Bu çalışmada Fotovoltaik Üretim Teknolojileri için Kobalt doplu ZnO nanomateryali hidrotermal proses kullanılarak sentezlenmiş ve üretilen fotovoltaiklerin verimleri değerlendirilmiştir. Kobalt doplu ...ZnO nanomateryaller katkılama oranı % 0.5 den % 1.5’e kadar değişen verimlerde sentezlenmiştir. Katkılanan kobalt doplu ZnO nanomateryaller XRD, SEM ve EDX teknikleri ile analizlenmiştir. SEM görüntüleri kobalt doplu ZnO nanoyapıların morfolojilerinin nanorod düzeyinden nanotabaka morfolojisine değişimini ispatlamıştır. EDX analizleri kobalt doplu ZnO yapıların oluşumunu kanıtlamıştır. Fotovoltaik enerji dönüşüm verimleri analizlenmiştir. Bu çalışmada % 1 kobalt katkılama oranı için 3.48 mA/cm2 kısa devre akımı, 600 mV açık devre voltajı, 0.56 dolum faktörü ve % 1.17 verim ile en yüksek verim rapor edilmiştir
In this study, the synthesis and characterization of cobalt doped zinc oxide (Co:ZnO) nanocomposite materials were achieved using hydrothermal method from zinc nitrate and Cobalt (II) chloride precursors. Zinc oxide nanostructures were doped with cobalt in different dopant concentrations. The Co concentration was varied from 0.5 to 1.5 mol % in ZnO crystalline structure. Cobalt doped ZnO materials were analysed using XRD, SEM and EDX. Also DSSC performances of cobalt doped ZnOs were studied. Best efficiency was obtained with 1% doped Co:ZnO as 3.48 mA/cm2 of short circuit photocurrent density, 600 mV of open circuit voltage, 0.56 of filling factor, 1.17 of overall conversion efficiency.
A simple and sensitive solid phase extraction procedure on Amberlite XAD-1180 resin is presented for the determination of chromium, cobalt, manganese and nickel at trace levels by atomic absorption ...spectrometry. The analyte ions were quantitatively taken at pH 9 by using ammonia/ammonium acetate buffer without any chelating agent. The influences of some analytical parameters such as sample volume, eluent type and flow rates on the retention of Cr, Co, Mn and Ni ions were examined. No influences were observed from the matrix ions of table salt samples. The detection limits for Cr, Co, Mn and Ni were 0.27 $\mu g/g$, 0.11 $\mu g/g$, 0.13 $\mu g/g$ and 0.086 $\mu g/g$, respectively. The proposed separation-enrichment method was applied for the atomic absorption spectrometric determinations of analyte ions in table salt with satisfactory results (recoveries greater than 95%, relative standard deviations lower than 10%).
Son yıllardaki yeni nano üretim ve karakterizasyon tekniklerindeki gelişmeler mevcut birçok malzemenin nano boyutta üretilmesine imkân sağlamış ve üretilen nanomalzemelerin cihazlarda kullanımıyla ...cihazların verimliliklerinde artışlara imkân sağlamıştır. İstenen birden fazla özelliğin eldesi ise nano hetero yapıların üretilmesiyle mümkündür. Yapılan bu çalışmamızda elektro çekim yöntemiyle kobalt klorür/poliakrilonitril (CoCl2/PAN) kompozit nanolifler üretilmiş ve üretilen liflerin hidrojen sülfüre (H2S) karşı olan tepkisi araştırılmıştır. CoCl2/PAN nanoliflerin H2S ile muamelesinde kobalt tuzunun yapısındaki kobalt iyonları çökelerek nanolifler içerisinde altıgen şekilde kobalt bileşenli nanoplakaların oluştuğu gözlemlenmiştir. Üretilen kompozit nanoliflerin morfolojik özellikleri taramalı elektron mikroskobuyla (SEM) ile elementel analizleri ise X-ray fotoelektron spektra (XPS) tekniğiyle incelenmiştir. Elde edilen bulgularla CoCl2/PAN nanoliflerle toksik bir kimyasal olan H2S in tespiti ve uzaklaştırılmasının mümkün olmasının yanı sıra nanolif içerisinde fonksiyonel başka bir nano yapının üretilebileceği sonucuna varılmıştır
An extremely efficient cobalt catalyst for the hydroboration of both vinylarenes and aliphatic α‐olefins with pinacolborane is described, providing the anti‐Markovnikov products with excellent regio‐ ...and chemoselectivity, broad functional‐group tolerance, and high turnover numbers (up to 19 800). The alkene hydroboration route is further extended to a two‐step, one‐pot hydroboration and cross‐coupling of alkylboronates with aryl chlorides.
Ein PNN‐Pinzetten‐Cobaltkomplex (siehe Bild) wurde für die katalytische Hydroborierung von Alkenen mit Pinakolboran entwickelt. Das Katalysatorsystem ist hoch aktiv, toleriert viele funktionelle Gruppen und weist exzellente Regio‐ und Chemoselektivitäten in der Hydroborierung von α‐Olefinen auf.
Oxidative removal of a small quantity of CO from hydrogen atmosphere has been attempted by using catalysts consisting of 3d transition metal oxides. The oxidation of CO takes place in preference to ...that of H
2 on catalysts containing Co or Mn in a temperature range from 323–423 K. At higher temperatures, the oxidation of H
2 becomes to coincide and then the selectivity to the CO oxidation decreases. Hydrogenation of CO giving methane also occurs over the catalysts containing Ni or Co. Reduction of catalysts at high temperatures might be the reason for the observed change in the catalytic properties. Among the catalysts tested, CoO showed the best performance and was considered to be one of the candidates for the refinement of the hydrogen fuel for the polymer-electrolyte type fuel cells (PEFCs).
