To see the other types of publications on this topic, follow the link: Cobalt oxide.
Dissertations / Theses on the topic 'Cobalt oxide'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Cobalt oxide.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Shukri, Rashid Jaber Asa'd. "Supported oxide catalysts : cobalt oxide and molybdena on titania." Thesis, Brunel University, 1989. http://bura.brunel.ac.uk/handle/2438/7385.
Full textAbstract:
TiO2 supported MoO3 catalysts were prepared by aqueous impregnation of low area anatase (10 m2g-1) with solutions of (NH4)6Mo7024,4H20 (MT/C series), and H2[Mo03(C204)].H20 (MOT /C series), Three series of CoOx/Ti02 catalysts were fabricated by aqueous impregnation of the same support with solutions of Co(N03)2,6H20 (CT/C series), and Co(CH3COO)2.4H20 (CAT/C series), and by homogeneous precipitation using Co(N03)2,6H20 (CT/HP series), CoO and Mo03 were deposited on Degussa P-25 (55 m2g-1) by aqueous impregnation using (NH4)6Mo7024,4H20 and Co(N03)2,6H20 in three ways: ( i) CoO impregnated first, Mo03 second (CMT series); (ii) Mo03 impregnated first, CoO second (MCT series); and (iii) CoO and Mo03 together (CMTg series). The catalysts were characterized by laser Raman spectroscopy (LRS) , temperature-programmed reduction (TPR) , X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), Monolayer coverage by XPS was independent of the precursor for the MoOx/Ti02 catalysts, but a function of the method of preparat ion and the precursor for the CoOx /Ti02 catalysts. XPS results for the CMTg series differed from those for the CMT and MCT series, suggesting different surface species had been formed by varying the mode of impregnation, Phase diagrams relating semiquantitatively to the oxide contents are presented. 2-propanol decomposition was studied to probe the acid-base properties of the catalysts, Ti02 and Mo03 exhibi ted dehydration activity, whereas CoO showed dehydrogenation activity, All the supported catalysts gave activation energies for dehydration higher than dehydrogenation. In the sub-monolayer region, the catalytic activity for dehydration was in the order: MCT > CMTg > CMT > MT/C > CT/C, while the selectivity remained almost unchanged, In the monolayer region, the activity was: MT/C > CMT > CMTg > MCT > CT/C and the selectivity increased compared with the sub-monolayer region. In the four-monolayer reg ion, the activity decreased compared with the sub-monolayer and monolayer regions, but the selectivity increased relative to the previous two regimes. "Compensation effect 0, plots revealed different types of active centres responsible for dehydration and dehydrogenation processes in the MoOx /Ti02 and CoO-Mo03/Ti02 catalysts, while active centres were almost identical with the CoOx /Ti02 system.
2
Yar-Mukhamedova, G. Sh, M. V. Ved, A. V. Karakurkchi, and N. D. Sakhnenko. "Mixed alumina and cobalt containing plasma electrolytic oxide coatings." Thesis, IOP Publishing Ltd, 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/30798.
Full textAbstract:
Principles of plasma electrolytic oxidation of the AL25 aluminum alloy in diphosphate alkali solutions containing cobalt(2+) cations are discussed. It has been established that a variation in the concentration of the electrolyte components provides the formation of mixed-oxide coatings consisting of the basic matrix materials and the cobalt oxides of different content. An increase in the cobalt oxide content in the coating is achieved by the variation in electrolysis current density as well as the treatment time due to both the electrochemical and thermo-chemical reactions at substrate surface and in spark region. Current density intervals that provide micro-globular surface formation and uniform cobalt distribution in the coating are determined. The composition and morphology of the surface causes high catalytic properties of synthesized materials, which confirmed the results of testing in model reaction CO and benzene oxidation as well as fuel combustion for various modes of engine operation.
3
Pachuta, Kevin. "Accessing Controlled Nanostructures from Lithium Cobalt Oxide." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1607704644249276.
Full text
4
Owings, Robert Reed. "Polarons and impurities in nickel cobalt oxide." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002242.
Full text
5
Haffer, Stefanie [Verfasser]. "Mesoporous spinel-type cobalt oxide, cobalt ferrite and alumina by nanocasting / Stefanie Haffer." Paderborn : Universitätsbibliothek, 2014. http://d-nb.info/1046651994/34.
Full text
6
Hao, Yalin. "Continuous Hydrothermal Production of Iron Oxide (Fe[subscript 2]0[subscript 3]) and Cobalt Oxide (Co[subscript 3]O[subscript 4])." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/11217.
Full text
7
Wong, Lai Ally, and 王麗. "Electronic spectroscopy of cobalt monohalides and nitric oxide." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29468127.
Full text
8
Freese, Susan Delia. "A study of lithium/cobalt oxide electrochemical cells." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/17048.
Full textAbstract:
Bibliography: pages 109-117.The electrochemical behaviour of high temperature Li-Al/LiCl, KCl/cobalt oxide cells was investigated. Powder X-ray diffraction techniques were used for the qualitative analysis of the phases generated during charge and discharge of the cells.
9
Åkre, Torjus. "Electrowinning of Cobalt from Chloride Solutions: Anodic Deposition of Cobalt Oxide on DSA®." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2200.
Full text
10
Chodosovskaja, Ala. "Influence of cobalt oxide nanostructuring on electrochemical pseudo-capacitance." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120131_092732-72596.
Full textAbstract:
Design of high efficiency energy accumulators has recently become an important issue of science and technology. Electrochemical capacitors are distinguished for a greater power, a longer self-discharge time and a greater number of work cycles as compared to those of traditional electrochemical batteries. Effective supercapacitors are mainly produced of RuO2, which is distinguished from other metals for its nearly highest specific capacity, however its practical application is limited by its high price, therefore efforts are under way to find cheaper substitutes. Recently cobalt oxide has been intensively studied. It is important to find economically effective and simple methods which will make it possible to increase the pseudocapacities of cobalt oxides. The conditions of electrochemical cobalt deposition, under which the fiber Co nanostructure possessing a great surface area is formed, have been determined in the work. Cobalt hydro/oxide layers were formed by the anodic polarization method and their pseudocapacity was studied on various substrates: nanostructured, magnetron-sputtered coating and metallurgical cobalt. The pseudocapacitor behaviour of cobalt hydro/oxides was studied by using the cyclic voltammetry method along with electrochemical quartz crystal mocrobalance (EKKM). Oxide layers showed oxidation-reduction and corresponding pseudo-capacitor behaviour.It has been shown that the oxide layer is stable and it withstands a few thousand polarization cycles. It has... [to full text]Energijos kaupiklių kūrimas pastaraisiais metais tapo svarbia mokslo aktualija. Elektrocheminiai kondensatoriai pasižymi didesne galia, ilgesniu savaiminio išsikrovimo laiku ir didesniu darbo ciklų skaičiumi negu tradicinės elektrocheminės baterijos. Didžiausia savitąja talpa pasižymi RuO2, tačiau jo praktinį taikymą riboja didelė kaina, todėl ieškoma pigesnių pakaitalų. Pastaraisiais metais aktyviai tiriamas kobalto oksidas. Svarbu yra surasti ekonomiškai efektyvius ir paprastus metodus, leidžiančius padidinti kobalto oksidų pseudotalpas. Darbe nustatytos elektrocheminio Co nusodinimo sąlygos, kurioms esant yra formuojama pluoštinė nanostruktūra, pasižyminti dideliu paviršiaus plotu. Anodinės poliarizacijos būdu buvo suformuoti kobalto hidro/oksido sluoksniai ir ištirta jų pseudotalpa ant skirtingų substratų: nanostruktūrinės, magnetroninės-plazminės dangos ir metalurginio Co. Pseudotalpinė kobalto hidro/oksidų elgsena buvo ištirta ciklinės voltamperometrijos metodu kartu su elektrocheminėmis kvarco kristalo svarstyklėmis (EKKM). Oksidiniai sluoksniai parodė grįžtamą redukcijos-reoksidacijos ir atitinkamą pseudotalpinę elgseną. Per kelis tūkstančius anodinių ciklų buvo parodyta, kad oksidinis sluoksnis išliko stabilus. Nustatyta, kad hidro/oksidų, suformuotų ant nanostruktūrinės Co dangos, talpa maždaug 5 kartus didesnė nei suformuotų ant metalurginio Co. Šiame darbe pasiūlytas naujas kobalto oksido formavimo būdas: sulfidinės Co(OH)2–CoS kompozicijos formavimas ir... [toliau žr. visą tekstą]
11
Jiang, San-Ping. "A study of teflon-bonded cobalt oxide/graphite electrodes." Thesis, City University London, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306058.
