Copper monosulfide

Copper monosulfide is a chemical compound of copper and sulfur with the empirical formula CuS. It occurs in nature as the dark indigo blue mineral covellite. It is one of a number of binary compounds of copper and sulfur (see copper sulfide for an overview of this subject), and has attracted interest because of its potential uses in catalysis and photovoltaics. It is a moderate conductor of electricity. A black colloidal precipitate of copper monosulfide is formed when hydrogen sulfide (H2S) is bubbled through solutions of Cu(II) salts. This is the basis of its industrial production. Special forms of CuS for certain applications can be prepared by melting an excess of sulfur with copper(I) sulfide or by precipitation with hydrogen sulfide from a solution of anhydrous copper(II) chloride in anhydrous ethanol. Nanoparticles of CuS can be prepared by reaction of dissolved copper(II) chloride with thioglycolic acid. The reaction of copper with molten sulfur followed by boiling sodium hydroxide and the reaction of sodium sulfide with aqueous copper sulfate will also produce copper sulfide. Copper sulfide crystallizes in the hexagonal crystal system, and this is the form of the mineral covellite.