many of these metals and alloys have excellent properties, high strength, low density and very good corrosion resistance, but their use is restricted by its high cost. Electro-deoxidation is a very simple technique where an oxide is made cathodic in a fused salt of an alkaline earth chloride. By applying a voltage, below the decomposition potential of the salt, it has been found that the cathodic reaction is the ionization of oxygen from the oxide to leave a pure metal, rather than the reduction of the ion alkaline earth ion element. Laboratory experiments have shown that this approach can be applied to the reduction of a large number of metal oxides. Another important observation is that when a mixture of oxides is used as the cathode, the product is an alloy of uniform composition. This is a considerable advantage for many alloys that are difficult to prepare using conventional technology. (Original)

Reagent-Free Electrophoretic Synthesis of Few-Atom-Thick Metal Oxide Nanosheets

DEFF Research Database (Denmark)

Hou, Chengyi; Zhang, Minwei; Zhang, Lili

2017-01-01

Engineering traditional materials into the new form of atomic and free-standing two-dimensional structures is of both fundamental interest and practical significance, but it is in general facing challenges especially for metal oxide semiconductors. We herein report an ultragreen method for the cost......-effective and fast preparation of atomic metal oxide nanosheets that can be further transformed into nanofilms. The method combines top-down building block synthesis and bottom-up electrophoretic assembly in water under ambient conditions, using only bulk metal and Milli-Q water without involving any additional...

Radiation chemical route for preparation of metal nanoparticles

International Nuclear Information System (INIS)

Kapoor, S.; Mukherjee, T.

2006-01-01

Nanoparticles show properties that are neither seen in the bulk or at atomic level. The unusual properties are governed by quantum size effect. Due to this various methodologies have been endeavored to control the size of the particles. In the present work we show the use of two complimentary techniques (radiation and photo) to synthesize and control the size of the metal particles. In-situ synthesis of fine silver, thallium and cadmium particles has been carried out by gamma-irradiation and electron pulse irradiation at room temperature in the pre-organized gel of polyacrylamide or cyclodextrin cavity. The role of generation of nuclei in high concentrations in stabilization of metal nanoparticles in hydrophobic cavity is shown. Similarly the importance of entrapment of metal ions in the polymer matrix during its formation is highlighted. The work is further extended to exploit the microemulsion droplets for stabilization of Cd nanoparticles. Utility of pulse radiolysis in probing the mechanism of the formation of metal nanoparticles is also shown. Ultrafast laser pulses were employed to control the morphology of the pre-prepared Pt nanoparticles. The changes in reduction of shape and size are considered to occur through melting and vaporization of the nanoparticles. Pt nanoparticles were coated on the inner walls of the tubular pyrex reactor and tested for their catalytic activity for oxidation of CO. It was observed that Pt nanoparticles prepared in the presence of a stabilizer (gelatin) showed a higher tendency to adhere to the inner walls of the pyrex reactor as compared to that prepared in the presence of silica nanoparticles. The catalyst was found to be active at ≥150 degree C giving CO 2 . Chemically reduced Pt nanoparticles stabilized on silica nanoparticles gave ∼7% CO conversion per hr. However, radiolytically prepared Pt nanoaprticles stabilized by gelatin gave ∼10% conversion per hr. The data indicates that catalytic oxidation of CO takes place

Methods for synthesizing metal oxide nanowires

Science.gov (United States)

Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

2016-08-09

A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

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.

Preparation and Characterization of Uranium Oxides in Support of the K Basin Sludge Treatment Project

International Nuclear Information System (INIS)

Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

2008-01-01

Uraninite (UO2) and metaschoepite (UO3-2H2O) are the uranium phases most frequently observed in K Basin sludge. Uraninite arises from the oxidation of uranium metal by anoxic water and metaschoepite arises from oxidation of uraninite by atmospheric or radiolytic oxygen. Studies of the oxidation of uraninite by oxygen to form metaschoepite were performed at 21 C and 50 C. A uranium oxide oxidation state characterization method based on spectrophotometry of the solution formed by dissolving aqueous slurries in phosphoric acid was developed to follow the extent of reaction. This method may be applied to determine uranium oxide oxidation state distribution in K Basin sludge. The uraninite produced by anoxic corrosion of uranium metal has exceedingly fine particle size (6 nm diameter), forms agglomerates, and has the formula UO2.004 ± 0.007; i.e., is practically stoichiometric UO2. The metaschoepite particles are flatter and wider when prepared at 21 C than the particles prepared at 50 C. These particles are much smaller than the metaschoepite observed in prolonged exposure of actual K Basin sludge to warm moist oxidizing conditions. The uraninite produced by anoxic uranium metal corrosion and the metaschoepite produced by reaction of uraninite aqueous slurries with oxygen may be used in engineering and process development testing. A rapid alternative method to determine uranium metal concentrations in sludge also was identified.

A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

International Nuclear Information System (INIS)

Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang

2016-01-01

Highlights: • A general melt-injection-decomposition (MID) route is proposed for the fabrication of oriented metal oxide nanowire arrays. • Four kinds of metal oxide (CuO, Mn_2O_3, Co_3O_4 and Cr_2O_3) nanowire arrays have been realized as examples through the developed MID route. • The mechanism of the developed MID route is discussed using Thermogravimetry and Differential Thermal Analysis technique. • The MID route is a versatile, simple, facile and effective way to prepare different kinds of oriented metal oxide nanowire arrays in the future. - Abstract: In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn_2O_3, Co_3O_4 and Cr_2O_3) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

Preparation of lead titanate zirconate from metal citrates

International Nuclear Information System (INIS)

Bastos, C.M.R.

1994-01-01

Lead titanate zirconate (PZT) preparation from its metal constituent citrates have been investigated. Metal citrates were obtained by forced precipitation using a dehydration alcohol mixture. Salt solutions of lead nitrate and octahydrated zirconyl chloride, and titanium tetrachloride were treated separately with citric acid and ammonium hydroxide. Zirconium, titanium and lead oxides resulted from thermal decomposition of corresponding citrates at 500 0 C, 450 0 C and 250 0 C, respectively. Lead titanate (PT) and lead zirconate (P Z) were obtained by calcining at 450 0 C and 500 0 C, respectively, after adequate heating of citrates mechanically mixed in ethyl ether. PZT samples were obtained with different starting stoichiometry. Rhombohedral PZT-1 53/47 sample was prepared from co precipitating zirconyl ammonium and ammonium lead citrates in presence of ethanolic titanium oxide dispersion, and calcinating at 800 0 C. Rhombohedral PZT-q 52/48 sample was obtained from heating at 500 0 C for 2 hours a mixture of metal citrates coprecipitated by dehydration mixture of acetone-ethanol-formic acid (2:1:0,06). Tetragonal PZT-m stoichiometry 53/47 sample were obtained by calcining at after 600 0 C for 2 hours after heating a mechanically mixed metal citrates. PT phase arose at 400 0 C. PZT-m powders obtained in a range of 400 0 C-800 0 C were isostatically pressed, and sintered at 1100 0 C and 1200 0 C in saturated Pb O atmosphere. Rhombohedral sintered PZT was obtained with 7,78 g.cm -3 at 1200 0 C. (author). 123 refs, 53 figs, 32 tabs

Plutonium metal preparation and purification at Los Alamos, 1984

International Nuclear Information System (INIS)

Christensen, D.C.; Williams, J.D.; McNeese, J.A.; Fife, K.W.

1984-01-01

Plutonium metal preparation and purification are well established at Los Alamos. Metal is prepared by calcothermic reduction of both PuF 4 and PuO 2 . Metal is purified by halide slagging, casting, and electrorefining. The product from the production sequence is ultrapure plutonium metal. All of the processes involve high temperature operation and all but casting involve molten salt media. Development efforts are fourfold: (1) recover plutonium values from residues; (2) reduce residue generation through process improvements and changes; (3) recycle of reagents, and (4) optimize and integrate all processes into a close-loop system. Plutonium residues are comprised of oxides, chlorides, colloidal metal suspensions, and impure metal heels. Pyrochemical recovery techniques are under development to address each residue. In addition, we are looking back at each residue generation step and are making process changes to reduce plutonium content in each residue. Reagent salt is the principle media used in pyrochemical processing. The regeneration and recycle of these reagents will both reduce our waste handling and operating expense. The fourth area, process optimization, involves both existing processes and new process developments. A status of efforts in all four of these areas will be summarized

Recent Advances in Antimicrobial Hydrogels Containing Metal Ions and Metals/Metal Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Fazli Wahid

2017-11-01

Full Text Available Recently, the rapid emergence of antibiotic-resistant pathogens has caused a serious health problem. Scientists respond to the threat by developing new antimicrobial materials to prevent or control infections caused by these pathogens. Polymer-based nanocomposite hydrogels are versatile materials as an alternative to conventional antimicrobial agents. Cross-linking of polymeric materials by metal ions or the combination of polymeric hydrogels with nanoparticles (metals and metal oxide is a simple and effective approach for obtaining a multicomponent system with diverse functionalities. Several metals and metal oxides such as silver (Ag, gold (Au, zinc oxide (ZnO, copper oxide (CuO, titanium dioxide (TiO2 and magnesium oxide (MgO have been loaded into hydrogels for antimicrobial applications. The incorporation of metals and metal oxide nanoparticles into hydrogels not only enhances the antimicrobial activity of hydrogels, but also improve their mechanical characteristics. Herein, we summarize recent advances in hydrogels containing metal ions, metals and metal oxide nanoparticles with potential antimicrobial properties.

Experimental Methodology for Determining Optimum Process Parameters for Production of Hydrous Metal Oxides by Internal Gelation

Energy Technology Data Exchange (ETDEWEB)

Collins, J.L.

2005-10-28

The objective of this report is to describe a simple but very useful experimental methodology that was used to determine optimum process parameters for preparing several hydrous metal-oxide gel spheres by the internal gelation process. The method is inexpensive and very effective in collection of key gel-forming data that are needed to prepare the hydrous metal-oxide microspheres of the best quality for a number of elements.

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).

Syntheses of rare-earth metal oxide nanotubes by the sol-gel method assisted with porous anodic aluminum oxide templates

International Nuclear Information System (INIS)

Kuang Qin; Lin Zhiwei; Lian Wei; Jiang Zhiyuan; Xie Zhaoxiong; Huang Rongbin; Zheng Lansun

2007-01-01

In this paper, we report a versatile synthetic method of ordered rare-earth metal (RE) oxide nanotubes. RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction (XRD) have been employed to characterize the morphology and composition of the as-prepared nanotubes. It is found that as-prepared RE oxides evolve into bamboo-like nanotubes and entirely hollow nanotubes. A new possible formation mechanism of RE oxide nanotubes in the AAO channels is proposed. These high-quantity RE oxide nanotubes are expected to have promising applications in many areas such as luminescent materials, catalysts, magnets, etc. - Graphical abstract: A versatile synthetic method for the preparation of ordered rare-earth (RE) oxide nanotubes is reported, by which RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates

Direct preparation of Al-base alloys from their oxides/metal precursors in the eutectic LiCl–KCl melt

International Nuclear Information System (INIS)

Gao, Bingliang; Zhu, Hao; Xia, Yuxiang; Shi, Zhongning; Hu, Xianwei; Wang, Zhaowen

2016-01-01

A study was carried out on the preparation of Al–Cu–Li alloy from their oxides/metal precursors using the method of electro-deoxidation in the eutectic LiCl–KCl melt at 648 K. Cyclic voltammetry was used to characterize the system. The samples were prepared by potentiostatic electrolysis at −1.0 V to −2.0 V (vs. Ag + /Ag) for 5 h. XRD analysis shows that Li 2 O is not electrochemically reduced to Li at −1.0 V (vs. Ag + /Ag) or more negative potential. During the preparation process of Al–Cu–Li alloy, lithium peroxide is formed as an intermediate compound. Al–Cu–Li alloy is chemically prepared through the reaction between aluminum and lithium peroxide by heating of Al–Cu–Li 2 O precursors in KCl–LiCl–LiF melt at 1023 K. Eelectro-deoxidation in LiCl–KCl melt can increase the lithium content in the final alloy product. Al–Mg and Al–Nd alloy were also prepared by using the same method from their mixture of aluminum and corresponding oxide, respectively. Al–Nd alloy can only be obtained at the temperature above 773 K. Al–Li alloy could not be obtained in eutectic CaCl 2 –LiCl melt because of formation of calcium aluminates. - Highlights: • Al–Cu–Li alloy was prepared using electrochemical deoxidation of Al–Cu–Li 2 O precursor in eutectic KCl–LiCl melt at 648 K. • Al–Nd alloy was successfully produced by the same method at 773 K. • CaCl 2 –LiCl melt is not a good choice for preparing Al–Li alloy because of formation of calcium aluminate.

Direct preparation of Al-base alloys from their oxides/metal precursors in the eutectic LiCl–KCl melt

Energy Technology Data Exchange (ETDEWEB)

Gao, Bingliang, E-mail: blgao@mail.neu.edu.cn; Zhu, Hao; Xia, Yuxiang; Shi, Zhongning; Hu, Xianwei; Wang, Zhaowen

2016-04-25

A study was carried out on the preparation of Al–Cu–Li alloy from their oxides/metal precursors using the method of electro-deoxidation in the eutectic LiCl–KCl melt at 648 K. Cyclic voltammetry was used to characterize the system. The samples were prepared by potentiostatic electrolysis at −1.0 V to −2.0 V (vs. Ag{sup +}/Ag) for 5 h. XRD analysis shows that Li{sub 2}O is not electrochemically reduced to Li at −1.0 V (vs. Ag{sup +}/Ag) or more negative potential. During the preparation process of Al–Cu–Li alloy, lithium peroxide is formed as an intermediate compound. Al–Cu–Li alloy is chemically prepared through the reaction between aluminum and lithium peroxide by heating of Al–Cu–Li{sub 2}O precursors in KCl–LiCl–LiF melt at 1023 K. Eelectro-deoxidation in LiCl–KCl melt can increase the lithium content in the final alloy product. Al–Mg and Al–Nd alloy were also prepared by using the same method from their mixture of aluminum and corresponding oxide, respectively. Al–Nd alloy can only be obtained at the temperature above 773 K. Al–Li alloy could not be obtained in eutectic CaCl{sub 2}–LiCl melt because of formation of calcium aluminates. - Highlights: • Al–Cu–Li alloy was prepared using electrochemical deoxidation of Al–Cu–Li{sub 2}O precursor in eutectic KCl–LiCl melt at 648 K. • Al–Nd alloy was successfully produced by the same method at 773 K. • CaCl{sub 2}–LiCl melt is not a good choice for preparing Al–Li alloy because of formation of calcium aluminate.

A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang, E-mail: sgyang@nju.edu.cn

2016-12-30

Highlights: • A general melt-injection-decomposition (MID) route is proposed for the fabrication of oriented metal oxide nanowire arrays. • Four kinds of metal oxide (CuO, Mn{sub 2}O{sub 3}, Co{sub 3}O{sub 4} and Cr{sub 2}O{sub 3}) nanowire arrays have been realized as examples through the developed MID route. • The mechanism of the developed MID route is discussed using Thermogravimetry and Differential Thermal Analysis technique. • The MID route is a versatile, simple, facile and effective way to prepare different kinds of oriented metal oxide nanowire arrays in the future. - Abstract: In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn{sub 2}O{sub 3}, Co{sub 3}O{sub 4} and Cr{sub 2}O{sub 3}) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

Preparation and Characterization of Uranium Oxides in Support of the K Basin Sludge Treatment Project

Energy Technology Data Exchange (ETDEWEB)

Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

2008-07-08

Uraninite (UO2) and metaschoepite (UO3·2H2O) are the uranium phases most frequently observed in K Basin sludge. Uraninite arises from the oxidation of uranium metal by anoxic water and metaschoepite arises from oxidation of uraninite by atmospheric or radiolytic oxygen. Studies of the oxidation of uraninite by oxygen to form metaschoepite were performed at 21°C and 50°C. A uranium oxide oxidation state characterization method based on spectrophotometry of the solution formed by dissolving aqueous slurries in phosphoric acid was developed to follow the extent of reaction. This method may be applied to determine uranium oxide oxidation state distribution in K Basin sludge. The uraninite produced by anoxic corrosion of uranium metal has exceedingly fine particle size (6 nm diameter), forms agglomerates, and has the formula UO2.004±0.007; i.e., is practically stoichiometric UO2. The metaschoepite particles are flatter and wider when prepared at 21°C than the particles prepared at 50°C. These particles are much smaller than the metaschoepite observed in prolonged exposure of actual K Basin sludge to warm moist oxidizing conditions. The uraninite produced by anoxic uranium metal corrosion and the metaschoepite produced by reaction of uraninite aqueous slurries with oxygen may be used in engineering and process development testing. A rapid alternative method to determine uranium metal concentrations in sludge also was identified.

Synthesis of vertically aligned metal oxide nanostructures

KAUST Repository

Roqan, Iman S.

2016-03-03

Metal oxide nanostructure and methods of making metal oxide nanostructures are provided. The metal oxide nanostructures can be 1 -dimensional nanostructures such as nanowires, nanofibers, or nanotubes. The metal oxide nanostructures can be doped or undoped metal oxides. The metal oxide nanostructures can be deposited onto a variety of substrates. The deposition can be performed without high pressures and without the need for seed catalysts on the substrate. The deposition can be performed by laser ablation of a target including a metal oxide and, optionally, a dopant. In some embodiments zinc oxide nanostructures are deposited onto a substrate by pulsed laser deposition of a zinc oxide target using an excimer laser emitting UV radiation. The zinc oxide nanostructure can be doped with a rare earth metal such as gadolinium. The metal oxide nanostructures can be used in many devices including light-emitting diodes and solar cells.

Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide.

Science.gov (United States)

Hirai, Kenji; Isobe, Shigehito; Sada, Kazuki

2015-12-18

Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants.

A study of the kinetics and mechanisms of electrocrystallization of indium oxide on an in situ prepared metallic indium electrode

International Nuclear Information System (INIS)

Omanovic, S.; Metikos-Hukovic, M.

2004-01-01

The mechanisms and kinetics of nucleation and growth of indium oxide film on an in situ prepared metallic indium electrode was studied in a borate buffer solution of pH 10.0 using cyclic voltammetry and chroanoamperometry techniques. It was shown that the initial stage of nucleation of the oxide film includes a three-dimensional progressive nucleation process, combined with a diffusion-controlled growth of the stable indium oxide crystals. The thermodynamic data obtained indicated a strong tendency of indium to form an indium oxide film on its surface in an aqueous solution. It was found that the rate-determining step in the nucleation and growth process is the surface diffusion of electroactive species. The nucleation rate constant, and the number of nucleation active sites were calculated independently. It was shown that between 2 and 15% of sites on the indium surface act as active nucleation centers, and that each active site represents a critical nucleus

Co3O4 protective coatings prepared by Pulsed Injection Metal Organic Chemical Vapour Deposition

DEFF Research Database (Denmark)

Burriel, M.; Garcia, G.; Santiso, J.

2005-01-01

of deposition temperature. Pure Co3O4 spinel structure was found for deposition temperatures ranging from 360 to 540 degreesC. The optimum experimental parameters to prepare dense layers with a high growth rate were determined and used to prepare corrosion protective coatings for Fe-22Cr metallic interconnects......Cobalt oxide films were grown by Pulsed Injection Metal Organic Chemical Vapour Deposition (PI-MOCVD) using Co(acac)(3) (acac=acetylacetonate) precursor dissolved in toluene. The structure, morphology and growth rate of the layers deposited on silicon substrates were studied as a function......, to be used in Intermediate Temperature Solid Oxide Fuel Cells. (C) 2004 Elsevier B.V. All rights reserved....

Tetrathiafulvalene S-oxide: a Potential Donor Impurity in the Organic Metal TTF-TCNQ

DEFF Research Database (Denmark)

Carlsen, Lars; Bechgaard, Klaus; Jacobsen, Claus Schelde

1979-01-01

Tetrathiafulvalene S-oxide, which because of its size similarity with tetrathiafulvalene is a potential ‘donor impurity’ in the organic metal TTF–TCNQ, was prepared and characterized spectroscopically. Experiments in which tetrathiafulvalene S-oxide was purposely doped into TTF–TCNQ indicate, how...

Alkoxide-based precursors for direct drawing of metal oxide micro- and nanofibres

Energy Technology Data Exchange (ETDEWEB)

Taette, Tanel; Hussainov, Medhat; Paalo, Madis; Part, Marko; Talviste, Rasmus; Kiisk, Valter; Maendar, Hugo; Pohako, Kaija; Reivelt, Kaido; Lohmus, Ants [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Pehk, Tonis [National Institute of Chemical and Biological Physics, Akadeemia tee 23, Tallinn 12618 (Estonia); Natali, Marco [ICIS-CNR, Corso Stati Uniti 4, Padova 35127 (Italy); Gurauskis, Jonas [Instituto de Ciencia de Materiales de Aragon C.S.I.C., University of Zaragoza Fac. De Ciencias, c/Pedro Cerbuna 12, Zaragoza 50009 (Spain); Maeeorg, Uno, E-mail: tanelt@fi.tartu.ee [Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411 (Estonia)

2011-06-15

The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO{sub 2}, TiO{sub 2}, ZrO{sub 2}, HfO{sub 2} and CeO{sub 2}) fibres with a high aspect ratio (up to 10 000) and a diameter as small as 200 nm. The sol-gel processing includes consumption of precursors obtained from alkoxides by aqueous or non-aqueous polymerization. Shear thinning of the precursors enables pulling a material into a fibre. This rheological behaviour can be explained by sliding of particles owing to external forces. Transmission (propagation) of light along microscaled fibres and their excellent surface morphology suggest that metal oxide nanofibres can be directly drawn from sol precursors for use in integrated photonic systems.

Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

Directory of Open Access Journals (Sweden)

Xiaoli Wang

2016-01-01

Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

Shocked plate metal atom oxidation laser

International Nuclear Information System (INIS)

De Koker, J.G.; Rice, W.W. Jr.; Jensen, R.J.

1975-01-01

A method and apparatus for producing metal atom oxidation lasing wherein an explosively shocked grooved metal plate produces metal vapor jets directed through an appropriate gaseous oxidizer are described. Reaction of the metal vapor with the oxidizer produces molecular species having a population inversion therein. (U.S.)

Metal oxide nanorod arrays on monolithic substrates

Energy Technology Data Exchange (ETDEWEB)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

2018-01-02

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

Conductometric gas sensors based on metal oxides modified with gold nanoparticles: a review

International Nuclear Information System (INIS)

Korotcenkov, Ghenadii; Cho, Beong K.; Brinzari, Vladimir

2016-01-01

This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required. (author)

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

Science.gov (United States)

Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

2017-01-01

Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O3 catalytic decomposition and utilization. Benzene and O3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O3 was catalytically decomposed, generating highly reactive oxidants such as rad OH and rad O for benzene oxidation.

Facile and large-scale preparation of sandwich-structured graphene-metal oxide composites as anode materials for Li-ion batteries

International Nuclear Information System (INIS)

Fang, Hongmei; Zhao, Li; Yue, Wenbo; Wang, Yuan; Jiang, Yang; Zhang, Yuan

2015-01-01

Graphene-based metal oxides are desirable as potential anode materials for lithium-ion batteries (LIBs) owing to their superior electrochemical properties. In this work, sandwich-structured graphene-metal oxide (ZnO, NiO) composites are facilely synthesized on a large scale through self-assembly of graphene oxide nanosheets and metal ammine complexes, and then thermal decomposition of the self-assembled products. ZnO or NiO nanoparticles with diameters of 5∼10 nm are immobilized between the layers of graphene nanosheets, which may provide the space for accommodating the volume change of metal oxides during cycles, and highly improve the electronic conductivity of the composites. Accordingly, these sandwich-structured composites exhibit enhanced electrochemical performances compared to metal oxide particles or stacked graphene nanosheets. This facile synthesis method is very suitable for the large-scale production of three-dimensional graphene-based composites as high-performance anodes for LIBs.

Metal atom oxidation laser

International Nuclear Information System (INIS)

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-01-01

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides

Study of Pd-Sn/Al{sub 2}O{sub 3} catalysts prepared by an oxide colloidal route; Etude de catalyseurs Pd-Sn/Al{sub 2}O{sub 3} prepares par voie colloidale oxyde

Energy Technology Data Exchange (ETDEWEB)

Verdier, St.

2001-09-01

The oxide colloidal route, developed in the laboratory for mono-metallic catalysts, consists in preparing a metallic oxide hydro-sol which leads to the supported catalyst after deposition onto a support and an activation stage. In this work, this method has been adapted to the preparation of alumina supported bimetallic Pd-Sn catalysts to determine its interest for the control of the properties of the bimetallic phase (size, composition and structure). In the preliminary study concerning tin oxide sols, SnO{sub 2} (size=2,3 nm) and Sn{sub 6}O{sub 4}(OH){sub 4} (size = 25 nm) nano-particles were synthesized by neutralization respectively for tin(IV) and tin(H). The control through the pH of the aggregation of the PdO and SnO{sub 2} particles revealed that increasing oxide solubility promotes integral re-dispersion of the oxide particles. To synthesize oxide bimetallic sols, three strategies were defined. Copolymerization (formation of a mixed oxide nano-sol by cross condensation of both metals) does not lead to a mixed oxide Pd-Sn phase. Surface precipitation (neutralization of the second metal in the presence of the first oxide sol) yields nano-particles of both oxides in close interaction. Adsorption (adsorption of the second metal onto the first oxide sol) significantly occurs when contacting tin with a basic PdO sol (hydrolytic adsorption). The characterization and the assessment of the catalytic properties (selective hydrogenation of buta-1,3-diene) of the catalysts prepared by deposition of oxide bimetallic sols showed that the oxide colloidal route allows the control of the properties of the supported bimetallic phase. Moreover, our results display that both Pd-Sn alloy formation and,aggregation of the metallic particles contribute to increase the selectivity for this reaction. (author)

Bipolar resistive switching in graphene oxide based metal insulator metal structure for non-volatile memory applications

Science.gov (United States)

Singh, Rakesh; Kumar, Ravi; Kumar, Anil; Kashyap, Rajesh; Kumar, Mukesh; Kumar, Dinesh

2018-05-01

Graphene oxide based devices have attracted much attention recently because of their possible application in next generation electronic devices. In this study, bipolar resistive switching characteristics of graphene oxide based metal insulator metal structure were investigated for nonvolatile memories. The graphene oxide was prepared by the conventional Hummer's method and deposited on ITO coated glass by spin-coating technique. The dominant mechanism of resistive switching is the formation and rupture of the conductive filament inside the graphene oxide. The conduction mechanism for low and high resistance states are dominated by two mechanism the ohmic conduction and space charge limited current (SCLC) mechanism, respectively. Atomic Force Microscopy, X-ray diffraction, Cyclic-Voltammetry were conducted to observe the morphology, structure and behavior of the material. The fabricated device with Al/GO/ITO structure exhibited reliable bipolar resistive switching with set & reset voltage of -2.3 V and 3V respectively.

Nanotoxicology of Metal Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Amedea B. Seabra

2015-06-01

Full Text Available This review discusses recent advances in the synthesis, characterization and toxicity of metal oxide nanoparticles obtained mainly through biogenic (green processes. The in vitro and in vivo toxicities of these oxides are discussed including a consideration of the factors important for safe use of these nanomaterials. The toxicities of different metal oxide nanoparticles are compared. The importance of biogenic synthesized metal oxide nanoparticles has been increasing in recent years; however, more studies aimed at better characterizing the potent toxicity of these nanoparticles are still necessary for nanosafely considerations and environmental perspectives. In this context, this review aims to inspire new research in the design of green approaches to obtain metal oxide nanoparticles for biomedical and technological applications and to highlight the critical need to fully investigate the nanotoxicity of these particles.

Mesoporous Transition Metal Oxides for Supercapacitors

OpenAIRE

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-01-01

Recently, transition metal oxides, such as ruthenium oxide (RuO2), manganese dioxide (MnO2), nickel oxides (NiO) and cobalt oxide (Co3O4), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are result...

Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

International Nuclear Information System (INIS)

1980-01-01

Finely divided powders are prepared by first reacting an aqueous solution containing dissolved metal values with excess urea. After the reaction of water in the solution with urea is complete, the resulting molten urea solution is heated to cause metal values in solution to precipitate. The resulting mixture containing precipitated metal values is heated to evaporate volatile material, leaving a dry powder containing the metal values. Detailed examples are given. (U.K.)

Nanotoxicity: oxidative stress mediated toxicity of metal and metal oxide nanoparticles.

Science.gov (United States)

Sarkar, Abhijit; Ghosh, Manoranjan; Sil, Parames Chandra

2014-01-01

Metal and metal oxide nanoparticles are often used as industrial catalysts or to improve product's functional properties. Recent advanced nanotechnology have been expected to be used in various fields, ranging from sensors, environmental remediation to biomedicine, medical biology and imaging, etc. However, the growing use of nanoparticles has led to their release into environment and increased levels of these particles at nearby sites or the surroundings of their manufacturing factories become obvious. The toxicity of metal and metal oxide nanoparticles on humans, animals, and certainly to the environment has become a major concern to our community. However, controversies still remain with respect to the toxic effects and the mechanisms of these nanoparticles. The scientific community now feels that an understanding of the toxic effects is necessary to handle these nanoparticles and their use. A new discipline, named nanotoxicology, has therefore been developed that basically refers to the study of the interactions of nanoparticles with biological systems and also measures the toxicity level related to human health. Nanoparticles usually generate reactive oxygen species to a greater extent than micro-sized particles resulting in increased pro-inflammatory reactions and oxidative stress via intracellular signaling pathways. In this review, we mainly focus on the routes of exposure of some metal and metal oxide nanoparticles and how these nanoparticles affect us or broadly the cells of our organs. We would also like to discuss the responsible mechanism(s) of the nanoparticle-induced reactive oxygen species mediated organ pathophysiology. A brief introduction of the characterization and application of these nanoparticles has also been included in the article.

The development of latent fingerprints by zinc oxide and tin oxide nanoparticles prepared by precipitation technique

Science.gov (United States)

Luthra, Deepali; Kumar, Sacheen

2018-05-01

Fingerprints are the very important evidence at the crime scene which must be developed clearly with shortest duration of time to solve the case. Metal oxide nanoparticles could be the mean to develop the latent fingerprints. Zinc oxide and Tin Oxide Nanoparticles were prepared by using chemical precipitation technique which were dried and characterized by X-ray diffraction, UV-Visible spectroscopy and FTIR. The size of zinc oxide crystallite was found to be 14.75 nm with minimum reflectance at 360 nm whereas tin oxide have the size of 90 nm and reflectance at minimum level 321 nm. By using these powdered samples on glass, plastic and glossy cardboard, latent fingerprints were developed. Zinc oxide was found to be better candidate than tin oxide for the fingerprint development on all the three types of substrates.

Catalytic production of metal carbonyls from metal oxides

Science.gov (United States)

Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

1984-01-01

This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

Preparation of magnesium metal matrix composites by powder metallurgy process

Science.gov (United States)

Satish, J.; Satish, K. G., Dr.

2018-02-01

Magnesium is the lightest metal used as the source for constructional alloys. Today Magnesium based metal matrix composites are widely used in aerospace, structural, oceanic and automobile applications for its light weight, low density(two thirds that of aluminium), good high temperature mechanical properties and good to excellent corrosion resistance. The reason of designing metal matrix composite is to put in the attractive attributes of metals and ceramics to the base metal. In this study magnesium metal matrix hybrid composite are developed by reinforcing pure magnesium with silicon carbide (SiC) and aluminium oxide by method of powder metallurgy. This method is less expensive and very efficient. The Hardness test was performed on the specimens prepared by powder metallurgy method. The results revealed that the micro hardness of composites was increased with the addition of silicon carbide and alumina particles in magnesium metal matrix composites.

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)

Mesoporous Transition Metal Oxides for Supercapacitors.

Science.gov (United States)

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-10-14

Recently, transition metal oxides, such as ruthenium oxide (RuO₂), manganese dioxide (MnO₂), nickel oxides (NiO) and cobalt oxide (Co₃O₄), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO₂, MnO₂, NiO, Co₃O₄ and nickel cobaltite (NiCo₂O₄), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Enzyme-Free Electrochemical Glucose Sensors Prepared by Dealloying Pd-Ni-P Metallic Glasses

Directory of Open Access Journals (Sweden)

Yuqiao Zeng

2014-01-01

Full Text Available We report the formation of enzyme-free electrochemical glucose sensors by electrochemical dealloying palladium-containing Pd-Ni-P metallic glasses. When metallic glasses with different Pd contents are used as the dealloying precursor alloys, palladium-based nanoporous metals with different ligament and pore sizes can be obtained. The chemical compositions of the nanoporous metals also vary according to the different precursor compositions. All the as-obtained nanoporous metals exhibit electrochemical catalytic activity towards the oxidation of d-glucose, indicating that the nanoporous metals prepared by dealloying the Pd-Ni-P metallic glasses are promising materials for enzyme-free electrochemical glucose sensor.