Full text
12
Pinnell, Rebecca. "Cobalt oxide catalysts for the total oxidation of propane." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/73543/.
Full textAbstract:
The three-way catalyst (TWC) greatly reduces emissions of hydrocarbons, carbon monoxide and nitrogen oxides from gasoline powered vehicles. However up to 80% of all hydrocarbons are emitted in the first 120 seconds after the engine is started, before the TWC achieves light-off. Catalysts which are active at lower temperatures offer a potential solution to this ‘cold-start’ problem. Co3O4 is one of the most active transition metal oxide catalysts for the total oxidation of hydrocarbons. In this work the synthesis of bulk and supported cobalt oxide catalysts has been investigated. The catalysts were thoroughly characterised and tested for the total oxidation of propane, a model hydrocarbon. Variables in the mechanochemical synthesis and precipitation of bulk Co3O4 were studied. Cobalt hydroxycarbonate hydrate synthesised by both techniques was found to give rise to active and stable Co3O4 catalysts upon calcination. Small Co3O4 crystallites, high surface areas, weak Co3+-O bonds, and the absence of contaminants were found to be required for high propane oxidation activity. Deposition precipitation, wet impregnation and powder blending methods were investigated for supporting Co3O4 on a high surface area, non-porous silica. Wet impregnation from cobalt nitrate was found to be the most effective method of synthesising supported Co3O4 with minimal formation of undesired cobalt silicates. Activity increased with increased cobalt weight loading but supported catalysts displayed lower activity than bulk catalysts.
13
Shojaee, Kambiz. "Fundamental aspects of ammonia oxidation on cobalt oxide catalysts." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/13657.
Full textAbstract:
The current thesis deals with the ammonia oxidation on cobalt oxide catalyst at the molecular level. The catalytic oxidation of ammonia to NO is crucial in the industrial process of nitric acid production. Cobalt oxide catalysts are being used together with platinum gauzes to reduce the production cost and emission of greenhouse gas N2O. However, the fundamentals of ammonia oxidation on cobalt oxides are not known. This thesis aims to provide insights into our fundamental understanding of ammonia oxidation on Co3O4 surfaces. The performance of cobalt oxide catalysts in the oxidation of NH3 strongly depends upon the exposed surface terminations. Results indicate that different surfaces of Co3O4 behave markedly differently in oxidative reactions due to the difference in binding energy and O recombination energies and oxygen vacancy formation. Overall, NH3 oxidation follows stepwise dehydrogenative route (NH3* → NH2* → NH* → N*) on Co3O4 surfaces. Desorption of lattice products results in the formation of O vacancy sites opening the way for a Mars-van Krevelen mechanism. The successive dehydrogenation of ammonia preferably occurs on the surfaces exposing active lattice O sites. Removal of active lattice O sites from the Co3O4 surfaces in the form of products results in the surface reduction. If the rate of reduction is faster than that of re-oxidation, a CoO-like phase might form. The formation of CoO in Co3O4 catalysts during NH3 oxidation not only reduces the NH3 conversion but also alters the selectivity towards N2 rather than NO due to weak ability of lattice O at the CoO surface to assist the hydrogen abstraction process. A surface with a lower oxygen vacancy formation energy and a higher binding energy of hydrogen exhibits a higher activity towards ammonia oxidation to NO.
14
Andronic, Laura Simona. "Photochemical metal organic deposition of layered materials of chromium oxide and lead oxide and of uranium oxide and cobalt oxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61529.pdf.
Full text
15
Yung, Matthew Maurice. "Oxidation catalysis in environmental applications nitric oxide and carbon monoxide oxidation for the reduction of combustion emissions and purification of hydrogen streams /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187128442.
Full text
16
Sen, Ebubekir. "Synthesis Of Sba-15 And Incorporation Of Cobalt Oxide Nanoparticles." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607705/index.pdf.
Full textAbstract:
Mesoporous materials attracted great interest due to their huge surface area and adjustable pore sizes. One of the important mesoporous materials is SBA-15 and has larger pore size, hydrothermal stability and thicker walls than other
mesoporous materials. In this study, SBA-15 is synthesized by using sol-gel technique and cobalt oxide nanoparticles are incorporated in mesochannels by direct method.
SBA-15 was produced from the self-assembly of non-ionic triblock co-polymer (Pluronic 123) and tetra ethyl ortho silicate (TEOS). Then cobalt chloride and cobalt nitrate were added at different loading ratios with two different addition
sequencesafter polymer and after TEOS. The loading ratios are in Si/Co mols and these ratios are
15, 10, 5, 3, 1.5, 1 and 0.75 in increasing cobalt amount loaded. Characterization of the produced materials was performed by Powder X-Ray Diffraction (PXRD), Infrared (FTIR) analysis. Nitrogen Phisisorption measurements (BET and BJH Methods) were used to examine the textural properties of produced materials. By means of Transmission Electron Microscopy (TEM) the micro structures of materials were investigated. From the PXRD studies it is observed that the long range order of pores is preserved at even high loading amounts for cobalt chloride addition after TEOS. Co3O4 (JCPDS card no: 42-1467) crystallites are observed for Si/Co mol loading ratios 3, 1.5, 1 and 0.75. Above these loading ratios cobalt oxide is highly dispersed in SBA-15-type structure. FTIR studies revealed the formation of condensed silica network. From the Nitrogen Phisisorption measurements it is observed that addition of cobalt salt decreases the BET surface area of produced materials. All Nitrogen Adsorption-Desorption Isotherms are Type-IV, and has H-1 hysteresis which is a fulfillment of mesoporous structures according to IUPAC classification. BET surface area of samples loaded with cobalt chloride after TEOS possessed higher surface area than other samples. TEM images proved that at loading ratios above 3 there were not any cobalt oxide nanoparticles, cobalt oxide is highly dispersed on silica surface whereas at loading ratios 3 and below there were cobalt oxide nanoparticles embedded in the mesochannels for the samples prepared by addition of cobalt chloride after TEOS.
