Cobalt selenides

The solid compounds Coi tSe(cr), CoSc2(cr), and Co9Ses(cr) have been reported to form in the system cobalt-selenium. The phase diagram of the system is presented in [72KOM/WES]. 

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Vayner E, Sidik RA, Anderson AB, Popov B. 2007. Experimental and theoretical study of cobalt selenide as a catalyst for O2 electroreduction. J Phys Chem C 111 10508-10513. 

Cobalt Selenide, CoSe, is yielded in an amorphous condition by heating cobalt in selenium vapour. It also results when hydrogen selenide is passed over cobalt oxide, or preferably the anhydrous chlorate, at bright red heat. 

MAT/GEI2] Matlasevich, O. B., Geiderikh, V. A., Thermodynamic properties of cobalt selenides (CoSe2 and Coo 72Se), Russ. J. Phys. Chem., 46, (1972), 1048-1049. Cited on pages 317,318,535. 

Alumina catalysts activated by additions of dehydrogenating catalysts, e.g., nickel oxide, copper oxide or sulfide, zinc oxide or sulfide, cobalt selenide, zinc phosphate, cadmium tungstate, mixtures of the oxides of zinc and tungsten, of cadmium and molybdenum, etc., are claimed to be superior in the formation of acetaldehyde from mixtures of steam and acetylene at 350° to 400° C.l-la Zinc oxide catalysts may be activated in a similar way by the addition of small amounts of molybdates or molybdic acid, and are effective at 300° to 350° C.121b... 

Gao JH, Zhang B, Zhang XX et al (2006) Magnetic-dipolar-interaction-induced self-assembly affords wires of hollow nanocrystals of cobalt selenide. Angew Chem Int Ed. 45(8) 1220-1223... 

Cobalt selenide nanocrystals were prepared by a hot injection method where in selenium powder was added to a solvent mixture of OLA and dimethylaminoborane at 120 °C giving a transparent solution. In a three neck flask cobalt chloride dissolved in OLA was added and a Schlenk line was attached and heated to 120 °C in vacuum for 30 minutes and back filled with Ar. The solution was then heated to 250 °C and at this temperature Se precursor was injected quickly leading to a dark coloured solutions which was vigorously stirred for 30 minutes at 250 °C. After rapidly cooling to room temperature the flask was added with toluene for... 

As a result of the simulation, the widening of the A/B diffusion zone is observed and small voids start forming at the pure B/aUoy interface. In the process of a computer experiment, the voids expand, leaving between themselves the bridges of pure B. At high temperature, we observed the subsequent coalescence of voids into a single spherical void in the center of the nanoparticle (Figure 7.23). These simulation results correlate with experiments on the formation of cobalt selenides and sulfides [4, 5, 30]. 

Other low-band gap semieonducting particles have been explored cobalt selenide nanoparticles ca. 10 nm) were prepared by slowly heating the single-source precursor [Co(Se2P Pr2)2] in HDA or TOPO at 320 °C. Similarly, thermal decomposition of cobalt dithiophosphinate [Co(S2P Bu2)2] single-source precursor in the presence of HDA or TOPO at... 

Cobalt(II) sulfide, CoS cobalt disulfide, C0S2 cobalt(III) sulfide, C02S3 cobalt(II) selenide, CoSe cobalt selenium, CoSc2 (trogtalite) cobalt(II) telluride, CoTe. 

Susac et al. [33] showed that the cobalt-selenium (Co-Se) system prepared by sputtering and chemical methods was catalytically active toward the ORR in an acidic medium. Lee et al. [34] synthesized ternary non-noble selenides based on W and Co by the reaction of the metal carbonyls and elemental Se in xylenes. These W-Co-Se systems showed catalytic activity toward ORR in acidic media, albeit lower than with Pt/C and seemingly proceeding as a two-electron process. It was pointed out that non-noble metals too can serve as active sites for catalysis, in fact generating sufficient activity to be comparable to that of a noble metal, provided that electronic effects have been induced by the chalcogen modification. 

Green - chrome oxide, cobalt green, polychloro copper phthalocyanine Orange - cadmium sulphide/selenide Red - iron oxide... 

Caesium selenide, 4265 Calcium polysulfide, 3942 Calcium sulfide, 3941 Cerium trisulfide, 3967 Chromium(II) sulfide, 4245 Cobalt(II) sulfide, 4218 Copper iron(II) sulfide, 4269 Copper(II) sulfide, 4285 Europium(II) sulfide, 4293... 

For the route A, acyl radicals donors like iS are readily generated from acyl selenides (ISa) or acyl cobalt derivatives (iSb) and radicals acceptors 2S are usually multiple bonds as in methyl vinyl ketone (2Sa) -although some homolytic substitutions are possible. On the other hand, nitriles GSal are useful acceptors (3S) in radical cyclisations and 4Sa is an obvious synthon equivalent of radical donor 4S (See Table 7.2). 

In 1823 Johann Karl Ludwig Zincken (1790—1862) detected selenium in some ores from Zorge and Tilkerode in the eastern part of the Harz, and in 1825 Heinrich Rose analyzed them quantitatively. By heating them in a current of chlorine gas, Rose converted all the metals to chlorides and separated the selenium chloride, which was the only volatile chloride present, from the non-volatile chlorides of the metals (34). He found these minerals to be selenides of lead, copper, cobalt, and mercury. 

Caesium selenide, 4259 Calcium polysulfide, 3936 Calcium sulfide, 3935 Cerium trisulfide, 3961 Chromium(II) sulfide, 4239 Cobalt(II) sulfide, 4212 Copper iron(II) sulfide, 4263 Copper(II) sulfide, 4279 Europium(II) sulfide, 4287 Germanium(II) sulfide, 4413 Gold(ni) sulfide, 0116... 

Inorganic pigments are found in the earth. Iron and lead oxides provide earth colors. Copper calcium silicate and cobalt stannate provide blues. The colors burnt sienna and burnt umber come from iron oxides. Green pigments come from chromic oxide, calcinated cobalt, and zinc and aluminum oxides. Red pigments come from cadmium sulfide, cadmium selenide, and barium sulfate. All these chemical compounds come from the earth. 

Cobalt Sesquiselenide, Co2Se3, is formed by passing hydrogen selenide over cobalt chloride at dull red heat. It is a grey amorphous mass. 

Cobalt Diselenide, CoSe2, is obtained in a similar manner to the preceding compound as a violet-grey and friable mass which readily loses selenium on heating. Consequently it is necessary to cease heating when the current of hydrogen selenide is stopped, and to cool in an atmosphere of nitrogen. 

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