Ultrafine yttria-stabilized zirconia powders prepared by pyrolysis of a metal-oxalate-cellulose complex

Energy Technology Data Exchange (ETDEWEB)

Solov`eva, L.V.; Bashmakov, I.A.; Kaputskii, F.N. [Research Institute of Physicochemical Problems, Minsk (Belarus)] [and others

1995-12-01

Preparation of high-purity submicron powders with uniform particles is a key stage in the fabrication of high-quality ceramics. For this purpose, chemical methods are commonly used. Recently, pyrolysis of salt-cellulose compositions has gained acceptance for the preparation of mixed oxide powders. This method ensures control of the morphology and particle size of the resultant powders. In this work, the authors present an environmentally safe method for preparing ZrO{sub 2}-based powders from metal-oxalate-cellulose complexes (MOCC) used as precursors instead of soluble metal salts physisorbed on the cellulose surface. The powders obtained by this method feature higher dispersity than their commercially available analogs.

Cordierite-supported metal oxide for non-methane hydrocarbon oxidation in cooking oil fumes.

Science.gov (United States)

Huang, Yonghai; Yi, Honghong; Tang, Xiaolong; Zhao, Shunzheng; Gao, Fengyu; Wang, Jiangen; Yang, Zhongyu

2018-05-21

Cooking emission is an important reason for the air quality deterioration in the metropolitan area in China. Transition metal oxide and different loading of manganese oxide supported on cordierite were prepared by incipient wetness impregnation method and were used for non-methane hydrocarbon (NMHC) oxidation in cooking oil fumes (COFs). The effects of different calcination temperature and different Mn content were also studied. The SEM photographs and CO 2 temperature-programmed desorption revealed 5 wt% Mn/cordierite had the best pore structure and the largest number of the weak and moderate basic sites so it showed the best performance for NMHC oxidation. XRD analysis exhibited 5 wt% Mn/cordierite had the best dispersion of active phase and the active phase was MnO 2 when the calcination temperature was 400℃ which were good for the catalytic oxidation of NMHC.

X-Ray Absorption Studies of Vanadium-Containing Metal Oxide Nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Hohn, Keith, L.

2006-01-09

Metal oxide nanocrystals offer significant potential for use as catalysts or catalyst supports due to their high surface areas and unique chemical properties that result from the high number of exposed corners and edges. However, little is known about the catalytic activity of these materials, especially as oxidation catalysts. This research focused on the preparation, characterization and use of vanadium-containing nanocrystals as selective oxidation catalysts. Three vanadium-containing nanocrystals were prepared using a modified sol-gel procedure: V/MgO, V/SiO2, and vanadium phosphate (VPO). These represent active oxidation catalysts for a number of industrially relevant reactions. The catalysts were characterized by x-ray diffraction and Raman, UV-VIS, infrared and x-ray absorption spectroscopies with the goal of determining the primary structural and chemical differences between nanocrystals and microcrystals. The catalytic activity of these catalysts was also studied in oxidative dehydrogenation of butane and methanol oxidation to formaldehyde. V/MgO nanocrystals were investigated for activity in oxidative dehydrogenation of butane and compared to conventional V/MgO catalysts. Characterization of V/MgO catalysts using Raman spectroscopy and x-ray absorption spectroscopy showed that both types of catalysts contained magnesium orthovanadate at vanadium loadings below 15 weight%, but above that loading, magnesium pyrovanadate may have been present. In general, MgO nanocrystals had roughly half the crystal size and double the surface area of the conventional MgO. In oxidative dehydrogenation of butane, nanocrystalline V/MgO gave higher selectivity to butene than conventional V/MgO at the same conversion. This difference was attributed to differences in vanadium domain size resulting from the higher surface areas of the nanocrystalline support, since characterization suggested that similar vanadium phases were present on both types of catalysts. Experiments in

Sol-gel/hydrothermal synthesis of mixed metal oxide of Titanium and ...

African Journals Online (AJOL)

Mixed metal oxides of titanium and zinc nanocomposites were prepared through sol-gel method under hydrothermal condition using titanium oxy-(1, 2 - pentadione) and zinc acetate without hazardous additives. The resulting composites were characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscope ...

Mesoporous Transition Metal Oxides for Supercapacitors

Science.gov (United States)

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-01-01

Recently, transition metal oxides, such as ruthenium oxide (RuO2), manganese dioxide (MnO2), nickel oxides (NiO) and cobalt oxide (Co3O4), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO2, MnO2, NiO, Co3O4 and nickel cobaltite (NiCo2O4), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors. PMID:28347088

Mesoporous Transition Metal Oxides for Supercapacitors

Directory of Open Access Journals (Sweden)

Yan Wang

2015-10-01

Full Text Available Recently, transition metal oxides, such as ruthenium oxide (RuO2, manganese dioxide (MnO2, nickel oxides (NiO and cobalt oxide (Co3O4, have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO2, MnO2, NiO, Co3O4 and nickel cobaltite (NiCo2O4, and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Indium tin oxide films prepared by atmospheric plasma annealing and their semiconductor-metal conductivity transition around room temperature

International Nuclear Information System (INIS)

Li Yali; Li Chunyang; He Deyan; Li Junshuai

2009-01-01

We report the synthesis of indium tin oxide (ITO) films using the atmospheric plasma annealing (APA) technique combined with the spin-coating method. The ITO film with a low resistivity of ∼4.6 x 10 -4 Ω cm and a high visible light transmittance, above 85%, was achieved. Hall measurement indicates that compared with the optimized ITO films deposited by magnetron sputtering, the above-mentioned ITO film has a higher carrier concentration of ∼1.21 x 10 21 cm -3 and a lower mobility of ∼11.4 cm 2 V -1 s -1 . More interestingly, these electrical characteristics result in the semiconductor-metal conductivity transition around room temperature for the ITO films prepared by APA.

Microwave-assisted one-pot synthesis of metal/metal oxide nanoparticles on graphene and their electrochemical applications

International Nuclear Information System (INIS)

Wang Shuangyin; Jiang San Ping; Wang Xin

2011-01-01

Graphical abstract: Display Omitted Research highlights: → Microwave polyol method is efficient to deposit nanoparticles on graphene. → SnO 2 /graphene is more efficient than graphene for supercapacitor. → PtRu/graphene is more active than commercial PtRu/C for methanol oxidation. - Abstract: An effective synthesis strategy of hybrid metal (PtRu)/metal oxide (SnO 2 ) nanoparticles on graphene nanocomposites is developed using a microwave-assisted one-pot reaction process. The mixture of ethylene glycol (EG) and water is used as both solvent and reactant. In the reaction system for the synthesis of SnO 2 /graphene nanocomposite, EG not only reduces graphene oxide (GO) to graphene, but also results in the formation of SnO 2 facilitated by the presence of a small amount of water. On the other hand, in the reaction system for preparation of PtRu/graphene nanocomposites, EG acts as solvent and reducing agent for reduction of PtRu nanoparticles from their precursors and reduction of graphene from graphene oxide. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) characterizations confirm the feasibility of the microwave-assisted reaction system to simultaneously reduce graphene oxide and to form SnO 2 or PtRu nanoparticles. The as-synthesized SnO 2 /graphene hybrid composites show a much higher supercapacitance than the pure graphene, and the as-prepared PtRu/graphene show much better electrocatalytic activity for methanol oxidation compared to the commercial E-TEK PtRu/C electrocatalysts.

Plasmon-enhanced Solar Fuel Production with Gold-metal Oxide Hybrid Nanomaterials

DEFF Research Database (Denmark)

Engelbrekt, Christian; Law, Matt; Zhang, Jingdong

, provide new catalytic routes and expands the scope of solar photocatalysis. We prepare metal oxide SNPs, gold PNPs and their hybrids through mild aqueous syntheses to develop efficient photocatalyst for solar fuel production. Focus is placed on the synergetic interplay between SNPs and PNPs, understanding...

Solution combustion synthesis of metal oxide nanomaterials for energy storage and conversion

Science.gov (United States)

Li, Fa-Tang; Ran, Jingrun; Jaroniec, Mietek; Qiao, Shi Zhang

2015-10-01

The design and synthesis of metal oxide nanomaterials is one of the key steps for achieving highly efficient energy conversion and storage on an industrial scale. Solution combustion synthesis (SCS) is a time- and energy-saving method as compared with other routes, especially for the preparation of complex oxides which can be easily adapted for scale-up applications. This review summarizes the synthesis of various metal oxide nanomaterials and their applications for energy conversion and storage, including lithium-ion batteries, supercapacitors, hydrogen and methane production, fuel cells and solar cells. In particular, some novel concepts such as reverse support combustion, self-combustion of ionic liquids, and creation of oxygen vacancies are presented. SCS has some unique advantages such as its capability for in situ doping of oxides and construction of heterojunctions. The well-developed porosity and large specific surface area caused by gas evolution during the combustion process endow the resulting materials with exceptional properties. The relationship between the structural properties of the metal oxides studied and their performance is discussed. Finally, the conclusions and perspectives are briefly presented.

Transition Metal Dopants Essential for Producing Ferromagnetism in Metal Oxide Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Johnson, Lydia; Thurber, Aaron P.; Anghel, Josh; Sabetian, Maryam; Engelhard, Mark H.; Tenne, D.; Hanna, Charles; Punnoose, Alex

2010-08-13

Recent claims that ferromagnetism can be produced in nanoparticles of metal oxides without the presence of transition metal dopants has been refuted in this work by investigating 62 high quality well-characterized nanoparticle samples of both undoped and Fe doped (0-10% Fe) ZnO. The undoped ZnO nanoparticles showed zero or negligible magnetization, without any dependence on the nanoparticle size. However, chemically synthesized Zn₁₋xFexO nanoparticles showed clear ferromagnetism, varying systematically with Fe concentration. Furthermore, the magnetic properties of Zn₁₋xFexO nanoparticles showed strong dependence on the reaction media used to prepare the samples. The zeta potentials of the Zn₁₋xFexO nanoparticles prepared using different reaction media were significantly different, indicating strong differences in the surface structure. Electron paramagnetic resonance studies clearly showed that the difference in the ferromagnetic properties of Zn₁₋xFexO nanoparticles with different surface structures originate from differences in the fraction of the doped Fe³⁺ ions that are coupled ferromagnetically.

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

Science.gov (United States)

Li, L H; Deng, Z X; Xiao, J X; Yang, G W

2015-01-26

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

Directory of Open Access Journals (Sweden)

Jacques C. Védrine

2016-01-01

Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

Methods of producing adsorption media including a metal oxide

Science.gov (United States)

Mann, Nicholas R; Tranter, Troy J

2014-03-04

Methods of producing a metal oxide are disclosed. The method comprises dissolving a metal salt in a reaction solvent to form a metal salt/reaction solvent solution. The metal salt is converted to a metal oxide and a caustic solution is added to the metal oxide/reaction solvent solution to adjust the pH of the metal oxide/reaction solvent solution to less than approximately 7.0. The metal oxide is precipitated and recovered. A method of producing adsorption media including the metal oxide is also disclosed, as is a precursor of an active component including particles of a metal oxide.

Nanoscale Chemical and Valence Evolution at the Metal/Oxide Interface: A Case Study of Ti/SrTiO 3

KAUST Repository

Li, Yangyang

2016-06-27

Metal/oxide interfaces are ubiquitous in a wide range of applications such as electronics, photovoltaics, memories, catalysis, and sensors. However, there have been few investigations dedicated to the nanoscale structural and chemical characteristics of these buried interfaces. In this work, the metal/oxide interface between Ti and SrTiO3 (STO) is examined as a prototypical system using high-resolution scanning transmission electron microscopy and electron energy loss spectroscopy. An atomic-thin Ti2O3-like layer at the Ti/STO interface prepared at room temperature is discovered, and first-principles calculations predict a metallic band structure of this 2D electron system. As a universal feature of such interfaces prepared at different temperatures, near the interface nanoscale oxygen-deficient domains and continuous modulation of Ti oxidation states are found. Overall, these results directly reveal complex chemical and valence evolutions at the metal/oxide interfaces, providing microscopic insights on such heterostructures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

A facile self-assembly approach to prepare palladium/carbon nanotubes catalyst for the electro-oxidation of ethanol

Science.gov (United States)

Wen, Cuilian; Zhang, Xinyuan; Wei, Ying; Zhang, Teng; Chen, Changxin

2018-02-01

A facile self-assembly approach is reported to prepare palladium/carbon nanotubes (Pd/CNTs) catalyst for the electro-oxidation of ethanol. In this method, the Pd-oleate/CNTs was decomposed into the Pd/CNTs at an optimal temperature of 195 °C in air, in which no inert gas is needed for the thermal decomposition process due to the low temperature used and the decomposed products are also environmental friendly. The prepared Pd/CNTs catalyst has a high metallic Pd0 content and the Pd particles in the catalyst are disperse, uniform-sized with an average size of ˜2.1 nm, and evenly distributed on the CNTs. By employing our strategy, the problems including the exfoliation of the metal particles from the CNTs and the aggregation of the metal particles can be solved. Comparing with the commercial Pd/C one, the prepared Pd/CNTs catalyst exhibits a much higher electrochemical activity and stability for the electro-oxidation of ethanol in the direct ethanol fuel cells.

Synthesis of Metal-Oxide/Carbon-Fiber Heterostructures and Their Properties for Organic Dye Removal and High-Temperature CO2 Adsorption

Science.gov (United States)

Shao, Liangzhi; Nie, Shibin; Shao, Xiankun; Zhang, LinLin; Li, Benxia

2018-03-01

One-dimensional metal-oxide/carbon-fiber (MO/CF) heterostructures were prepared by a facile two-step method using the natural cotton as a carbon source the low-cost commercial metal salts as precursors. The metal oxide nanostructures were first grown on the cotton fibers by a solution chemical deposition, and the metal-oxide/cotton heterostructures were then calcined and carbonized in nitrogen atmosphere. Three typical MO/CF heterostructures of TiO2/CF, ZnO/CF, and Fe2O3/CF were prepared and characterized. The loading amount of the metal oxide nanostructures on carbon fibers can be tuned by controlling the concentration of metal salt in the chemical deposition process. Finally, the performance of the as-obtained MO/CF heterostructures for organic dye removal from water was tested by the photocatalytic degradation under a simulated sunlight, and their properties of high-temperature CO2 adsorption were predicted by the temperature programmed desorption. The present study would provide a desirable strategy for the synthesis of MO/CF heterostructures for various applications.

Systematic study of metal-insulator-metal diodes with a native oxide

Science.gov (United States)

Donchev, E.; Gammon, P. M.; Pang, J. S.; Petrov, P. K.; Alford, N. McN.

2014-10-01

In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna). The requirement of having a sub-10nm oxide scale is met by using the native oxide, which forms on most metals exposed to an oxygen containing environment. This, therefore, provides a simplified MIM fabrication process as the complex, controlled oxide deposition step is omitted. We shall present the results of an investigation into the current-voltage characteristics of various MIM combinations that incorporate a native oxide, in order to establish whether the native oxide is of sufficient quality for good diode operation. The thin native oxide layers are formed by room temperature oxidation of the first metal layer, deposited by magnetron sputtering. This is done in-situ, within the deposition chamber before depositing the second metal electrode. Using these structures, we study the established trend where the bigger the difference in metal workfunctions, the better the rectification properties of MIM structures, and hence the selection of the second metal is key to controlling the device's rectifying properties. We show how leakage current paths through the non-optimised native oxide control the net current-voltage response of the MIM devices. Furthermore, we will present the so-called diode figures of merit (asymmetry, non-linearity and responsivity) for each of the best performing structures.

Systematic study of metal-insulator-metal diodes with a native oxide

KAUST Repository

Donchev, E.

2014-10-07

© 2014 SPIE. In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna). The requirement of having a sub-10nm oxide scale is met by using the native oxide, which forms on most metals exposed to an oxygen containing environment. This, therefore, provides a simplified MIM fabrication process as the complex, controlled oxide deposition step is omitted. We shall present the results of an investigation into the current-voltage characteristics of various MIM combinations that incorporate a native oxide, in order to establish whether the native oxide is of sufficient quality for good diode operation. The thin native oxide layers are formed by room temperature oxidation of the first metal layer, deposited by magnetron sputtering. This is done in-situ, within the deposition chamber before depositing the second metal electrode. Using these structures, we study the established trend where the bigger the difference in metal workfunctions, the better the rectification properties of MIM structures, and hence the selection of the second metal is key to controlling the device\\'s rectifying properties. We show how leakage current paths through the non-optimised native oxide control the net current-voltage response of the MIM devices. Furthermore, we will present the so-called diode figures of merit (asymmetry, non-linearity and responsivity) for each of the best performing structures.

Metal oxide multilayer hard mask system for 3D nanofabrication

Science.gov (United States)

Han, Zhongmei; Salmi, Emma; Vehkamäki, Marko; Leskelä, Markku; Ritala, Mikko

2018-02-01

We demonstrate the preparation and exploitation of multilayer metal oxide hard masks for lithography and 3D nanofabrication. Atomic layer deposition (ALD) and focused ion beam (FIB) technologies are applied for mask deposition and mask patterning, respectively. A combination of ALD and FIB was used and a patterning procedure was developed to avoid the ion beam defects commonly met when using FIB alone for microfabrication. ALD grown Al2O3/Ta2O5/Al2O3 thin film stacks were FIB milled with 30 keV gallium ions and chemically etched in 5% tetramethylammonium hydroxide at 50 °C. With metal evaporation, multilayers consisting of amorphous oxides Al2O3 and Ta2O5 can be tailored for use in 2D lift-off processing, in preparation of embedded sub-100 nm metal lines and for multilevel electrical contacts. Good pattern transfer was achieved by lift-off process from the 2D hard mask for micro- and nano-scaled fabrication. As a demonstration of the applicability of this method to 3D structures, self-supporting 3D Ta2O5 masks were made from a film stack on gold particles. Finally, thin film resistors were fabricated by utilizing controlled stiction of suspended Ta2O5 structures.

Metal-core@metal oxide-shell nanomaterials for gas-sensing applications: a review

Energy Technology Data Exchange (ETDEWEB)

Mirzaei, A.; Janghorban, K.; Hashemi, B. [Shiraz University, Department of Materials Science and Engineering (Iran, Islamic Republic of); Neri, G., E-mail: gneri@unime.it [University of Messina, Department of Electronic Engineering, Chemistry and Industrial Engineering (Italy)

2015-09-15

With an ever-increasing number of applications in many advanced fields, gas sensors are becoming indispensable devices in our daily life. Among different types of gas sensors, conductometric metal oxide semiconductor (MOS) gas sensors are found to be the most appealing for advanced applications in the automotive, biomedical, environmental, and safety sectors because of the their high sensitivity, reduced size, and low cost. To improve their sensing characteristics, new metal oxide-based nanostructures have thus been proposed in recent years as sensing materials. In this review, we extensively review gas-sensing properties of core@ shell nanocomposites in which metals as the core and metal oxides as the shell structure, both of nanometer sizes, are assembled into a single metal@metal oxide core–shell. These nanostructures not only combine the properties of both noble metals and metal oxides, but also bring unique synergetic functions in comparison with single-component materials. Up-dated achievements in the synthesis and characterization of metal@metal oxide core–shell nanostructures as well as their use in MOS sensors are here reported with the main objective of providing an overview about their gas-sensing properties.

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.

Template-directed formation of functional complex metal-oxide nanostructures by combination of sol-gel processing and spin coating

International Nuclear Information System (INIS)

Choi, Y.C.; Kim, J.; Bu, S.D.

2006-01-01

We report the template-based formation of functional complex metal-oxide nanostructures by a combination of sol-gel processing and spin coating. This method employs the spin-coating of a sol-gel solution into an anodic aluminum oxide membrane (SSAM). Various metal-oxide nanowires and nanotubes with a high aspect-ratio were prepared. The aspect-ratios of the PbO 2 nanowires and Pb(Zr 0.52 Ti 0.48 )O 3 nanowires were about 300 and 400, respectively, and their diameters were about 50 nm. The fabricated PbTiO 3 nanotubes have a relatively constant wall thickness of about 20 nm with an outer diameter of about 60 nm. The deposition time for all of the fabricated metal-oxide nanowires and nanotubes is less than 120 s, which is far shorter than those required in both the sol-gel dipping and sol-gel electrophoretic methods. These results indicate that the SSAM method can be a versatile pathway to prepare functional complex metal-oxide nanowires and nanotubes with a high aspect-ratio. The possible formation process for the one-dimensional nanostructures by SSAM is discussed

Electron microscopy and EXAFS studies on oxide-supported gold-silver nanoparticles prepared by flame spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Hannemann, Stefan [Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland); Grunwaldt, Jan-Dierk [Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland)]. E-mail: grunwaldt@chem.ethz.ch; Krumeich, Frank [Laboratory of Inorganic Chemistry, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland); Kappen, Peter [Department of Physics, La Trobe University, Victoria 3086 (Australia); Baiker, Alfons [Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland)

2006-09-15

Gold and gold-silver nanoparticles prepared by flame spray pyrolysis (FSP) were characterized by electron microscopy, in situ X-ray absorption spectroscopy (XANES and EXAFS), X-ray diffraction (XRD) and their catalytic activity in CO oxidation. Within this one-step flame-synthesis procedure, precursor solutions of dimethyl gold(III) acetylacetonate and silver(I) benzoate together with the corresponding precursor of the silica, iron oxide or titania support, were sprayed and combusted. In order to prepare small metal particles, a low noble metal loading was required. A loading of 0.1-1 wt.% of Au and Ag resulted in 1-6 nm particles. The size of the noble metal particles increased with higher loadings of gold and particularly silver. Both scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDXS) and X-ray absorption spectroscopy (XAS) studies proved the formation of mixed Au-Ag particles. In case of 1% Au-1% Ag/SiO{sub 2}, TEM combined with electron spectroscopic imaging (ESI) using an imaging filter could be used in addition to prove the presence of silver and gold in the same noble metal particle. CO oxidation in the presence of hydrogen was chosen as a test reaction sensitive to small gold particles. Both the influence of the particle size and the alloying of gold and silver were reflected in the CO oxidation activity.

Electron microscopy and EXAFS studies on oxide-supported gold-silver nanoparticles prepared by flame spray pyrolysis

International Nuclear Information System (INIS)

Hannemann, Stefan; Grunwaldt, Jan-Dierk; Krumeich, Frank; Kappen, Peter; Baiker, Alfons

2006-01-01

Gold and gold-silver nanoparticles prepared by flame spray pyrolysis (FSP) were characterized by electron microscopy, in situ X-ray absorption spectroscopy (XANES and EXAFS), X-ray diffraction (XRD) and their catalytic activity in CO oxidation. Within this one-step flame-synthesis procedure, precursor solutions of dimethyl gold(III) acetylacetonate and silver(I) benzoate together with the corresponding precursor of the silica, iron oxide or titania support, were sprayed and combusted. In order to prepare small metal particles, a low noble metal loading was required. A loading of 0.1-1 wt.% of Au and Ag resulted in 1-6 nm particles. The size of the noble metal particles increased with higher loadings of gold and particularly silver. Both scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDXS) and X-ray absorption spectroscopy (XAS) studies proved the formation of mixed Au-Ag particles. In case of 1% Au-1% Ag/SiO 2 , TEM combined with electron spectroscopic imaging (ESI) using an imaging filter could be used in addition to prove the presence of silver and gold in the same noble metal particle. CO oxidation in the presence of hydrogen was chosen as a test reaction sensitive to small gold particles. Both the influence of the particle size and the alloying of gold and silver were reflected in the CO oxidation activity

Conducting metal oxide and metal nitride nanoparticles

Science.gov (United States)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

2017-12-26

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst support in a fuel cell.

Process for electrolytically preparing uranium metal

Science.gov (United States)

Haas, Paul A.

1989-01-01

A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

Analysis of the stability of native oxide films at liquid lead/metal interfaces

International Nuclear Information System (INIS)

Lesueur, C.; Chatain, D.; Gas, P.; Bergman, C.; Baque, F.

2002-01-01

The interface between liquid lead and different metallic solids (pure metals: Al, Fe and Ni, and T91 steel) was investigated below 400 deg C under ultrahigh vacuum (UHV) by wetting experiments. The aim was to check the physical stability of native oxide films grown at the surface of the substrates, along a contact with liquid lead. Two types of metallic substrates were used: i) conventional bulk polycrystals, and ii) nanocrystalline films obtained by e-beam evaporation under UHV. The actual contact between liquid lead and the solid substrates was achieved by preparing lead drops in-situ. Wetting experiments were performed using sessile drop and/or liquid bridge methods. Fresh solid surfaces and former liquid/solid interfaces can be explored by squeezing and stretching a liquid lead bridge formed between two parallel and horizontal substrates. It is shown that the contact with liquid lead produces the detachment of the native oxide films grown on the metallic solids. It is concluded that if oxide coatings are needed to protect a metallic solid from attack by liquid lead, they should be self-renewable. (authors)

Reduced graphene oxide-wrapped MoO3 composites prepared by using metal-organic frameworks as precursor for all-solid-state flexible supercapacitors.

Science.gov (United States)

Cao, Xiehong; Zheng, Bing; Shi, Wenhui; Yang, Jian; Fan, Zhanxi; Luo, Zhimin; Rui, Xianhong; Chen, Bo; Yan, Qingyu; Zhang, Hua

2015-08-26

Reduced graphene oxide-wrapped MoO3M (rGO/MoO3 ) is prepared by a novel and simple method that is developed by using a metal-organic framework as the precursor. After a two-step annealing process, the obtained rGO/MoO3 composite is used for a high-performance supercapacitor electrode. Moreover, an all-solid-state flexible supercapacitor is fabricated based on the rGO/MoO3 composite, which shows stable performance under different bending states. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Processing and properties of silver-metal oxide electrical contact materials

Directory of Open Access Journals (Sweden)

Nadežda M. Talijan

2012-12-01

Full Text Available The presented study gives a brief overview of the experimental results of investigations of different production technologies of silver-metal oxide electrical contact materials in relation: processing method - properties. The two most common routes of production, i.e. internal oxidation/ingot metallurgy and powder metallurgy are demonstrated on the example of Ag-CdO and Ag-ZnO materials. For illustration of alternative processing routes that provide higher dispersion of metal-oxide particles in silver matrix more environmentally friendly Ag-SnO2 contact materials are used. Processing of electrical contact materials by mechanical mixing of starting powders in high energy ball mill is presented. The obtained experimental results of application of different methods of introduction of SnO2 nanoparticles in the silver matrix such as conventional powder metallurgy mixing and template method are given and discussed in terms of their influence on microstructure and physical properties (density, hardness and electrical conductivity of the prepared Ag-SnO2 electrical contact materials.

Alternative Processes for Manufacturing of Metal Oxide-based Potentiometric Chemosensors

Directory of Open Access Journals (Sweden)

Winfried VONAU

2015-10-01

Full Text Available New possibilities for the preparation of partially selective redox electrodes based on passivated metals of the subgroups IV to VI of the periodic system are presented by the example of vanadium. The gas phase oxidation at controlled oxygen partial pressures (CPO and the pulsed laser deposition (PLD as an high-vacuum method are utilised as alternative methods beside the well- established chemical and electrochemical passivation which usually lead to the highest possible oxidation state of the passivated metal. These newly available methods enable in principle the tailoring of oxidation states in the sensitive layer and therefore the optimisation of the electrochemical sensitivity and selectivity of sensors equipped with it. The use of vanadium as basic electrode material is crucial because it shows in several matrices a remarkable corrosion susceptibility. This problem can be solved by the introduction of stable alloys with high vanadium contents. These materials can be efficiently produced by pulsed laser deposition (PLD.

Plutonium-241 processing: from impure oxide to high purity metal target disks

International Nuclear Information System (INIS)

Conner, W.V.; Baaso, D.L.

1975-01-01

The preparation of three plutonium-241 metal target disks, using a precision casting technique, is described. The disks were 0.625 inch in diameter and 0.125, 0.025, and 0.010 inch thick. All three disks were prepared simultaneously in a single casting. The variation in thickness of each disk was within +-1 percent of the disk's average thickness. The plutonium-241 was highly pure, and the finished disks contained a total of only 297 parts per million of detectable impurities. Purification of the plutonium oxide ( 241 PuO 2 ) and the conversion of the purified 241 PuO 2 to metal are also described. (U.S.)

Oxidation-Mediated Fingering in Liquid Metals

Science.gov (United States)

Eaker, Collin B.; Hight, David C.; O'Regan, John D.; Dickey, Michael D.; Daniels, Karen E.

2017-10-01

We identify and characterize a new class of fingering instabilities in liquid metals; these instabilities are unexpected due to the large interfacial tension of metals. Electrochemical oxidation lowers the effective interfacial tension of a gallium-based liquid metal alloy to values approaching zero, thereby inducing drastic shape changes, including the formation of fractals. The measured fractal dimension (D =1.3 ±0.05 ) places the instability in a different universality class than other fingering instabilities. By characterizing changes in morphology and dynamics as a function of droplet volume and applied electric potential, we identify the three main forces involved in this process: interfacial tension, gravity, and oxidative stress. Importantly, we find that electrochemical oxidation can generate compressive interfacial forces that oppose the tensile forces at a liquid interface. The surface oxide layer ultimately provides a physical and electrochemical barrier that halts the instabilities at larger positive potentials. Controlling the competition between interfacial tension and oxidative (compressive) stresses at the interface is important for the development of reconfigurable electronic, electromagnetic, and optical devices that take advantage of the metallic properties of liquid metals.

Preparation of glasses and glass ceramics of heavy metal oxides containing silver: optical, structural and electrochemical properties; Preparacao de vidros e vitroceramicas de oxidos de metais pesados contendo prata: propriedades opticas, estruturais e eletroquimicas

Energy Technology Data Exchange (ETDEWEB)

Bregadiolli, Bruna A. [Departamento de Fisica, Faculdade de Ciencias, Universidade Estadual Paulista, Bauru - SP (Brazil); Souza, Ernesto R.; Sigoli, Fernando A. [Instituto de Quimica, Universidade Estadual de Campinas, Campinas - SP (Brazil); Caiut, Jose M.A. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto - SP (Brazil); Alencar, Monica A.S.; Benedetti, Assis V. [Instituto de Quimica, Universidade Estadual Paulista, Araraquara - SP (Brazil); Nalin, Marcelo, E-mail: mnalin@ufscar.br [Departamento de Quimica, Universidade Federal de Sao Carlos, SP, (Brazil)

2012-07-01

Silver containing heavy metal oxide glasses and glass ceramics of the system WO{sub 3}-SbPO{sub 4} -PbO-AgCl with different AgCl contents have been prepared and their thermal, structural and optical properties characterized. Glass ceramics containing metallic silver nanoparticles have been prepared by annealing glass samples at temperatures above the glass transition and analyzed by transmission electron microscopy and energy dispersive X-ray microanalysis. The presence of the metallic clusters has been also confirmed by the observation of a surface plasmon resonance band in the visible range. Cyclic voltammetric measurements indicated the presence of metallic silver into the glasses, even before to perform the thermal treatment. (author)

Polydopamine-mediated surface-functionalization of graphene oxide for heavy metal ions removal

International Nuclear Information System (INIS)

Dong, Zhihui; Zhang, Feng; Wang, Dong; Liu, Xia; Jin, Jian

2015-01-01

By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly via a Michael-Addition reaction and produced a PEI–PD/GO composite nanosheets. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu 2+ , Cd 2+ , Pb 2+ , Hg 2+ are up to 87, 106, 197, and 110 mg/g, respectively. To further make the GO based composite operable, PEI–PD/RGO aerogel was prepared through hydrothermal and achieved a high surface area up to 373 m 2 /g. Although the adsorption capacity of PEI–PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI–PD/GO composite dispersion (38, 32, 95, 113 mg/g corresponding to Cu 2+ , Cd 2+ , Pb 2+ , and Hg 2+ , respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater. - Graphical abstract: Polyethylenimine (PEI) brushes were grafted onto the surface of graphene oxide (GO) uniformly via a Michael-Addition reaction between the PEI and polydopamine interlayer coated on GO surface. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions compared to PEI-coated GO and pure GO. - Highlights: • We prepared polyethylenimine grafted polydopamine-mediated graphene oxide composites. • Introduction of PD layer increases metal ions adsorption capacity. • PEI–PD/RGO aerogel exhibited a superior adsorption performance. • PEI–PD/RGO aerogel can be recycled several times in a simple way

Preparation and Characterization of Some Nanometal Oxides Using Microwave Technique and Their Application to Cotton Fabrics

Directory of Open Access Journals (Sweden)

M. Gouda

2015-01-01

Full Text Available The objective of this paper is the synthesis of some nanometal oxides via microwave irradiation technique and their application to augment multifunctional properties of cotton fabric. Cotton fabrics containing nanometal oxides were prepared via a thiol-modification of cotton fabric samples and then dipped into the metal salt solutions precursors and transferred to the microwave oven. The surface morphology and quantitative analysis of the obtained modified cotton fabrics containing nanometal oxides were studied by scanning electron microscopy coupled with high energy dispersive X-ray (SEM-EDX. The shape and distribution of nanometal oxide inside the fabric samples were analyzed by transmission electron microscopy of cross-section fabric samples. The iron oxide nanoparticles had a nanosphere with particle size diameter 15–20 nm, copper oxide nanoparticles had a nanosphere with particle size diameter 25–30 nm, and cobalt oxide nanoparticles had a nanotube-like shape with a length of 100–150 nanometer and a diameter of ~58 nanometer, whereas the manganese oxide nanoparticles had a linear structure forming nanorods with a diameter of 50–55 nanometer and a length of 70–80 nanometers. Antibacterial activity was evaluated quantitatively against gram-positive bacteria such as Staphylococcus aureus and gram-negative bacteria such as Escherichia coli, UV-protection activity was analyzed using UV-DRS spectroscopy, and flame retardation of prepared fabric samples was evaluated according to the limiting oxygen index (LOI. Results revealed that the prepared fabric sample containing nanometal oxide possesses improved antibacterial, LOI, and UV-absorbing efficiency. Moreover, the metal oxide nanoparticles did not leach out the fabrics by washing even after 30 laundering washing cycles.