17
Kozhukh, Julia 1985. "Nitric oxide reactions of bio-Inspired zinc and cobalt complexes." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/73360.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2012.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter 1. Bioinorganic Chemistry of Nitric Oxide and of Some of Its Targets The redox-active nature of nitric oxide (NO) regulates the chemistry and roles of NO in biology. The interactions of NO with nitric oxide synthases, metallothioneins, and cobalamin-containing enzymes are discussed. Bioinspired small molecule models for metalloprotein active sites are introduced, and the ability of ligands to control the steric and electronic properties of coordinated metal centers is demonstrated. The bioinorganic chemistry of NO and its targets is described in the context of the investigations presented in this thesis. Chapter 2. Zinc Thiolate Reactivity toward Nitrogen Oxides: Insights into the Interaction of Zn2+ with S-Nitrosothiols and Implications for Nitric Oxide Synthase Zinc thiolate complexes containing N2S tridendate ligands were prepared to investigate their reactivity toward reactive nitrogen species. This type of chemistry is proposed to occur at the zinc tetracysteine thiolate site of nitric oxide synthase (NOS). The complexes are unreactive toward nitric oxide in the absence of dioxygen, strongly indicating that NO cannot be the species directly responsible for S-nitrosothiol formation and loss of Zn2* at the NOS dimer interface in vivo. S-Nitrosothiol formation does occur upon exposure of zinc thiolate solutions to NO in the presence of air, however, or to NO2 or NOBF4, indicating that these reactive nitrogen/oxygen species are capable of generating the S-nitrosothiol. Interaction between simple Zn2+ salts and pre-formed S-nitrosothiols leads to decomposition of the -SNO moiety, resulting in release of gaseous NO and N20. The potential biological relevance of this chemistry is discussed. Chapter 3. Reactions of Organozinc Thiolates with Nitrosonium Ion: C-Nitroso Formation by Intramolecular Transnitrosation The organometallic species [ZnPAThEt] and [ZnPAThMes] are prepared, and their reactions with NOBF4 are characterized. The formation of C-nitrosoethane and C-nitrosomesitylene is confirmed, and structural characterization of C-nitrosomesitylene conclusively establishes the dimeric nature of the molecule in the solid state. An intramolecular transnitrosation reaction pathway for C-nitroso formation is proposed based on theoretical calculations. Chapter 4. Influence of Ligand Constraints on the Reactivity of Co(II) Complexes of Tetraazamacrocyclic Tropocoronand Ligands with Nitric Oxide Previous work on the reactivity of cobalt(II) complexes of tetraazamacrocyclic tropocoronand ligands with nitric oxide (NO) was extended to include the [Co(TC-5,5)] and [Co(TC-6,6)] derivatives. The cobalt mononitrosyl [Co(NO)(TC-5,5)] is isolated and structurally characterized from the reaction of [Co(TC-5,5)] and NO (g). In contrast, a {Co(NO) 2}'0 species is observed when [Co(TC-6,6)] is exposed to NO (g) and the nitrite complex [Co(NO2)(TC-6,6)] is structurally and spectroscopically characterized from reaction mixtures. The di(cobalt dinitrosyl) [Co2(NO) 4(TC-6,6)] is independently synthesized for spectroscopic comparison with reaction mixtures. This Chapter describes the first characterization of the dependence of cobalt(II) tropocoronand reactivity on linker chain length..
(cont.) Chapter 5. Reactivity of Tropocoronand-Bound Cobalt(III) Nitrite with Nitric Oxide as a Function of Polymethylene Linker Chain Length The studies on the dependence of cobalt(II) tropocoronand reactivity with nitric oxide (NO) on linker chain length, described in Chapter 4, were expanded to include the chemistry of the cobalt(III) nitrites [Co(NO2)(TC-n,n)] (n = 4 - 6) with NO. Complete conversion from the cobalt(III) nitrite to the cobalt mononitrosyl [Co(NO)(TC-4,4)] is demonstrated upon exposure to NO (g). In contrast, exposure of [Co(N0 2)(TC-5,5)] and [Co(N0 2)(TC-6,6)] to NO (g) results in conversion to a cobalt dinitrosyl adduct. This Chapter aims to broaden the field of cobalt(III) chemistry with NO. Chapter 6. Nitric Oxide Reactivity of Cobalt(III) Triflate and Cobalt(III) Thiolate Tropocoronand Complexes The reactivity of two cobalt(III) tropocoronands with NO (g) is described. [Co(TC-4,4)](OTf) undergoes reductive nitrosylation in the presence of NO (g), forming [Co(NO)(TC-4,4)], N20, and additional reactive species. The reaction releases one equivalent of protons for every equivalent of [Co(TC-4,4)](OTf) consumed. [Co(SC 6F5)(TC-4,4)] forms [Co(NO)(TC-4,4)] and the disulfide F5C6SSC6F5 in the presence of NO (g). We hypothesize that disulfide formation is followed by electrophilic aromatic substitution of F5C6S* onto the tropocoronand aromatic ring. Efforts to prepare substituted tropocoronand ligands and test the electrophilic aromatic substitution hypothesis are described. Chapter 7. Synthesis and Characterization of Mononuclear, Pseudotetrahedral Cobalt(III) Compounds The synthesis and characterization of two mononuclear cobalt(III) tropocoronand complexes, [Co(TC-5,5)](BF 4) and [Co(TC-6,6)](BPh 4), are reported. The cobalt(III) centers exist in rare pseudotetrahedral conformations, with twist angles of 650 and 740 for the [Co(TC-5,5]* and [Co(TC-6,6)]* species, respectively. Structural and electrochemical characteristics are compared with those of newly synthesized [Ga(TC-5,5)](GaCl4) and [Ga(TC-6,6)](GaCl 4) analogs.
by Julia Kozhukh.
Ph.D.
18
Lagerqvist, Ulrika. "Solution-Chemical Synthesis of Cobalt and Iron:Zinc Oxide Nanocomposite Films." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280619.
Full textAbstract:
The potentially most important challenges today are related to energy and the environment. New materials and methods are needed in order to, in a sustainable way, convert and store energy, reduce pollution, and clean the air and water from contaminations. In this, nanomaterials and nanocomposites play a key role, and hence knowledge about the relation between synthesis, structure, and properties of nanosystems is paramount. This thesis demonstrates that solution-chemical synthesis, using amine-modified acetates and nitrates, can be used to prepare widely different nanostructured films. By adjusting the synthesis parameters, metals, oxides, and metal–oxide or oxide–oxide nanocomposites were prepared for two systems based on Co and Zn:Fe, respectively, and the films were characterised using diffraction, spectroscopy, and microscopy techniques, and SQUID magnetometry. A variety of crystalline cobalt films—Co metal, CoO, Co3O4, and composites with different metal:oxide ratios—were synthesised. Heat-treatment parameters and control of the film thickness enabled tuning of the phase ratios. Random and layered Co–CoO composites were prepared by utilising different heating rates and gas flow rates together with a morphology effect associated with the furnace tube. The Co–CoO films exhibited exchange bias due to the ferromagnetic–antiferromagnetic interaction between the Co and CoO, whereas variations in e.g. coercivity and exchange bias field were attributed to differences in the structure and phase distribution. Ordered structures of wurtzite ZnO surrounded by amorphous ZnxFeyO were prepared through controlled phase segregation during the heating, which after multiple coating and heating cycles yielded ZnO–ZnxFeyO superlattices. The amorphous ZnxFeyO was a prerequisite for superlattice formation, and it profoundly affected the ZnO phase, inhibiting grain growth and texture, already from 1% Fe. In addition, ZnO–ZnxFeyO exhibited a photocatalytic activity for the oxidation of water that was higher than results reported for pure ZnO, and comparable to recent results reported for graphene-modified ZnO.
19
Tuan, Allan C. "Epitaxial growth and characterization of cobalt-doped zinc oxide and cobalt-doped titanium dioxide for spintronic applications /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/9878.
Full text
20
Abou, Serhal Cynthia. "Oxydation totale des Composés Organiques Volatils (COV) sur des catalyseurs à base de métaux de transition préparés par voie hydrotalcite : Effet des micro-ondes sur la méthode de synthèse." Thesis, Littoral, 2018. http://www.theses.fr/2018DUNK0529/document.
