Search results for "Cobalt"

Solid-State Synthesis of “Bamboo-Like” and Straight Carbon Nanotubes by Thermolysis of Hexa-peri-hexabenzocoronene–Cobalt Complexes

2006

CoOx catalysts supported on alumina and alumina-baria: influence of the support on the cobalt species and their activity in NO reduction by C3H6 in l…

2003

Abstract CoO x catalysts (Co 1 and 3 wt.%) were prepared by incipient-wetness impregnation of the supports, Al 2 O 3 and Al 2 O 3 (80 wt.%)-BaO (20 wt.%), and calcined at 500 and 800 °C. The samples were characterized by X-ray diffraction (XRD) and BET techniques. H 2 -temperature programmed reduction (TPR) and UV-Vis diffuse reflectance spectroscopy (DRS) spectra were recorded with the aim to identify the different Co species formed. The presence of Co 2+ species tetrahedrally and octahedrally coordinated appears strongly influenced by the nature of the support and the cobalt content. Co 3 O 4 particles were detected after calcination at 500 °C, a successive treatment at 800 °C promotes th…

On thermal behaviour of DMC catalysts for ring opening polymerization of epoxides

2016

Abstract The thermoanalytical studies of two types of the double metal cyanide catalysts were carried out. The identity of the catalysts was characterized by an elemental analysis and FTIR. The thermoanalytical examinations performed with the use of TG-DSC, EGA-FTIR, EGA-MS shed new light on views of the bonding of the ligands in the DMC. The chemical justification of the processes responsible for the TG/DSC steps was proposed. Several organic ligand complexing states were found in both types of catalysts. The ligand-DMC bondings were decomposing stepwise in relatively low temperature ranges, which could suggest their negligible role at catalytic reaction being performed usually at higher t…

High-performing Sn-Co nanowire electrodes as anodes for lithium-ion batteries

2012

Abstract The preparation of Sn 2 Co 3 nanowire arrays (NWs) electrogrown inside the channels of polycarbonate membranes and their characterization as anodes for Li-ion batteries both in half-cell vs. Li and in battery configuration are reported. The Sn 2 Co 3 NW electrodes tested by deep galvanostatic charge/discharge cycles in ethylene carbonate-dimethylcarbonate (1:1) – LiPF 6 1 M displayed 80% capacity retention after 200 cycles at C/2 and 30 °C, and a high charge and discharge rate capability at C-rate from C/3 (0.33 A/g) to 10C (10 A/g) at 30° and 10 °C. Electrodes with the highest alloy loading delivered up to 0.6 mAh cm −2 at C/2. The performance of these electrodes in battery config…

Toward Tin-Based High-Capacity Anode for Lithium-Ion Battery

2014

Electrochemical deposition of SnCo alloys inside the nanometric pores of commercial membranes is described. Composition, morphology and crystallographic structure of the synthesized nanostructured alloys are reported as well as the results of electrochemical tests carried out both in half-cell and in full battery configuration to investigate the performance of these SnCo alloys as anodes for lithium-ion batteries. Optimized depositions yielded nanostructured alloys that performed 200 deep galvanostatic cycles at C/2 and 30 °C with 80 % capacity retention and coulombic efficiency higher than 97 % after 40 cycles Moreover, charge-discharge rate capability tests showed the high performance of …

A CuIICoII Metallacyclophane-Based Metamagnet with a Corrugated Brick-Wall Sheet Architecture

2004

Cobalt−NHC Catalyzed C(sp2)−C(sp3) and C(sp2)−C(sp2) Kumada Cross‐Coupling of Aryl Tosylates with Alkyl and Aryl Grignard Reagents

2021

The first cobalt‐catalyzed cross‐coupling of aryl tosylates with alkyl and aryl Grignard reagents is reported. The catalytic system uses CoF3 and NHCs (NHC=N‐heterocyclic carbene) as ancillary ligands. The reaction proceeds via highly selective C−O bond functionalization, leading to the corresponding products in up to 98 % yield. The employment of alkyl Grignard reagents allows to achieve a rare C(sp2)−C(sp3) cross‐coupling of C−O electrophiles, circumventing isomerization and β‐hydride elimination problems. The use of aryl Grignards leads to the formation of biaryls. The C−O cross‐coupling sets the stage for a sequential cross‐coupling by exploiting the orthogonal selectivity of the cataly…

Metāla daudzuma noteikšana sikatīvā

2018

Metāla daudzuma noteikšana sikatīvā. Kokina P., zinātniskais vadītājs prof., Dr. ķīm. Artūrs Vīksna. Bakalaura darbs analītiskajā ķīmijā, 37 lappuses, 14 attēli, 13 tabulas, 20 literatūras avoti, 1 pielikums. Latviešu valodā. Darbā ir veikta Co(II) jonu kvantitatīva noteikšana Co(10%) sikatīva paraugā, lietojot divas kompleksonometriskās titrēšanas un spektrofotometriju. Darba teorētiskajā daļā ietilpst sikatīva, un noteikšanas metožu literatūras apskats. Darba eksperimentālajā daļā tika konstruēts kalibrācijas grafiks (spektrofotometrijas metodē), standartizēti titranti (titrēšanas metodēs), ar metodēm masas daļas vienībās noteikts Co(II) jonu daudzums Co(10%) sikatīva paraugā un veikts ie…

Rate-retarding effects of mixed anionic/non-ionic micelles on the alkaline hydrolysis of the chloropentamminocobalt(III) complex - Role of the anioni…

2006

Rate data for the alkaline hydrolysis of the chloropentaamminecobalt(III) cation in the presence of mixed micelles composed of (i) anionic sodium decylsulphate (SDeS) and non-ionic dodecylpenta(oxyethylene glycol) monoether (C12E5) surfactants and (ii) anionic sodium perfluorooctanoate (SPFO) and non-ionic C12E5 surfactants has been obtained at T 298K and constant electrolyte concentration 0.08 mol dm−3 ([NaOH] = 0.01 mol dm−3, [NaClO4] = 0.07 mol dm−3) over a wide range of total surfactant concentration (Ct) and anionic mole fraction (χ). The critical micelle concentrations (c.m.c.s) of the mixed micelles have been determined over the entire χ range by means of surface tension measurements…

Cobalt Electrolyte/Dye Interactions in Dye-Sensitized Solar Cells: A Combined Computational and Experimental Study

2012

We report a combined experimental and computational investigation to understand the nature of the interactions between cobalt redox mediators and TiO2 surfaces sensitized by :ruthenium and organic dyes, and their impact on. the performance of the corresponding dye-sensitized solar cells (DSSCs). We : focus: on different ruthenium dyes and fully organic dyes, to understand the dramatic loss of efficiency observed for the prototype Ru(II) N719 dye in conjunction with :Cobalt: electrolytes. Both N719- and Z907-based DSSCs showed an increased lifetime in iodine-based electrolyte compared to the cobalt-based redox-shuttle; While the organic D21L6 and D25L6 cycles endowed.With long alkoxy chains,…