Preparation of 147Pm metal and the determination of the melting point and phase transformation temperatures

International Nuclear Information System (INIS)

Angelini, P.; Adair, H.L.

1976-07-01

The promethium metal used in the determination of the melting point and phase transformation temperatures was prepared by reduction of promethium oxide with thorium metal at 1600 0 C and distilling the promethium metal into a quartz dome. The melting point and phase transformation temperatures of promethium metal were found to be 1042 +- 5 0 C and 890 +- 5 0 C, respectively. The ratio for the heat of the high-temperature transformation to the heat of fusion was determined to be 0.415

A new way for preparing superconducting materials: the electrochemical oxidation of La2CuO4

International Nuclear Information System (INIS)

Wattiaux, A.; Park, J.C.; Grenier, J.C.; Pouchard, M.

1990-01-01

The electrochemical oxidation in alkaline medium is described as a new way for preparing superconducting oxides at room temperature. The application of this method to La 2 CuO 4 gave rise to a metallic material with a superconducting behaviour below 39 K and whose physical and chemical features appear as quite promising [fr

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.

A Comparative Study of Mn/Co Binary Metal Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of Benzene

Directory of Open Access Journals (Sweden)

Marco Tomatis

2018-03-01

Full Text Available Two commercial diatomaceous earths were used as supports for the preparation of Mn/Co binary metal catalysts at different metal loads (5 to 10 wt % Mn and 5 to 15 wt % Co by incipient wetness deposition. The activity of the prepared catalysts towards the complete oxidation of benzene to CO2 and water was investigated between 100 and 400 °C. Raw supports and synthesized catalysts were characterized by XRD, N2 physisorption, SEM-EDS, H2-TPR, and TPD. The purification treatment of food-grade diatomite significantly affected the crystallinity of this support while reducing its specific surface area (SSA. A loss of SSA, associated with the increase in the metal load, was observed on samples prepared on natural diatomite, while the opposite trend occurred with food-grade diatomite-supported catalysts. Metal nanoparticles of around 50 nm diameter were observed on the catalysts’ surface by SEM analysis. EDS analysis confirmed the uniform deposition of the active phases on the support’s surface. A larger H2 consumption was found by TPR analysis of natural diatomite-based samples in comparison to those prepared at the same metal load on food-grade diatomite. During the catalytic oxidation experiment, over 90% conversion of benzene were achieved at a reaction temperature of 225 °C by all of the prepared samples. In addition, the formation of coke during the oxidation tests was demonstrated by TGA analysis and the soluble fraction of the produced coke was characterized by GC-MS.

The competing oxide and sub-oxide formation in metal-oxide molecular beam epitaxy

International Nuclear Information System (INIS)

Vogt, Patrick; Bierwagen, Oliver

2015-01-01

The hetero-epitaxial growth of the n-type semiconducting oxides β-Ga 2 O 3 , In 2 O 3 , and SnO 2 on c- and r-plane sapphire was performed by plasma-assisted molecular beam epitaxy. The growth-rate and desorbing flux from the substrate were measured in-situ under various oxygen to metal ratios by laser reflectometry and quadrupole mass spectrometry, respectively. These measurements clarified the role of volatile sub-oxide formation (Ga 2 O, In 2 O, and SnO) during growth, the sub-oxide stoichiometry, and the efficiency of oxide formation for the three oxides. As a result, the formation of the sub-oxides decreased the growth-rate under metal-rich growth conditions and resulted in etching of the oxide film by supplying only metal flux. The flux ratio for the exclusive formation of the sub-oxide (e.g., the p-type semiconductor SnO) was determined, and the efficiency of oxide formation was found to be the highest for SnO 2 , somewhat lower for In 2 O 3 , and the lowest for Ga 2 O 3 . Our findings can be generalized to further oxides that possess related sub-oxides

Control of lipid oxidation by nonmigratory active packaging films prepared by photoinitiated graft polymerization.

Science.gov (United States)

Tian, Fang; Decker, Eric A; Goddard, Julie M

2012-08-08

Transition metal-promoted oxidation impacts the quality, shelf life, and nutrition of many packaged foods. Metal-chelating active packaging therefore offers a means to protect foods against oxidation. Herein, we report the development and characterization of nonmigratory metal-chelating active packaging. To prepare the films, carboxylic acids were grafted onto the surfaces of polypropylene films by photoinitiated graft polymerization of acrylic acid. Attenuated total reflectance/Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, and iron-chelating assay were used to characterize film properties. Graft polymerization yielded a carboxylic acid density of 68.67 ± 9.99 nmol per cm(2) film, with ferrous iron-chelating activity of 71.07 ± 12.95 nmol per cm(2). The functionalized films extended the lag phase of lipid oxidation in a soybean oil-in-water emulsion system from 2 to 9 days. The application of such nonmigratory active packaging films represents a promising approach to reduce additive use while maintaining food quality.

Reductive mineralization of cellulose with vanadium, iron and tungsten chlorides and access to MxOy metal oxides and MxOy/C metal oxide/carbon composites.

Science.gov (United States)

Henry, Aurélien; Hesemann, Peter; Alauzun, Johan G; Boury, Bruno

2017-10-15

M x O y and M x O y /C composites (M=V, Fe and W) were obtained by mineralization of cellulose with several metal chlorides. Cellulose was used both as a templating agent and as an oxygen and a carbon source. Soluble chloride molecules (VOCl 3 and WCl 6 ) and a poorly soluble ionic chloride compound (FeCl 3 ) were chosen as metal oxide precursors. In a first time, primary metal oxide/cellulose composites were obtained via a thermal treatment by reacting urea impregnated filter paper with the corresponding metal chlorides in an autoclave at 150°C after 3days. After either pyrolysis or calcination steps of these intermediate materials, interesting metal oxides with various morphologies were obtained (V 2 O 5, V 2 O 3 , Fe 3 O 4 , WO 3, H 0.23 WO 3 ), composites (V 2 O 3 /C) as well as carbides (hexagonal W 2 C and WC, Fe 3 C) This result highlight the reductive role that can play cellulose during the pyrolysis step that allows to tune the composition of M x O y /C composites. The materials were characterized by FTIR, Raman, TGA, XRD and SEM. This study highlights that cellulose can be used for a convenient preparation of a variety of highly demanded M x O y and M x O y /C composites with original shapes and morphologies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bismuth silicate glass containing heavy metal oxide as a promising radiation shielding material

Science.gov (United States)

Elalaily, Nagia A.; Abou-Hussien, Eman M.; Saad, Ebtisam A.

2016-12-01

Optical and FTIR spectroscopic measurements and electron paramagnetic resonance (EPR) properties have been utilized to investigate and characterize the given compositions of binary bismuth silicate glasses. In this work, it is aimed to study the possibility of using the prepared bismuth silicate glasses as a good shielding material for γ-rays in which adding bismuth oxide to silicate glasses causes distinguish increase in its density by an order of magnitude ranging from one to two more than mono divalent oxides. The good thermal stability and high density of the bismuth-based silicate glass encourage many studies to be undertaken to understand its radiation shielding efficiency. For this purpose a glass containing 20% bismuth oxide and 80% SiO2 was prepared using the melting-annealing technique. In addition the effects of adding some alkali heavy metal oxides to this glass, such as PbO, BaO or SrO, were also studied. EPR measurements show that the prepared glasses have good stability when exposed to γ-irradiation. The changes in the FTIR spectra due to the presence of metal oxides were referred to the different housing positions and physical properties of the respective divalent Sr2+, Ba2+ and Pb2+ ions. Calculations of optical band gap energies were presented for some selected glasses from the UV data to support the probability of using these glasses as a gamma radiation shielding material. The results showed stability of both optical and magnetic spectra of the studied glasses toward gamma irradiation, which validates their irradiation shielding behavior and suitability as the radiation shielding candidate materials.

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

International Nuclear Information System (INIS)

Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

2017-01-01

Graphical abstract: Mn nanoparticles are highly dispersed on ZSM-5 and most efficient in benzene degradation in the VUV-OZCO process. - Highlights: • Vacuum UV irradiation is well combined with O_3 catalytic oxidation. • O_3 byproducts was used to enhance catalytic oxidation of VOCs. • Mn/ZSM-5 achieved the best catalytic activity for benzene degradation. - Abstract: Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O_3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O_3 catalytic decomposition and utilization. Benzene and O_3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O_3 was catalytically decomposed, generating highly reactive oxidants such as ·OH and ·O for benzene oxidation.

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

Energy Technology Data Exchange (ETDEWEB)

Huang, Haibao, E-mail: seabao8@gmail.com [School of Environmental Science and Engineering, Sun Yat-Sen University (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University) (China); Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo [School of Environmental Science and Engineering, Sun Yat-Sen University (China)

2017-01-01

Graphical abstract: Mn nanoparticles are highly dispersed on ZSM-5 and most efficient in benzene degradation in the VUV-OZCO process. - Highlights: • Vacuum UV irradiation is well combined with O{sub 3} catalytic oxidation. • O{sub 3} byproducts was used to enhance catalytic oxidation of VOCs. • Mn/ZSM-5 achieved the best catalytic activity for benzene degradation. - Abstract: Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O{sub 3}, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O{sub 3} catalytic decomposition and utilization. Benzene and O{sub 3} removal efficiency reached as high as 97% and 100% after 360 min, respectively. O{sub 3} was catalytically decomposed, generating highly reactive oxidants such as ·OH and ·O for benzene oxidation.

Preparation and characteristics of CNT-metal composites

CSIR Research Space (South Africa)

Pityana, SL

2006-01-01

Full Text Available The success in keeping carbon nanotubes (CNT) bonded to stainless steel provides a possible method for the preparation of CNT-metal composites. Alternative methods for the preparation of CNT-metal composites include hot pressing, sintering, etc...

Unified computational model of transport in metal-insulating oxide-metal systems

Science.gov (United States)

Tierney, B. D.; Hjalmarson, H. P.; Jacobs-Gedrim, R. B.; Agarwal, Sapan; James, C. D.; Marinella, M. J.

2018-04-01

A unified physics-based model of electron transport in metal-insulator-metal (MIM) systems is presented. In this model, transport through metal-oxide interfaces occurs by electron tunneling between the metal electrodes and oxide defect states. Transport in the oxide bulk is dominated by hopping, modeled as a series of tunneling events that alter the electron occupancy of defect states. Electron transport in the oxide conduction band is treated by the drift-diffusion formalism and defect chemistry reactions link all the various transport mechanisms. It is shown that the current-limiting effect of the interface band offsets is a function of the defect vacancy concentration. These results provide insight into the underlying physical mechanisms of leakage currents in oxide-based capacitors and steady-state electron transport in resistive random access memory (ReRAM) MIM devices. Finally, an explanation of ReRAM bipolar switching behavior based on these results is proposed.

Technology of Processing of Fluorol with Metallic Oxides and It's Resistance toward Active Fluid

International Nuclear Information System (INIS)

Mahmoud, G.M.; Hadhoud, M.K.; Mohamed, A.Z.; Sherif, S.A

2004-01-01

Fluorocarbon polymers are the best elastomers for a variety of applications. In this work we investigate the characteristics of fluorocarbon rubber for use in different applications, via preparation different formulations. We investigate the effect of added metallic oxides ( CaO, MgO, ZnO and PbO ) on the chemical and physical properties of prepared formulations. Chemical resistance tests were made for conc. H 2 SO 4 , conc. HCl, conc. HNO 3 , ASTM Oil No.2, ASTM Ref. Fuel C and conc. NaOH solution. Results showed that the prepared fluorocarbon rubber have high chemical resistance to various acids, alkalis, oils and fuels, also chemical resistance towards conc. HNO 3 is enhanced in the presence of lead oxide

Oxidation of ethanol on NaX zeolite modified with transition metals

Science.gov (United States)

Mirzai, J. I.; Nadirov, P. A.; Velieva, A. D.; Muradkhanli, V. G.

2017-06-01

NaLaX, NaX + Co, and NaPdX catalysts are synthesized by modification of NaX zeolite with transition metals (La, Co, Pd). The activity of the prepared materials in catalytic ethanol oxidation is studied in the temperature range of 423-723 K. It is shown that NaPdX and NaX + Co accelerate the reactions of partial and complete oxidation of ethanol as the temperature rises. NaLaX accelerates both intramolecular and intermolecular dehydration of alcohol. It is shown that the NaPdX (1.0% Pd) sample has the highest activity in the complete oxidation of alcohol with the formation of CO2.

Sol-gel prepared active ternary oxide coating on titanium in cathodic protection

Directory of Open Access Journals (Sweden)

VLADIMIR V. PANIC

2007-12-01

Full Text Available The characteristics of a ternary oxide coating, on titanium, which consisted of TiO2, RuO2 and IrO2 in the molar ratio 0.6:0.3:0.1, calculated on the metal atom, were investigated for potential application for cathodic protection in a seawater environment. The oxide coatings on titanium were prepared by the sol gel procedure from a mixture of inorganic oxide sols, which were obtained by forced hydrolysis of metal chlorides. The morphology of the coating was examined by scanning electron microscopy. The electrochemical properties of activated titanium anodes were investigated by cyclic voltammetry and polarization measurements in a H2SO4- and NaCl-containing electrolyte, as well as in seawater sampled on the Adriatic coast in Tivat, Montenegro. The anode stability during operation in seawater was investigated by the galvanostatic accelerated corrosion stability test. The morphology and electrochemical characteristics of the ternary coating are compared to that of a sol-gel-prepared binary Ti0.6Ru0.4O2 coating. The activity of the ternary coating was similar to that of the binary Ti0.6Ru0.4O2 coating in the investigated solutions. However, the corrosion stability in seawater is found to be considerably greater for the ternary coating.

Ni-M-O (M=Sn, Ti and W) catalysts prepared from dry mixing method for oxidative dehydrogenation of ethane

KAUST Repository

Zhu, Haibo; Rosenfeld, Devon C.; Harb, Moussab; Anjum, Dalaver H.; Hedhili, Mohamed N.; Ould-Chikh, Samy; Basset, Jean-Marie

2016-01-01

A new generation of Ni-Sn-O, Ni-Ti-O, and Ni-W-O catalysts has been prepared by a solid state grinding method. In each case the doping metal varied from 2.5% to 20%. These catalysts exhibited higher activity and selectivity for ethane oxidative dehydrogenation (ODH) than conventionally prepared mixed oxides. Detailed characterisation was achieved using XRD, N2 adsorption, H2-TPR, SEM, TEM, and HAADF-STEM in order to study the detailed atomic structure and textural properties of the synthesized catalysts. Two kinds of typical structures are found in these mixed oxides, which are (major) “NixMyO” (M = Sn, Ti or W) solid solution phases (NiO crystalline structure with doping atom incorporated in the lattice) and (minor) secondary phases (SnO2, TiO2 or WO3). The secondary phase exists as a thin layer around small “NixMyO” particles, lowering the aggregation of nanoparticles during the synthesis. DFT calculations on the formation energies of M-doped NiO structures (M = Sn, Ti, W) clearly confirm the thermodynamic feasibility of incorporating these doping metals into NiO struture. The incorporation of doping metals into the NiO lattice decreases the number of holes (h+) localized on lattice oxygen (O2- + h+ ➔ O●-), which is the main reason for the improved catalytic performance (O●- is known to favor complete ethane oxidation to CO2). The high efficiency of ethylene production achieved in these particularly prepared mixed oxide catalysts indicates that the solid grinding method could serve as a general and practical approach for the preparation of doped NiO based catalysts.

Ni-M-O (M=Sn, Ti and W) catalysts prepared from dry mixing method for oxidative dehydrogenation of ethane

KAUST Repository

Zhu, Haibo

2016-03-25

A new generation of Ni-Sn-O, Ni-Ti-O, and Ni-W-O catalysts has been prepared by a solid state grinding method. In each case the doping metal varied from 2.5% to 20%. These catalysts exhibited higher activity and selectivity for ethane oxidative dehydrogenation (ODH) than conventionally prepared mixed oxides. Detailed characterisation was achieved using XRD, N2 adsorption, H2-TPR, SEM, TEM, and HAADF-STEM in order to study the detailed atomic structure and textural properties of the synthesized catalysts. Two kinds of typical structures are found in these mixed oxides, which are (major) “NixMyO” (M = Sn, Ti or W) solid solution phases (NiO crystalline structure with doping atom incorporated in the lattice) and (minor) secondary phases (SnO2, TiO2 or WO3). The secondary phase exists as a thin layer around small “NixMyO” particles, lowering the aggregation of nanoparticles during the synthesis. DFT calculations on the formation energies of M-doped NiO structures (M = Sn, Ti, W) clearly confirm the thermodynamic feasibility of incorporating these doping metals into NiO struture. The incorporation of doping metals into the NiO lattice decreases the number of holes (h+) localized on lattice oxygen (O2- + h+ ➔ O●-), which is the main reason for the improved catalytic performance (O●- is known to favor complete ethane oxidation to CO2). The high efficiency of ethylene production achieved in these particularly prepared mixed oxide catalysts indicates that the solid grinding method could serve as a general and practical approach for the preparation of doped NiO based catalysts.

Environmentally friendly preparation of metal nanoparticles

Science.gov (United States)

The book chapter summarizes the “state of the art” in the exploitation of various environmentally-friendly synthesis approaches, reaction precursors and conditions to manufacture metal and metal oxide nanoparticles for a vast variety of purposes.

Improved description of metal oxide stability

DEFF Research Database (Denmark)

Jauho, Thomas Stenbæk; Olsen, Thomas; Bligaard, Thomas

2015-01-01

The renormalized adiabatic PBE (rAPBE) method has recently been shown to comprise a significant improvement over the random phase approximation (RPA) for total energy calculations of simple solids and molecules. Here we consider the formation energies of 19 group I and II metal oxides and a few...... transition-metal oxides. The mean absolute error relative to experiments is 0.21 eV and 0.38 eV per oxygen atom for rAPBE and RPA, respectively, and thus the rAPBE method greatly improves the description of metal-oxygen bonds across a wide range of oxides. The failure of the RPA can be partly attributed...... to the lack of error cancellation between the correlation energy of the oxide on the one hand and the bulk metal and oxygen molecule on the other hand, which are all separately predicted much too negative by the RPA. We ascribe the improved performance of the rAPBE to its significantly better description...

Metal adsorption of gamma-irradiated carboxymethyl cellulose/polyethylene oxide blend films

Science.gov (United States)

El-Naggar, Amal A.; Magida, M. M.; Ibrahim, Sayeda M.

2016-03-01

Blend films of different ratios of carboxymethyl cellulose (CMC)/polyethylene oxide (PEO) were prepared by the solution casting method. To investigate the effect of irradiation on all properties of prepared blend, it was exposed to different gamma irradiation doses (10, 20, and 30 kGy). Physical properties such as gel fraction (GF) (%) and swelling (SW) (%) were investigated. It was found that the GF (%) increases with increasing irradiation dose up to 20 kGy, while SW (%) decreases with an increase in the irradiation doses for all blend compositions. Moreover, the structural and mechanical properties of the prepared films were studied. The results of the mechanical properties obtained showed that there is an improvement in these properties with an increase in both CMC and irradiation dose up to 20 kGy. The efficiency of metal ions uptake was measured using a UV spectrophotometer. The prepared films showed good tendency to absorb and release metal ions from aqueous media. Thus, the CMC/PEO film can be used in agricultural domain.

A Novel Synthesis of Gold Nanoparticles Supported on Hybrid Polymer/Metal Oxide as Catalysts for p-Chloronitrobenzene Hydrogenation

Directory of Open Access Journals (Sweden)

Cristian H. Campos

2017-01-01

Full Text Available This contribution reports a novel preparation of gold nanoparticles on polymer/metal oxide hybrid materials (Au/P[VBTACl]-M metal: Al, Ti or Zr and their use as heterogeneous catalysts in liquid phase hydrogenation of p-chloronitrobenzene. The support was prepared by in situ radical polymerization/sol gel process of (4-vinyl-benzyltrimethylammonium chloride and 3-(trimethoxysilylpropyl methacrylate in conjunction with metal-alkoxides as metal oxide precursors. The supported catalyst was prepared by an ion exchange process using chloroauric acid (HAuCl4 as gold precursor. The support provided the appropriate environment to induce the spontaneous reduction and deposition of gold nanoparticles. The hybrid material was characterized. TEM and DRUV-vis results indicated that the gold forms spherical metallic nanoparticles and that their mean diameter increases in the sequence, Au/P[VBTACl]-Zr > Au/P[VBTACl]-Al > Au/P[VBTACl]-Ti. The reactivity of the Au catalysts toward the p-CNB hydrogenation reaction is attributed to the different particle size distributions of gold nanoparticles in the hybrid supports. The kinetic pseudo-first-order constant values for the catalysts in the hydrogenation reaction increases in the order, Au/P[VBTACl]-Al > Au/P[VBTACl]-Zr > Au/P[VBTACl]-Ti. The selectivity for all the catalytic systems was greater than 99% toward the chloroaniline target product. Finally the catalyst supported on the hybrid with Al as metal oxide could be reused at least four times without loss in activity or selectivity for the hydrogenation of p-CNB in ethanol as solvent.

A Plasma-Assisted Route to the Rapid Preparation of Transition-Metal Phosphides for Energy Conversion and Storage

KAUST Repository

Liang, Hanfeng

2017-06-06

Transition-metal phosphides (TMPs) are important materials that have been widely used in catalysis, supercapacitors, batteries, sensors, light-emitting diodes, and magnets. The physical and chemical structure of a metal phosphide varies with the method of preparation as the electronic, catalytic, and magnetic properties of the metal phosphides strongly depend on their synthesis routes. Commonly practiced processes such as solid-state synthesis and ball milling have proven to be reliable routes to prepare TMPs but they generally require high temperature and long reaction time. Here, a recently developed plasma-assisted conversion route for the preparation of TMPs is reviewed, along with their applications in energy conversion and storage, including water oxidation electrocatalysis, sodium-ion batteries, and supercapacitors. The plasma-assisted synthetic route should open up a new avenue to prepare TMPs with tailored structure and morphology for various applications. In fact, the process may be further extended to the synthesis of a wide range of transition-metal compounds such as borides and fluorides at low temperature and in a rapid manner.

Insights into the superhydrophobicity of metallic surfaces prepared by electrodeposition involving spontaneous adsorption of airborne hydrocarbons

International Nuclear Information System (INIS)

Liu, Peng; Cao, Ling; Zhao, Wei; Xia, Yue; Huang, Wei; Li, Zelin

2015-01-01

Graphical abstract: - Highlights: • Several superhydrophobic metallic surfaces were fabricated by fast electrodeposition. • Both micro/nanostructures and adsorption of airborne hydrocarbons make contributions. • XPS analyses confirm presence of airborne hydrocarbons on these metallic surfaces. • The adsorption of airborne hydrocarbons on the clean metal Au surface was very quick. • UV-O 3 treatment oxidized the hydrocarbons to hydrophilic oxygen-containing organics. - Abstract: Electrochemical fabrication of micro/nanostructured metallic surfaces with superhydrophobicity has recently aroused great attention. However, the origin still remains unclear why smooth hydrophilic metal surfaces become superhydrophobic by making micro/nanostructures without additional surface modifications. In this work, several superhydrophobic micro/nanostructured metal surfaces were prepared by a facile one-step electrodeposition process, including non-noble and noble metals such as copper, nickel, cadmium, zinc, gold, and palladium with (e.g. Cu) or without (e.g. Au) surface oxide films. We demonstrated by SEM and XPS that both hierarchical micro/nanostructures and spontaneous adsorption of airborne hydrocarbons endowed these surfaces with excellent superhydrophobicity. We revealed by XPS that the adsorption of airborne hydrocarbons at the Ar + -etched clean Au surface was rather quick, such that organic contamination can hardly be prevented in practical operation of surface wetting investigation. We also confirmed by XPS that ultraviolet-O 3 treatment of the superhydrophobic metal surfaces did not remove the adsorbed hydrocarbons completely, but mainly oxidized them into hydrophilic oxygen-containing organic substances. We hope our findings here shed new light on deeper understanding of superhydrophobicity for micro/nanostructured metal surfaces with and without surface oxide films

Ammonia release method for depositing metal oxides

Energy Technology Data Exchange (ETDEWEB)

Silver, G.L.; Martin, F.S.

1993-12-31

A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

Metal/metal-oxide interfaces: A surface science approach to the study of adhesion

Energy Technology Data Exchange (ETDEWEB)

Peden, C.H.F.; Kidd, K.B.; Shinn, N.D. (Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 (USA))

1991-05-01

Metal-oxide/metal interfaces play an important role, for example, in the joining of an oxide ceramic to a metal for sealing applications. In order to probe the chemical and physical properties of such an interface, we have performed Auger electron spectroscopic (AES) and temperature programed desorption (TPD) experiments on a model system composed of very thin films of Cr, Fe, Ni, or Cu evaporated onto a very thin thermally grown oxide on a W single crystal. Monolayer films of Fe and Cr were found (by AES) to completely wet the oxide surface upon deposition, and were stable up to temperatures at which the films desorbed ({approx}1300 K). In contrast, monolayer Ni and Cu films formed three-dimensional islands exposing the oxidized W surface either upon annealing (Ni) or even upon room-temperature deposition (Cu). The relative interfacial interaction between the overlayer metal and the oxide, as assessed by TPD, increases in the series Cu{lt}Ni{lt}Fe{lt}Cr. This trend follows the heats of formation of the various oxides of these metals.

Synthesis, Characterization, and Ultrafast Dynamics of Metal, Metal Oxide, and Semiconductor Nanomaterials

OpenAIRE

Wheeler, Damon Andreas

2013-01-01

SYNTHESIS, CHARACTERIZATION, AND ULTRAFAST DYNAMICS OF METAL, METAL OXIDE, AND SEMICONDUCTOR NANOMATERIALSABSTRACTThe optical properties of each of the three main classes of inorganic nanomaterials, metals, metal oxides, and semiconductors differ greatly due to the intrinsically different nature of the materials. These optical properties are among the most fascinating and useful aspects of nanomaterials with applications spanning cancer treatment, sensors, lasers, and solar cells. One techn...

Biocompatible nanocarriers that respond to oxidative environments via interactions between chitosan and multiple metal ions

Directory of Open Access Journals (Sweden)

Zhang S

2016-06-01

Full Text Available Shichang Zhang, Liye Xia, Chenchen Ding, Lu Wen, Weihua Wan, Gang Chen Department of Pharmaceutics, Guangdong Pharmaceutical University, Guangzhou, People’s Republic of China Abstract: Hydrogen peroxide (H2O2 functions as an early damage signal contributing to the oxidative stress response and can act as a trigger in smart oxidation-responsive drug delivery systems that are currently in development. Current H2O2-triggered oxidation-responsive polymeric systems are usually derived from chemical synthesis and rarely include natural polymers. Herein, we report two series of nanoparticle (NP complexes prepared with the biopolymer chitosan (CS and four different metal ions (Cu2+, Ca2+, Zn2+, and Fe3+, defined as CSNPs-metal complexes (Series 1 and CS-metal complexes NPs (Series 2, which responded to oxidation by dissolving upon H2O2 exposure. Experiments examining Nile red release and H2O2-triggered degradation confirmed that both series of complexes showed better sensitivity to oxidation than the CSNPs alone. Furthermore, preliminary cytotoxicity and histological observations indicated that the two series exhibited little or no cytotoxicity and generated a mild inflammatory response. Our work provides a novel and promising strategy for developing NPs for use as intelligent oxidation-responsive systems. Keywords: oxidation-responsive system, chitosan, nanoparticles, hydrogen peroxide, metal complexes

Nanocrystalline transition metal oxides as catalysts in the thermal decomposition of ammonium perchlorate

Energy Technology Data Exchange (ETDEWEB)

Kapoor, Inder Pal Singh; Srivastava, Pratibha; Singh, Gurdip [Department of Chemistry, DDU Gorakhpur University, Gorakhpur (India)

2009-08-15

Nanocrystalline transition metal oxides (NTMOs) have been successfully prepared by three different methods: novel quick precipitation method (Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}); surfactant mediated method (CuO), and reduction of metal complexes with hydrazine as reducing agent (Mn{sub 2}O{sub 3}). The nano particles have been characterized by X-ray diffraction (XRD) which shows an average particle diameter of 35-54 nm. Their catalytic activity was measured in the thermal decomposition of ammonium perchlorate (AP). AP decomposition undergoes a two step process where the addition of metal oxide nanocrystals led to a shifting of the high temperature decomposition peak toward lower temperature. The kinetics of the thermal decomposition of AP and catalyzed AP has also been evaluated using model fitting and isoconversional method. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

Science.gov (United States)

Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

2014-08-14

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

Application of metal oxide refractories for melting and casting reactive metals

International Nuclear Information System (INIS)

Jessen, N.C. Jr.; Holcombe, C.E. Jr.; Townsend, A.B.

1979-01-01

Extensive investigations have been conducted to develop metal oxide refractories for containment of molten uranium and uranium alloys. Since uranium and uranium alloys are readily susceptable to the formation of complex oxides, carbides, nitrides, intermetallic compounds, and suboxide reactions, severe problems exist for the production of quality castings. These contamination reactions are dependent on temperature, pressure, and molten metal interfacial reactions. The need for high purity metals to meet specification repeatedly has resulted in the development of improved metal oxide refractories and sophisticated furnace controls. Applications of Y 2 O 3 for use as a crucible and mold coating, precision molds and cores, and high temperature castable ceramics are discussed. Experimental results on melt impurity levels, thermal controls during melting, surface interactions and casting quality are presented

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

International Nuclear Information System (INIS)

Richard T. Scalettar; Warren E. Pickett

2005-01-01

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

Energy Technology Data Exchange (ETDEWEB)

Scalettar, Richard T.; Pickett, Warren E.

2004-07-01

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

Energy Technology Data Exchange (ETDEWEB)

Richard T. Scalettar; Warren E. Pickett

2005-08-02

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.

Oxidation behaviour of metallic glass foams

Energy Technology Data Exchange (ETDEWEB)

Barnard, B.R. [Department of Materials Science and Engineering, 434 Dougherty Hall, University of Tennessee, Knoxville, TN 37996-2200 (United States)], E-mail: bbarnard@utk.edu; Liaw, P.K. [Department of Materials Science and Engineering, 434 Dougherty Hall, University of Tennessee, Knoxville, TN 37996-2200 (United States); Demetriou, M.D.; Johnson, W.L. [Department of Materials Science, Keck Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)

2008-08-15

In this study, the effects of porosity on the oxidation behaviour of bulk-metallic glasses were investigated. Porous Pd- and Fe-based bulk-metallic glass (BMG) foams and Metglas ribbons were studied. Oxidizing experiments were conducted at 70 deg. C, and around 80 deg. C below glass-transition temperatures, (T{sub g}s). Scanning-electron microscopy/energy-dispersive spectroscopy (SEM/EDS) studies revealed little evidence of oxidation at 70 deg. C. Specimens exhibited greater oxidation at T{sub g} - 80 deg. C. Oxides were copper-based for Pd-based foams, Fe-, Cr-, and Mo-based for Fe-based foams, and Co-based with borosilicates likely for the Metglas. Pd-based foams demonstrated the best oxidation resistance, followed by Metglas ribbons, followed by Fe-based foams.

Synthesis and functionalisation of metal and metal oxide nanoparticles for theranostics

OpenAIRE

Mundell, VJ

2013-01-01

Metal and metal oxide nanoparticles including calcium oxide, gold, and superparamagnetic iron oxide nanoparticles (SPIOs) were synthesised using a range of techniques including reduction, co-precipitation and spinning disc technology. SPIOs were primarily synthesised via a co-precipitation method using iron (II) chloride, iron (III) chloride and ammonia; a spinning disc reactor and gaseous ammonia were trialled successfully for scale up, producing spherical particles of 10-40 nm in diameter a...