Full textAbstract:
Ce travail vise l'étude de l'oxydation catalytique des Composés Organiques Volatils (COVs). L'objectif principal est de trouver des matériaux catalytiques qui sont des alternatives aux métaux nobles très onéreux. La recherche des matériaux catalytiques actifs, sélectifs, stables dans le temps et à base de métaux de transition est abordée. Afin d'améliorer les performances catalytiques des métaux de transition, la dispersion de l'espèce métallique doit être optimisée en utilisant une méthode de synthèse adéquate. Les différents solides préparés ont été caractérisés par différentes techniques physico-chimiques : la Diffraction des Rayons X (DRX), les Analyses Thermiques (ATD/ATG), la Spectroscopie Infrarouge (IR), la Réduction en Température Programmée (H₂-RTP), la Microscopie Electronique à Balayage (MEB), la Spectroscopie de Photoélectrons induits par rayons X (SPX)...De plus, les oxydes obtenus ont été testés dans les réactions d'oxydation totale du COV propène. En premier lieu, nous avons focalisé notre travail sur la préparation d'une série d'oxydes mixtes Co-Mg/Al-Fe par voie hydrotalcite afin d'obtenir des propriétés intéressantes en catalyse hétérogène. Cette étude consiste surtout à évaluer la substitution des cations bivalents et trivalents. Il s'est avéré que le solide contenant à la fois du cobalt et du fer (CoFe) possède l'activité catalytique la plus élevée. L'intérêt de la voie hydrotalcite par rapport à d'autres méthodes de synthèse, telles que la méthode classique et le mélange mécanique des oxydes a été mis en évidence. En second lieu, l'utilisation des irradiations micro-ondes lors de la synthèse des matériaux hydrotalcites a été également étudiée comme une méthode de synthèse non-conventionnelle. Un effet bénéfique a été observé avec l'utilisation des micro-ondes dû principalement à des surfaces spécifiques plus élevées et à une meilleure réductibilité des espèces oxydes. En outre, cette étude vise également la mise au point de cette nouvelle méthode. De ce fait, l'optimisation de la température, durée et puissance des irradiations micro-ondes a été effectuée sur le solide CoFe, afin de montrer l'influence de chaque paramètre sur les propriétés physico-chimiques des matériaux. En troisième lieu, la synthèse d'une série de catalyseurs par voie hydrotalcite avec différentes teneurs en Co²⁺ et Fe³⁺ a été effectuée. L'influence du rapport molaire sur la structure hydrotalcite a été montrée. Une comparaison entre ces solides et ceux préparés par la méthode micro-ondes a été également abordéeThis work aims to study the catalytic oxidation of Volatile Organic Compounds (VOCs). The main objective is to find catalytic materials that are alternatives to very expensive noble metals. The search for transition metal based catalysts is investigated. Furthermore, to improve the catalytic performance of the transition metals, their dispersion must be optimized using an adequate synthetic method. The various prepared solids were characterized by different physicochemical techniques : X-ray Diffraction (XRD), Thermal Analysis (TDA/TGA), Infrared Spectroscopy (IR), Temperature Programmed Reduction by hydrogen (H₂-TPR), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS)...Moreover, the obtained oxides were tested in the total oxidation of the VOC propene. Firstly, we focused our work on the preparation of a series of Co/Fe hydrotalcites -like samples by the traditional co-precipitation method. This study consists mainly of evaluating the substitution of bivalent and trivalent cations. It has been found that the solid containing both cobalt and iron (CoFe) has the highest catalytic activity. The interest of the hydrotalcite route compared to other methods of synthesis, such as the classical method and the mechanical mixing of oxides was put into evidence. Secondly, the use of microwave irradiation during the synthesis of hydrotalcite materials has also been studied as an unconventional method of synthesis. A beneficial effect has been observed with the use of microwaves due mainly to higher specific surface areas and better reducibility of the oxide species. In addition, an optimization of the temperature, duration, and power of the microwave irradiations was carried out on the CoFe solid, in order to show the influence of each parameter on the physico-chemical properties of the materials. Thirdly, the synthesis of a series of hydrotalcite catalysts with different ratio of Co²⁺ and Fe³⁺ was carried out. The influence of the molar ratio on the hydrotalcite structure has been shown. A comparison between these solids and those prepared by the microwave method was also discussed
21
Wei, Guang. "Lithium cobalt oxide thin films : preparation and characterization for electrochromic applications /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1991.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 1991.Submitted to the Dept. of Electrical Engineering (Electro-Optics Option). Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
22
Cox, Alison Sarah Jane. "Development of a nickel-cobalt oxide catalyst for carbon monoxide oxidation." Thesis, University of Essex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392691.
Full text
23
Ball, Ian K. "Preparation, characterisation and catalytic testing of vanadium promoted tin(IV) oxide and cobalt promoted cerium(IV) oxide." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364674.
Full text
24
Idris, Mohd Sobri. "Synthesis and characterisation of lithium nickel managanese cobalt oxide as cathode material." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543300.
Full text
25
Lei, Yuechuan. "Determination of the synthesis diagram of sodium cobalt oxide and electrochemical study." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89985.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.Cataloged from PDF version of thesis. Page 53 blank.
Includes bibliographical references (pages 51-52).
A complete and uniform synthesis diagram of NaxCoO₂ has been proposed based on forty-one samples synthesized at various temperatures from 450°C to 750°C by solid-state reactions with initial Na:Co ratio ranging from 0.60 to 1.05. Four monophasic domains of' O3, O3', P3' and P2 and four biphasic regions were revealed based on an XRD analysis. The sodium contents in these phases were determined according to the d00j-x relations obtained by an in situ XRD experiment and it is found O3, O3' and P3' phase almost form with only one stoichiometry, that is x=1.00, 0.83 and 0.67 respectively, by solid-state reaction while P2 phase forms in a slightly larger composition range from 0.68 to 0.76. Galvanostatic charging on O3-Na₁.₀₀CoO₂ battery reveals several plateaus and steep steps on the voltage curve, the corresponding phase transitions and solid solution behaviors were studied by a simultaneous in situ XRD experiment. The composition driven structural evolution in three layer NaXCoO₂ follows the sequence: O3-O3'-P3'-P3-P3', with a generally increased interslab distance d₀₀l.
by Yuechuan Lei.
S.M.
26
Wu, Junwei. "Electrodeposition of manganese/cobalt alloys for solid oxide fuel cell interconnect applications." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10611.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains xiii, 163 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
27
Franz, Katherine J. (Katherine Jennings) 1972. "Nitric oxide reactivity of manganese, iron and cobalt tropocoronands and development of fluorescent aminotroponiminates for nitric oxide sensing." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/29590.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2000.Vita.
Includes bibliographical references.
Chapter 1. Environmental and Biological Implications of Transition Metal-Nitric Oxide Interactions. This introductory chapter reviews various aspects of NO reactivity by transition metals and in biological systems. Chapter 2. Disproportionation of Nitric Oxide Promoted by a Mn Tropocoronand The first example of a manganese-induced nitric oxide (NO) disproportionation reaction is reported. The synthesis and characterization of divalent [Mn(THF)(TC-5,5)] (1) is presented, along with its reactivity with excess NO to yield N20 and [Mn(NO2)(TC-5,5)] (2). The NO disproportionation involves the formation of a discrete mononitrosyl [Mn(NO)(TC-5,5)j (3), which has been isolated and characterized formally as (MnmNO-) by infrered spectroscopy, normal coordinate analysis, X-ray crystallography and SQUID susceptometry. Chapter 3. NO Disproportionation Reactivity of Fe Tropocoronand Complexes The synthesis and characterization of divalent [Fe(TC-5,5)] (1) and trivalent [Fe(OTf)(TC-5,5)] (2) tropocoronand complexes are described. Compound 1 reacts with one equivalent of NO to form the trigonal bipyramidal (FeNO)7 complex 3, which contains a linearly coordinated nitrosyl (Fe-N-O = 174.3(4)). EPR and M6ssbauer spectroscopy, SQUID susceptometry and normal coordinate analysis indicate 3 to be a low spin (Fem(NO-))2 species. In the presence of excess NO, 3 converts to a metastable nitrosyl-nitrito complex that decomposes by losing NO2. The final products of the NO disproportionation reaction are N2O and [Fe(NO)(TC-5,5-NO2)] (4), a compound that no longer promotes the disproportionation of NO. Mechanistic aspects of the reaction are discussed. Chapter 4. Aminotroponiminates as Ligands for Potential Metal-Based NO Sensors. Part I. Synthesis and Characterization Fluorescently labeled ligands, HRDATI, are described that are composed of aminotroponiminates (ATI) with a dansyl fluorophore on one of the imine nitrogen atoms and an alkyl substituent on the other.
