Cobalt sulfide

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Cobalt sulfide
Sulfid kobaltnatý.PNG
RTECS number GG332500
CoS (varied)
Molar mass 90.9982 g/mol
Appearance black solid (alpha)
grayish-red crystals (beta)
Density 5.45 g/cm3
Melting point 1195 °C
0.00038 g/100 mL (18 °C)
Solubility slightly soluble in acid
+225.0·10−6 cm3/mol
octahedral (beta)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cobalt sulfide is the name for chemical compounds with a formula CoxSy. Well-characterized species include minerals with the formula CoS, CoS2, Co3S4, and the synthetic material Co9S8. In combination with molybdenum, the sulfides of cobalt are used as catalysts for the industrial process called hydrodesulfurization, which is implemented on a large scale in refineries. Cobalt sulfide thin films can be used as counter electrodes (CEs) of dye-sensitized solar cells (DSSCs).[1][2] Several research works demonstrate that CoxSy can be used to substitute the high expensive platinum (Pt), commonly used for the preparation of high efficient CEs.[3] Thin films of CoxSy can be deposited on different substrates using chemical precursor Inks based on organic solvents [4] or water.[5] Also electrochemical techniques are suitable for the preparation of efficient and cheap CoxSy CEs.[6][7] It has been demonstrated that CoS CEs can be also used in p-type DSSCs.[8][9]

Cobalt sulfides precipitate when aqueous solutions of cobalt(II) ions are treated with hydrogen sulfide. This reaction is useful in the purification of cobalt from its ores as well as in qualitative inorganic analysis. In general, the sulfides of cobalt are black, semiconducting, insoluble in water, and nonstoichiometric. They react with strong acids to release hydrogen sulfide gas again. They are weak reducing agents and can be oxidized to cobalt sulfate[citation needed].

Cobalt sulfide exists in two forms: alpha and beta.


The best defined sulfides of cobalt occur as minerals. The rare mineral cattierite has the stoichiometry CoS2. It is isostructural with iron pyrite, featuring disulfide groups, i.e. Co2+S22−. Linnaeite, also rare, has the formula Co3S4 and crystallizes in the spinel motif.[10]


  1. ^ Congiu, M.; Albano, L. G. S.; Decker, F.; Graeff, C. F. O. (2015-01-01). "Single precursor route to efficient cobalt sulphide counter electrodes for dye sensitized solar cells". Electrochimica Acta. 151: 517–524. doi:10.1016/j.electacta.2014.11.001. 
  2. ^ Mathew, Simon; Yella, Aswani; Gao, Peng; Humphry-Baker, Robin; Curchod, Basile F. E.; Ashari-Astani, Negar; Tavernelli, Ivano; Rothlisberger, Ursula; Nazeeruddin, Md. Khaja. "Dye-sensitized solar cells with 13% efficiency achieved through the molecular engineering of porphyrin sensitizers". Nature Chemistry. 6 (3): 242–247. doi:10.1038/nchem.1861. 
  3. ^ Huo, Jinghao; Zheng, Min; Tu, Yongguang; Wu, Jihuai; Hu, Linhua; Dai, Songyuan (2015-03-20). "A high performance cobalt sulfide counter electrode for dye-sensitized solar cells". Electrochimica Acta. 159: 166–173. doi:10.1016/j.electacta.2015.01.214. 
  4. ^ Congiu, M.; Albano, L. G. S.; Decker, F.; Graeff, C. F. O. (2015-01-01). "Single precursor route to efficient cobalt sulphide counter electrodes for dye sensitized solar cells". Electrochimica Acta. 151: 517–524. doi:10.1016/j.electacta.2014.11.001. 
  5. ^ Congiu, Mirko; Lanuti, Alessandro; di Carlo, Aldo; Graeff, Carlos F. O. (2015-12-01). "A novel and large area suitable water-based ink for the deposition of cobalt sulfide films for solar energy conversion with iodine-free electrolytes". Solar Energy. 122: 87–96. doi:10.1016/j.solener.2015.08.032. 
  6. ^ Lin, Jeng-Yu; Liao, Jen-Hung; Wei, Tzu-Chien (2011-04-01). "Honeycomb-like CoS Counter Electrodes for Transparent Dye-Sensitized Solar Cells". Electrochemical and Solid-State Letters. 14 (4): D41–D44. ISSN 1099-0062. doi:10.1149/1.3533917. 
  7. ^ Lin, Jeng-Yu; Liao, Jen-Hung; Chou, Shu-Wei (2011-10-01). "Cathodic electrodeposition of highly porous cobalt sulfide counter electrodes for dye-sensitized solar cells". Electrochimica Acta. 56 (24): 8818–8826. doi:10.1016/j.electacta.2011.07.080. 
  8. ^ Congiu, Mirko; Bonomo, Matteo; Marco, Maria Letizia De; Dowling, Denis P.; Di Carlo, Aldo; Dini, Danilo; Graeff, Carlos F. O. (2016-07-16). "Cobalt Sulfide as Counter Electrode in p-Type Dye-Sensitized Solar Cells". ChemistrySelect. 1 (11): 2808–2815. ISSN 2365-6549. doi:10.1002/slct.201600297. 
  9. ^ Nattestad, Andrew; Ferguson, Michael; Kerr, Robert; Cheng, Yi-Bing; Bach, Udo. "Dye-sensitized nickel(II)oxide photocathodes for tandem solar cell applications". Nanotechnology. 19 (29). doi:10.1088/0957-4484/19/29/295304. 
  10. ^ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. ISBN 0-08-022057-6.