Inverse spinel transition metal oxides for lithium-ion storage with different discharge/charge conversion mechanisms

International Nuclear Information System (INIS)

Wang, Jiawei; Ren, Yurong; Huang, Xiaobing; Ding, Jianning

2016-01-01

Highlights: • Inverse spinel structure relieves the irreversible phase transition of electrodes. • Anodes with the same structure show different discharge/charge conversion mechanisms. • High reversible capacity confirms the potential feasibility of composites. - Abstract: Inverse spinel transition metal oxides (Fe 3 O 4 , MnFe 2 O 4 , Fe 3 O 4 /reduced graphene oxide and MnFe 2 O 4 /reduced graphene oxide) are prepared by a facile ethylene-glycol-assisted hydrothermal method. The stability of inverse spinel structure and the high specific surface area of nanoscale provide transition metal oxides with high specific capacity. And the surface modification with reduced graphene oxide improves the poor conductivity of pristine transition metal oxides. Pristine Fe 3 O 4 and MnFe 2 O 4 deliver the high initial discharge capacity of 1137.1 and 1088.9 mAh g −1 , respectively. Fe 3 O 4 /reduced graphene oxide and MnFe 2 O 4 /reduced graphene oxide get the reversible capacity of 645.8 and 720 mAh g −1 , respectively, even after 55 cycles. The different discharge/charge conversion mechanisms make them different capacity stability. The great electrochemical performances of composites offer electrodes with suitable characteristics for high-performance energy storage application.

Polymer-supported metals and metal oxide nanoparticles: synthesis, characterization, and applications

International Nuclear Information System (INIS)

Sarkar, Sudipta; Guibal, E.; Quignard, F.; SenGupta, A. K.

2012-01-01

Metal and metal oxide nanoparticles exhibit unique properties in regard to sorption behaviors, magnetic activity, chemical reduction, ligand sequestration among others. To this end, attempts are being continuously made to take advantage of them in multitude of applications including separation, catalysis, environmental remediation, sensing, biomedical applications and others. However, metal and metal oxide nanoparticles lack chemical stability and mechanical strength. They exhibit extremely high pressure drop or head loss in fixed-bed column operation and are not suitable for any flow-through systems. Also, nanoparticles tend to aggregate; this phenomenon reduces their high surface area to volume ratio and subsequently reduces effectiveness. By appropriately dispersing metal and metal oxide nanoparticles into synthetic and naturally occurring polymers, many of the shortcomings can be overcome without compromising the parent properties of the nanoparticles. Furthermore, the appropriate choice of the polymer host with specific functional groups may even lead to the enhancement of the properties of nanoparticles. The synthesis of hybrid materials involves two broad pathways: dispersing the nanoparticles (i) within pre-formed or commercially available polymers; and (ii) during the polymerization process. This review presents a broad coverage of nanoparticles and polymeric/biopolymeric host materials and the resulting properties of the hybrid composites. In addition, the review discusses the role of the Donnan membrane effect exerted by the host functionalized polymer in harnessing the desirable properties of metal and metal oxide nanoparticles for intended applications.

Method for converting uranium oxides to uranium metal

International Nuclear Information System (INIS)

Duerksen, W.K.

1988-01-01

A method for converting uranium oxide to uranium metal is described comprising the steps of heating uranium oxide in the presence of a reducing agent to a temperature sufficient to reduce the uranium oxide to uranium metal and form a heterogeneous mixture of a uranium metal product and oxide by-products, heating the mixture in a hydrogen atmosphere at a temperature sufficient to convert uranium metal in the mixture to uranium hydride, cooling the resulting uranium hydride-containing mixture to a temperature sufficient to produce a ferromagnetic transition in the uranium hydride, magnetically separating the cooled uranium hydride from the mixture, and thereafter heating the separated uranium hydride in an inert atmosphere to a temperature sufficient to convert the uranium hydride to uranium metal

Synthesis of a sugar-organometallic compound 1,1′-difurfurylferrocene and its microwave preparation of carbon/iron oxide nanocomposite

International Nuclear Information System (INIS)

Zhao Shanyu; Cooper, Daniel C.; Xu, Haixun; Zhu Pinghua; Suggs, J. William

2013-01-01

Graphical abstract: In order to synthesize a carbon–metal or metal oxide combination sphere, carbonaceous resource furfural was introduced, which was nucleophilic treated with 1,1′-dilithioferrocene to form a sugar-organometallic compound: ferrocenyl monosaccharide derivative 1,1′-difurfurylferrocene, which can be hydrothermally treated in a microwave reactor to give 300–500 nm microspheres with the α-Fe 2 O 3 or Fe 3 O 4 formed on the surface, which may be favorable for new magnetic materials preparation or instead of iron with other metal ions, versatile carbon/metal composites will be possibly synthesized for catalysis, drug delivery and magnetic uses. Highlights: ► We synthesized 1,1′-difurfurylferrocene by nucleophilic treating furfural with 1,1′-dilithioferrocene. ► 1,1′-Difurfurylferrocene can be hydrothermally treated by microwave to give microspheres with iron oxides on the surface. ► 1,1′-Difurfurylferrocene has 2 reactive furanose units, which form carbonspheres and ferrocenyl can give iron oxides. ► REDOX atmosphere influences the coating structures. - Abstract: In order to synthesize a carbon–metal or metal oxide combination sphere, carbonaceous resource furfural 1 was introduced, which was nucleophilic treated with 1,1′-dilithioferrocene 2 to form a sugar-organometallic compound: ferrocenyl monosaccharide derivative 1,1′-difurfurylferrocene 3. 1,1′-Difurfurylferrocene 3 can be hydrothermally treated in a microwave reactor to give 300–500 nm microspheres with the α-Fe 2 O 3 or Fe 3 O 4 nanocrystals formed on the surface, which may be favorable for new magnetic materials preparation or instead of iron with other metal ions, versatile carbon/metal composites will be possibly synthesized for catalysis, drug delivery and magnetic uses.

Synthesis of a sugar-organometallic compound 1,1 Prime -difurfurylferrocene and its microwave preparation of carbon/iron oxide nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Zhao Shanyu, E-mail: syzhao65@gmail.com [School of Environmental and Safty Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Department of Chemistry, Brown University, Providence, RI 02912-9108 (United States); Cooper, Daniel C. [Department of Chemistry, Brown University, Providence, RI 02912-9108 (United States); Xu, Haixun [Institute of Building Materials, Dalian University of Technology, Dalian, Liaoning 116024 (China); Zhu Pinghua [School of Environmental and Safty Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Suggs, J. William, E-mail: j_suggs@brown.edu [Department of Chemistry, Brown University, Providence, RI 02912-9108 (United States)

2013-01-01

Graphical abstract: In order to synthesize a carbon-metal or metal oxide combination sphere, carbonaceous resource furfural was introduced, which was nucleophilic treated with 1,1 Prime -dilithioferrocene to form a sugar-organometallic compound: ferrocenyl monosaccharide derivative 1,1 Prime -difurfurylferrocene, which can be hydrothermally treated in a microwave reactor to give 300-500 nm microspheres with the {alpha}-Fe{sub 2}O{sub 3} or Fe{sub 3}O{sub 4} formed on the surface, which may be favorable for new magnetic materials preparation or instead of iron with other metal ions, versatile carbon/metal composites will be possibly synthesized for catalysis, drug delivery and magnetic uses. Highlights: Black-Right-Pointing-Pointer We synthesized 1,1 Prime -difurfurylferrocene by nucleophilic treating furfural with 1,1 Prime -dilithioferrocene. Black-Right-Pointing-Pointer 1,1 Prime -Difurfurylferrocene can be hydrothermally treated by microwave to give microspheres with iron oxides on the surface. Black-Right-Pointing-Pointer 1,1 Prime -Difurfurylferrocene has 2 reactive furanose units, which form carbonspheres and ferrocenyl can give iron oxides. Black-Right-Pointing-Pointer REDOX atmosphere influences the coating structures. - Abstract: In order to synthesize a carbon-metal or metal oxide combination sphere, carbonaceous resource furfural 1 was introduced, which was nucleophilic treated with 1,1 Prime -dilithioferrocene 2 to form a sugar-organometallic compound: ferrocenyl monosaccharide derivative 1,1 Prime -difurfurylferrocene 3. 1,1 Prime -Difurfurylferrocene 3 can be hydrothermally treated in a microwave reactor to give 300-500 nm microspheres with the {alpha}-Fe{sub 2}O{sub 3} or Fe{sub 3}O{sub 4} nanocrystals formed on the surface, which may be favorable for new magnetic materials preparation or instead of iron with other metal ions, versatile carbon/metal composites will be possibly synthesized for catalysis, drug delivery and magnetic uses.

Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin.

Science.gov (United States)

Franco, Ana; De, Sudipta; Balu, Alina M; Garcia, Araceli; Luque, Rafael

2017-01-01

Vanillin is one of the most commonly used natural products, which can also be produced from lignin-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, ferulic acid etc.) have been effectively used in the past few years. However, selective and efficient production of vanillin from these feedstocks still remains an issue to replace the existing process. In this work, new transition metal-based catalysts were proposed to investigate their efficiency in vanillin production. Reduced graphene oxide supported Fe and Co catalysts showed high conversion of isoeugenol under mild reaction conditions using H 2 O 2 as oxidizing agent. Fe catalysts were more selective as compared to Co catalysts, providing a 63% vanillin selectivity at 61% conversion in 2 h. The mechanochemical process was demonstrated as an effective approach to prepare supported metal catalysts that exhibited high activity for the production of vanillin from isoeugenol.

Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

Science.gov (United States)

Renaud, Gilles

Experimental determinations of the atomic structure of insulating oxide surfaces and metal/oxide interfaces are scarce, because surface science techniques are often limited by the insulating character of the substrate. Grazing incidence X-ray scattering (GIXS), which is not subject to charge effects, can provide very precise information on the atomic structure of oxide surfaces: roughness, relaxation and reconstruction. It is also well adapted to analyze the atomic structure, the registry, the misfit relaxation, elastic or plastic, the growth mode and the morphology of metal/oxide interfaces during their growth, performed in situ. GIXS also allows the analysis of thin films and buried interfaces, in a non-destructive way, yielding the epitaxial relationships, and, by variation of the grazing incidence angle, the lattice parameter relaxation along the growth direction. On semi-coherent interfaces, the existence of an ordered network of interfacial misfit dislocations can be demonstrated, its Burger's vector determined, its ordering during in situ annealing cycles followed, and sometimes even its atomic structure can be addressed. Careful analysis during growth allows the modeling of the dislocation nucleation process. This review emphasizes the new information that GIXS can bring to oxide surfaces and metal/oxide interfaces by comparison with other surface science techniques. The principles of X-ray diffraction by surfaces and interfaces are recalled, together with the advantages and properties of grazing angles. The specific experimental requirements are discussed. Recent results are presented on the determination of the atomic structure of relaxed or reconstructed oxide surfaces. A description of results obtained during the in situ growth of metal on oxide surfaces is also given, as well as investigations of thick metal films on oxide surfaces, with lattice parameter misfit relaxed by an array of dislocations. Recent work performed on oxide thin films having

Study of transition metal oxides by photoelectron spectroscopy

International Nuclear Information System (INIS)

Rao, C.N.R.; Sarma, D.D.; Vasudevan, S.; Hegde, M.S.

1979-01-01

Systematics in the X-ray photoelectron spectra (X.p.e.s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row of transition metals have been investigated in detail. Core level binding energies, spin-orbit splittings and exchange splittings are found to exhibit interesting variations with the oxidation state of the metal or the nuclear charge. The 3d binding energies of the monoxides show a proportionality to Goodenough's (R - RC). Other aspects of interest in the study are the satellite structure and final state effects in the X.p.e.s. of the oxides, and identification of different valence states in oxides of the general formulae Mn02n-1 and M304. The nature of changes in the 3d bands of oxides undergoing metal-insulator transitions is also indicated. (author)

Metal ion binding to iron oxides

Science.gov (United States)

Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

2006-06-01

The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

Biofouling of various metal oxides in marine environment

Science.gov (United States)

Kougo, T.; Kuroda, D.; Wada, N.; Ikegai, H.; Kanematsu, H.

2012-03-01

Biofouling has induced serious problems in various industrial fields such as marine structures, bio materials, microbially induced corrosion (MIC) etc. The effects of various metals on biofouling have been investigated so far and the mechanism has been clarified to some extent(1,2), and we proposed that Fe ion attracted lots of bacteria and formed biofilm very easily(3). In this study, we investigated the possibility for biofouling of Pseudomonas aeruginosa on various metal oxides such as Fe2O3, TiO2, WO3, AgO, Cr2O3 etc. And in addition of such a model experiment on laboratory scale, they were immersed into actual sea water as well as artificial sea water. As for the preparation of metal oxides, commercial oxide powders were used as starting material and those whose particle sizes were under 100 micrometers were formed into pellets by a press. Some of them were heated to 700 °C and sintered for 10 hours at the temperatures. After the calcinations, they were immersed into the culture of P. aeruginosa at 35 °C in about one week. After the immersion, they were taken out of the culture and the biofouling behaviors were observed by optical microscopy, low pressure scanning electron microscopy (low pressure SEM) etc. Biofouling is generally classified into several steps. Firstly, conditioning films composed of organic matters were formed on specimens. Then bacterial were attached to the specimen's surfaces, seeking for conditioning films as nutrition. Then bacteria formed biofilm on the specimens. In marine environment, more larger living matters such as shells etc would be attached to biofilms. However, in the culture media, only biofilms were formed.

Method for converting uranium oxides to uranium metal

Science.gov (United States)

Duerksen, Walter K.

1988-01-01

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

Interaction of terbium group metal oxides with carbon

International Nuclear Information System (INIS)

Vodop'yanov, A.G.; Baranov, S.V.; Kozhevnikov, G.N.

1990-01-01

Mechanism of carbothermal reduction of terbium group metals from oxides is investigated using thermodynamic and kinetic analyses. Interaction of metal oxides with carbon covers dissociation of metal oxides and reduction by carbon monoxide, which contribution into general reduction depends on CO pressure. Temperatures of reaction beginning for batch initial components at P=1.3x10 -4 and P CO =0.1 MPa and of formation of oxycarbide melts are determined

Nanocomposite of graphene and metal oxide materials

Science.gov (United States)

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2012-09-04

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10C.

Nanocomposite of graphene and metal oxide materials

Science.gov (United States)

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2013-10-15

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Synthesis and characterization of metal - metal oxide nano structured electrode materials for electrolysis of water

International Nuclear Information System (INIS)

Stoevska-Gogovska, Dafinka

2012-01-01

The goal in this Ph.D. study was to prepare hypo-hyper r f-electrocatalysts (aimed for water splitting) without or with reduced precious metals load and then to characterize them, i.e. to prove whether the goal was fulfilled. The synthesized electrocatalysts contain metallic (10% wt.) and metal-oxide phase (18% wt.), applied on a carrier (72% wt). The metallic phase was mainly cobalt one, varied from 0%, 50% wt., 80% wt. and 100%, (the rest up to 100% wt. being Ru). Only in one case the metallic phase contained 3 different metals, i.e. Co, Ru and Pt in a proportion of 80% : 10% : 10%, respectively. Metal oxide phase was TiO 2 (as a crystalline anatase) deposited on a carrier of multi walled carbon nano tubes (MWCNTs). MWCNTs were pre-activated in 28% nitric acid and effect of the activation process was studied, as well. As a reference electro catalyst for hydrogen evolution reaction, corresponding catalyst with metallic phase of pure Pt was prepared. The prepared electrocatalysts were structurally characterized by means of a number of contemporary experimental techniques. So, by means of X-ray Diffraction Analysis (XRD) the crystal state of each catalyst’s phase was determined, and the size of crystal grains was estimated. So, for Pt particles it was found that the size changes from 12 nm, in a systems with Pt as the only metal phase, to 3÷4 nm in systems that contain Co (Co:Pt = 1:1 or 4:1). It was determined as well that the anatase particles size in all synthesized catalysts is cca 4 nm. By means of Photoelectron Microscopy (XPS), the bond energy of catalyst’s components was determined, and the extent of interaction was estimated. The components oxidation state was estimated according to their peak amplitude in the XPS spectrum. So, for the carbon the peaks were identified that indicate the existence of double bond (C=C), as well as C-O, C=0 (and/or C-OH), -0-0*0 and (COO) bonds. The shift of the metallic Ru bond energy was attributed to the existence of

Catalytic activity of metall-like carbides in carbon oxide oxidation reaction

International Nuclear Information System (INIS)

Kharlamov, A.I.; Kosolapova, T.Ya.; Rafal, A.N.; Kirillova, N.V.

1980-01-01

Kinetics of carbon oxide oxidation upon carbides of hafnium, niobium, tantalum, molybdenum, zirconium and chromium is studied. Probable mechanism of the catalysts action is suggested. The established character of the change of the carbide catalytic activity is explained by the change of d-electron contribution to the metal-metal interaction

Metal oxide nanostructures as gas sensing devices

CERN Document Server

Eranna, G

2016-01-01

Metal Oxide Nanostructures as Gas Sensing Devices explores the development of an integrated micro gas sensor that is based on advanced metal oxide nanostructures and is compatible with modern semiconductor fabrication technology. This sensor can then be used to create a compact, low-power, handheld device for analyzing air ambience. The book first covers current gas sensing tools and discusses the necessity for miniaturized sensors. It then focuses on the materials, devices, and techniques used for gas sensing applications, such as resistance and capacitance variations. The author addresses the issues of sensitivity, concentration, and temperature dependency as well as the response and recovery times crucial for sensors. He also presents techniques for synthesizing different metal oxides, particularly those with nanodimensional structures. The text goes on to highlight the gas sensing properties of many nanostructured metal oxides, from aluminum and cerium to iron and titanium to zinc and zirconium. The final...

Improving the scratch resistance of sol-gel metal oxide coatings cured at 250 C through use of thermogenerated amines

NARCIS (Netherlands)

Langanke, J.; Arfsten, N.; Buskens, P.; Habets, R.; Klankermayer, J.; Leitner, W.

2013-01-01

Scratch resistant sol-gel metal oxide coatings typically require a thermal post-treatment step (curing process) at temperatures between 400 and 700 C. In this report, we demonstrate that the in situ generation of amines within sol-gel films facilitates the preparation of scratch resistant metal

Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

International Nuclear Information System (INIS)

Borgatti, F.; Torelli, P.; Panaccione, G.

2016-01-01

Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

Energy Technology Data Exchange (ETDEWEB)

Borgatti, F., E-mail: francesco.borgatti@cnr.it [Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Consiglio Nazionale delle Ricerche (CNR), via P. Gobetti 101, Bologna I-40129 (Italy); Torelli, P.; Panaccione, G. [Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, Trieste I-34149 (Italy)

2016-04-15

Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

Science.gov (United States)

Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

2015-11-16

Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced photoelectrochemical activity in all-oxide heterojunction devices based on correlated "metallic" oxides.

Science.gov (United States)

Apgar, Brent A; Lee, Sungki; Schroeder, Lauren E; Martin, Lane W

2013-11-20

n-n Schottky, n-n ohmic, and p-n Schottky heterojunctions based on TiO2 /correlated "metallic" oxide couples exhibit strong solar-light absorption driven by the unique electronic structure of the "metallic" oxides. Photovoltaic and photocatalytic responses are driven by hot electron injection from the "metallic" oxide into the TiO2 , enabling new modalities of operation for energy systems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of Arrays of Metal and Metal Oxide Nanotubes by Shadow Evaporation

NARCIS (Netherlands)

Dickey, Michael D.; Weiss, Emily A.; Smythe, Elizabeth J.; Chiechi, Ryan C.; Capasso, Federico; Whitesides, George M.

2008-01-01

This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The

Current-induced metal-insulator transition in VO x thin film prepared by rapid-thermal-annealing

International Nuclear Information System (INIS)

Cho, Choong-Rae; Cho, SungIl; Vadim, Sidorkin; Jung, Ranju; Yoo, Inkyeong

2006-01-01

The phenomenon of metal-insulator transition (MIT) in polycrystalline VO x thin films and their preparations have been studied. The films were prepared by sputtering of vanadium thin films succeeded by Rapid Thermal Annealing (RTA) in oxygen ambient at 500 deg. C. Crystalline, compositional, and morphological characterizations reveal a continuous change of phase from vanadium metal to the highest oxide phase, V 2 O 5 , with the time of annealing. Electrical MIT switching has been observed in these films. Sweeping mode, electrode area, and temperature dependent MIT has been studied in Pt/VO x /Pt vertical structure. The important parameters for MIT in VO x have been found to be the current density and the electric field, which depend on carrier density in the films

Preparation of polymers suitable for radiation shielding and studying its properties (polyester composites with heavy metals salts)

International Nuclear Information System (INIS)

Kharita, M. H.; Al-Ajji, Z.; Yousef, S.

2010-12-01

Four composites were prepared in this work, based on polyester and heavy metals oxides and salts. The attenuation properties, as well as mechanical properties were studied, and the chemical stability was evaluated. It has been shown, that these composites can be used in radiation shielding for X-rays successfully, and the exact composition of these composites can be optimized according to the radiation energy to prepare the lightest possible shield. (author)

Electrochemical preparation of new uranium oxide phases

International Nuclear Information System (INIS)

Smolenskij, V.V.; Lyalyushkin, N.V.; Bove, A.L.; Komarov, V.K.; Kapshukov, I.I.

1992-01-01

Behaviour of uranium ions in oxidation states 3+ and 4+ in molten chlorides of alkali metals in the temperature range of 700-900 degC in the atmosphere of an inert gas was studied by the method of cyclic voltametry. It is shown that as a result of introduction of crystal uranium dioxide into the salt melt formation of uranium oxide ions of the composition UO + and UO 2+ occurs, the ions participating in electrode reactions and bringing about formation of the following uranium oxides on the cathode: UO and, presumably, U 3 O 4 . Oxides UO and U 3 O 4 are thermodynamically unstable at low temperatures and decompose into uranium oxide of the composition UO 2-x , where x varies from 0 to 0.05, and metal uranium

Highly efficient one-step synthesis of carbon encapsulated nanocrystals by the oxidation of metal π-complexes

Science.gov (United States)

Liu, Boyang; Shao, Yingfeng; Xiang, Xin; Zhang, Fuhua; Yan, Shengchang; Li, Wenge

2017-08-01

Various carbon encapsulated nanocrystals, including MnS and MnO, Cr2O3, MoO2, Fe7S8 and Fe3O4, and ZrO2, are prepared in one step and in situ by a simple and highly efficient synthesis approach. The nanocrystals have an equiaxed morphology and a median size smaller than 30 nm. Tens and hundreds of these nanocrystals are entirely encapsulated by a wormlike amorphous carbon shell. The formation of a core-shell structure depends on the strongly exothermic reaction of metal π-complexes with ammonium persulfate in an autoclave at below 200 °C. During the oxidation process, the generated significant amounts of heat will destroy the molecular structure of the metal π-complex and cleave the ligands into small carbon fragments, which further transform into an amorphous carbon shell. The central metal atoms are oxidized to metal oxide/sulfide nanocrystals. The formation of a core-shell structure is independent of the numbers of ligands and carbon atoms as well as the metal types, implying that any metal π-complex can serve as a precursor and that various carbon encapsulated nanocrystals can be synthesized by this method.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

KAUST Repository

Nanda, Himansu Sekhar

2016-11-03

The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

KAUST Repository

Nanda, Himansu Sekhar

2016-01-01

The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

Directory of Open Access Journals (Sweden)

Himansu Sekhar Nanda

2016-11-01

Full Text Available The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium-doped cerium oxide nanoparticles (SmCNPs as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy-ethoxy]-ethoxy}-hexyl triethoxysilane (MEEETES were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Actinide metal processing

International Nuclear Information System (INIS)

Sauer, N.N.; Watkin, J.G.

1992-01-01

A process for converting an actinide metal such as thorium, uranium, or plutonium to an actinide oxide material by admixing the actinide metal in an aqueous medium with a hypochlorite as an oxidizing agent for sufficient time to form the actinide oxide material and recovering the actinide oxide material is described together with a low temperature process for preparing an actinide oxide nitrate such as uranyl nitrate. Additionally, a composition of matter comprising the reaction product of uranium metal and sodium hypochlorite is provided, the reaction product being an essentially insoluble uranium oxide material suitable for disposal or long term storage

Gas phase deposition of oxide and metal-oxide coatings on fuel particles

International Nuclear Information System (INIS)

Patokin, A.P.; Khrebtov, V.L.; Shirokov, B.M.

2008-01-01

Production processes and properties of oxide (Al 2 O 3 , ZrO 2 ) and metal-oxide (Mo-Al 2 O 3 , Mo-ZrO 2 , W-Al 2 O 3 , W-ZrO 2 ) coatings on molybdenum substrates and uranium dioxide fuel particles were investigated. It is shown that the main factors that have an effect on the deposition rate, density, microstructure and other properties of coatings are the deposition temperature, the ratio of H 2 and CO 2 flow rates, the total reactor pressure and the ratio of partial pressures of corresponding metal chlorides during formation of metal-oxide coatings

Metal porphyrin intercalated reduced graphene oxide nanocomposite utilized for electrocatalytic oxygen reduction

Directory of Open Access Journals (Sweden)

Mingyan Wang

2017-07-01

Full Text Available In this paper, we report a simple and facile self-assembly method to successfully fabricate cationic metal porphyrin –MtTMPyP (Mt= Cobalt (II, Manganese (III, or Iron (III; TMPyP = 5, 10, 15, 20-tetrakis (N-methylpyridinium-4-yl porphyrin intercalated into the layer of graphene oxide (GO by the cooperative effects of electrostatic and π–π stacking interaction between positively charged metal porphyrin and negatively charged GO sheets. Followed by reduction with hydrazine vapor, a series of novel 2D MtTMPyP/rGOn were fabricated. The as-prepared 2D hybrids were fully characterized and tested as non-noble metal catalysts for oxygen reduction reaction (ORR in an alkaline medium. The MtTMPyP/rGOn hybrids, especially CoTMPyP/rGO5, demonstrated an improved electrocatalytic activity for ORR and a number of exchanged electrons close to 4-electron reaction, increased stability and excellent tolerance to methanol, showing a potential alternative catalyst for ORR in fuel cells and air batteries. Keywords: Metal porphyrin, Reduced graphene oxide, Intercalation, Oxygen reduction reaction, Catalyst

Transesterification of Jatropha and Karanja oils by using waste egg shell derived calcium based mixed metal oxides

International Nuclear Information System (INIS)

Joshi, Girdhar; Rawat, Devendra S.; Lamba, Bhawna Y.; Bisht, Kamal K.; Kumar, Pankaj; Kumar, Nayan; Kumar, Sanjay

2015-01-01

Highlights: • Waste chicken eggshell derived CaO(cesp) based mixed metal oxides were prepared. • Transesterification of high free fatty acid containing non-edible oils were achieved using prepared catalysts. • CaO(cesp) based mixed metal oxides have shown better activity in comparison to neat CaO(cesp). • Best Conversions were achieved with ZnO–CaO(cesp). • Catalyst has shown good reusability up to 4 cycles without significant loss in its activity. - Abstract: Solid base heterogeneous catalysts are one of the promising materials for the transesterification of vegetable oils because these catalysts are generally more reactive than solid acid catalysts which require very severe operating conditions. Calcium oxide has shown good catalytic activity due to its high basicity which is required for transesterification of triacylglycerides (TAGs). In the present study, the transesterification of non-edible, high free fatty acid containing Jatropha and Karanja oils was studied by using waste chicken egg shell derived calcium (i.e. CaO(cesp)) based mixed metal oxides (M-CaO; M = ZnO, MnO 2 , Fe 2 O 3 and Al 2 O 3 ) as heterogeneous catalyst. A comparison was also made on the catalytic performance of these prepared catalysts. The catalyst characterizations were done by XRD, SEM, TGA, FT-IR and BET techniques. The effectiveness of the catalysts was highly influenced by the calcination temperature. ZnO–CaO(cesp) catalyst was found to be the most efficient catalyst among all. The maximum conversion for the transesterification of Jatropha and Karanja oils were achieved using 5 wt% catalyst, 65 °C temperature and 12:1 methanol/oil ratio. The catalyst could be re-used effectively during four cycles. Use of the CaO(cesp) based mixed oxides made the process more environmental benign and economical. The biodiesel prepared has shown good fuel characteristics as per EN, ASTM and IS standards

Oxidation Characteristics and Electrical Properties of Doped Mn-Co Spinel Reaction Layer for Solid Oxide Fuel Cell Metal Interconnects

Directory of Open Access Journals (Sweden)

Pingyi Guo

2018-01-01

Full Text Available To prevent Cr poisoning of the cathode and to retain high conductivity during solid oxide fuel cell (SOFC operation, Cu or La doped Co-Mn coatings on a metallic interconnect is deposited and followed by oxidation at 750 °C. Microstructure and composition of coatings after preparation and oxidation is analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM. High energy micro arc alloying process, a low cost technique, is used to prepare Cu or La doped Co-Mn coatings with the metallurgical bond. When coatings oxidized at 750 °C in air for 20 h and 100 h, Co3O4 is the main oxide on the surface of Co-38Mn-2La and Co-40Mn coatings, and (Co,Mn3O4 spinel continues to grow with extended oxidation time. The outmost scales of Co-33Mn-17Cu are mainly composed of cubic MnCo2O4 spinel with Mn2O3 after oxidation for 20 h and 100 h. The average thickness of oxide coatings is about 60–70 μm after oxidation for 100 h, except that Co-40Mn oxide coatings are a little thicker. Area-specific resistance of Cu/La doped Co-Mn coatings are lower than that of Co-40Mn coating. (Mn,Co3O4/MnCo2O4 spinel layer is efficient at blocking the outward diffusion of chromium and iron.

Electrical memory features of ferromagnetic CoFeAlSi nano-particles embedded in metal-oxide-semiconductor matrix

International Nuclear Information System (INIS)

Lee, Ja Bin; Kim, Ki Woong; Lee, Jun Seok; An, Gwang Guk; Hong, Jin Pyo

2011-01-01

Half-metallic Heusler material Co 2 FeAl 0.5 Si 0.5 (CFAS) nano-particles (NPs) embedded in metal-oxide-semiconductor (MOS) structures with thin HfO 2 tunneling and MgO control oxides were investigated. The CFAS NPs were prepared by rapid thermal annealing. The formation of well-controlled CFAS NPs on thin HfO 2 tunneling oxide was confirmed by atomic force microscopy (AFM). Memory characteristics of CFAS NPs in MOS devices exhibited a large memory window of 4.65 V, as well as good retention and endurance times of 10 5 cycles and 10 9 s, respectively, demonstrating the potential of CFAS NPs as promising candidates for use in charge storage.

Oxidation of vanadium metal in oxygen plasma and their characterizations

Science.gov (United States)

Sharma, Rabindar Kumar; Singh, Megha; Kumar, Prabhat; Reddy, G. B.

2015-09-01

In this report, the role of oxygen plasma on oxidation of vanadium (V) metal and the volatilization of its oxides has been studied as a function of source (V metal strip) temperature (Tss) and oxygen partial pressure (PO2). The presence of O2-plasma not only enhances the oxidation rate but also ficilitates in transport of oxide molecules from metal to substrate, as confirmed by the simultanous deposition of oxide film onto substrate. Both the oxidized metal strips and oxide films deposited on substrates are characterized separately. The structural and vibrational results evidence the presence of two different oxide phases (i.e. orthorhombic V2O5 and monocilinic V O2) in oxide layers formed on V metal strips, whereas the oxide films deposited on substrates exhibit only orthorhombic phase (i.e. V2O5). The decrease in peak intensities recorded from heated V metal strips on increasing Tss points out the increment in the rate of oxide volatilization, which also confirms by the oxide layer thickness measurements. The SEM results show the noticeable surface changes on V-strips as the function of Tss and PO2 and their optimum values are recorded to be 500 ˚ C and 7.5 × 10-2 Torr, respectively to deposit maximum thick oxide film on substrate. The formation of microcracks on oxidized V-strips, those responsible to countinue oxidation is also confirmed by SEM results. The compositional study of oxide layers formed on V-strips, corroborates their pureness and further assures about the existence of mixed oxide phases. The effect of oxygen partial pressure on oxidation of V-metal has also been discussed in the present report. All the results are well in agreement to each other.

Electrochromic device containing metal oxide nanoparticles and ultraviolet blocking material

Science.gov (United States)

Garcia, Guillermo; Koo, Bonil; Gregoratto, Ivano; Basu, Sourav; Rosen, Evelyn; Holt, Jason; Thomsen, Scott

2017-10-17

An electrochromic device includes a nanostructured transition metal oxide bronze layer that includes one or more transition metal oxide and one or more dopant. The electrochromic device also includes nanoparticles containing one or more transparent conducting oxide (TCO), a solid state electrolyte, a counter electrode, and at least one protective layer to prevent degradation of the one or more nanostructured transition metal oxide bronze. The nanostructured transition metal oxide bronze selectively modulates transmittance of near-infrared (NIR) and visible radiation as a function of an applied voltage to the device.