(cont.) Bis(chelate) ... complexes were prepared and characterized by X-ray crystallography. The bis-ATI complex [Co(i-Pr2ATI)2] 11 was also prep ared and its X-ray crystal structure determined. When excited at 350 nm, the H DATI ligands and the diamagnetic Zn complex 13 fluoresce around 500 nm, whereas the paramagnetic Co complexes quench the fluorescence. Chapter 5. Aminotroponiminates as Ligands for Potential Metal-Based NO Sensors. Part II. NO Reactivity and Sensing Air-stable cobalt coordination complexes of dansylated aminotroponiminate ligands, [Co(RDATI)2], react with nitric oxide to dissociate a DATI ligand and form neutral dinitrosyl complexes, [Co(NO)2(RDATI)]. The release of the fluorophore-containing ligand is accompanied by an increase in fluorescence intensity, thus providing a strategy for fluorescent NO sensing. Linking two DATI moieties via a 4-methylene chain affords the ligand H2DATI-4. The Co2+ complex [Co(DATI-4)] reacts more readily with NO than the bis-DATI compounds and also demonstrates an increase in fluorescence intensity upon NO binding. Chapter 6. Nitric Oxide Reactivity of Cobalt DenATI, DapATI and Tropocoronand Complexes Dansyl fluorophores are linked to aminotroponiminates via alkyl amine chains to form H2DenATI and H2DapATI ligands ...
by Katherine J. Franz.
Ph.D.
28
Klettlinger, Jennifer Lindsey Suder. "Fischer-Tropsch Cobalt Catalyst Improvements with the Presence of TiO2, La2O3, and ZrO2 on an Alumina Support." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333981467.
Full text
29
Deng, Yuanyuan, and 邓远源. "Magnetic circular dichroism and Hall measurement of cobalt-doped zinc oxide thin films." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B50434494.
Full textAbstract:
The observation of ferromagnetism of (Ga,Mn)As by Ohno in 1998 has inspired great interest in diluted magnetic semiconductors (DMS). DMS’s features combining ferromagnetism and semiconducting make them of great potential for conceptual spintronic devices, which is a promising field of research for the emerging electronics. The practical application of DMS requires a Curie temperature well above room temperature and an intrinsic ferromagnetism. There are several types of DMS materials. The typical ones are transition-metal (TM) doped GaAs, GaN and ZnO. The TM-doped ZnO has drawn particular attention due to the observation of room temperature ferromagnetism in this system including cobalt-doped ZnO.But the origin of ferromagnetic TM-doped ZnO is still unknown after a decade’s theoretical and experimental effort on this material.
In this thesis, we do the magnetic circular dichroism(MCD) and Hall measurement of high quality Cobalt-doped ZnO thin films grown by molecular beam epitaxy (MBE). Room temperature ferromagnetism is observed in these samples. Combining the data from MCD and Hall measurement, we attribute the room temperature ferromagnetism in this system to the impurity band of the doped Cobalt cations.published_or_final_version
Physics
Master
Master of Philosophy
30
Luo, Wenjia. "First-Principles Study of Ethanol and Methanol Steam Reforming on Co-based Materials." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429188977.
Full text
31
Roy, Nirmita. "Electrical, Optical and Thermal Investigations of Cobalt Oxide-Antimony Doped Tin Oxide (CoO-ATO) Thin Films and Nanofiber Membranes." Scholar Commons, 2017. https://scholarcommons.usf.edu/etd/7441.
Full textAbstract:
The main aim of this thesis work is to investigate the electrical, optical and thermal impact characteristics of cobalt oxide doped antimony tin oxide (CoO-ATO) in the form of thin films and nanofiber membranes. CoO-ATO is a novel composite material that has the potential to be used as reinforced aircraft coatings, military garment coatings, or more specifically as an anti-reflective (AR) top coating for photovoltaic (PV) cells. This work will be critical in determining the effectiveness of using a CoO-ATO layer in these applications. Electrospun nanofibers and spin coated thin films consisting of a polymeric solution of CoO-ATO will be used. Thin films are created using spin coating techniques, and nanofiber membranes are created using an electrospinning technique. Polystyrene (PS) will be used as a solute, and chloroform as a solvent, to create the solution. It is hypothesized that coatings of this material will have improved optical characteristics as compared to traditional ATO coatings and minimum impact from thermal cycling making it a favorable candidate for PV cells. This work will do an electrical, optical and thermal cycling impact characterization of CoO-ATO thin films and nanofiber membranes for a doping range of x% CoO where x ranged from 0.2
32
Eychmüller, Alexander, Chengzhou Zhu, Dan Wen, Susanne Leubner, Martin Oschatz, Wei Liu, Matthias Holzschuh, Frank Simon, and Stefan Kaskel. "Nickel cobalt oxide hollow nanosponges as advanced electrocatalysts for the oxygen evolution reaction." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-188848.
Full textAbstract:
A class of novel nickel cobalt oxide hollow nanosponges were synthesized through a sodium borohydride reduction strategy. Due to their porous and hollow nanostructures, and synergetic effects between their components, the optimized nickel cobalt oxide nanosponges exhibited excellent catalytic activity towards oxygen evolution reaction.
33
Visser, Gunnar Lieb. "Permeable reaction barrier system for the treatment of textile wastewater using cobalt oxide." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2631.
Full textAbstract:
Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2018.Advanced oxidation processes (AOPs) have gained considerable interest in the wastewater treatment industry. Low selectivity to organic pollutants and the high oxidation potentials provided by the free radicals produced from these processes are the root of this interest. Hydroxyl radical based AOPs seemed to dominate the field but recently sulphate radical based AOPs started to become more popular due to their even higher oxidation potential. The textile industry is known to be a considerable contributor to wastewater production. Many pollutants in this wastewater are organic pollutants which are very persistent to the more traditional treatment processes such as biological treatment and membrane filtration. Numerous studies have shown the potential and success of catalytic AOPs for the degradation of organic pollutants in wastewater. One such process is the use of a cobalt oxide nano-catalyst in conjunction with a peroxymonosulfate (PMS) oxidizer (Co3O4/PMS). The shortcoming with nano-catalysts however are the difficulty of recovering the catalyst in a slurry system or the effective immobilization of the catalyst in a continuous system. To address the issue of nano-catalyst immobilization, two different methods were used in the study to effectively immobilize the catalyst in a substrate. The methods were compared by utilizing the permeable reaction barriers in a continuous flow reactor. A bench scale reactor of 2.4 L/hr was designed and used to study the effect of PMS, catalyst mass and flow rate on the degradation efficiency and to determine the residence time and catalyst per PRB cross-sectional area ratio. A scale up rationale was formulated based on a constant residence time and the catalyst mass per PRB cross-sectional area ratio. Two design correlations were developed to predict the size of the permeable barrier and the catalyst mass required for the scale up PRB system. These parameters were used to design a reactor 30 times that of the bench scale reactor. In both reactors the optimum degradation occurred within 2 minutes indicating the success for catalyst immobilization and the development of a continuous reactor utilizing the Co3O4/PMS advanced oxidation technology.
34
Jakubianecienė, Miroslava. "Ličio kobaltato (III)susidarymo ypatumai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050613_190653-59391.