The temperature behavior of the resistance of the thermo exfoliated graphite thermo exfoliated graphite and cobalt‐containing nanocomposites on its base have been investigated. It is shown that the ...electrical properties of these materials could be easy explained within the incipient localization model. The influence of the metal modifier on the electric transport has been also analyzed.
Es wurden Struktur, Morphologie und Temperaturabhängigkeiten des elektrischen Widerstands des thermisch erweiterten Graphits und der kobalthaltigen Legierungen auf dessen Basis untersucht. Es wurde gezeigt, dass das Modell der anfänglichen (schwachen) Lokalisation ein alternatives Modell zur Beschreibung elektrischer Charakteristiken von Kohlenstoff‐Metall‐Nanokompositen darstellt. Im Rahmen dieses Modells wurde der Einfluss des Metalls‐Modifikators auf elektrischen Transport analysiert.
Amaç: Bu araştırmanın amacı farklı laboratuvarlarca dökümü yapılmış tek parça döküm parsiyel protezlerde kullanılan metal alaşımların değerlendirilmesidir.sitotoksisite yönünden Gereç ve Yöntem: ...Sivas’ta faaliyet gösteren 4 farklı laboratuvardan, kumlama ve kumlama+cila işlemi uygulanmış 1 mm çapında,1.5 mm kalınlıkta disk şeklindeki metal örnekler elde edildi. Hazırlanan metal örnekler etilen oksit gazıyla sterilize edildi ve L929 fibroblast hücre serisi kullanlarak elde edilen kültüre yerleştirildi. Agar overley testi kullanılarak sitotoksisitenin belirlenmesinde ISO 2009 yılı 10993-5 numaralı protokolü takip edildi.Bulgular: Hücrelerin lizis miktarna göre yapılan laboratuvardan 3 tanesinden elde edilen örnekler sitotoksik bulunmamışken, 1 tanesinden elde edilen bulunmuştur. Ayrıca çalışmamızda tüm gruplarda kumlama ve kumlama+cila arasında sitotoksite açısından fark bulunamamıştır
A new and simple method for obtaining highly dispersed Co/ZrO2 catalyst is described. The presence of ethylenediamine during the preparation of Co/ZrO2 was studied and compared with a reference ...catalyst conventionally prepared. Addition of an aqueous solution of ethylenediamine to a cobalt nitrate solution had a dramatic effect on the catalytic performance of the catalyst as compared with a reference catalyst. This promotional effect was explained in terms of higher cobalt dispersion in the catalysts using ethylenediamine. The reason why ethylenediamine improves dispersion of the cobalt species was explained in terms of the size of the stable complex ions which could be formed in situ during impregnation. The best catalytic results were also explained in terms of Co-support interaction since new cobalt species were reducible at lower temperatures.
Scraps of hardmetal tools and pieces of original size were contacted with aqueous solutions of acetic acid under simultaneous introduction of pure oxygen or air to dissolve selectively the cobalt ...binder and recover the tungsten carbide. The influences of nominal composition of the scrap on the necessary time for a complete removal of the binder, as well as temperature, concentration and pressure were evaluated. Increasing the pressure during leach operation, as well as the temperature and the oxygen potential in the solution, significantly improves the rates of dissolution. Increasing the concentration of acetic acid does not necessarily increase the rates, also a decrease can be observed mainly depending on the tungsten concentration in the binder. The time for a complete binder removal also strongly depends on the nominal composition, respectively the grain size providing a mean free path for the penetration of the solvent and the oxygen into the scrap pieces. Altogether it was shown that it is possible to work up hardmetal scraps without any preceding comminution by a very selectively removal of the binder within reasonable times by applying a simple and very effective process, as the rates of dissolution are surprisingly high. The proposed process uses ecologically friendly educts and gives high-quality tungsten carbide raw materials as well as cobalt acetate solutions from which the cobalt can be easily recovered.
Microbially catalyzed reactions, which occur in the natural sulfur cycle, have been integrated in a microbiological process to remove toxic metals from contaminated soils. Bioleaching using sulfuric ...acid produced by sulfur-oxidizing bacteria was followed by precipitation of the leachate metals as insoluble sulfides by sulfate-reducing bacteria. Metal contaminants including Cd, Co, Cr, Cu, Mn, Ni, and Zn were efficiently leached from an artificially contaminated soil. Mn, Ni, and Zn were the only target elements that were significantly leached from soil minerals. Pb leaching was slow and remained incomplete over a period of 180 days. Mineral components such as Fe, Ca and Mg were also leached but the eventual reduction in soil mass was only approximately 10%. An industrially contaminated soil was also efficiently leached and approximately 69% of the main toxic metals present, Cu, Ni, and Mn, were removed after 175 days. The leachate that resulted from the action of sulfur-oxidizing bacteria on contaminated soil was stripped of metals using an anaerobic bioreactor containing a mixed culture of sulfate-reducing bacteria which precipitated soluble metal species as solid metal sulfides. More than 98% of the metals were removed from solution with the exception of Mn, Ni, and Pb, where 80-90% were removed. The metal content of the resultant effluent liquor was low enough to meet European criteria for discharge into the environment.