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.

Hydrogen storage evaluation based on investigations of the catalytic properties of metal/metal oxides in electrospun carbon fibers

Energy Technology Data Exchange (ETDEWEB)

Im, Ji Sun; Lee, Young-Seak [Department of Fine Chemical Engineering and Chemistry, Chungnam National University, Daejeon 305-764 (Korea); Park, Soo-Jin [Department of Chemistry, Inha University, Incheon 402-751 (Korea); Kim, Taejin [Core Technology Research Center for Fuel Cell, Jeollabuk-do 561-844 (Korea)

2009-05-15

In order to investigate the catalytic capacity of metals and metal oxides based on electrospun carbon fibers for improving hydrogen storage, electrospinning and heat treatments were carried out to obtain metal/metal oxide-embedded carbon fibers. Although the fibers were treated with the same activation procedure, they had different pore structures, due to the nature of the metal oxide. When comparing the catalytic capacity of metal and metal oxide, metal exhibits better performance as a catalyst for the improvement of hydrogen storage, when considering the hydrogen storage system. When a metal oxide with an m.p. lower than the temperature of heat treatment was used, the metal oxide was changed to metal during the heat treatment, developing a micropore structure. The activation process produced a high specific surface area of up to 2900 m{sup 2}/g and a pore volume of up to 2.5 cc/g. The amount of hydrogen adsorption reached approximately 3 wt% at 100 bar and room temperature. (author)

Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

Directory of Open Access Journals (Sweden)

Nguyen Duc Hoa

2015-01-01

Full Text Available Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas sensor applications are introduced. The advantages of meso-/nanoporous metal oxides are also presented, taking into account the crystallinity and ordered/disordered porous structures. Second, the synthesis methods of meso-/nanoporous metal oxides including the soft-template, hard-template, and temple-free methods are introduced, in which the advantages and disadvantages of each synthetic method are figured out. Third, the applications of meso-/nanoporous metal oxides as gas sensors are presented. The gas nanosensors are designed based on meso-/nanoporous metal oxides for effective detection of toxic gases. The sensitivity, selectivity, and stability of the meso-/nanoporous gas nanosensors are also discussed. Finally, some conclusions and an outlook are presented.

Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin

Directory of Open Access Journals (Sweden)

Ana Franco

2017-07-01

Full Text Available Vanillin is one of the most commonly used natural products, which can also be produced from lignin-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, ferulic acid etc. have been effectively used in the past few years. However, selective and efficient production of vanillin from these feedstocks still remains an issue to replace the existing process. In this work, new transition metal-based catalysts were proposed to investigate their efficiency in vanillin production. Reduced graphene oxide supported Fe and Co catalysts showed high conversion of isoeugenol under mild reaction conditions using H2O2 as oxidizing agent. Fe catalysts were more selective as compared to Co catalysts, providing a 63% vanillin selectivity at 61% conversion in 2 h. The mechanochemical process was demonstrated as an effective approach to prepare supported metal catalysts that exhibited high activity for the production of vanillin from isoeugenol.

Effect of Different Binders on the Electrochemical Performance of Metal Oxide Anode for Lithium-Ion Batteries

Science.gov (United States)

Wang, Rui; Feng, Lili; Yang, Wenrong; Zhang, Yinyin; Zhang, Yanli; Bai, Wei; Liu, Bo; Zhang, Wei; Chuan, Yongming; Zheng, Ziguang; Guan, Hongjin

2017-10-01

When testing the electrochemical performance of metal oxide anode for lithium-ion batteries (LIBs), binder played important role on the electrochemical performance. Which binder was more suitable for preparing transition metal oxides anodes of LIBs has not been systematically researched. Herein, five different binders such as polyvinylidene fluoride (PVDF) HSV900, PVDF 301F, PVDF Solvay5130, the mixture of styrene butadiene rubber and sodium carboxymethyl cellulose (SBR+CMC), and polyacrylonitrile (LA133) were studied to make anode electrodes (compared to the full battery). The electrochemical tests show that using SBR+CMC and LA133 binder which use water as solution were significantly better than PVDF. The SBR+CMC binder remarkably improve the bonding capacity, cycle stability, and rate performance of battery anode, and the capacity retention was about 87% after 50th cycle relative to the second cycle. SBR+CMC binder was more suitable for making transition metal oxides anodes of LIBs.

Reduction of metal oxides in metal carbide fusion superheated with plasma

Energy Technology Data Exchange (ETDEWEB)

Hedai, L

1981-01-01

A significant part of metals is capable of binding a high quantity of carbon in the form of carbide. The carbide fusion produced as a result of smelting and superheating, metal carbides with the use of plasma might be a medium to be utilized for the reduction of different metal oxides, whilst also the original carbide structure of the metal carbides will be reduced to metallic structure. The experiments conducted by making use of plasma equipment, of 20, 55 and 100 kW performances are described. On the basis of the results of the experiments performed, the following statements are to be made. The oxide reductions taking place in the metal carbide fusion might also be carried out in open-hearth furnaces, because reducing atmosphere is not necessitated during this procedure. The quantity of energy required is basically defined by the energy needed for smelting and superheating the metal carbide. The method for producing the metal described may be mainly applied for the allied production of high-purity steels as well as for that of ferro-alloys.

A General Synthesis Strategy for Hierarchical Porous Metal Oxide Hollow Spheres

Directory of Open Access Journals (Sweden)

Huadong Fu

2015-01-01

Full Text Available The hierarchical porous TiO2 hollow spheres were successfully prepared by using the hydrothermally synthesized colloidal carbon spheres as templates and tetrabutyl titanate as inorganic precursors. The diameter and wall thickness of hollow TiO2 spheres were determined by the hard templates and concentration of tetrabutyl titanate. The particle size, dispersity, homogeneity, and surface state of the carbon spheres can be easily controlled by adjusting the hydrothermal conditions and adding certain amount of the surfactants. The prepared hollow spheres possessed the perfect spherical shape, monodispersity, and hierarchically pore structures, and the further experiment verified that the present approach can be used to prepare other metal oxide hollow spheres, which could be used as catalysis, fuel cells, lithium-air battery, gas sensor, and so on.

Metal Oxide/Graphene Composites for Supercapacitive Electrode Materials.

Science.gov (United States)

Jeong, Gyoung Hwa; Baek, Seungmin; Lee, Seungyeol; Kim, Sang-Wook

2016-04-05

Graphene composites with metal or metal oxide nanoparticles have been extensively investigated owing to their potential applications in the fields of fuel cells, batteries, sensing, solar cells, and catalysis. Among them, much research has focused on supercapacitor applications and have come close to realization. Composites include monometal oxides of cobalt, nickel, manganese, and iron, as well as their binary and ternary oxides. In addition, their morphological control and hybrid systems of carbon nanotubes have also been investigated. This review presents the current trends in research on metal oxide/graphene composites for supercapacitors. Furthermore, methods are suggested to improve the properties of electrochemical capacitor electrodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Texture and microstructure analysis of epitaxial oxide layers prepared on textured Ni-12wt%Cr tapes

Energy Technology Data Exchange (ETDEWEB)

Huehne, R; Kursumovic, A; Tomov, R I; Glowacki, B A [Department of Materials Science and IRC in Superconductivity, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Holzapfel, B [Institut fuer Festkoerper- und Werkstoffforschung, Helmholtzstrasse 20, 01069 Dresden (Germany); Evetts, J E [Department of Materials Science and IRC in Superconductivity, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

2003-05-07

Oxide layers for the preparation of YBa{sub 2}Cu{sub 3}O{sub 7-x} coated conductors were grown on highly textured Ni-12wt%Cr tapes in pure oxygen using surface oxidation epitaxy at temperatures between 1000 deg. C and 1300 deg. C. Microstructural investigations revealed a layered oxide structure. The upper layer consists mainly of dense cube textured NiO. This is followed by a porous layer containing NiO and NiCr{sub 2}O{sub 4} particles. A detailed texture analysis showed a cube-on-cube relationship of the NiCr{sub 2}O{sub 4} spinel to the metal substrate. Untextured Cr{sub 2}O{sub 3} particles in a nickel matrix were found in a third layer arising from internal oxidation of the alloy. A high surface roughness and mechanical instability of the oxide were observed, depending on oxidation temperature and film thickness. However, mechanically stable oxide layers have been prepared using an additional annealing step in a protective atmosphere. Additionally, mechanical polishing or a second buffer layer, which grows with a higher smoothness, may be applied to reduce the surface roughness for coated conductor applications.

Self-assembled monolayers on metal oxides : applications in nanotechnology

NARCIS (Netherlands)

Yildirim, O.

2010-01-01

The thesis describes the use of phosph(on)ate-based self-assembled monolayers (SAMs) to modify and pattern metal oxides. Metal oxides have interesting electronic and magnetic properties such as insulating, semiconducting, metallic, ferromagnetic etc. and SAMs can tailor the surface properties. FePt

Adsorption of heavy metals from aqueous solutions by Mg-Al-Zn mingled oxides adsorbent.

Science.gov (United States)

El-Sayed, Mona; Eshaq, Gh; ElMetwally, A E

2016-10-01

In our study, Mg-Al-Zn mingled oxides were prepared by the co-precipitation method. The structure, composition, morphology and thermal stability of the synthesized Mg-Al-Zn mingled oxides were analyzed by powder X-ray diffraction, Fourier transform infrared spectrometry, N 2 physisorption, scanning electron microscopy, differential scanning calorimetry and thermogravimetry. Batch experiments were performed to study the adsorption behavior of cobalt(II) and nickel(II) as a function of pH, contact time, initial metal ion concentration, and adsorbent dose. The maximum adsorption capacity of Mg-Al-Zn mingled oxides for cobalt and nickel metal ions was 116.7 mg g -1 , and 70.4 mg g -1 , respectively. The experimental data were analyzed using pseudo-first- and pseudo-second-order kinetic models in linear and nonlinear regression analysis. The kinetic studies showed that the adsorption process could be described by the pseudo-second-order kinetic model. Experimental equilibrium data were well represented by Langmuir and Freundlich isotherm models. Also, the maximum monolayer capacity, q max , obtained was 113.8 mg g -1 , and 79.4 mg g -1 for Co(II), and Ni(II), respectively. Our results showed that Mg-Al-Zn mingled oxides can be used as an efficient adsorbent material for removal of heavy metals from industrial wastewater samples.

A new rapid chemical route to prepare reduced graphene oxide using copper metal nanoparticles

International Nuclear Information System (INIS)

Wu Tao; Gao Jianping; Xu Xiaoyang; Qiu Haixia; Wang Wei; Gao Chunjuan

2013-01-01

Copper metal nanoparticles were used as a reducing agent to reduce graphene oxide (GO). The reaction was complete in about 10 min and did not involve the use of any toxic reagents or acids that are typically used in the reduction of GO by Zn and Fe powders. The high reduction activity of the Cu nanoparticles, compared to Cu powder, may be the result of the formation of Cu 2 O nanoparticles. The effect of the mass ratio of the metal to GO for this reduction was also investigated. The reduction of the GO was verified by ultraviolet–visible absorption spectroscopy, x-ray diffraction, thermogravimetric analysis, Raman spectroscopy, x-ray photoelectron spectroscopy and transmission electron microscopy. After reduction, Cu 2 O supported on reduced GO was formed and showed superior catalytic ability for the degradation of a model dye pollutant, methylene blue. (paper)

Pure and multi metal oxide nanoparticles: synthesis, antibacterial and cytotoxic properties.

Science.gov (United States)

Stankic, Slavica; Suman, Sneha; Haque, Francia; Vidic, Jasmina

2016-10-24

Th antibacterial activity of metal oxide nanoparticles has received marked global attention as they can be specifically synthesized to exhibit significant toxicity to bacteria. The importance of their application as antibacterial agents is evident keeping in mind the limited range and effectiveness of antibiotics, on one hand, and the plethora of metal oxides, on the other, along with the propensity of nanoparticles to induce resistance being much lower than that of antibiotics. Effective inhibition against a wide range of bacteria is well known for several nano oxides consisting of one metal (Fe 3 O 4 , TiO 2 , CuO, ZnO), whereas, research in the field of multi-metal oxides still demands extensive exploration. This is understandable given that the relationship between physicochemical properties and biological activity seems to be complex and difficult to generalize even for metal oxide nanoparticles consisting of only one metal component. Also, despite the broad scope that metal oxide nanoparticles have as antibacterial agents, there arise problems in practical applications taking into account the cytotoxic effects. In this respect, the consideration of polymetallic oxides for biological applications becomes even greater since these can provide synergetic effects and unify the best physicochemical properties of their components. For instance, strong antibacterial efficiency specific of one metal oxide can be complemented by non-cytotoxicity of another. This review presents the main methods and technological advances in fabrication of nanostructured metal oxides with a particular emphasis to multi-metal oxide nanoparticles, their antibacterial effects and cytotoxicity.

Pure and multi metal oxide nanoparticles: synthesis, antibacterial and cytotoxic properties

Directory of Open Access Journals (Sweden)

Slavica Stankic

2016-10-01

Full Text Available Abstract Th antibacterial activity of metal oxide nanoparticles has received marked global attention as they can be specifically synthesized to exhibit significant toxicity to bacteria. The importance of their application as antibacterial agents is evident keeping in mind the limited range and effectiveness of antibiotics, on one hand, and the plethora of metal oxides, on the other, along with the propensity of nanoparticles to induce resistance being much lower than that of antibiotics. Effective inhibition against a wide range of bacteria is well known for several nano oxides consisting of one metal (Fe3O4, TiO2, CuO, ZnO, whereas, research in the field of multi-metal oxides still demands extensive exploration. This is understandable given that the relationship between physicochemical properties and biological activity seems to be complex and difficult to generalize even for metal oxide nanoparticles consisting of only one metal component. Also, despite the broad scope that metal oxide nanoparticles have as antibacterial agents, there arise problems in practical applications taking into account the cytotoxic effects. In this respect, the consideration of polymetallic oxides for biological applications becomes even greater since these can provide synergetic effects and unify the best physicochemical properties of their components. For instance, strong antibacterial efficiency specific of one metal oxide can be complemented by non-cytotoxicity of another. This review presents the main methods and technological advances in fabrication of nanostructured metal oxides with a particular emphasis to multi-metal oxide nanoparticles, their antibacterial effects and cytotoxicity.

Preparation of PtRu/C anode electrocatalysts using gamma radiation for methanol electro-oxidation

International Nuclear Information System (INIS)

Silva, Dionisio Fortunato da

2006-01-01

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

Effect of oxygen on decomposition of nitrous oxide over various metal oxide catalysts

International Nuclear Information System (INIS)

Satsuma, Atsushi; Maeshima, Hajime; Watanabe, Kiyoshi; Hattori, Tadashi

2001-01-01

The inhibitory effect of oxygen on decomposition of nitrous oxide over various metal oxide catalysts was investigated. The activity of nitrous oxide decomposition significantly decreased over CuO, Co 3 O 4 , NiO, Fe 2 O 3 , SnO 2 , In 2 O 3 and Cr 2 O 3 by reversible adsorption of oxygen onto the active sites. On the contrary to this, there was no or small change in the activity of TiO 2 , Al 2 O 3 , MgO, La 2 O 3 and CaO. A good correlation was observed between the degree of inhibition and the heat of formation of metal oxides. On the basis of kinetic model, the reduction of catalytic activity in the presence of oxygen was rationalized with the strength of oxygen adsorption on the metal oxide surface. (author)

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....

Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

International Nuclear Information System (INIS)

Galloway, H.C.

1995-12-01

Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides

Comparison of properties of silver-metal oxide electrical contact materials

Directory of Open Access Journals (Sweden)

Ćosović V.

2012-01-01

Full Text Available Changes in physical properties such as density, porosity, hardness and electrical conductivity of the Ag-SnO2 and Ag-SnO2In2O3 electrical contact materials induced by introduction of metal oxide nanoparticles were investigated. Properties of the obtained silver-metal oxide nanoparticle composites are discussed and presented in comparison to their counterparts with the micro metal oxide particles as well as comparable Ag-SnO2WO3 and Ag-ZnO contact materials. Studied silvermetal oxide composites were produced by powder metallurgy method from very fine pure silver and micro- and nanoparticle metal oxide powders. Very uniform microstructures were obtained for all investigated composites and they exhibited physical properties that are comparable with relevant properties of equivalent commercial silver based electrical contact materials. Both Ag-SnO2 and Ag- SnO2In2O3 composites with metal oxide nanoparticles were found to have lower porosity, higher density and hardness than their respective counterparts which can be attributed to better dispersion hardening i.e. higher degree of dispersion of metal oxide in silver matrix.

Selective propene oxidation on mixed metal oxide catalysts

International Nuclear Information System (INIS)

James, David William

2002-01-01

Selective catalytic oxidation processes represent a large segment of the modern chemical industry and a major application of these is the selective partial oxidation of propene to produce acrolein. Mixed metal oxide catalysts are particularly effective in promoting this reaction, and the two primary candidates for the industrial process are based on iron antimonate and bismuth molybdate. Some debate exists in the literature regarding the operation of these materials and the roles of their catalytic components. In particular, iron antimonate catalysts containing excess antimony are known to be highly selective towards acrolein, and a variety of proposals for the enhanced selectivity of such materials have been given. The aim of this work was to provide a direct comparison between the behaviour of bismuth molybdate and iron antimonate catalysts, with additional emphasis being placed on the component single oxide phases of the latter. Studies were also extended to other antimonate-based catalysts, including cobalt antimonate and vanadium antimonate. Reactivity measurements were made using a continuous flow microreactor, which was used in conjunction with a variety of characterisation techniques to determine relationships between the catalytic behaviour and the properties of the materials. The ratio of Fe/Sb in the iron antimonate catalyst affects the reactivity of the system under steady state conditions, with additional iron beyond the stoichiometric value being detrimental to the acrolein selectivity, while extra antimony provides a means of enhancing the selectivity by decreasing acrolein combustion. Studies on the single antimony oxides of iron antimonate have shown a similarity between the reactivity of 'Sb 2 O 5 ' and FeSbO 4 , and a significant difference between these and the Sb 2 O 3 and Sb 2 O 4 phases, implying that the mixed oxide catalyst has a surface mainly comprised of Sb 5+ . The lack of reactivity of Sb 2 O 4 implies a similarity of the surface with

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.

Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium–Oxygen Batteries

Energy Technology Data Exchange (ETDEWEB)

Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E.; Wang, Chong-Min; Zhang, Ji-Guang

2016-08-10

Lithium-oxygen (Li-O2) battery has an extremely high theoretical specific energy density as compared with conventional energy storage systems. However, practical application of Li-O2 battery system still faces significant challenges, especially its poor cyclability. In this work, we report a new approach to synthesis ultrafine metal oxide nanocatalysts through an electrochemical pre-lithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20~30 nm to a uniformly distributed domain of ~ 2 nm and largely improved their catalytic activity. Structurally, the pre-lithiated NCO NWs are featured by ultrafine NiO/CoO nanoparticles, which show high stability during prolonged cycles in terms of morphology and the particle size, therefore maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. Li-O2 battery using this catalyst has demonstrated an initial capacity of 29,280 mAh g-1 and has retained a stable capacity of over 1,000 mAh g-1 after 100 cycles based on the weight of NCO active material. Direct in-situ TEM observation conclusively reveals the lithiation/delithiation process of as-prepared NCO NWs, clarifying the NCO/Li electrochemical reaction mechanism that can be extended to other transition-metal oxides and providing the in depth understandings on the catalysts and battery chemistries of other ternary transition-metal oxides.

Preparation and characterization of sugar cane bagasse fiber modified with nanoparticles of zirconium oxide

International Nuclear Information System (INIS)

Carvalho, K.C.C. de; Mulinari, D.R.; Voorwald, H.C.J.; Cioffi, M.O.H.

2010-01-01

The sugar cane bagasse fiber are renewable materials and have great application potential when used as reinforcement in a polymer matrix to give rise to composite materials and as supports for adsorption of heavy metals. This paper therefore describes the preparation and characterization of bleached and hydrated zirconium oxide modified sugar cane bagasse fiber by conventional precipitation method. Through the technique of electron microscopy we observed the presence of oxide nanoparticles on the fiber surface, proving the efficiency of the conventional precipitation method. With the X-ray diffraction analysis it was determined a decrease of 6.2% in the crystallinity index of modified fibers when compared to the bleached fibers showing the deposition of amorphous zirconium oxide on the fiber surface. (author)

Synthesis of vertically aligned metal oxide nanostructures

KAUST Repository

Roqan, Iman S.; Flemban, Tahani H.

2016-01-01

ablation of a target including a metal oxide and, optionally, a dopant. In some embodiments zinc oxide nanostructures are deposited onto a substrate by pulsed laser deposition of a zinc oxide target using an excimer laser emitting UV radiation. The zinc

Preparation, properties, and some recent studies of the actinide metals

International Nuclear Information System (INIS)

Haire, R.G.

1985-01-01

The actinide elements form a unique series of metals. The variation in their physial properties combined with the varying availability of the different elements offers a challenge to the preparative scientist. This article provides a brief review of selected methods used for preparing μg to kg amounts of the actinide metals and the properties of these metals. In addition, some recent studies on selected actinide metals are discussed. 62 refs

Multiscale model of metal alloy oxidation at grain boundaries

International Nuclear Information System (INIS)

Sushko, Maria L.; Alexandrov, Vitaly; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

2015-01-01

High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr 2 O 3 . This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl 2 O 4 . Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3–10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr 2 O 3 has a plate-like structure with 1.2–1.7 nm wide pores running along the grain boundary, while NiAl 2 O 4 has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular direction providing an additional

Formation of iron oxides from acid mine drainage and magnetic separation of the heavy metals adsorbed iron oxides

Energy Technology Data Exchange (ETDEWEB)

Kwon, Hee Won; Kim, Jeong Jin; Kim, Young Hun [Andong National University, Andong (Korea, Republic of); Ha, Dong Woo [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

2016-03-15

There are a few thousand abandoned metal mines in South Korea. The abandoned mines cause several environmental problems including releasing acid mine drainage (AMD), which contain a very high acidity and heavy metal ions such as Fe, Cu, Cd, Pb, and As. Iron oxides can be formed from the AMD by increasing the solution pH and inducing precipitation. Current study focused on the formation of iron oxide in an AMD and used the oxide for adsorption of heavy metals. The heavy metal adsorbed iron oxide was separated with a superconducting magnet. The duration of iron oxide formation affected on the type of mineral and the degree of magnetization. The removal rate of heavy metal by the adsorption process with the formed iron oxide was highly dependent on the type of iron oxide and the solution pH. A high gradient magnetic separation (HGMS) system successfully separated the iron oxide and harmful heavy metals.

Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

Science.gov (United States)

Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

2010-07-13

Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

Chemically synthesized metal-oxide-metal segmented nanowires with high ferroelectric response

International Nuclear Information System (INIS)

Herderick, Edward D; Padture, Nitin P; Polomoff, Nicholas A; Huey, Bryan D

2010-01-01

A chemical synthesis method is presented for the fabrication of high-definition segmented metal-oxide-metal (MOM) nanowires in two different ferroelectric oxide systems: Au-BaTiO 3 -Au and Au-PbTiO 3 -Au. This method entails electrodeposition of segmented nanowires of Au-TiO 2 -Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO 2 segments into BaTiO 3 or PbTiO 3 segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.

Method for continuous synthesis of metal oxide powders

Science.gov (United States)

Berry, David A.; Haynes, Daniel J.; Shekhawat, Dushyant; Smith, Mark W.

2015-09-08

A method for the rapid and continuous production of crystalline mixed-metal oxides from a precursor solution comprised of a polymerizing agent, chelated metal ions, and a solvent. The method discharges solution droplets of less than 500 .mu.m diameter using an atomizing or spray-type process into a reactor having multiple temperature zones. Rapid evaporation occurs in a first zone, followed by mixed-metal organic foam formation in a second zone, followed by amorphous and partially crystalline oxide precursor formation in a third zone, followed by formation of the substantially crystalline mixed-metal oxide in a fourth zone. The method operates in a continuous rather than batch manner and the use of small droplets as the starting material for the temperature-based process allows relatively high temperature processing. In a particular embodiment, the first zone operates at 100-300.degree. C., the second zone operates at 300-700.degree. C., and the third operates at 700-1000.degree. C., and fourth zone operates at at least 700.degree. C. The resulting crystalline mixed-metal oxides display a high degree of crystallinity and sphericity with typical diameters on the order of 50 .mu.m or less.

Heavy metal oxide glasses as gamma rays shielding material

International Nuclear Information System (INIS)

Kaur, Preet; Singh, Devinder; Singh, Tejbir

2016-01-01

The gamma rays shielding parameters for heavy metal oxide glasses and concrete samples are comparable. However, the transparent nature of glasses provides additional feature to visualize inside the shielding material. Hence, different researchers had contributed in computing/measuring different shielding parameters for different configurations of heavy metal oxide glass systems. In the present work, a detailed study on different heavy metal (_5_6Ba, _6_4Gd, _8_2Pb, _8_3Bi) oxide glasses has been presented on the basis of different gamma rays shielding parameters as reported by different researchers in the recent years. It has been observed that among the selected heavy metal oxide glass systems, Bismuth based glasses provide better gamma rays shielding. Hence, Bismuth based glasses can be better substitute to concrete walls at nuclear reactor sites and nuclear labs.

Heavy metal oxide glasses as gamma rays shielding material

Energy Technology Data Exchange (ETDEWEB)

Kaur, Preet; Singh, Devinder; Singh, Tejbir, E-mail: dr.tejbir@gmail.com

2016-10-15

The gamma rays shielding parameters for heavy metal oxide glasses and concrete samples are comparable. However, the transparent nature of glasses provides additional feature to visualize inside the shielding material. Hence, different researchers had contributed in computing/measuring different shielding parameters for different configurations of heavy metal oxide glass systems. In the present work, a detailed study on different heavy metal ({sub 56}Ba, {sub 64}Gd, {sub 82}Pb, {sub 83}Bi) oxide glasses has been presented on the basis of different gamma rays shielding parameters as reported by different researchers in the recent years. It has been observed that among the selected heavy metal oxide glass systems, Bismuth based glasses provide better gamma rays shielding. Hence, Bismuth based glasses can be better substitute to concrete walls at nuclear reactor sites and nuclear labs.

Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

Science.gov (United States)

Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

2015-08-01

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

Science.gov (United States)

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-02-01

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

Systematic study of metal-insulator-metal diodes with a native oxide

KAUST Repository

Donchev, E.; Gammon, P. M.; Pang, J. S.; Petrov, P. K.; Alford, N. McN.

2014-01-01

© 2014 SPIE. In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna

Room temperature plasma oxidation: A new process for preparation of ultrathin layers of silicon oxide, and high dielectric constant materials

International Nuclear Information System (INIS)

Tinoco, J.C.; Estrada, M.; Baez, H.; Cerdeira, A.

2006-01-01

In this paper we present basic features and oxidation law of the room temperature plasma oxidation (RTPO), as a new process for preparation of less than 2 nm thick layers of SiO 2 , and high-k layers of TiO 2 . We show that oxidation rate follows a potential law dependence on oxidation time. The proportionality constant is function of pressure, plasma power, reagent gas and plasma density, while the exponent depends only on the reactive gas. These parameters are related to the physical phenomena occurring inside the plasma, during oxidation. Metal-Oxide-Semiconductor (MOS) capacitors fabricated with these layers are characterized by capacitance-voltage, current-voltage and current-voltage-temperature measurements. Less than 2.5 nm SiO 2 layers with surface roughness similar to thermal oxide films, surface state density below 3 x 10 11 cm -2 and current density in the expected range for each corresponding thickness, were obtained by RTPO in a parallel-plate reactor, at 180 mW/cm 2 and pressure range between 9.33 and 66.5 Pa (0.07 and 0.5 Torr) using O 2 and N 2 O as reactive gases. MOS capacitors with TiO 2 layers formed by RTPO of sputtered Ti layers are also characterized. Finally, MOS capacitors with stacked layers of TiO 2 over SiO 2 , both layers obtained by RTPO, were prepared and evaluated to determine the feasibility of the use of TiO 2 as a candidate for next technology nodes

Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

Energy Technology Data Exchange (ETDEWEB)

Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

2015-07-01

Stress corrosion cracking (SCC)can cause failures of CANDU Zircaloy-4 fuel sheathing. The process occurs when a corrosive element (i.e.,iodine) interacts with a susceptible material that is under sufficient strain at a high temperature. Currently, there is an ongoing effort to improve SCC mitigation strategies for future iterations of CANDU reactors. A potential mechanism for SCC mitigation involves utilizing alkali metal oxides and alkaline earth metal oxides that will sequester corrosive iodine while actively repairing a protective oxide layer on the sheath. SCC tests performed with sodium oxide (Na{sub 2}O) and calcium oxide (CaO) have shown to decrease significantly the sheath degradation. (author)

Plasma metallization of aluminium oxide powder

International Nuclear Information System (INIS)

Smirnov, A.I.; Petrunichev, V.A.

1981-01-01

The sintering ability of cermets of metallized granulas of aluminium and matrix materials, such as chromium, nickel and nichrome is studied. Deformation tests of samples of cermets with molybdenum coated granules show satisfactory results at normal and high temperatures without fracture of metall-oxide interfaces [ru

Plasma electrolytic oxidation of metals

Directory of Open Access Journals (Sweden)

Stojadinović Stevan

2013-01-01

Full Text Available In this lecture results of the investigation of plasma electrolytic oxidation (PEO process on some metals (aluminum, titanium, tantalum, magnesium, and zirconium were presented. Whole process involves anodizing metals above the dielectric breakdown voltage where numerous micro-discharges are generated continuously over the coating surface. For the characterization of PEO process optical emission spectroscopy and real-time imaging were used. These investigations enabled the determination of electron temperature, electron number density, spatial density of micro-discharges, the active surface covered by micro-discharges, and dimensional distribution of micro-discharges at various stages of PEO process. Special attention was focused on the results of the study of the morphology, chemical, and phase composition of oxide layers obtained by PEO process on aluminum, tantalum, and titanium in electrolytes containing tungsten. Physicochemical methodes: atomic force microscopy (AFM, scanning electron microscopy (SEM-EDS, x-ray diffraction (XRD, x-ray photoelectron spectroscopy (XPS, and Raman spectroscopy served as tools for examining obtained oxide coatings. Also, the application of the obtained oxide coatings, especially the application of TiO2/WO3 coatings in photocatalysis, were discussed.

Hard template synthesis of metal nanowires

Science.gov (United States)

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-11-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

Development of the method for preparation of actinide metals

International Nuclear Information System (INIS)

Shiokawa, Y.; Hasegawa, K.; Takahashi, M.; Suzuki, K.

1997-01-01

The uranium amalgam was quantitatively prepared by electrolysis from the aqueous solution containing acetic acid and sodium acetate using mercury cathode. A bright button or brown porous one of uranium metal was obtained by thermal decomposition of the amalgam. The purity was found to be much higher than commercial grade metal of ca.99.95%. As a result of this work, the simple and easy procedure for preparation of uranium metal with high purity level on the laboratory scale has been developed. (author)

Development of the Method for Preparation of Actinide Metals

OpenAIRE

Shiokawa, Y.; Hasegawa, K.; Takahashi, M.; Suzuki, K.

1997-01-01

The uranium amalgam was quantitatively prepared by electrolysis from the aqueous solution containing acetic acid and sodium acetate using mercury cathode. A bright button or brown porous one of uranium metal was obtained by thermal decomposition of the amalgam. The purity was found to be much higher than commercial grade metal of ca.99.95%. As a result of this work, the simple and easy procedure for preparation of uranium metal with high purity level on the laboratory scale has been developed.

Electrocatalytic Activity for CO, MeOH, and EtOH Oxidation on the Surface of Pt-Ru Nanoparticles Supported by Metal Oxide

Directory of Open Access Journals (Sweden)

Kwang-Sik Sim

2011-01-01

Full Text Available This paper describes the electrocatalytic activity for CO, MeOH, and EtOH oxidation on the surface of Pt-Ru nanoparticles supported by metal oxide (Nb-TiO2-H prepared for use in a fuel cell. To prepare Nb-TiO2-supported Pt-Ru nanoparticles, first, the Nb-TiO2 supports were prepared by sol-gel reaction of titanium tetraisopropoxide with a small amount of the niobium ethoxide in polystyrene (PS colloids. Second, Pt-Ru nanoparticles were then deposited by chemical reduction of the Pt4+ and Ru3+ ions onto Nb-TiO2 supports (Pt-Ru@Nb-TiO2-CS. Nb element was used to reduce electrical resistance to facilitate electron transport during the electrochemical reactions on a fuel cell electrode. Finally, the Pt-Ru@Nb-TiO2-H catalysts were formed by the removal of core-polystyrene ball from Pt-Ru@TiO2-CS at 500∘C. The successfully prepared Pt-Ru electrocatalysts were confirmed via TEM, XPS, and ICP analysis. The electrocatalytic efficiency of Pt-Ru nanoparticles was evaluated via CO, MeOH, and EtOH oxidation for use in a direct methanol fuel cell (DMFC. As a result, the Pt-Ru@Nb-TiO2-H electrodes showed high electrocatalytic activity for the electrooxidation of CO, MeOH, and EtOH.