Full textAbstract:
Lithium cobalt oxide was synthesized by solid-state reactions and SPRAY-DRY method. Its investigation of the formation were perform of lithium and cobalt acetate, lithium and cobalt citrate, LiOH and Co(NO3)2· 6H2O mixtures in high-temperatures. Their formation was analyzed and with the help of the X-ray diffraction the structure of the products of the solid-state reactions was determined. The thermal processes, that take place during the synthesis, were analyzed with the help of differential-thermal analysis.
35
Zheng, Panni. "The Design and Optimization of a Lithium-ion Battery Direct Recycling Process." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93212.
Full textAbstract:
Nowadays, Lithium-ion batteries (LIBs) have dominated the power source market in a variety of applications. Lithium cobalt oxide (LiCoO2) is one of the most common cathode materials for LIBs in consumer electronics. The recycling of LIBs is important because cobalt is an expensive element that is dependent on foreign sources for production. Lithium-ion batteries need to be recycled and disposed properly when they reach the end of life (EOL) to avoid negative environmental impact. This project focuses on recycling cathode material (LiCoO2) by direct method. Two automation stages, tape peeling stage and unrolling stage, are designed for disassembling prismatic winding cores. Different sintering conditions (e.g., temperature, sintering atmosphere, the amount of lithium addition) are investigated to recycle EOL cathode materials. The results show that the capacity of the recycled cathode materials increases with increasing temperature. The extra Li addition leads to worse cycling performance. In addition, the sintering atmosphere has little influence on small- scale sintering. Also, most of directly recycled cathode materials have better electrochemical (EC) performance than commercial LiCoO2 (LCO) from Sigma, especially when cycling with 4.45V cutoff voltage.Master of Science
Nowadays, Lithium-ion batteries (LIBs) have dominated the power source market in a variety of applications. A LIB contains an anode, a cathode and electrolyte. The cathode material is the most valuable component in the LIB. Lithium cobalt oxide (LiCoO2) is one of the most common cathode materials for LIBs in consumer electronics. The recycling of LIBs is important because cobalt is an expensive element that is dependent on foreign sources for production. Lithium-ion batteries need to be recycled and disposed properly when they reach end of life (EOL) to avoid negative environmental impact. The direct recycling is a cost effective and energy conservative method which can be divided into two steps: retrieving the cathode materials from EOL LIBs and regenerating the cathode materials. This project focuses on recycling LiCoO2 by direct method. Two automation modules, tape peeling stage and unrolling stage, are designed for a disassembling line which is the automation line to collect the cathodes materials. The EOL cathode materials is lithium deficient (Li1-xCoO2). To regenerate the EOL cathode materials, lithium is added into structure of cathode materials which is called the re-lithiation process. The different sintering conditions (e.g., temperature, sintering atmosphere, the amount of lithium addition) are investigated for the re-lithiation process. The results show that the capacity of the recycled cathode materials increases with increasing temperature. The extra Li addition in iv Li1-xCoO2 leads to worse cycling performance. In addition, sintering atmosphere has little influence on small- scale sintering. Most of directly recycled cathode materials have better electrochemical (EC) performance than commercial LiCoO2, especially when cycling with 4.45V cutoff voltage.
36
Kabre, Tushar Shriram. "Co3O4 Thin Films: Sol-Gel Synthesis, Electrocatalytic Properties & Photoelectrochemistry." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316552072.
Full text
37
Gonçalves, Nizomar de Sousa. "Síntese e caracterização de nanopartículas de ferritas de níquel e de colbalto preparadas pelo método sol-gel proteico." reponame:Repositório Institucional da UFC, 2011. http://www.repositorio.ufc.br/handle/riufc/9794.
Full textAbstract:
GONÇALVES, Nizomar de Sousa. Síntese e caracterização de nanopartículas de ferritas de níquel e de colbalto preparadas pelo método sol-gel proteico. 2011. 119 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2011.Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-11-14T18:02:46Z No. of bitstreams: 1 2011_tese_nsgoncalves.pdf: 10518347 bytes, checksum: e003b7eaec2ac72b848255b9299513ce (MD5)
Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2014-11-14T18:18:09Z (GMT) No. of bitstreams: 1 2011_tese_nsgoncalves.pdf: 10518347 bytes, checksum: e003b7eaec2ac72b848255b9299513ce (MD5)
Made available in DSpace on 2014-11-14T18:18:09Z (GMT). No. of bitstreams: 1 2011_tese_nsgoncalves.pdf: 10518347 bytes, checksum: e003b7eaec2ac72b848255b9299513ce (MD5) Previous issue date: 2011
In this work we present the study of the synthesis of nanosized nickel and cobalt ferrites by sol-gel proteic method. This work revisited the method of X-ray powder diffraction analysis known as Williamson-Hall plotting. This method provides size-strain studies in nanoparticles samples. Nickel ferrites has presented particle sizes that increase when the calcination temperature increases. Nickel ferrites nanoparticles were characterized by Mössbauer spectroscopy. Sample calcined at 400°C has presented superparamagnetic properties and those calcined at higher temperatures behavior as magnetic materials. Cobalt ferrites nanoparticles were charcterized by X-ray powder diffraction, small angle X-ray scattering e magnetization. Cobalt ferrites has not presented superparamagnetic behavior. For the synthesis of cobalt ferrites some parameters that are important to the process control were studied: calcination temperature, calcination time, heat rate. We have shown the relation among those parameters and the particle size and properties control to the cobalt ferrite nanoparticles.
Este trabalho apresenta o estudo da síntese de nanopartículas de ferritas de níquel e de cobalto usando o método sol-gel proteico. Inicialmente, é resgatado o método do gráfico de Williamson-Hall na análise dos dados de difração de raios X. Este método permite calcular o tamanho médio de partícula e a microdeformação. Ferritas de níquel apresentaram tamanhos de partículas que crescem com o aumento da temperatura de calcinação. Nanopartículas de ferrita de níquel foram caracterizadas por espectroscopia Mössbauer. As amostras calcinadas a 400 °C apresentaram comportamento superparamagnético ao passo que aquelas calcinadas em temperaturas superiores apresentaram comportamento magnético. As ferritas de cobalto foram caracterizadas usando difração de raios X, espalhamento de raios X a baixo ângulo e medidas de magnetização. As ferritas de cobalto não apresentaram comportamento superparamagnético. Na síntese das ferritas de cobalto, alguns parâmetros associados com o controle do processo foram estudados: temperatura de calcinação, tempo de calcinação, taxa de aquecimento/resfriamento. Deduziu-se a relação de cada parâmetro com o controle do tamanho de partícula e das propriedades das ferritas de cobalto.
38
Vadala, Michael Lawrence. "Preparation and Functionalization of Macromolecule-Metal and Metal Oxide Nanocomplexes for Biomedical Applications." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27098.