PREPARATION OF A POLYMER ARTICLE FOR SELECTIVE METALLIZATION

DEFF Research Database (Denmark)

2008-01-01

The present invention relates to the field of selective metallization, and in particular to preparing a polymer article for selective metallization by submerging the article in a first liquid, and while submergedirradiate the article by a laser beam the area of the article on which the metal...... is to be deposited. An activation step, prior to the selective metallization, comprises submerging the article in an activation liquid for depositing seedparticles in the selected area. The irradiation of the selected area is proportionate so as to cause a temporary meltingof the polymer in the surface...... of the selected area of the polymer article. The invention is advantageous in that the preparation may be performed with a relatively high scan rate across the polymer article, and in that a quite limited use of toxic chemicals....

Impacts of metal and metal oxide nanoparticles on marine organisms

International Nuclear Information System (INIS)

Baker, Tony J.; Tyler, Charles R.; Galloway, Tamara S.

2014-01-01

Increasing use of metal and metal oxide nanoparticles [Me(O)NPs] in products means many will inevitably find their way into marine systems. Their likely fate here is sedimentation following hetero-aggregation with natural organic matter and/or free anions, putting benthic, sediment-dwelling and filter feeding organisms most at risk. In marine systems, Me(O)NPs can absorb to micro-organisms with potential for trophic transfer following consumption. Filter feeders, especially bivalves, accumulate Me(O)NPs through trapping them in mucus prior to ingestion. Benthic in-fauna may directly ingest sedimented Me(O)NPs. In fish, uptake is principally via the gut following drinking, whilst Me(O)NPs caught in gill mucus may affect respiratory processes and ion transport. Currently, environmentally-realistic Me(O)NP concentrations are unlikely to cause significant adverse acute health problems, however sub-lethal effects e.g. oxidative stresses have been noted in many organisms, often deriving from dissolution of Ag, Cu or Zn ions, and this could result in chronic health impacts. -- Highlights: • Nanoparticle (NP) use increasing, and NPs ultimately discharged to marine systems. • Metal ion dissolution from NPs causes oxidative stress at relevant concentrations. • Bioaccumulation and trophic transfer of NPs likely at all levels of marine food webs. • Biofilms and filter feeders are major NP accumulators, but many Classes lack study. • Current release levels unlikely to cause chronic damage, but may be a future issue. -- Exposure to metal (oxide) nanoparticles causes sub-lethal effects in marine organisms, the extent of which is related principally to the organisms' feeding regime, habitat and lifestyle

Glycerol electro-oxidation in alkaline medium using Pd/C and PdSn/C electrocatalysts prepared by electron beam irradiation

International Nuclear Information System (INIS)

Geraldes, Adriana Napoleao; Silva, Dionisio Fortunato da; Pino, Eddy Segura; Spinace, Estevan Vitorio; Oliveira Neto, Almir; Linardi, Marcelo; Santos, Mauro Coelhos dos

2013-01-01

Carbon-supported metal nanoparticles were prepared for fuel cell applications by radiation-induced reduction of metal ions precursors. Pd/C and PdSn/C electrocatalysts (Pd:Sn atomic ratio 90:10), prepared by using electron beam irradiation, were tested for glycerol electro-oxidation in single alkaline direct glycerol fuel cell (ADGFC). EDX analysis showed that the Pd:Sn atomic ratio is very similar to the nominal one. X-ray diffractograms of PdSn/C electrocatalyst showed the presence of Pd (fcc) phase. Cyclic voltammetry (CV) indicated that Pd/C and PdSn/C electrocatalysts have good activity for glycerol electro-oxidation, at room temperature. Experiments with single ADGFC were carried out from 60 to 90 deg C, using Pd/C and PdSn/C electrocatalysts and glycerol 2.0 mol.L -1 , as fuel. The best performance was obtained at 85 deg C, for both electrocatalysts. The Pd/C and PdSn/C electrocatalysts showed similar performance (34 mW cm -2 ), at 85 deg C. (author)

Electrochromism in transition metal oxides

International Nuclear Information System (INIS)

Estrada, W.

1993-01-01

Electrochromism is discussed for transition metal oxides. Particularly tungsten oxide and nickel oxide are reviewed, in order to put forth the different aspects of the field. Since this phenomena has been reviewed by several authors, it is not tried to be comprehensive but rather pedagogical. The basic requirements for a material -in both non-emissive displays and energy efficiency applications- to be electrochromic, a general view of electrochromic mechanism, anodic and cathodic electrochromic materials, and current problems for a electrochromic theory are presented. (author) 45 refs., 8 figs

Chemically synthesized metal-oxide-metal segmented nanowires with high ferroelectric response

Energy Technology Data Exchange (ETDEWEB)

Herderick, Edward D; Padture, Nitin P [Department of Materials Science and Engineering, Center for Emergent Materials, Ohio State University, Columbus, OH 43210 (United States); Polomoff, Nicholas A; Huey, Bryan D, E-mail: padture.1@osu.edu [Department of Chemical, Materials, and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

2010-08-20

A chemical synthesis method is presented for the fabrication of high-definition segmented metal-oxide-metal (MOM) nanowires in two different ferroelectric oxide systems: Au-BaTiO{sub 3}-Au and Au-PbTiO{sub 3}-Au. This method entails electrodeposition of segmented nanowires of Au-TiO{sub 2}-Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO{sub 2} segments into BaTiO{sub 3} or PbTiO{sub 3} segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.

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

Hard template synthesis of metal nanowires

OpenAIRE

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-01-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance, and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production o...

Dissolution of Fe(III) (hydr) oxides by metal-EDTA complexes

Science.gov (United States)

Ngwack, Bernd; Sigg, Laura

1997-03-01

The dissolution of Fe(III)(hydr)oxides (goethite and hydrous ferric oxide) by metal-EDTA complexes occurs by ligand-promoted dissolution. The process is initiated by the adsorption of metal-EDTA complexes to the surface and is followed by the dissociation of the complex at the surface and the release of Fe(III)EDTA into solution. The dissolution rate is decreased to a great extent if EDTA is complexed by metals in comparison to the uncomplexed EDTA. The rate decreases in the order EDTA CaEDTA ≫ PbEDTA > ZnEDTA > CuEDTA > Co(II)EDTA > NiEDTA. Two different rate-limiting steps determine the dissolution process: (1) detachment of Fe(III) from the oxide-structure and (2) dissociation of the metal-EDTA complexes. In the case of goethite, step 1 is slower than step 2 and the dissolution rates by various metals are similar. In the case of hydrous ferric oxide, step 2 is rate-limiting and the effect of the complexed metal is very pronounced.

The base metal of the oxide-coated cathode

International Nuclear Information System (INIS)

Poret, F.; Roquais, J.M.

2005-01-01

The oxide-coated cathode has been the most widely used electron emitter in vacuum electronic devices. From one manufacturing company to another the emissive oxide is either a double-Ba, Sr-or a triple-Ba, Sr, Ca-oxide, having always the same respective compositions. Conversely, the base metal composition is very often proprietary because of its importance in the cathode emission performances. The present paper aims at explaining the operation of the base metal through a review. After a brief introduction, the notion of activator is detailed along with their diffusivities and their associated interfacial compounds. Then, the different cathode life models are described prior to few comments on the composition choice of a base metal. Finally, the specificities of the RCA/Thomson 'bimetal' base metal are presented with a discussion on the optimized composition choice illustrated by a long-term life-test of five different melts

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes

Energy Technology Data Exchange (ETDEWEB)

Jiang, Hao [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ma, Jan [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Li, Chunzhong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2012-08-08

Supercapacitors have attracted huge attention in recent years as they have the potential to satisfy the demand of both huge energy and power density in many advanced technologies. However, poor conductivity and cycling stability remains to be the major challenge for its widespread application. Various strategies have been developed for meeting the ever-increasing energy and power demands in supercapacitors. This Research News article aims to review recent progress in the development of mesoporous carbon incorporated metal oxide nanomaterials, especially metal oxide nanoparticles confined in ordered mesoporous carbon and 1D metal oxides coated with a layer of mesoporous carbon for high-performance supercapacitor applications. In addition, a recent trend in supercapacitor development - hierarchical porous graphitic carbons (HPGC) combining macroporous cores, mesoporous walls, and micropores as an excellent support for metal oxides - is also discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On chemical activity of heavy metal oxides

International Nuclear Information System (INIS)

Mechev, V.V.

1994-01-01

Interaction of solid oxides of heavy nonferrous metals with sulfur and carbon is investigated. The results are discussed. Direct dependence of chemical activity of oxides on disordering of their crystal lattice at heating is established. Beginning of interaction in the systems studied is accompanied by change of oxide conductivity type

Metal oxide/polyaniline nanocomposites: Cluster size and ...

Indian Academy of Sciences (India)

Wintec

Metal oxide/polyaniline nanocomposites; structural properties; magnetic properties. 1. Introduction ... The powder obtained was ground in a motor and pestle, sonicated in ... Figure 1. XRD of (a) iron oxide nanoparticles and (b) iron oxide/PANI (1 : 0⋅4) composite. .... shape of the particles and the anisotropy energy, as also.

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review

Science.gov (United States)

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2012-12-01

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review.

Science.gov (United States)

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2013-01-07

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

Non-traditional Oxidants in Preparative Coordination Chemistry

Science.gov (United States)

Kukushkin, Vadim Yu; Kukushkin, Yurii N.

1986-10-01

The application of nitrosonium and arenediazonium salts, carbenium, silver(I), and mercury(II) ions, protic acids, and amine oxides as oxidants in preparative coordination chemistry is examined. Specific examples illustrate which problems in the field of the synthesis and reactions of coordination compounds can be solved with the aid of these oxidants. The bibliography includes 158 references.

Oxidation Behavior of Simudated Metallic U-Nb Alloys in Air

International Nuclear Information System (INIS)

Lee, Eun Pyo; Ju, June Sik; You, Gil Sung; Cho, Il Je; Kook, Dong Hak; Kim, Ho Dong

2004-01-01

In order to enhance an oxidation resistance of the pure uranium metal under air condition, a small quantity of niobium(Nb) which is known to mitigate metal oxidation is added into uranium metal as an alloying element. A simulated metallic uranium alloy, U-Nb has been fabricated and then oxidized in the range of 200 to under the environment of the pure oxygen gas. The oxidized quantity in terms of the weight gain (wt%) has been measured with the help of a thermogravimetric analyzer. The results show that the oxidation resistance of the U-Nb alloy is considerably enhanced in comparison with that of the pure uranium metal. It is revealed that the oxidation resistance of the former with the niobium content of 1, 2, 3, and 4 wt% is : 1) 1.61, 7.78, 11.76 and 20.14 times at the temperature of 200 .deg. C; 2) 1.45, 5.98, 10.08 and 11.15 times at 250 .deg. C; and 3) 1.33, 4.82, 8.87 and 6.84 times at 300 .deg. C higher than that of the latter, respectively. Besides, it is shown that the activation energy attributable to the oxidation is 17.13-21.92 kcal/mol.

Hydrogen chemisorption and oxidation of transition metal carbides

International Nuclear Information System (INIS)

Bethin, J.R.

1979-01-01

A study was made of the catalytic activity of WC, focusing on the possible influence of point defects. The chemisorption of H on WC and titanium oxycarbides was studied with differential scanning calorimetry. The catalytic activity of these materials for oxidation of H was determined by potentiostatic steady-state and potentiodynamic measurements in acid electrolyte. Compositions of WC surfaces were determined by x-ray photoemission and related to the catalytic behavior. Titanium oxycarbide surfaces were analyzed by Auger electron spectroscopy. Of the carbides tested only one WC preparation was able to chemisorb H. Both WC powders investigated catalyzed H oxidation with similar specific activities. Spectroscopic studies showed that the active surface of WC was a mixture of WO 3 and a carbon-deficient WC phase. This result indicates that carbon vacancies are the active sites in tungsten carbide. Theoretical models of a carbon vacancy surrounded by metal atoms suggested by calculations by other workers support this assignment and identify the important role of the W6s level. The measured value of the heat of chemisorption is consistent with the proposed model

An economic route to mass production of graphene oxide solution for preparing graphene oxide papers

Energy Technology Data Exchange (ETDEWEB)

Liou, Yan-Jia; Tsai, Bo-Da; Huang, Wu-Jang, E-mail: wjhuang@mail.npust.edu.tw

2015-03-15

Highlights: • Graphene oxide paper can be prepared from synthesized graphene sheet containing carbon materials. • Graphene oxide paper can be used as a phase change materials for thermal storage. • To prepare graphene oxide paper from synthesized graphene sheet containing carbon materials could highly reduce the cost. - Abstract: Graphene oxide paper (GOP) is a composite material fabricated from graphene oxide (GO) solution. In addition, it can be a novel and potential material for application on the separation of water vapor from gaseous steam or larger alkali ions from aqueous solution. GOP could be used as electricity and thermal storage materials. The preparation of GO commonly uses high purity natural or artificial graphite. It is difficult to prepare GOP from artificial graphite powder due to the cost of $1,450 US/ton. In this study, we tried to prepare GOPs from homemade graphene sheets containing carbon materials (GSCCMs) and evaluate the thermal properties of GSCCM derived GOPs. Results show that GSCCM derived GOPs have a higher phase transition temperature, and the average mesophase phase change enthalpy is 9.41 J/g, which is 2.87 times higher than graphite derived GOP. Therefore, to prepare GOP from GSCCMs could highly reduce the cost.

A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

Science.gov (United States)

Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang

2016-12-01

In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn2O3, Co3O4 and Cr2O3) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

Metal/silicon Interfaces and Their Oxidation Behavior - Photoemission Spectroscopy Analysis.

Science.gov (United States)

Yeh, Jyh-Jye

Synchrotron radiation photoemission spectroscopy was used to study Ni/Si and Au/Si interface properties on the atomic scale at room temperature, after high temperature annealing and after oxygen exposures. Room temperature studies of metal/Si interfaces provide background for an understanding of the interface structure after elevated temperature annealing. Oxidation studies of Si surfaces covered with metal overlayers yield insight about the effect of metal atoms in the Si oxidation mechanisms and are useful in the identification of subtle differences in bonding relations between atoms at the metal/Si interfaces. Core level and valence band spectra with variable surface sensitivities were used to study the interactions between metal, Si, and oxygen for metal coverages and oxide thickness in the monolayer region. Interface morphology at the initial stage of metal/Si interface formation and after oxidation was modeled on the basis of the evolutions of metal and Si signals at different probing depths in the photoemission experiment. Both Ni/Si and Au/Si interfaces formed at room temperature have a diffusive region at the interface. This is composed of a layer of metal-Si alloy, formed by Si outdiffusion into the metal overlayer, above a layer of interstitial metal atoms in the Si substrate. Different atomic structures of these two regions at Ni/Si interface can account for the two different growth orientations of epitaxial Ni disilicides on the Si(111) surface after thermal annealing. Annealing the Au/Si interface at high temperature depletes all the Au atoms except for one monolayer of Au on the Si(111) surface. These phenomena are attributed to differences in the metal-Si chemical bonding relations associated with specific atomic structures. After oxygen exposures, both the Ni disilicide surface and Au covered Si surfaces (with different coverages and surface orderings) show silicon in higher oxidation states, in comparison to oxidized silicon on a clean surface

Structural and Optical Properties of ZnO Thin Film Prepared by Oxidation of Zn Metal Powders

International Nuclear Information System (INIS)

Hassan, N.K.; Hashim, M.R.

2013-01-01

High quality ZnO nano structures have been fabricated at room temperature by a simple vacuum thermal evaporator from metallic Zn powders (99.999 % purity) on a silicon (100) substrate. The Zn thin films were then transferred into a thermal tube furnace for oxidation at 700 degree Celsius for different time durations. Time was found to be a critical factor in the synthesis. This was followed by characterization of their morphological, structural and optical properties. The morphology of the grown ZnO nano structures exhibited several large grains, which increased gradually with increasing oxidation time. The crystallinity of the grown nano structures was investigated using X-ray diffraction, revealing that the synthesized ZnO was in hexagonal wurtzite phase. The photoluminescence (PL) spectra of the fabricated ZnO nano structures showed high intensity peak in the UV region due to near-band-edge (NBE) emission in which the structures oxidized for 30 min showing highest intensity. (author)

Hard template synthesis of metal nanowires

Directory of Open Access Journals (Sweden)

Go eKawamura

2014-11-01

Full Text Available Metal nanowires (NWs have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

Review on preparation techniques of particle reinforced metal matrix composites

Directory of Open Access Journals (Sweden)

HAO Bin

2006-02-01

Full Text Available This paper reviews the investigation status of the techniques for preparation of metal matrix composites and the research outcomes achieved recently. The mechanisms, characteristics, application ranges and levels of development of these preparation techniques are analyzed. The advantages and the disadvantages of each technique are synthetically evaluated. Lastly, the future directions of research and the prospects for the preparation techniques of metal matrix composites are forecasted.

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

International Nuclear Information System (INIS)

Sieben, Juan Manuel; Duarte, Marta M.E.; Mayer, Carlos E.

2011-01-01

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

Decontamination of U-metal surface by an oxidation etching system

Energy Technology Data Exchange (ETDEWEB)

Stout, R.B.; Kansa, E.J.; Shaffer, R.J.; Weed, H.C. [California Univ., Livermore, CA (United States). Lawrence Livermore National Lab

2001-07-01

A surface treatment to remove surface contamination from uranium (U) metal and/or hydrides of uranium and heavy metals (HM) from U-metal parts is described. In the case of heavy metal atomic contamination on a surface, and potentially several atomic layers beneath, the surface oxidation treatment combines both chemical and chemically driven mechanical processes. The chemical process is a controlled temperature-time oxidation process to create a thin film of uranium oxide (UO{sub 2} and higher oxides) on the U-metal surface. The chemically driven mechanical process is strain induced by the volume increase as the U-metal surface transforms to a UO{sub 2} surface film. These volume strains are significantly large to cause surface failure spalling/scale formation and thus, removal of a U-oxide film that contains the HM-contaminated surface. The case of a HM-hydride surface contamination layer can be treated similarly by using inert hot gas to decompose the U-hydrides and/or HM-hydrides that are contiguous with the surface. A preliminary analysis to design and to plan for a sequence of tests is developed. The tests will provide necessary and sufficient data to evaluate the effective implementation and operational characteristics of a safe and reliable system. The following description is limited to only a surface oxidation process for HM-decontamination. (authors)

General access to metal oxide (Metal = Mn, Co, Ni) double-layer nanospheres for application in lithium ion batteries and supercapacitors

International Nuclear Information System (INIS)

Xia, Yuan; Wang, Gang; Zhang, Xing; Wang, Beibei; Wang, Hui

2016-01-01

Highlights: • A series of metal oxide double layer nanospheres were prepared. • The obtained materials show excellent performances in lithium ion batteries and supercapacitors. • The unique structure of double layers is beneficial for superior electrochemical performances. - Abstract: In this work, a series of metal oxide double-layer nanospheres (DLNs), such as Mn 2 O 3 , Co 3 O 4 , NiO, NiCo 2 O 4 , and MnCo 2 O 4 have been successfully synthesized through a general template method. The layers of nanospheres were assembled by different nanostructure units and the removing of the SiO 2 template formed a void of several ten nanometers between the double layers, resulting large specific surface areas for them. The energy storage performances of the as-prepared double-layer nanospheres were further investigated in lithium ion battery and supercapacitor systems. Based on their unique nanostructures, the double-layer nanospheres exhibit excellent electrochemical performance with long cycle stability and high specific capacities or capacitances. The best of these, DLNs-NiCo 2 O 4 can deliver a reversible capacity of 1107 mAh g −1 at 0.25C after 200 cycles in lithium ion battery system, and shows a capacitance of 1088 F g −1 with capacitance loss of less than 3% at 5 A g −1 after 5000 cycles in supercapacitors.

The fabrication and characterization of an ex situ plated lead film electrode prepared with the use of a reversibly deposited mediator metal

International Nuclear Information System (INIS)

Tyszczuk, Katarzyna

2011-01-01

Research highlights: → The lead film electrode prepared with use of the mediator metal was elaborated. → The lead-based sensors were characterized by optical and voltammetric methods. → The adsorptive system of folic acid was employed to investigate a new electrode. → The application of the mediator metal improved properties of a lead film electrode. - Abstract: In this paper an ex situ plated lead film electrode prepared with use of the mediator metal (Zn) was elaborated. The electrochemical method for lead film formation is based on a co-deposition of a metal of interest (Pb) with a reversibly deposited mediator metal (Zn) and then on an oxidation of zinc and further deposition of lead by the appropriate potential. This serves to increase the density of islands of lead atoms, promoting lead film growth. The lead-based sensors were characterized by optical method (atomic force microscopy (AFM)) and as well as cyclic, linear sweep and square wave voltammetry. The adsorptive system of folic acid was employed to investigate the electrochemical characteristics a novel type of lead film electrode. Well-formed stripping peaks and a linear dependence of the stripping current on the folic acid concentration were observed on the lead film electrode prepared with use of the mediator metal while comparative measurements attempted with the lead film electrode prepared without use of the mediator metal were unsuccessful.

Molten salt oxidation of ion-exchange resins doped with toxic metals and radioactive metal surrogates

International Nuclear Information System (INIS)

Yang, Hee-Chul; Cho, Yong-Jun; Yoo, Jae-Hyung; Kim, Joon-Hyung; Eun, Hee-Chul

2005-01-01

Ion-exchange resins doped with toxic metals and radioactive metal surrogates were test-burned in a bench-scale molten salt oxidation (MSO) reactor system. The purposes of this study are to confirm the destruction performance of the two-stage MSO reactor system for the organic ion-exchange resin and to obtain an understanding of the behavior of the fixed toxic metals and the sulfur in the cationic exchange resins. The destruction of the organics is very efficient in the primary reactor. The primarily destroyed products such as carbon monoxide are completely oxidized in the secondary MSO reactor. The overall collection of the sulfur and metals in the two-stage MSO reactor system appeared to be very efficient. Over 99.5% of all the fixed toxic metals (lead and cadmium) and radioactive metal surrogates (cesium, cobalt, strontium) remained in the MSO reactor bottom. Thermodynamic equilibrium calculations and the XRD patterns of the spent salt samples revealed that the collected metals existed in the form of each of their carbonates or oxides, which are non-volatile species at the MSO system operating conditions. (author)

Global DNA methylation and oxidative stress biomarkers in workers exposed to metal oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Liou, Saou-Hsing; Wu, Wei-Te; Liao, Hui-Yi [National Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China); Chen, Chao-Yu; Tsai, Cheng-Yen; Jung, Wei-Ting [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China); Lee, Hui-Ling, E-mail: huilinglee3573@gmail.com [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China)

2017-06-05

Highlights: • Global methylation and oxidative DNA damage levels in nanomaterial handling workers were assessed. • 8-isoprostane in exhaled breath condensate of workers exposed to nanoparticles was higher. • 8-OHdG was negatively correlated with global methylation. • Exposure to metal oxide nanoparticles may lead to global methylation and DNA oxidative damage. - Abstract: This is the first study to assess global methylation, oxidative DNA damage, and lipid peroxidation in workers with occupational exposure to metal oxide nanomaterials (NMs). Urinary and white blood cell (WBC) 8-hydroxydeoxyguanosine (8-OHdG), and exhaled breath condensate (EBC) 8-isoprostane were measured as oxidative stress biomarkers. WBC global methylation was measured as an epigenetic alteration. Exposure to TiO{sub 2}, SiO{sub 2,} and indium tin oxide (ITO) resulted in significantly higher oxidative biomarkers such as urinary 8-OHdG and EBC 8-isoprostane. However, significantly higher WBC 8-OHdG and lower global methylation were only observed in ITO handling workers. Significant positive correlations were noted between WBC and urinary 8-OHdG (Spearman correlation r = 0.256, p = 0.003). Furthermore, a significant negative correlation was found between WBC 8-OHdG and global methylation (r = −0.272, p = 0.002). These results suggest that exposure to metal oxide NMs may lead to global methylation, DNA oxidative damage, and lipid peroxidation.

Metal oxide nanostructures and their gas sensing properties: a review.

Science.gov (United States)

Sun, Yu-Feng; Liu, Shao-Bo; Meng, Fan-Li; Liu, Jin-Yun; Jin, Zhen; Kong, Ling-Tao; Liu, Jin-Huai

2012-01-01

Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion. Besides, doping is also an effective method to decrease particle size and improve gas sensing properties. Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article. The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given.

Arc plasma assisted rotating electrode process for preparation of metal pebbles

International Nuclear Information System (INIS)

Mohanty, T.; Tripathi, B.M.; Mahata, T.; Sinha, P.K.

2014-01-01

Spherical beryllium pebbles of size ranging from 0.2-2 mm are required as neutron multiplying material in solid Test Blanket Module (TBM) of International Thermonuclear Experimental Reactor (ITER). Rotating electrode process (REP) has been identified as a suitable technique for preparation of beryllium pebbles. In REP, arc plasma generated between non-consumable electrode (cathode) and rotating metal electrode (anode) plays a major role for continuous consumption of metal electrode and preparation of spherical metal pebbles. This paper focuses on description of the process, selection of sub-systems for development of REP experimental set up and optimization of arc parameters, such as, cathode geometry, arc current, arc voltage, arc gap and carrier gas flow rate for preparation of required size spherical metal pebbles. Other parameters which affect the pebbles sizes are rotational speed, metal electrode diameter and physical properties of the metal. As beryllium is toxic in nature its surrogate metals such as stainless steel (SS) and Titanium (Ti) were selected to evaluate the performance of the REP equipment. Several experiments were carried out using SS and Ti electrode and process parameters have been optimized for preparation of pebbles of different sizes. (author)

Kinetic and catalytic analysis of mesoporous metal oxides on the oxidation of Rhodamine B

Science.gov (United States)

Xaba, Morena S.; Noh, Ji-Hyang; Mokgadi, Keabetswe; Meijboom, Reinout

2018-05-01

In this study, we demonstrate the synthesis and catalytic activity of different mesoporous transition metal oxides, silica (SiO2), copper oxide (CuO), chromium oxide (Cr2O3), iron oxide (Fe2O3) cobalt oxide (Co3O4), cerium oxide (CeO2) and nickel oxide (NiO), on the oxidation of a pollutant dye, Rhodamine B (RhB). These metal oxides were synthesized by inverse micelle formation method and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), adsorption-desorption isotherms (BET) and H2-temperature programmed reduction (TPR). UV-vis spectrophotometry was used to monitor the time-resolved absorbance of RhB at λmax = 554 nm. Mesoporous copper oxide was calcined at different final heating temperatures of 250, 350, 450 and 550 °C, and each mesoporous copper oxide catalyst showed unique physical properties and catalytic behavior. Mesoporous CuO-550 with the smallest characteristic path length δ, proved to be the catalyst of choice for the oxidation of RhB in aqueous media. We observed that the oxidation of RhB in aqueous media is dependent on the crystallite size and characteristic path length of the mesoporous metal oxide. The Langmuir-Hinshelwood model was used to fit the experimental data and to prove that the reaction occurs on the surface of the mesoporous CuO. The thermodynamic parameters, EA, ΔH#, ΔS# and ΔG# were calculated and catalyst recycling and reusability were demonstrated.

The Resonance Absorption of Uranium Metal and Oxide

Energy Technology Data Exchange (ETDEWEB)

Hellstrand, E; Lundgren, G

1962-06-15

The resonance integrals for uranium metal and uranium oxide have been determined for a 1/E flux. The following results were obtained Metal RI 2.95 + 25.8{radical}(S/M); Oxide RI = 4.15 + 26.6{radical}(S/M). The oxide value agrees with the expression found earlier at this laboratory. But the result for the metal is 4. 5 % larger than the earlier one. In addition, the resonance absorption in a R1 fuel rod has been compared with that for a cadmium-covered rod placed in an approximate cell boundary flux. The former came out 3 % larger than the latter. A comparison of the fuel rod absorption with that for a 1/E flux yields a corresponding figure of 7 %. The neutron flux was monitored below the lowest resonance in uranium.

Clustered atom-replaced structure in single-crystal-like metal oxide

Science.gov (United States)

Araki, Takeshi; Hayashi, Mariko; Ishii, Hirotaka; Yokoe, Daisaku; Yoshida, Ryuji; Kato, Takeharu; Nishijima, Gen; Matsumoto, Akiyoshi

2018-06-01

By means of metal organic deposition using trifluoroacetates (TFA-MOD), we replaced and localized two or more atoms in a single-crystalline structure having almost perfect orientation. Thus, we created a new functional structure, namely, clustered atom-replaced structure (CARS), having single-crystal-like metal oxide. We replaced metals in the oxide with Sm and Lu and localized them. Energy dispersive x-ray spectroscopy results, where the Sm signal increases with the Lu signal in the single-crystalline structure, confirm evidence of CARS. We also form other CARS with three additional metals, including Pr. The valence number of Pr might change from 3+ to approximately 4+, thereby reducing the Pr–Ba distance. We directly observed the structure by a high-angle annular dark-field image, which provided further evidence of CARS. The key to establishing CARS is an equilibrium chemical reaction and a combination of additional larger and smaller unit cells to matrix cells. We made a new functional metal oxide with CARS and expect to realize CARS in other metal oxide structures in the future by using the above-mentioned process.

Application of Two Cobalt-Based Metal-Organic Frameworks as Oxidative Desulfurization Catalysts.

Science.gov (United States)

Masoomi, Mohammad Yaser; Bagheri, Minoo; Morsali, Ali

2015-12-07

Two new porous cobalt-based metal-organic frameworks, [Co6(oba)5(OH)2(H2O)2(DMF)4]n · 5DMF (TMU-10) and [Co3(oba)3(O) (Py)0.5] n · 4DMF · Py (TMU-12) have been synthesized by solvothermal method using a nonlinear dicarboxylate ligand. Under mild reaction conditions, these compounds exhibited good catalytic activity and reusability in oxidative desulfurization (ODS) reaction of model oil which was prepared by dissolving dibenzothiophene (DBT) in n-hexane. FT-IR and Mass analysis showed that the main product of DBT oxidation is its corresponding sulfone, which was adsorbed on the surfaces of catalysts. The activation energy was obtained as 13.4 kJ/mol.

Effect of CO on surface oxidation of uranium metal

International Nuclear Information System (INIS)

Wang, X.; Fu, Y.; Xie, R.

1997-01-01

The surface reactions of uranium metal with carbon monoxide at 25 and 200 deg C have been studied by X-ray photoelectron spectroscopy (XPS);respectively. Adsorption of carbon monoxide on the surface layer of uranium metal leads to partial reduction of surface oxide and results in U4f photoelectron peak shifting to the lower binding energy. The content of oxygen in the surface oxide is decreased and O1s/O4f ratio decreases with increasing the exposure of carbon monoxide. The investigation indicates the surface layer of uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide. (author)

Optical and electrical experiments at some transition-metal oxide foil-electrolyte interfaces

International Nuclear Information System (INIS)

Sari, S.O.; Ahlgren, W.L.

1977-01-01

Metal-oxide layers formed from transition-metal foils oxidized by heating in air have been examined for their photoelectrolytic response. The metals examined are Y, Ti, Zr, Hf, V, Nb, Ta, Mo, W, and Pt. Weak photoeffects are observed for oxide layers of all of these metals. Sizable light-dependent oxygen gas evolution rates are found in Ti and also in W oxides. The spectral dependence of the oxygen response in these compounds is investigated, and interpretation is given of these experiments

Preparation and photovoltaic properties of CdS quantum dot-sensitized solar cell based on zinc tin mixed metal oxides.

Science.gov (United States)

Cao, Jiupeng; Zhao, Yifan; Zhu, Yatong; Yang, Xiaoyu; Shi, Peng; Xiao, Hongdi; Du, Na; Hou, Wanguo; Qi, Genggeng; Liu, Jianqiang

2017-07-15

The present study reports a new type of quantum dot sensitized solar cells (QDSSCs) using the zinc tin mixed metal oxides (MMO) as the anode materials, which were obtained from the layered double hydroxide (LDH) precursor. The successive ionic layer adsorption and reaction (SILAR) method is applied to deposit CdS quantum dots. The effects of sensitizing cycles on the performance of CdS QDSSC are studied. Scanning electron microscopy (SEM), Transmission electron microscope (TEM) and X-ray diffraction (XRD) are used to identify the surface profile and crystal structure of the mixed metal oxides anode. The photovoltaic performance of the QDSSC is studied by the electrochemical method. The new CdS QDSSC exhibits power conversion efficiency (PCE) up to 0.48% when the anode was sensitized for eight cycles. Copyright © 2017 Elsevier Inc. All rights reserved.