Full textAbstract:
Copolymer-cobalt complexes have been formed by thermolysis of dicobalt octacarbonyl in solutions of copolysiloxanes. The copolysiloxane-cobalt complexes formed from toluene solutions of PDMS-b-[PMVS-co-PMTMS] block copolymers were annealed at 600-700 °C under nitrogen to form protective siliceous shells around the nanoparticles. Magnetic measurements after aging for several months in both air and in water suggest that the ceramic coatings do protect the cobalt against oxidation. However, after mechanical grinding, oxidation occurs. The specific saturation magnetization of the siliceous-cobalt nanoparticles increased substantially as a function of annealing temperature, and they have high magnetic moments for particles of this size of 60 emu g-1 Co after heat-treatment at temperatures above 600 °C. The siliceous-cobalt nanoparticles can be re-functionalized with aminopropyltrimethoxysilane by condensing the coupling agent onto the nanoparticle surfaces in anhydrous, refluxing toluene. The concentration of primary amine obtained on the surfaces is in reasonable agreement with the charged concentrations. The surface amine groups can initiate L-lactide and the biodegradable polymer, poly(L-lactide), can be polymerized directly from the surface. The protected cobalt surface can also be re-functionalized with poly(dimethylsiloxane) and poly(ethylene oxide-co-propylene oxide) providing increased versatility for reacting polymers and functional groups onto the siliceous-cobalt nanoparticles.Phthalonitrile containing graft copolysiloxanes were synthesized and investigated as enhanced oxygen impermeable shell precursors for cobalt nanoparticles. The siloxane provided a silica precursor whereas the phthalonitrile provided a graphitic precursor. After pyrolysis, the surfaces were silicon rich and the complexes exhibited a substantial increase in Ms. Early aging data suggests that these complexes are oxidatively stable in air after mechanical grinding. Aqueous dispersions of macromolecule-magnetite complexes are desirable for biomedical applications. A series of vinylsilylpropanol initiators, where the vinyl groups vary from one to three, were prepared and utilized for the synthesis of heterobifunctional poly(ethylene oxide) oligomers with a free hydroxy group on one end and one to three vinylsilyl groups on the other end. The oligomers were further modified with carboxylic acids via ene-thiol addition reactions while preserving the hydroxyl functionality at the opposite terminus. The resulting carboxylic acid heterobifunctional PEO are currently being investigated as possible dispersion stabilizers for magnetite in aqueous media.Ph. D.
39
JENG, PEI-DEI, and 鄭佩迪. "Abatement of CO over Cobalt Oxide and Carbon-Supported Cobalt Oxide Catalysts." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/40728007349457394394.
Full textAbstract:
碩士國防大學理工學院
化學工程碩士班
104
In ordor to apply in the fire-situ for CO abatement instead of Au catalyst as the mask filter, cobalt-supported cobalt oxide and cobalt oxide catalysts were prepared with different methods. Co/AC-X, Co/CNT-X, Co(S)-Y and Co(B)-Y catalysts were prepared by impregnation, precipitation and balling mixed-assisted precipitation methods , respectively. All catalysts were characterized through XRD, TEM, BET and TPR techniques. The catalytic activity on the CO oxidation reaction was evaluated in a self-designed continuous flow micro-reactor. The results indicated that the abatement of CO exceeded 85 % at room temperature over all catalysts. Both Co/AC-1 and Co(B)-2 catalysts were preferential among these catalysts. In the resistance of moisture experiments indicated that both Co/AC-X and Co/CNT-X catalysts showed resistant to moisture. In the stability test displayed that both Co/AC-1 and Co(B)-2 catalysts maintained active for around 200 h at room temperature.
40
Huang, Hong-Jhih, and 黃鴻志. "Growth and characterization of p-type spinel cobalt oxide and copper-cobalt oxide thin films." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/4sf684.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
105
Cobalt oxide and copper-cobalt oxide thin films have been successfully deposited by reactive ion beam sputter deposition utilizing an anode layer ion source sputtering module. Samples were deposited at 150 and 300℃ at various oxygen flow rates on both Si and quartz substrates. Experimental results show that samples deposited at 150℃ are all amorphous, while both cobalt and copper-cobalt oxide deposited at 300℃ exhibit a spinel structure. Increasing oxygen partial flow rates results in deteriorated crystalline quality and reduced resistivity, while the introduction of copper also results in deteriorated crystalline quality and reduced resistivity. Transmission spectra indicate that copper results in the formation of inter-band defect states. Photoelectrochemical measurements show that both cobalt and copper-cobalt oxide are of p-type, while copper-cobalt oxide shows the highest photocurrent density. This improved photocurrent density is attributed due to the presence of inter-band states that results in improved absorption of photons.
41
Chung, Chan-yo, and 鍾展有. "The Study of Cobalt Oxide and Cobalt Sulfide Prepared by Electrodeposited." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/99333164029946843208.
Full text
42
Chang, Chei-Wei, and 張智瑋. "Chemical Synthesis of Layered Cobalt Hexamine Cobalt Oxide [Co(NH3)6]0.0605Cs0.107CoO2." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73250292147603059431.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
97
Layered cobalt hexamine cobalt oxide with a interlayer spacing of d = 9.2 Å was synthesized by ion exchange in room temperature. A meta-stake precursor Cs0.29CoO2‧1.12H2O was prepared by a molten salt method and utilized in the ion exchange reaction. Ion exchange with high concentration of cobalt hexamine trichloride solution results a novel hydrogen-bonded structure [Co(NH3)6]0.0605Cs0.107CoO2. With the ability to sustain a greatly expanded structure in oxidation environment, the novel structure provides the opportunities for preparing a series of ions exchanged product and applying as the catalyst matrix for oxidation reaction. The structural stability of this novel compound was characterized by cyclic voltammetry
43
Baruth, Andrew Gerald. "Exchange coupling at cobalt/nickel oxide interfaces." 2009. http://proquest.umi.com/pqdweb?did=1694329101&sid=6&Fmt=2&clientId=14215&RQT=309&VName=PQD.
Full textAbstract:
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.Title from title screen (site viewed June 26, 2009). PDF text: xxvii, 209 p. : ill. (some col.) ; 17 Mb. UMI publication number: AAT 3350440. Includes bibliographical references. Also available in microfilm and microfiche formats.
44
Ko, Po-Ta, and 柯伯達. "Growth and characterization of cobalt oxide and copper doped cobalt oxide thin films prepared by reactive ion beam sputter deposition." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/60287375506989162329.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
104
Cobalt oxide and copper doped cobalt oxide have been deposited by reactive ion beam sputter deposition. The effect of deposition temperatures and oxygen partial flow rates Opf (= O2/(O2+Ar)) on the properties of cobalt oxide and copper-cobalt oxide thin films were characterized. Experimental results show that cobalt oxide samples deposited at 150°C and 300°C are all Co3O4 and copper doped cobalt oxide samples result in the formation of CuCo2O4. As Opf increases, both XRD signal intensity drops, while the resistivity of Co3O4 and CuCo2O4 decrease as well. CuCo2O4 deposited at 300°C with Opf = 1.0 shows the lowest resistivity of 2.410-3 (·cm). The hole carrier concentration and mobility were estimated to be 9.721019 (cm-3) and 26.6 cm2 (Vs)-1, respectively. Hall measurement shows that both cobalt oxide and copper-cobalt oxide are all p-type semiconductor thin films. Co3O4 shows two band gap at ~1.4 and 2.0 eV, while CuCo2O4 shows only one direct band gap at 1.5~2 eV. The decrease in resistivity of CuCo2O4 is likely due to the presence of Cu that results in higher metal vacancy defects.
45
TSAI, BO-YUAN, and 蔡柏緣. "The Preparation and Electrochemical Performance of Cathode Materials of Lithium Nickel Manganese Cobalt Oxide and Lithium Nickel Cobalt Aluminium Oxide." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/cmtnf8.
Full textAbstract:
碩士國立臺北科技大學
化學工程與生物科技系化學工程碩士班
107
LiNi0.5Co0.2Mn0.3O2 (NCM) This material is a ternary cathode material with high utilization rate in China. In Japan, LiNi0.8Co0.1Al0.1O2 (NCA) is synthesized by aluminum instead of manganese. It is hoped that the doping of different ions can enhance the stability of the material and improve the cycle performance of the material. However, in the production process, since Al is an amphoteric metal, it is not easy to precipitate, so there is a threshold for the production process of NCA materials. This experiment can show the best capacitance and stability by comparing NCA and NCM under various conditions. Using nickel sulfate, cobalt sulfate, aluminum sulfate, manganese sulfate, sodium aluminate, sodium hydroxide as raw materials, the synthesis is carried out in a coprecipitation method to prepare a precursor, and then calcined with lithium hydroxide at a high temperature to obtain LiNi0.5Co0.2Mn0.3O2 / LiNi0.8Co0.1Al0.1O2 powder. In this experiment, the effects of pH change, ammonia concentration change, manganese and aluminum difference and aluminum source on LiNi0.5Co0.2Mn0.3O2 / LiNi0.8Co0.1Al0.1O2 powder were investigated. XRD, tap density meter, SEM, ICP-OES, DLS, and electrochemical analyzer were used to observe the crystallization, TD size, surface morphology, elemental composition, particle size and electrochemical performance of the material. According to the experimental results, it is known that cobalt sulfate, nickel sulfate, manganese sulfate, and sodium hydroxide are used as raw materials to synthesize the precursor at a pH of 9, and the ammonia ratio of the ammonia is 0.5, and the two step calcinations with lithium hydroxide. First calcined temperature at 450°C for 4 hours, second calcined temperature at 850°C for 8 hours, under these conditions can maintain the best electrochemical properties(The initial discharge is 221.01 mAhg-1, the capacitance decay rate is 0.5%, and the rate of charge and discharge decay rate of 30 cycles is 5.872%.).
46
Hu, Cheng-Hong, and 胡正鴻. "Application of Cobalt Oxide on Sensors for Carbon Monoxide." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/19734368734706697746.
Full textAbstract:
碩士國立清華大學
化學系
90
ABSTRACT Catalysts of Co3O4 and Au/Co3O4 were prepared for sensing materials of CO sensor. Two types of CO sensors i.e. Solid electrolyte (SES) and semiconductor (SCS) were developed. For the sake of applicability, low working temperature, high sensitivity, good selectivity, fast response time and low cost are expected from the prepared sensors. Sensitivity of prepared catalysts towards CH4 and H2 also were tested in the experiment. In SES, yttria stabilized zirconia (YSZ) was used as the conductor of oxygen ions. Different oxides i.e. CoOx, SnO2, TiO2 and CuO were compared as catalysts in the anode to decrease partial pressure of oxygen. Co3O4 (S = 60 mV) showed higher CO sensitivity (S) than the other oxides. An addition of nanoparticles of Au to Co3O4 raised its CO sensitivity to S = 121 mV. The Au/Co3O4 could detect CO at T > 130 oC. The temperature was restricted by the oxygen ionic conductivity of YSZ disk. In SCS, CO could be detected by the conductivity of Co3O4 at 40 oC. The optimum working temperature of CO detection was about 80 oC (S = 3.8). An addition of nanoparticles of Au to Co3O4 did not improve the CO sensitivity. Both the response time of SES (YSZ) and SCS based on Co3O4 and Au/Co3O4 were short (< 1 min).
47
Lan, Kai Wei, and 藍凱威. "Cobalt Tungsten Oxide Target Fabrication and Thin Film Deposition." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/s2e73p.
Full text
48
Ye, Syun-Long, and 葉勳隆. "Magneto-Optical Property of Cobalt-Coated Zinc Oxide Nanorods." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5wp8wk.
Full textAbstract:
碩士國立屏東大學
應用物理系碩士班
105
ZnO has attracted a lot of research interests and become a popular material in last decades because of its unique electrical、optical、chemical and piezoelectricity characteristic. In addition, transition metal (TM) doped ZnO has also been considered as a potentials for realized magnetic semiconductor for spintronics application. However, whether coating a TM on semiconductor nanostructures can make them ferromagnetic by interfacial charge transfer is also worthy of investigation. In this work, the room-temperature ferromagnetic ZnO spin-polarized semiconductor band can be achieved by Co coating. Energy-dependent magnetic circular dichroism (MCD) and spectra, from which the difference between the absorptions of left and right circularly polarized light at particular energies can be determined, provide valuable information about the spin-polarized DOSs and their influence on the magnetic properties, helping to determine the origin of the ferromagnetism of the semiconductor. We expect such kind of hybrid magnetic nanostructures may be useful for opto-spintrionics application.
49
CHIU, HAO-WEI, and 邱浩威. "Microbial induced precipitation of cobalt oxide for super capacitor." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/41909392176149607237.
Full textAbstract:
碩士國立中正大學
應用地球物理研究所
104
Nano cobalt oxide was synthesized as an anode material for super capacitor electrode by a microbial induced precipitation method. The microorganism, Bacillus pasteurii, secreted high active urease which performed the hydrolysis of urea to an ammonia ion and a carbonate ion that subsequently produced precipitates with cobalt ion. The effects of concentration of cobalt ion and dilutions of bacterial broth for precipitation yield were investigated. The optimum parameters for the production yield were 0.1 M cobalt ion and original bacterial broth (named as 01BP30). XRD spectrum showed the amorphous structures for all the as-synthesized precipitations. TGA curves demonstrated the similar thermal-behavior. The effect of calcination temperature for cobalt oxide crystal using optimum 01BP30 has also been carried out. XRD of calcinated 01BP30 showed the crystal phase of Co3O4 (based on JCPDS #78-1970), and the 550°C displayed the best crystalline (named as 01BP30_550°C). 01BP30_550 showed the highest peak current and reversible in the cyclic voltammetry. It also demonstrated the highest capacitance of 163 F g-1 at 1 mA current and the highest specific energy density of 2.29 Whr kg-1 by the chronopotentiometry. My result showed a good electrochemical performance for super capacitors according to the figure of comparing specific power density and specific energy density from literature review. This study successfully achieved a novel, a low cost, an eco-friendly and a green chemistry method using microbial process for the synthesis of super capacitor.
50
HUANG, JHEN-TING, and 黃振庭. "Cobalt Oxide/Manganese Oxide/Nanocarbon Tube/Graphene Composite Electrophoretic Coating Process For Supercapacitor Development." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/26dgcc.
Full textAbstract:
碩士國立勤益科技大學
化工與材料工程系
107
Supercapacitors is energy storage components that have emerged in recent years, it have higher power density than chemical batteries, and energy density are superior to capacitor , it also have fast charge and discharge, and longer cycle life. It can be used in various fields, such as electronic equipment, backup energy, hybrid vehicle energy, etc. In addition to the physical adsorption/desorption of the electrolyte ions of a typical electric double-layer capacitor, the large capacitance provided by the Faraday redox reaction of the metal oxide on the surface of the material in the pseudo-capacitor also Very popular. There are many differences about the type of the supercapacitor, such as the most primitive symmetric supercapacitors, asymmetric supercapacitors that increase energy density, flexible capacitors designed to develop wearable products, and solid electrolyte supercapacitors with better safety. In the past studies, common electrode active materials include activated carbon and mesoporous carbon , which having a large specific surface area. On the other hand , graphene and carbon nanotubes research have risen in recent years. Among them, graphene has excellent electrical conductivity, Thermal conductivity, large specific surface area and excellent mechanical properties. However, due to the graphene will restore back to graphite and loses advantage of large specific surface area. Therefore, find the material doping to block graphene self-stacking has become a hot topic in recent years. On the other hand , in order to improve the energy density, researchers usually use transition metal oxides, due to its high theoretical capacitance, easy to manufacture, a variety of appearances and low cost.Common metal oxides such as Co3O4 and Mn3O4. However, the poor conductivity of metal oxides, low cycle stability, and high resistance of components are still one of the focuses of researchers. In this study, we added Graphene, CNT and Co3O4 precursors in the electrophoresis batch replication process, and created the electrode material with multi-porosity structure by using the interlayer to create the spatial effect, which greatly increased the application potential of the electrophoretic coating method. Further, MnO2 was added to the process to increase the Faraday capacitance. The results show that the study successfully obtained the EPD coating with hole type and effectively improved the power density; the excellent quality transmission structure enables the performance of the pseudo capacitor to be exerted.