Metal Oxide Nanomaterial QNAR Models: Available Structural Descriptors and Understanding of Toxicity Mechanisms

Directory of Open Access Journals (Sweden)

Jiali Ying

2015-10-01

Full Text Available Metal oxide nanomaterials are widely used in various areas; however, the divergent published toxicology data makes it difficult to determine whether there is a risk associated with exposure to metal oxide nanomaterials. The application of quantitative structure activity relationship (QSAR modeling in metal oxide nanomaterials toxicity studies can reduce the need for time-consuming and resource-intensive nanotoxicity tests. The nanostructure and inorganic composition of metal oxide nanomaterials makes this approach different from classical QSAR study; this review lists and classifies some structural descriptors, such as size, cation charge, and band gap energy, in recent metal oxide nanomaterials quantitative nanostructure activity relationship (QNAR studies and discusses the mechanism of metal oxide nanomaterials toxicity based on these descriptors and traditional nanotoxicity tests.

Lithium alloys and metal oxides as high-capacity anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Liang, Chu; Gao, Mingxia; Pan, Hongge; Liu, Yongfeng; Yan, Mi

2013-01-01

Highlights: •Progress in lithium alloys and metal oxides as anode materials for lithium-ion batteries is reviewed. •Electrochemical characteristics and lithium storage mechanisms of lithium alloys and metal oxides are summarized. •Strategies for improving electrochemical lithium storage properties of lithium alloys and metal oxides are discussed. •Challenges in developing lithium alloys and metal oxides as commercial anodes for lithium-ion batteries are pointed out. -- Abstract: Lithium alloys and metal oxides have been widely recognized as the next-generation anode materials for lithium-ion batteries with high energy density and high power density. A variety of lithium alloys and metal oxides have been explored as alternatives to the commercial carbonaceous anodes. The electrochemical characteristics of silicon, tin, tin oxide, iron oxides, cobalt oxides, copper oxides, and so on are systematically summarized. In this review, it is not the scope to retrace the overall studies, but rather to highlight the electrochemical performances, the lithium storage mechanism and the strategies in improving the electrochemical properties of lithium alloys and metal oxides. The challenges and new directions in developing lithium alloys and metal oxides as commercial anodes for the next-generation lithium-ion batteries are also discussed

Preparation and characterization of polyindole - iron oxide nanocomposite electrolyte

International Nuclear Information System (INIS)

Rajasudha, G.; Stephen, A.; Narayanan, V.

2009-01-01

Full text: A novel polyindole-iron oxide containing LiClO 4 solid polymer electrolyte has been prepared. The diverse property of magnetic nanoparticle has elicited wide interest from the point of view of technological applications. Their properties are known to be strongly dependent on size, anisotropy and inter particle interactions. The proton conducting materials has received considerable attention as electrolyte materials in technological applications such as fuel cells, sensors and electrochromic display. In this work, polyindole-iron oxide nanocomposite containing LiClO 4 was prepared by in situ polymerization. The indole was polymerized in the presence of iron oxide, using ammonium peroxy disulphate as an oxidizing agent. The polyindole-iron oxide nanocomposite was characterized by XRD, IR, SEM, TGA and TEM. The iron oxide nano particles was incorporated into polyindole and was confirmed by XRD and Fourier transform infrared (FTIR) spectroscopy. The surface Morphology and thermal stability were studied by thermogravimetric analysis (TGA) and SEM respectively. The ionic conductivity of polyindole electrolyte was analyzed from impedance spectrum. The prepared polyindole-iron oxide nanocomposite could be used as solid electrolyte in lithium ion batteries

Dark ambient degradation of Bisphenol A and Acid Orange 8 as organic pollutants by perovskite SrFeO3−δ metal oxide

International Nuclear Information System (INIS)

Leiw, Ming Yian; Guai, Guan Hong; Wang, Xiaoping; Tse, Man Siu; Ng, Chee Mang; Tan, Ooi Kiang

2013-01-01

Highlights: • Perovskite SFO prepared by high temperature and high-energy ball milling process. • SFO metal oxide shows good efficiency in degrading and mineralizing BPA. • Rapid decoloration of AO8 was achieved in the presence of SFO metal oxide. • O 2 · − is the predominant ROS for dark oxidative degradation of BPA and AO8. -- Abstract: Current advanced oxidation processes (AOPs) are chemically and energetically intensive processes, which are undesirable for cost-effective and large-scale system water treatment and wastewater recycling. This study explored the Strontium Ferrite (SFO) metal oxide on the degradation of highly concentrated organic pollutants under dark ambient condition without any external stimulants. The SFO particles with single perovskite structure were successfully synthesized with a combined high temperature and high-energy ball milling process. An endocrine disruptor, Bisphenol A (BPA) and an azo dye, Acid Orange 8 (AO8) were used as probe organic pollutants. BPA was completely degraded with 83% of mineralization in 24 h while rapid decoloration of AO8 was achieved in 60 min and complete breakdown into primary intermediates and aliphatic acids occurred in 24 h under the treatment of dispersed SFO metal oxide in water. Such efficient degradation could be attributed to the enhanced adsorption of these anionic pollutants on positively charged ball-milled SFO metal oxide surface, resulted in higher degradation activity. Preliminary degradation mechanisms of BPA and AO8 under the action of SFO metal oxide were proposed. These results showed that the SFO metal oxide could be an efficient alternative material as novel advanced oxidation technology for low cost water treatment

A study on optical properties of poly (ethylene oxide) based polymer electrolyte with different alkali metal iodides

Science.gov (United States)

Rao, B. Narasimha; Suvarna, R. Padma

2016-05-01

Polymer electrolytes were prepared by adding poly (ethylene glycol) dimethyl ether (PEGDME), TiO2 (nano filler), different alkali metal iodide salts RI (R+=Li+, Na+, K+, Rb+, Cs+) and I2 into Acetonitrile gelated with Poly (ethylene oxide) (PEO). Optical properties of poly (ethylene oxide) based polymer electrolytes were studied by FTIR, UV-Vis spectroscopic techniques. FTIR spectrum reveals that the alkali metal cations were coordinated to ether oxygen of PEO. The optical absorption studies were made in the wavelength range 200-800 nm. It is observed that the optical absorption increases with increase in the radius of alkali metal cation. The optical band gap for allowed direct transitions was evaluated using Urbach-edges method. The optical properties such as optical band gap, refractive index and extinction coefficient were determined. The studied polymer materials are useful for solar cells, super capacitors, fuel cells, gas sensors etc.

A combined theoretical and experimental approach of a new ternary metal oxide in molybdate composite for hybrid energy storage capacitors

Science.gov (United States)

Minakshi, M.; Watcharatharapong, T.; Chakraborty, S.; Ahuja, R.

2018-04-01

Sustainable energy sources require an efficient energy storage system possessing excellent electrochemical properties. The better understanding of possible crystal configurations and the development of a new ternary metal oxide in molybdate composite as an electrode for hybrid capacitors can lead to an efficient energy storage system. Here, we reported a new ternary metal oxide in molybdate composite [(Mn1/3Co1/3Ni1/3)MoO4] prepared by simple combustion synthesis with an extended voltage window (1.8 V vs. Carbon) resulting in excellent specific capacity 35 C g-1 (58 F g-1) and energy density (50 Wh kg-1 at 500 W kg-1) for a two electrode system in an aqueous NaOH electrolyte. The binding energies measured for Mn, Co, and Ni 2p are consistent with the literature, and with the metal ions being present as M(II), implying that the oxidation states of the transition metals are unchanged. The experimental findings are correlated well through density functional theory based electronic structure calculations. Our reported work on the ternary metal oxide studies (Mn1/3Co1/3Ni1/3)MoO4 suggests that will be an added value to the materials for energy storage.

Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nano tubes and Their Applications

International Nuclear Information System (INIS)

Motshekga, S.C.; Pillai, S.K.; Ray, S.S.; Motshekga, S.C.; Ray, S.S.; Jalama, K.; Krause, Rui.W.M.

2012-01-01

The study of coating carbon nano tubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nano tubes in various applications, it is necessary to attach functional groups or other nano structures to their surface. The combination of the distinctive properties of carbon nano tubes and metal/oxides is expected to be applied in field emission displays, nano electronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nano tube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

Recent Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nanotubes and Their Applications

Directory of Open Access Journals (Sweden)

Sarah C. Motshekga

2012-01-01

Full Text Available The study of coating carbon nanotubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nanotubes in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of carbon nanotubes and metal/oxides is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nanotube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

Ethanol oxidation on a nichrome-supported spherical platinum microparticle electrocatalyst prepared by electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhen-Hui; Li, Jing; Dong, Xiaoya; Wang, Dong; Chen, Tiwei; Qiao, Haiyan; Huang, Aiping [College of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Jianshe Road, Xinxiang 453007 (China)

2008-11-15

A novel electrode was rapidly prepared by depositing microparticle platinum onto a nichrome substrate in dilute chloroplatinic acid solution by cyclic voltammetry. The SEM results revealed that the deposits were composed of spherical Pt microparticles. Cyclic voltammetry and chronoamperometry were used for the characterization of the electrodes. Results of the electrochemical measurements showed that the spherical Pt microparticle electrodes retained the properties of metal platinum, increased the catalytic activity and promoted the electrocatalytic oxidation of ethanol. Moreover, the deposited Pt microparticles improved the electrochemical properties of the support material and reduced the dosage of noble metal platinum remarkably. The cost could be reduced dramatically by decreasing the contents of platinum. The spherical Pt microparticles deposited on the nichrome supports are likely a potential electrocatalyst for ethanol electrooxidation. (author)

Are metallothioneins equally good biomarkers of metal and oxidative stress?

Science.gov (United States)

Figueira, Etelvina; Branco, Diana; Antunes, Sara C; Gonçalves, Fernando; Freitas, Rosa

2012-10-01

Several researchers investigated the induction of metallothioneins (MTs) in the presence of metals, namely Cadmium (Cd). Fewer studies observed the induction of MTs due to oxidizing agents, and literature comparing the sensitivity of MTs to different stressors is even more scarce or even nonexistent. The role of MTs in metal and oxidative stress and thus their use as a stress biomarker, remains to be clearly elucidated. To better understand the role of MTs as a biomarker in Cerastoderma edule, a bivalve widely used as bioindicator, a laboratory assay was conducted aiming to assess the sensitivity of MTs to metal and oxidative stressors. For this purpose, Cd was used to induce metal stress, whereas hydrogen peroxide (H2O2), being an oxidizing compound, was used to impose oxidative stress. Results showed that induction of MTs occurred at very different levels in metal and oxidative stress. In the presence of the oxidizing agent (H2O2), MTs only increased significantly when the degree of oxidative stress was very high, and mortality rates were higher than 50 percent. On the contrary, C. edule survived to all Cd concentrations used and significant MTs increases, compared to the control, were observed in all Cd exposures. The present work also revealed that the number of ions and the metal bound to MTs varied with the exposure conditions. In the absence of disturbance, MTs bound most (60-70 percent) of the essential metals (Zn and Cu) in solution. In stressful situations, such as the exposure to Cd and H2O2, MTs did not bind to Cu and bound less to Zn. When organisms were exposed to Cd, the total number of ions bound per MT molecule did not change, compared to control. However the sort of ions bound per MT molecule differed; part of the Zn and all Cu ions where displaced by Cd ions. For organisms exposed to H2O2, each MT molecule bound less than half of the ions compared to control and Cd conditions, which indicates a partial oxidation of thiol groups in the cysteine

Using glucosamine as a reductant to prepare reduced graphene oxide and its nanocomposites with metal nanoparticles

International Nuclear Information System (INIS)

Li Chuanbao; Wang Xingrui; Liu Yu; Wang Wei; Wynn, Jeanne; Gao Jianping

2012-01-01

A green and facile approach of producing reduced graphene oxide (RGO) by the reduction of graphene oxide (GO) with a monosaccharide medicine glucosamine (GL) was developed. The effect of several factors on the GO reduction, including pH, the weight ratio of GL/GO, and the reaction temperature was studied. The deoxygenation process was monitored with UV–Vis absorption spectroscopy, and the reducing degree of GO was determined with X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. Au nanoparticles (about 3.3–4.2 nm) (AuNPs)/RGO and Ag nanoparticles (about 6 nm) (AgNPs)/RGO materials were prepared in two different ways using the above reduction method. They were then used to catalyze the Suzuki–Miyaura coupling reaction of phenyl halide and phenylboronic acid to produce biphenyl, and the highest yield of biphenyl for AuNPs/RGO was 99 %. In addition, the AgNPs/RGO materials exhibited a surface-enhanced Raman scattering effect, and some RGO peaks were enhanced. This approach opens up a new, practical, and green reducing method to prepare RGO for large-scale practical application.

Universal medium-range order of amorphous metal oxides.

Science.gov (United States)

Nishio, Kengo; Miyazaki, Takehide; Nakamura, Hisao

2013-10-11

We propose that the structure of amorphous metal oxides can be regarded as a dual-dense-random-packing structure, which is a superposition of the dense random packing of metal atoms and that of oxygen atoms. Our ab initio molecular dynamics simulations show that the medium-range order of amorphous HfO2, ZrO2, TiO2, In2O3, Ga2O3, Al2O3, and Cu2O is characterized by the pentagonal-bipyramid arrangement of metal atoms and that of oxygen atoms, and prove the validity of our dual-random-sphere-packing model. In other words, we find that the pentagonal medium-range order is universal independent of type of metal oxide.

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites

OpenAIRE

Gandhiraman, Ram P.; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E.; Chen, Bin; Meyyappan, M.

2014-01-01

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties...

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

Photoluminescence and semiconducting behavior of Fe, Co, Ni and Cu implanted in heavy metal oxide glasses

Directory of Open Access Journals (Sweden)

Mohamed A. Marzouk

2016-07-01

Full Text Available Transition metal ions (0.5 wt% of Fe2O3, CoO, NiO or CuO doped heavy metal oxide glasses having chemical composition of 60PbO·20Bi2O3·20 MxOy mol% (where MxOy = B2O3 or SiO2 or P2O5 were prepared by conventional melt annealing method. Combined optical and photoluminescence properties have been measured and employed to evaluate the prepared glassy samples. From the absorption edge data, the values of the optical band gap Eopt, Urbach energy (ΔE and refractive index were calculated to estimate semiconducting behavior. Photoluminescence and values of the optical energy gap were found to be dependent on the glass composition. The variations of the photoluminescence intensity, values of optical band gap, Urbach energy and refractive index gave an indication to use the prepared glasses for design of novel functional optical materials with higher optical performance.

Advances in metal-induced oxidative stress and human disease

International Nuclear Information System (INIS)

Jomova, Klaudia; Valko, Marian

2011-01-01

Detailed studies in the past two decades have shown that redox active metals like iron (Fe), copper (Cu), chromium (Cr), cobalt (Co) and other metals undergo redox cycling reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biological systems. Disruption of metal ion homeostasis may lead to oxidative stress, a state where increased formation of reactive oxygen species (ROS) overwhelms body antioxidant protection and subsequently induces DNA damage, lipid peroxidation, protein modification and other effects, all symptomatic for numerous diseases, involving cancer, cardiovascular disease, diabetes, atherosclerosis, neurological disorders (Alzheimer's disease, Parkinson's disease), chronic inflammation and others. The underlying mechanism of action for all these metals involves formation of the superoxide radical, hydroxyl radical (mainly via Fenton reaction) and other ROS, finally producing mutagenic and carcinogenic malondialdehyde (MDA), 4-hydroxynonenal (HNE) and other exocyclic DNA adducts. On the other hand, the redox inactive metals, such as cadmium (Cd), arsenic (As) and lead (Pb) show their toxic effects via bonding to sulphydryl groups of proteins and depletion of glutathione. Interestingly, for arsenic an alternative mechanism of action based on the formation of hydrogen peroxide under physiological conditions has been proposed. A special position among metals is occupied by the redox inert metal zinc (Zn). Zn is an essential component of numerous proteins involved in the defense against oxidative stress. It has been shown, that depletion of Zn may enhance DNA damage via impairments of DNA repair mechanisms. In addition, Zn has an impact on the immune system and possesses neuroprotective properties. The mechanism of metal-induced formation of free radicals is tightly influenced by the action of cellular antioxidants. Many low-molecular weight antioxidants (ascorbic acid (vitamin C), alpha

Aerobic Transition-Metal-Free Synthesis of 2,3-Diarylindoles and 5-Aryluracils via Oxidative Nucleophilic Substitution of Hydrogen Pathway

Energy Technology Data Exchange (ETDEWEB)

Yu, Jin; Moon, Hye Ran; Kim, Su Yeon; Kim, Jae Nyoung [Chonnam National Un iversity, Gwangju (Korea, Republic of)

2016-01-15

2,3-diarylindoles and 5-aryluracils were synthesized by ONSH pathway under transition-metal-free conditions in good to moderate yields using molecular oxygen as an oxidant. As 2,3-diarylindoles have been found in many biologically important compounds, the synthesis of this scaffold has received much attention. Most frequently, 2,3-diarylindoles have been prepared via palladium-catalyzed arylations of 2-arylindole with bromoarenes. During our recent transition metal-catalyzed arylations of indoles and uracils, we were interested in the arylation in the absence of an expensive transition metal catalyst.

Selective catalytic reduction of nitric oxide by ethylene over metal-modified ZSM-5- and {gamma}-Al{sub 2}O{sub 3}-catalysts

Energy Technology Data Exchange (ETDEWEB)

Eraenen, K; Kumar, N; Lindfors, L E [Aabo Akademi, Turku (Finland). Lab. of Industrial Chemistry

1997-12-31

Metal-modified ZSM-5 and {gamma}-Al{sub 2}O{sub 3} catalysts were tested in reduction of nitric oxide by ethylene. Different metals were introduced into the ZSM-5 catalyst by ion-exchange and by introduction of metals during the zeolite synthesis. To prepare bimetallic catalysts a combination of these methods was used. The {gamma}-Al{sub 2}O{sub 3} was impregnated with different metals by the incipient wetness technique and by adsorption. Activity measurements showed that the ZSM-5 based catalysts were more active than the {gamma}-Al{sub 2}O{sub 3} based catalysts. The highest conversion was obtained over a ZSM-5 catalyst prepared by introduction of Pd during synthesis of the zeolite and subsequently ion-exchanged with copper. (author)

Selective catalytic reduction of nitric oxide by ethylene over metal-modified ZSM-5- and {gamma}-Al{sub 2}O{sub 3}-catalysts

Energy Technology Data Exchange (ETDEWEB)

Eraenen, K.; Kumar, N.; Lindfors, L.E. [Aabo Akademi, Turku (Finland). Lab. of Industrial Chemistry

1996-12-31

Metal-modified ZSM-5 and {gamma}-Al{sub 2}O{sub 3} catalysts were tested in reduction of nitric oxide by ethylene. Different metals were introduced into the ZSM-5 catalyst by ion-exchange and by introduction of metals during the zeolite synthesis. To prepare bimetallic catalysts a combination of these methods was used. The {gamma}-Al{sub 2}O{sub 3} was impregnated with different metals by the incipient wetness technique and by adsorption. Activity measurements showed that the ZSM-5 based catalysts were more active than the {gamma}-Al{sub 2}O{sub 3} based catalysts. The highest conversion was obtained over a ZSM-5 catalyst prepared by introduction of Pd during synthesis of the zeolite and subsequently ion-exchanged with copper. (author)

Insertion compounds of transition-metal and uranium oxides

International Nuclear Information System (INIS)

Chippindale, A.M.; Dickens, P.G.; Powell, A.V.

1991-01-01

Several transition-metal and actinide oxides, in which the metal occurs in a high oxidation state, have open covalent structures and are capable of incorporating alkali and other electropositive metals under mild conditions to form insertion compounds A x MO n . These are solids which have several features in common: Over a range of compositions, A x MO n exists as one or more stable or metastable phases in which the structure of the parent oxide MO n is largely retained and the insertion element A is accommodated interstitially. Insertion is accompanied by a redox process A=A i . + e - M in which M is reduced and the electronic properties of the parent oxide change to those typical of a mixed-valence compound. The insertion process xA + MO n = A x MO n can be reversed, at least to some extent, by chemical or electrochemical reaction, with retention of structure (topotactic reaction). This review concentrates on methods of synthesis, characterisation, crystal structure and thermochemistry of these insertion compounds. It updates and extends previous work. (author)

Metal oxide semiconductor thin-film transistors for flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Petti, Luisa; Vogt, Christian; Büthe, Lars; Cantarella, Giuseppe; Tröster, Gerhard [Electronics Laboratory, Swiss Federal Institute of Technology, Zürich (Switzerland); Münzenrieder, Niko [Electronics Laboratory, Swiss Federal Institute of Technology, Zürich (Switzerland); Sensor Technology Research Centre, University of Sussex, Falmer (United Kingdom); Faber, Hendrik; Bottacchi, Francesca; Anthopoulos, Thomas D. [Department of Physics and Centre for Plastic Electronics, Imperial College London, London (United Kingdom)

2016-06-15

The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In

Literature information applicable to the reaction of uranium oxides with chlorine to prepare uranium tetrachloride

International Nuclear Information System (INIS)

Haas, P.A.

1992-02-01

The reaction of uranium oxides and chlorine to prepare anhydrous uranium tetrachloride (UCl 4 ) are important to more economical preparation of uranium metal. The most practical reactions require carbon or carbon monoxide (CO) to give CO or carbon dioxide (CO 2 ) as waste gases. The chemistry of U-O-Cl compounds is very complex with valances of 3, 4, 5, and 6 and with stable oxychlorides. Literature was reviewed to collect thermochemical data, phase equilibrium information, and results of experimental studies. Calculations using thermodynamic data can identify the probable reactions, but the results are uncertain. All the U-O-Cl compounds have large free energies of formation and the calculations give uncertain small differences of large numbers. The phase diagram for UCl 4 -UO 2 shows a reaction to form uranium oxychloride (UOCl 2 ) that has a good solubility in molten UCl 4 . This appears more favorable to good rates of reaction than reaction of solids and gases. There is limited information on U-O-Cl salt properties. Information on the preparation of titanium, zirconium, silicon, and thorium tetrachlorides (TiCl 4 , ZrCl 4 , SiCl 4 , ThCl 4 ) by reaction of oxides with chlorine (Cl 2 ) and carbon has application to the preparation of UCl 4

Oxidation behaviour of Zr-based bulk metallic glasses

International Nuclear Information System (INIS)

Wang, Bin

2011-01-01

The Zr-based bulk metallic glasses, developed since the late 1980's, have very interesting mechanical properties, which can be considered for many applications including working under oxidizing atmosphere conditions at high temperatures. It is therefore interesting to study their oxidation resistance and to characterize the oxide scale formed on alloys surface. The fundamental objective of this thesis is to enhance the understanding of the role of various thermodynamic and chemistry parameters on the oxidation behaviour of the Zr-based bulk metallic glasses at high temperature under dry air, to determine the residual stresses in the oxide layer, in comparison with their crystalline alloys with the same chemical composition after an annealing treatment. The oxidation kinetics of these glasses and the crystalline structure of oxide scale ZrO 2 depend on the temperature and the oxidation duration: for short periods of oxidation or at a temperature below Tg, the kinetics follows a parabolic law, whereas, if the sample is oxidized at T ≥ Tg, the kinetics can be divided into two parts. The crystalline counterparts are oxidized by a parabolic rule whatever the temperature; for long oxidation duration at a temperature close to Tg, the kinetics becomes more complex because of the crystallisation of the glasses during the oxidation tests. Also the crystalline structure of the oxide layers depends on the oxidation temperature: the oxide layer consists only in tetragonal Zirconia at T ≤ Tg, while monoclinic Zirconia was formed at higher temperature. The mechanism of the formation of the oxide scale is due to both the interior diffusion of Oxygen ions and the external diffusion of Zirconium ions. However the diffusion of Zirconium ions slows gradually during the crystallisation process of the glass matrix. When the crystallisation is completed, the formation of Zirconia is controlled by only the internal diffusion of oxygen ions. The corresponding residual stresses

NANOSTRUCTURED METAL OXIDE CATALYSTS VIA BUILDING BLOCK SYNTHESES

Energy Technology Data Exchange (ETDEWEB)

Craig E. Barnes

2013-03-05

A broadly applicable methodology has been developed to prepare new single site catalysts on silica supports. This methodology requires of three critical components: a rigid building block that will be the main structural and compositional component of the support matrix; a family of linking reagents that will be used to insert active metals into the matrix as well as cross link building blocks into a three dimensional matrix; and a clean coupling reaction that will connect building blocks and linking agents together in a controlled fashion. The final piece of conceptual strategy at the center of this methodology involves dosing the building block with known amounts of linking agents so that the targeted connectivity of a linking center to surrounding building blocks is obtained. Achieving targeted connectivities around catalytically active metals in these building block matrices is a critical element of the strategy by which single site catalysts are obtained. This methodology has been demonstrated with a model system involving only silicon and then with two metal-containing systems (titanium and vanadium). The effect that connectivity has on the reactivity of atomically dispersed titanium sites in silica building block matrices has been investigated in the selective oxidation of phenols to benezoquinones. 2-connected titanium sites are found to be five times as active (i.e. initial turnover frequencies) than 4-connected titanium sites (i.e. framework titanium sites).

Protein carbonylation and metal-catalyzed protein oxidation in a cellular perspective

DEFF Research Database (Denmark)

Møller, Ian Max; Rogowska-Wrzesinska, Adelina; Rao, R S P

2011-01-01

Proteins can become oxidatively modified in many different ways, either by direct oxidation of amino acid side chains and protein backbone or indirectly by conjugation with oxidation products of polyunsaturated fatty acids and carbohydrates. While reversible oxidative modifications are thought...... to be relevant in physiological processes, irreversible oxidative modifications are known to contribute to cellular damage and disease. The most well-studied irreversible protein oxidation is carbonylation. In this work we first examine how protein carbonylation occurs via metal-catalyzed oxidation (MCO) in vivo...... and in vitro with an emphasis on cellular metal ion homeostasis and metal binding. We then review proteomic methods currently used for identifying carbonylated proteins and their sites of modification. Finally, we discuss the identified carbonylated proteins and the pattern of carbonylation sites in relation...

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

Properties of InGaAs/GaAs metal-oxide-semiconductor heterostructure field-effect transistors modified by surface treatment

Energy Technology Data Exchange (ETDEWEB)

Gregušová, D., E-mail: Dagmar.Gregusova@savba.sk [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-84104 (Slovakia); Gucmann, F.; Kúdela, R. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-84104 (Slovakia); Mičušík, M. [Polymer Institute of Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-84541 (Slovakia); Stoklas, R.; Válik, L. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-84104 (Slovakia); Greguš, J. [Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, Bratislava SK-84248 (Slovakia); Blaho, M. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava SK-84104 (Slovakia); Kordoš, P. [Institute of Electronics and Photonics, Faculty of Electrical Engineering and Information Technology STU, Ilkovičova 3, Bratislava SK-81219 (Slovakia)

2017-02-15

Highlights: • AlGaAs/InGaAs/GaAs-based metal oxide semiconductor transistors-MOSHFET. • Thin Al-layer deposited in-situ and oxidize in air – gate insulator. • MOSHFET vs HFET transistor properties, density of traps evaluated. - Abstract: GaAs-based heterostructures exhibit excellent carrier transport properties, mainly the high carrier velocity. An AlGaAs-GaAs heterostructure field-effect transistor (HFET) with an InGaAs channel was prepared using metal-organic chemical vapor deposition (MOVPE). An AlOx layer was formed on the AlGaAs barrier layer by the air-assisted oxidation of a thin Al layer deposited in-situ in an MOVPE reactor immediately after AlGaAs/InGaAs growth. The HFETs and MOSHFETs exhibited a very low trap state density in the order of 10{sup 11} cm{sup −2} eV{sup −1}. Capacitance measurement yielded no significant difference between the HFET and MOSHFET structures. The formation of an AlOx layer modified the surface by partially eliminating surface states that arise from Ga-and As-based native oxides. The presence of an AlOx layer reflected in a reduced gate leakage current, which was evidenced by the two-terminal transistor measurement. Presented preparation procedure and device properties show great potential of AlGaAs/InGaAs-based MOSHFETs.

Antimicrobial Activity of Nitric Oxide-Releasing Ti-6Al-4V Metal Oxide

Science.gov (United States)

Reger, Nina A.; Meng, Wilson S.; Gawalt, Ellen S.

2017-01-01

Titanium and titanium alloy materials are commonly used in joint replacements, due to the high strength of the materials. Pathogenic microorganisms can easily adhere to the surface of the metal implant, leading to an increased potential for implant failure. The surface of a titanium-aluminum-vanadium (Ti-6Al-4V) metal oxide implant material was functionalized to deliver an small antibacterial molecule, nitric oxide. S-nitroso-penicillamine, a S-nitrosothiol nitric oxide donor, was covalently immobilized on the metal oxide surface using self-assembled monolayers. Infrared spectroscopy was used to confirm the attachment of the S-nitrosothiol donor to the Ti-Al-4V surface. Attachment of S-nitroso-penicillamine resulted in a nitric oxide (NO) release of 89.6 ± 4.8 nmol/cm2 under physiological conditions. This low concentration of nitric oxide reduced Escherichia coli and Staphylococcus epidermidis growth by 41.5 ± 1.2% and 25.3 ± 0.6%, respectively. Combining the S-nitrosothiol releasing Ti-6Al-4V with tetracycline, a commonly-prescribed antibiotic, increased the effectiveness of the antibiotic by 35.4 ± 1.3%, which allows for lower doses of antibiotics to be used. A synergistic effect of ampicillin with S-nitroso-penicillamine-modified Ti-6Al-4V against S. epidermidis was not observed. The functionalized Ti-6Al-4V surface was not cytotoxic to mouse fibroblasts. PMID:28635681

Synergistic effect of metal deactivator and antioxidant on oxidation stability of metal contaminated Jatropha biodiesel

Energy Technology Data Exchange (ETDEWEB)

Sarin, Amit [Department of Applied Sciences, Amritsar College of Engineering and Technology, Amritsar 143001 (India); Arora, Rajneesh; Singh, N.P. [Punjab Technical University, Jalandhar (India); Sarin, Rakesh; Malhotra, R.K. [Indian Oil Corporation Ltd., R and D Centre, Sector-13, Faridabad 121007 (India); Sharma, Meeta [Indian Oil Corporation Ltd., R and D Centre, Sector-13, Faridabad 121007 (India); University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Kashmere Gate, Delhi 110403 (India); Khan, Arif Ali [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Kashmere Gate, Delhi 110403 (India)

2010-05-15

Biodiesel is relatively unstable on storage and European biodiesel standard EN-14214 calls for determining oxidation stability at 110 C with a minimum induction time of 6 h by the Rancimat method (EN-14112). According to proposed National Mission on biodiesel in India, we have undertaken studies on stability of biodiesel from tree borne non-edible oil seeds Jatropha. Neat Jatropha biodiesel exhibited oxidation stability of 3.95 h. It is found possible to meet the desired EN specification for neat Jatropha biodiesel and metal contaminated Jatropha biodiesel by using antioxidants; it will have a cost implication, as antioxidants are costly chemicals. Research was conducted to increase the oxidation stability of metal contaminated Jatropha biodiesel by doping metal deactivator with antioxidant, with varying concentrations in order to meet the aforementioned standard required for oxidation stability. It was found that usage of antioxidant can be reduced by 30-50%, therefore the cost, even if very small amount of metal deactivator is doped in Jatropha biodiesel to meet EN-14112 specification. (author)

Composite catalyst for carbon monoxide and hydrocarbon oxidation

Science.gov (United States)

Liu, Wei; Flytzani-Stephanopoulos, Maria

1996-01-01

A method and composition for the complete oxidation of carbon monoxide and/or hydrocarbon compounds. The method involves reacting the carbon monoxide and/or hydrocarbons with an oxidizing agent in the presence of a metal oxide composite catalyst. The catalyst is prepared by combining fluorite-type oxygen ion conductors with active transition metals. The fluorite oxide, selected from the group consisting of cerium oxide, zirconium oxide, thorium oxide, hafnium oxide, and uranium oxide, and may be doped by alkaline earth and rare earth oxides. The transition metals, selected from the group consisting of molybdnum, copper, cobalt, maganese, nickel, and silver, are used as additives. The atomic ratio of transition metal to fluorite oxide is less than one.

Dark ambient degradation of Bisphenol A and Acid Orange 8 as organic pollutants by perovskite SrFeO{sub 3−δ} metal oxide

Energy Technology Data Exchange (ETDEWEB)

Leiw, Ming Yian, E-mail: LEIW0003@e.ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore); Guai, Guan Hong [GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore); School of Chemical and Biomedical Engineering and Center for Advanced Bionanosystems, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore); Wang, Xiaoping [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Tse, Man Siu [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Ng, Chee Mang [GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore); Tan, Ooi Kiang [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2013-09-15

Highlights: • Perovskite SFO prepared by high temperature and high-energy ball milling process. • SFO metal oxide shows good efficiency in degrading and mineralizing BPA. • Rapid decoloration of AO8 was achieved in the presence of SFO metal oxide. • O{sub 2}·{sup −} is the predominant ROS for dark oxidative degradation of BPA and AO8. -- Abstract: Current advanced oxidation processes (AOPs) are chemically and energetically intensive processes, which are undesirable for cost-effective and large-scale system water treatment and wastewater recycling. This study explored the Strontium Ferrite (SFO) metal oxide on the degradation of highly concentrated organic pollutants under dark ambient condition without any external stimulants. The SFO particles with single perovskite structure were successfully synthesized with a combined high temperature and high-energy ball milling process. An endocrine disruptor, Bisphenol A (BPA) and an azo dye, Acid Orange 8 (AO8) were used as probe organic pollutants. BPA was completely degraded with 83% of mineralization in 24 h while rapid decoloration of AO8 was achieved in 60 min and complete breakdown into primary intermediates and aliphatic acids occurred in 24 h under the treatment of dispersed SFO metal oxide in water. Such efficient degradation could be attributed to the enhanced adsorption of these anionic pollutants on positively charged ball-milled SFO metal oxide surface, resulted in higher degradation activity. Preliminary degradation mechanisms of BPA and AO8 under the action of SFO metal oxide were proposed. These results showed that the SFO metal oxide could be an efficient alternative material as novel advanced oxidation technology for low cost water treatment.

New Digital Metal-Oxide (MOx Sensor Platform

Directory of Open Access Journals (Sweden)

Daniel Rüffer

2018-03-01

Full Text Available The application of metal oxide gas sensors in Internet of Things (IoT devices and mobile platforms like wearables and mobile phones offers new opportunities for sensing applications. Metal-oxide (MOx sensors are promising candidates for such applications, thanks to the scientific progresses achieved in recent years. For the widespread application of MOx sensors, viable commercial offerings are required. In this publication, the authors show that with the new Sensirion Gas Platform (SGP a milestone in the commercial application of MOx technology has been reached. The architecture of the new platform and its performance in selected applications are presented.

Regeneration of sulfated metal oxides and carbonates

Science.gov (United States)

Hubble, Bill R.; Siegel, Stanley; Cunningham, Paul T.

1978-03-28

Alkali metal or alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate found in dolomite or limestone are employed for removal of sulfur dioxide from combustion exhaust gases. The sulfated carbonates are regenerated to oxides through use of a solid-solid reaction, particularly calcium sulfide with calcium sulfate to form calcium oxide and sulfur dioxide gas. The regeneration is performed by contacting the sulfated material with a reductant gas such as hydrogen within an inert diluent to produce calcium sulfide in mixture with the sulfate under process conditions selected to permit the sulfide-sulfate, solid-state reaction to occur.

Antimony (V) oxide adsorbed on a silica-zirconia mixed oxide obtained by the sol-gel processing method: preparation and acid properties

International Nuclear Information System (INIS)

Zaitseva, Galina; Gushikem, Yoshitaka

2002-01-01

The preparation, degree of dispersion, thermal stability and Lewis and Broensted acidity of antimony (V) oxide adsorbed on Si O 2 /Zr O 2 mixed oxide, previously prepared by the sol-gel processing method, are described herein. The samples Si O 2 /Zr O 2 /Sb 2 O 5 , with compositions (in wt %): (a) Zr= 8.1 and Sb= 6.3; (b) Zr= 14.9 and Sb= 11.4, were prepared. Scanning electron microscopy images connected to a X-ray energy dispersive spectrometer showed that both metals, Zr and Sb, were highly dispersed in the matrices. The X-ray diffraction patterns of Si O 2 /Zr O 2 /Sb 2 O 5 heated at different temperatures showed that, up to 1023 K, the matrix was amorphous. At 1273 K a crystalline phase of Zr O 2 (baddeleyite) was observed and raising the temperature to 1573 K, crystalline phases of Si O 2 (cristobalite) and presumably of Zr O 2 /Sb 2 O 5 were observed. Using pyridine as a molecular probe, Broensted acid sites on the Si O 2 /Zr O 2 /Sb 2 O 5 matrix, heat treated up to 523 K, were shown to be very stable. (author)

Antimony (V Oxide Adsorbed on a Silica-Zirconia Mixed Oxide Obtained by the Sol-Gel Processing Method: Preparation and Acid Properties

Directory of Open Access Journals (Sweden)

Zaitseva Galina

2002-01-01

Full Text Available The preparation, degree of dispersion, thermal stability and Lewis and Brphinsted acidity of antimony (V oxide adsorbed on SiO2/ZrO2 mixed oxide, previously prepared by the sol-gel processing method, are described herein. The samples SiO2/ZrO2/Sb2O5, with compositions (in wt %: (a Zr= 8.1 and Sb= 6.3; (b Zr= 14.9 and Sb= 11.4, were prepared. Scanning electron microscopy images connected to a X-ray energy dispersive spectrometer showed that both metals, Zr and Sb, were highly dispersed in the matrices. The X-ray diffraction patterns of SiO2/ZrO2/Sb2O5 heated at different temperatures showed that, up to 1023 K, the matrix was amorphous. At 1273 K a crystalline phase of ZrO2 (baddeleyite was observed and raising the temperature to 1573 K, crystalline phases of SiO2 (cristobalite and presumably of ZrO2/Sb2O5 were observed. Using pyridine as a molecular probe, Brphinsted acid sites on the SiO2/ZrO2/Sb2O5 matrix, heat treated up to 523 K, were shown to be very stable.

Raman spectroscopy of sputtered metal-graphene and metal-oxide-graphene interfaces

Science.gov (United States)

Chen, Ching-Tzu; Gajek, Marcin; Freitag, Marcus; Kuroda, Marcelo; Perebeinos, Vasili; Raoux, Simone

2012-02-01

In this talk, we report our recent development in sputtering deposition of magnetic and non-magnetic metal and metal-oxide thin films on graphene for applications in spintronics and nanoeleoctronics. TEM and SEM images demonstrate homogeneous coverage, uniform thickness, and good crystallinity of the sputtered films. Raman spectroscopy shows that the structure of the underlying graphene is well preserved, and the spectral weight of the defect D mode is comparable to that of the e-beam evaporated samples. Most significantly, we report the first observation of graphene-enhanced surface excitations of crystalline materials. Specifically, we discover two pronounced dispersive Raman modes at the interface of graphene and the nickel-oxide and cobalt-oxide films which we attribute to the strong light absorption and high-order resonant scattering process in the graphene layer. We will present the frequency-dependent, polarization-dependent Raman data of these two modes and discuss their microscopic origin.

Controlled metal nitrate decomposition for the preparation of supported metal Catalysts

NARCIS (Netherlands)

Wolters, M.

2010-01-01

High surface area supported metal (oxide) catalysts are essential for the production of fuels, chemicals, pharmaceuticals and the abatement of environmental pollution. Impregnation of high surface area supports, often silica or alumina, followed by drying, calcination and reduction is one of the

Uranium oxidation: characterization of oxides formed by reaction with water

International Nuclear Information System (INIS)

Fuller, E.L. Jr.; Smyrl, N.R.; Condon, J.B.; Eager, M.H.

1983-01-01

Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures

Fabrication of arrays of metal and metal oxide nanotubes by shadow evaporation.

Science.gov (United States)

Dickey, Michael D; Weiss, Emily A; Smythe, Elizabeth J; Chiechi, Ryan C; Capasso, Federico; Whitesides, George M

2008-04-01

This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The evaporating material enters the porous openings of the AAO membrane and deposits onto the walls of the pores. The membrane is tilted with respect to the column of evaporating material, so the shadows cast by the openings of the pores onto the inside walls of the pores define the geometry of the tubes. Rotation of the membrane during evaporation ensures uniform deposition inside the pores. After evaporation, dissolution of the AAO in base easily removes the template to yield an array of nanotubes connected by a thin backing of the same metal or metal oxide. The diameter of the pores dictates the diameter of the tubes, and the incident angle of evaporation determines the height of the tubes. Tubes up to approximately 1.5 mum in height and 20-200 nm in diameter were fabricated. This method is adaptable to any material that can be vapor-deposited, including indium-tin oxide (ITO), a conductive, transparent material that is useful for many opto-electronic applications. An array of gold nanotubes produced by this technique served as a substrate for surface-enhanced Raman spectroscopy: the Raman signal (per molecule) from a monolayer of benzenethiolate was a factor of approximately 5 x 10(5) greater than that obtained using bulk liquid benzenethiol.

Mesoporous metal oxide microsphere electrode compositions and their methods of making

Science.gov (United States)

Parans Paranthaman, Mariappan; Bi, Zhonghe; Bridges, Craig A.; Brown, Gilbert M.

2017-04-11

Compositions and methods of making are provided for treated mesoporous metal oxide microspheres electrodes. The compositions include microspheres with an average diameter between about 200 nanometers and about 10 micrometers and mesopores on the surface and interior of the microspheres. The methods of making include forming a mesoporous metal oxide microsphere composition and treating the mesoporous metal oxide microspheres by at least annealing in a reducing atmosphere, doping with an aliovalent element, and coating with a coating composition.

Highly Selective Aerobic Oxidation of 5-Hydroxymethyl Furfural into 2,5-Diformylfuran over Mn-Co Binary Oxides

DEFF Research Database (Denmark)

Gui, Zhenyou; Shunmugavel, Saravanamurugan; Cao, Wenrong

2017-01-01

A series of Mn−Co binary oxides were prepared by a simple thermal decomposition procedure and evaluated for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF). Investigation of the effects of metal amounts and calcination temperatures of the prepared catalysts rev...

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.

Low temperature incineration of mixed wastes using bulk metal oxide catalysts

International Nuclear Information System (INIS)

Gordon, M.J.; Gaur, S.; Kelkar, S.; Baldwin, R.M.

1996-01-01

Volume reduction of low-level mixed wastes from former nuclear weapons facilities is a significant environmental problem. Processing of these materials presents unique scientific and engineering problems due to the presence of minute quantities of radionuclides which must be contained and concentrated for later safe disposal. Low-temperature catalytic incineration is one option that has been utilized at the Rocky Flats facility for this purpose. This paper presents results of research regarding evaluation of bulk metal oxides as catalysts for low-temperature incineration of carbonaceous residues which are typical by-products of fluidized bed combustion of mixed wastes under oxygen-lean conditions. A series of 14 metal oxides were screened in a thermogravimetric analyzer, using on-line mass spectrometry for speciation of reaction product gases. Catalyst evaluation criteria focused on the thermal-redox activity of the metals using both carbon black and PVC char as surrogate waste materials. Results indicated that metal oxides which were P-type semiconductor materials were suitable as catalysts for this application. Oxides of cobalt, molybdenum, vanadium, and manganese were found to be particularly stable and active catalysts under conditions specific to this process (T<650C, low oxygen partial pressures). Bench-scale evaluation of these metal oxides with respect to stability to chlorine (HCl) attack was carried out at 550C using a TG/MS system. Cobalt oxide was found to be resistant to metal loss in a HCl/He gaseous environment while metal loss from Mo, Mn, and V-based catalysts was moderate to severe. XRD and SEM/EDX analysis of spent Co catalysts indicated the formation of non-stoichiometric cobalt chlorides. Regeneration of chlorinated cobalt was found to successfully restore the low-temperature combustion activity to that of the fresh metal oxide

Capacitor Property and Leakage Current Mechanism of ZrO2 Thin Dielectric Films Prepared by Anodic Oxidation

Science.gov (United States)

Kamijyo, Masahiro; Onozuka, Tomotake; Shinkai, Satoko; Sasaki, Katsutaka; Yamane, Misao; Abe, Yoshio

2003-07-01

Polycrystalline ZrO2 thin film capacitors were prepared by anodizing sputter-deposited Zr films. Electrical measurements are performed for the parallel-plate anodized capacitors with an Al-ZrO2-Zr (metal-insulator-metal) structure, and a high capacitance density (0.6 μF/cm2) and a low dielectric loss of nearly 1% are obtained for a very thin-oxide capacitor anodized at 10 V. In addition, the leakage current density of this capacitor is about 1.8 × 10-8 A/cm2 at an applied voltage of 5 V. However, the leakage current is somewhat larger than that of a low-loss HfO2 capacitor. The leakage current density (J) of ZrO2 capacitors as a function of applied electric field (E) was investigated for several capacitors with different oxide thicknesses, by plotting \\ln(J) vs E1/2 curves. As a result, it is revealed that the conduction mechanism is due to the Poole-Frenkel effect, irrespective of the oxide thickness.

Crystallization and deuterium permeation behaviors of yttrium oxide coating prepared by metal organic decomposition

Directory of Open Access Journals (Sweden)

Takumi Chikada

2016-12-01

Full Text Available Yttrium oxide coatings were fabricated on reduced activation ferritic/martensitic steels by metal organic decomposition with a dip-coating technique, and their deuterium permeation behaviors were investigated. The microstructure of the coatings varied with heat-treatment temperature: amorphous at 670ºC (amorphous coating and crystallized at 700ºC (crystallized coating. Deuterium permeation flux of the amorphous coating was lower than the uncoated steel by a factor of 5 at 500ºC, while that of the crystallized coating was lower by a factor of around 100 at 400‒550ºC. The permeation fluxes of both coatings were drastically decreased during the measurements at higher temperatures by a factor of up to 790 for the amorphous coating and 1000 for the crystallized one, indicating a microstructure modification occurred by an effect of test temperature with hydrogen flux. Temperature dependence of deuterium diffusivity in the coatings suggests that the decrease of the permeation flux has been derived from a decrease of the diffusivity. Characteristic permeation behaviors were observed with different annealing conditions; however, they can be interpreted using the permeation mechanism clarified in the previous erbium oxide coating studies.

Enhanced metal recovery through oxidation in liquid and/or supercritical carbon dioxide

KAUST Repository

Blanco, Mario; Buttner, Ulrich

2017-01-01

Process for enhanced metal recovery from, for example, metal-containing feedstock using liquid and/or supercritical fluid carbon dioxide and a source of oxidation. The oxidation agent can be free of complexing agent. The metal-containing feedstock

Hollow carbon sphere/metal oxide nanocomposites anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Wenelska, K.; Ottmann, A.; Schneider, P.; Thauer, E.; Klingeler, R.; Mijowska, E.

2016-01-01

HCS (Hollow carbon spheres) covered with metal oxide nanoparticles (SnO_2 and MnO_2, respectively) were successfully synthesized and investigated regarding their potential as anode materials for lithium-ion batteries. Raman spectroscopy shows a high degree of graphitization for the HCS host structure. The mesoporous nature of the nanocomposites is confirmed by Brunauer–Emmett–Teller analysis. For both metal oxides under study, the metal oxide functionalization of HCS yields a significant increase of electrochemical performance. The charge capacity of HCS/SnO_2 is 370 mA hg"−"1 after 45 cycles (266 mA hg"−"1 in HCS/MnO_2) which clearly exceeds the value of 188 mA hg"−"1 in pristine HCS. Remarkably, the data imply excellent long term cycling stability after 100 cycles in both cases. The results hence show that mesoporous HCS/metal oxide nanocomposites enable exploiting the potential of metal oxide anode materials in Lithium-ion batteries by providing a HCS host structure which is both conductive and stable enough to accommodate big volume change effects. - Highlights: • Strategy to synthesize hollow carbon spheres decorated by metal oxides nanoparticles. • High-performance of HCS/MOx storage as mesoporous hybrid material. • The results hence demonstrate high electrochemical activity of the HCS/MOx.

Non-uniform Solute Segregation at Semi-Coherent Metal/Oxide Interfaces

Science.gov (United States)

Choudhury, Samrat; Aguiar, Jeffery A.; Fluss, Michael J.; Hsiung, Luke L.; Misra, Amit; Uberuaga, Blas P.

2015-08-01

The properties and performance of metal/oxide nanocomposites are governed by the structure and chemistry of the metal/oxide interfaces. Here we report an integrated theoretical and experimental study examining the role of interfacial structure, particularly misfit dislocations, on solute segregation at a metal/oxide interface. We find that the local oxygen environment, which varies significantly between the misfit dislocations and the coherent terraces, dictates the segregation tendency of solutes to the interface. Depending on the nature of the solute and local oxygen content, segregation to misfit dislocations can change from attraction to repulsion, revealing the complex interplay between chemistry and structure at metal/oxide interfaces. These findings indicate that the solute chemistry at misfit dislocations is controlled by the dislocation density and oxygen content. Fundamental thermodynamic concepts - the Hume-Rothery rules and the Ellingham diagram - qualitatively predict the segregation behavior of solutes to such interfaces, providing design rules for novel interfacial chemistries.

Preparation of carbon-free TEM microgrids by metal sputtering

International Nuclear Information System (INIS)

Janbroers, S.; Kruijff, T.R. de; Xu, Q.; Kooyman, P.J.; Zandbergen, H.W.

2009-01-01

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775 K under vacuum conditions.

Preparation of carbon-free TEM microgrids by metal sputtering.

Science.gov (United States)

Janbroers, S; de Kruijff, T R; Xu, Q; Kooyman, P J; Zandbergen, H W

2009-08-01

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775K under vacuum conditions.

Comparative metal oxide nanoparticle toxicity using embryonic zebrafish

Directory of Open Access Journals (Sweden)

Leah C. Wehmas

2015-01-01

Full Text Available Engineered metal oxide nanoparticles (MO NPs are finding increasing utility in the medical field as anticancer agents. Before validation of in vivo anticancer efficacy can occur, a better understanding of whole-animal toxicity is required. We compared the toxicity of seven widely used semiconductor MO NPs made from zinc oxide (ZnO, titanium dioxide, cerium dioxide and tin dioxide prepared in pure water and in synthetic seawater using a five-day embryonic zebrafish assay. We hypothesized that the toxicity of these engineered MO NPs would depend on physicochemical properties. Significant agglomeration of MO NPs in aqueous solutions is common making it challenging to associate NP characteristics such as size and charge with toxicity. However, data from our agglomerated MO NPs suggests that the elemental composition and dissolution potential are major drivers of toxicity. Only ZnO caused significant adverse effects of all MO particles tested, and only when prepared in pure water (point estimate median lethal concentration = 3.5–9.1 mg/L. This toxicity was life stage dependent. The 24 h toxicity increased greatly (∼22.7 fold when zebrafish exposures started at the larval life stage compared to the 24 h toxicity following embryonic exposure. Investigation into whether dissolution could account for ZnO toxicity revealed high levels of zinc ion (40–89% of total sample were generated. Exposure to zinc ion equivalents revealed dissolved Zn2+ may be a major contributor to ZnO toxicity.

Redox switching and oxygen evolution at oxidized metal and metal oxide electrodes: iron in base.

Science.gov (United States)

Lyons, Michael E G; Doyle, Richard L; Brandon, Michael P

2011-12-28

Outstanding issues regarding the film formation, redox switching characteristics and the oxygen evolution reaction (OER) electrocatalytic behaviour of multicycled iron oxyhydroxide films in aqueous alkaline solution have been revisited. The oxide is grown using a repetitive potential multicycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of the hydrous oxide and the microdispersed nature of the latter material has been emphasised. The hydrous oxide is considered as a porous assembly of interlinked octahedrally coordinated anionic metal oxyhydroxide surfaquo complexes which form an open network structure. The latter contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution, and also charge compensating cations. The dynamics of redox switching has been quantified via analysis of the cyclic voltammetry response as a function of potential sweep rate using the Laviron-Aoki electron hopping diffusion model by analogy with redox polymer modified electrodes. Steady state Tafel plot analysis has been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slope values of ca. 60 mV dec(-1) and ca. 120 mV dec(-1) are found at low and high overpotentials respectively, whereas the reaction order with respect to hydroxide ion activity changes from ca. 3/2 to ca. 1 as the potential is increased. These observations are rationalised in terms of a kinetic scheme involving Temkin adsorption and the rate determining formation of a physisorbed hydrogen peroxide intermediate on the oxide surface. The dual Tafel slope behaviour is ascribed to the potential dependence of the surface coverage of adsorbed intermediates.

Surface modification and functionalization of metal and metal oxide nanoparticles by organic ligands

NARCIS (Netherlands)

Neouze, M.A.; Schubert, U.S.

2008-01-01

Metal or metal oxide nanoparticles possess unique features compared to equivalent larger-scale materials. For applications, it is often necessary to stabilize or functionalize such nanoparticles. Thus, modification of the surface of nanoparticles is an important chemical challenge. In this survey,

Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

Science.gov (United States)

Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

2017-01-10

A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

Sol-gel preparation of uranium oxide spheres

International Nuclear Information System (INIS)

Dolezal, J.; Urbanek, V.

1978-01-01

Information is presented on problems of preparing nuclear fuel by the sol-gel method. Basic data on different process types are given. A more detailed description of the method of preparation of spherical particles of uranium oxide gel developed and used at the Nuclear Research Institute at Rez is given. Advantages and disadvantages of sol-gel materials are discussed in comparison with fuel materials prepared by classical precipitation methods. The feasibility of the sol-gel methods for preparing other materials is shortly mentioned and their application outlined. (author)

Production of crystalline refractory metal oxides containing colloidal metal precipitates and useful as solar-effective absorbers

Science.gov (United States)

Narayan, Jagdish; Chen, Yok

1983-01-01

This invention is a new process for producing refractory crystalline oxides having improved or unusual properties. The process comprises the steps of forming a doped-metal crystal of the oxide; exposing the doped crystal in a bomb to a reducing atmosphere at superatmospheric pressure and a temperature effecting precipitation of the dopant metal in the crystal lattice of the oxide but insufficient to effect net diffusion of the metal out of the lattice; and then cooling the crystal. Preferably, the cooling step is effected by quenching. The process forms colloidal precipitates of the metal in the oxide lattice. The process may be used, for example, to produce thermally stable black MgO crystalline bodies containing magnetic colloidal precipitates consisting of about 99% Ni. The Ni-containing bodies are solar-selective absorbers, having a room-temperature absorptivity of about 0.96 over virtually all of the solar-energy spectrum and exhibiting an absorption edge in the region of 2 .mu.m. The process parameters can be varied to control the average size of the precipitates. The process can produce a black MgO crystalline body containing colloidal Ni precipitates, some of which have the face-centered-cubic structure and others of which have the body-centered cubic structure. The products of the process are metal-precipitate-containing refractory crystalline oxides which have improved or unique optical, mechanical, magnetic, and/or electronic properties.

Uranium Metal to Oxide Conversion by Air Oxidation –Process Development

Energy Technology Data Exchange (ETDEWEB)

Duncan, A

2001-12-31

Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

Preventing Bacterial Infections using Metal Oxides Nanocoatings on Bone Implant

Science.gov (United States)

Duceac, L. D.; Straticiuc, S.; Hanganu, E.; Stafie, L.; Calin, G.; Gavrilescu, S. L.

2017-06-01

Nowadays bone implant removal is caused by infection that occurs around it possibly acquired after surgery or during hospitalization. The purpose of this study was to reveal some metal oxides applied as coatings on bone implant thus limiting the usual antibiotics-resistant bacteria colonization. Therefore ZnO, TiO2 and CuO were synthesized and structurally and morphologically analized in order to use them as an alternative antimicrobial agents deposited on bone implant. XRD, SEM, and FTIR characterization techniques were used to identify structure and texture of these nanoscaled metal oxides. These metal oxides nanocoatings on implant surface play a big role in preventing bacterial infection and reducing surgical complications.

Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances

Science.gov (United States)

Gao, Qiuyue; Shi, Zhenyu; Xue, Kaiming; Ye, Ziran; Hong, Zhanglian; Yu, Xinyao; Zhi, Mingjia

2018-05-01

This work introduces the anion exchange method into the sol-gel process for the first time to prepare a metal sulfide aerogel. A porous Co9S8 aerogel with a high surface area (274.2 m2 g‑1) and large pore volume (0.87 cm3 g‑1) has been successfully prepared by exchanging cobalt citrate wet gel in thioacetamide and subsequently drying in supercritical ethanol. Such a Co9S8 aerogel shows enhanced supercapacitive performance and catalytic activity toward oxygen evolution reaction (OER) compared to its oxide aerogel counterpart. High specific capacitance (950 F g‑1 at 1 A g‑1), good rate capability (74.3% capacitance retention from 1 to 20 A g‑1) and low onset overpotential for OER (220 mV) were observed. The results demonstrated here have implications in preparing various sulfide chalcogels.

Oxygen partial pressure: a key to alloying and discovery in metal oxide--metal eutectic systems

International Nuclear Information System (INIS)

Holder, J.D.; Clark, G.W.; Oliver, B.F.

1978-01-01

Control of oxygen partial pressure is essential in the directional solidification of oxide--metal eutectic composites by techniques involving gas-solid and gas-liquid interactions. The existence of end components in the eutectic composite is Po 2 sensitive as are melt stoichiometry, solid phase compositions, and vapor losses due to oxidation-volatilization. Simple criteria are postulated which can aid the experimentalist in selecting the proper gas mixture for oxide--metal eutectic composite growth. The Cr 2 O 3 --Mo--Cr systems was used to verify certain aspects of the proposed criteria

Thermal oxidation of Zr–Cu–Al–Ni amorphous metal thin films

International Nuclear Information System (INIS)

Oleksak, R.P.; Hostetler, E.B.; Flynn, B.T.; McGlone, J.M.; Landau, N.P.; Wager, J.F.; Stickle, W.F.; Herman, G.S.

2015-01-01

The initial stages of thermal oxidation for Zr–Cu–Al–Ni amorphous metal thin films were investigated using X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The as-deposited films had oxygen incorporated during sputter deposition, which helped to stabilize the amorphous phase. After annealing in air at 300 °C for short times (5 min) this oxygen was found to segregate to the surface or buried interface. Annealing at 300 °C for longer times leads to significant composition variation in both vertical and lateral directions, and formation of a surface oxide layer that consists primarily of Zr and Al oxides. Surface oxide formation was initially limited by back-diffusion of Cu and Ni ( 30 min). The oxidation properties are largely consistent with previous observations of Zr–Cu–Al–Ni metallic glasses, however some discrepancies were observed which could be explained by the unique sample geometry of the amorphous metal thin films. - Highlights: • Thermal oxidation of amorphous Zr–Cu–Al–Ni thin films was investigated. • Significant short-range inhomogeneities were observed in the amorphous films. • An accumulation of Cu and Ni occurs at the oxide/metal interface. • Diffusion of Zr was found to limit oxide film growth.

Preparation and electrochemical characterization of MnOOH nanowire-graphene oxide

International Nuclear Information System (INIS)

Wang Lin; Wang Dianlong

2011-01-01

Highlights: → MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C, with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. → MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. → It is found that the electrochemical resistance of MnOOH nanowire-graphene oxide composites decreases and the capacitance increases to 76 F g -1 when hydrothermal reaction is conducted in ammonia aqueous solution. → MnOOH nanowire-graphene oxide composites prepared by hydrothermal reaction in 5% ammonia aqueous solution have excellent capacitance retention ratio at scan rate from 5 mV s -1 to 40 mV s -1 . - Abstract: MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. Powder X-ray diffraction (XRD) analyses and energy dispersive X-ray analyses (EDAX) show MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. The electrochemical capacitance of MnOOH nanowire-graphene oxide composites prepared in 5% ammonia aqueous solution is 76 F g -1 at current density of 0.1 A g -1 . Moreover, electrochemical impedance spectroscopy (EIS) suggests the electrochemical resistance of MnOOH nanowire-graphene oxide composites is reduced when hydrothermal reaction is conducted in ammonia aqueous solution. The relationship between the electrochemical capacitance and the structure of MnOOH nanowire-graphene oxide composites is characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FESEM). The results indicate the electrochemical performance of MnOOH nanowire-graphene oxide composites strongly depends on their

Metal Oxide Nano structures: Synthesis, Properties, and Applications

International Nuclear Information System (INIS)

Xu, L. H.; Patil, D. S.; Yang, J.; Xiao, J.

2015-01-01

In recent years, nano structured materials have attracted wide attention due to their fascinating optical and electrical properties, which make these materials potentially suitable for applications in electronics, optics, photonics, and sensors. Some metal oxides show a wide variety of morphologies such as nano wires, nano rods, nano tubes, nano rings, and nano belts. Synthesis and investigation of these metal-oxide nano structures are beneficial not only for understanding the fundamental phenomena in low dimensional systems, but also for developing new-generation nano devices with high performance.

Validation of MCNP6.1 for Criticality Safety of Pu-Metal, -Solution, and -Oxide Systems

Energy Technology Data Exchange (ETDEWEB)

Kiedrowski, Brian C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Conlin, Jeremy Lloyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Favorite, Jeffrey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kahler, III, Albert C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kersting, Alyssa R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parsons, Donald K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Walker, Jessie L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-05-13

Guidance is offered to the Los Alamos National Laboratory Nuclear Criticality Safety division towards developing an Upper Subcritical Limit (USL) for MCNP6.1 calculations with ENDF/B-VII.1 nuclear data for three classes of problems: Pu-metal, -solution, and -oxide systems. A benchmark suite containing 1,086 benchmarks is prepared, and a sensitivity/uncertainty (S/U) method with a generalized linear least squares (GLLS) data adjustment is used to reject outliers, bringing the total to 959 usable benchmarks. For each class of problem, S/U methods are used to select relevant experimental benchmarks, and the calculational margin is computed using extreme value theory. A portion of the margin of sub criticality is defined considering both a detection limit for errors in codes and data and uncertainty/variability in the nuclear data library. The latter employs S/U methods with a GLLS data adjustment to find representative nuclear data covariances constrained by integral experiments, which are then used to compute uncertainties in k_eff from nuclear data. The USLs for the classes of problems are as follows: Pu metal, 0.980; Pu solutions, 0.973; dry Pu oxides, 0.978; dilute Pu oxide-water mixes, 0.970; and intermediate-spectrum Pu oxide-water mixes, 0.953.

Zinc oxide nanocolloids prepared by picosecond pulsed laser ablation in water at different temperatures

Science.gov (United States)

D'Urso, Luisa; Spadaro, Salvatore; Bonsignore, Martina; Santangelo, Saveria; Compagnini, Giuseppe; Neri, Fortunato; Fazio, Enza

2018-01-01

Zinc oxide with wide direct band gap and high exciton binding energy is one of the most promising materials for ultraviolet (UV) light-emitting devices. It further exhibits good performance in the degradation of non-biodegradable pollutants under UV irradiation. In this work, zinc oxide (ZnO) and zinc oxide/gold (ZnO/Au) nanocolloids are prepared by picosecond pulsed laser ablation (ps-PLA), using a Zn and Au metallic targets in water media at room temperature (RT) and 80°C. ZnO and Au nanoparticles (NPs) with size in the 10-50 nm range are obtained at RT, while ZnO nanorods (NRs) are formed when water is maintained at 80°C during the ps-PLA process. Au NPs, added to ZnO colloids after the ablation process, decorate ZnO NRs. The crystalline phase of all ZnO nanocolloids is wurtzite. Methylene blue dye is used to investigate the photo-catalytic activity of all the synthesised nanocolloids, under UV light irradiation.

Mesoporous binary metal oxide nanocomposites: Synthesis, characterization and decontamination of sulfur mustard

Energy Technology Data Exchange (ETDEWEB)

Praveen Kumar, J., E-mail: praveenjella10@gmail.com; Prasad, G.K.; Ramacharyulu, P.V.R.K.; Singh, Beer; Gopi, T.; Krishna, R.

2016-04-15

Mesoporous MnO{sub 2}–ZnO, Fe{sub 2}O{sub 3}–ZnO, NiO–ZnO, and CeO{sub 2}–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard. They were synthesized by precipitation pyrolysis method and characterized by means of transmission electron microscopy, scanning electron microscopy coupled with energy dispersive analysis of X rays, X ray diffraction, and nitrogen adsorption techniques. The transmission electron microscopy and nitrogen adsorption data indicated the presence of pores with diameter ranging from 10 to 70 nm in the binary metal oxide nanocomposites and these materials exhibited surface area values in the range of 76–134 m{sup 2}/g. These binary metal oxide nanocomposites demonstrated large decontamination efficiencies against sulfur mustard when compared to their single component metal oxide nanoparticles. The binary metal oxide nanocomposites effectively decontaminated sulfur mustard into relatively non toxic products such as chloro ethyl vinyl sulfide, divinyl sulfide, 1,4-oxathiane, etc. The promising decontamination properties of binary metal oxide nanocomposites against sulfur mustard were attributed to the basic sites, Lewis acid sites, and the presence of these sites was confirmed by CO{sub 2} and NH{sub 3} temperature programmed desorption. - Graphical abstract: Mesoporous MnO{sub 2}–ZnO, Fe{sub 2}O{sub 3}–ZnO, NiO–ZnO, and CeO{sub 2}–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard. - Highlights: • Binary metal oxide nanocomposites were synthesized by co-precipitation method. • They were studied as sorbent decontaminants against sulfur mustard. • They decontaminated sulfur mustard into non toxic products. • MnO{sub 2}–ZnO and CeO{sub 2}–ZnO nanocomposites showed greater decontamination efficiency.

Platinum redispersion on metal oxides in low temperature fuel cells.