CuO

Copper(II) oxide, CuO, also known as cupric oxide, is an inorganic compound. It occurs naturally as the mineral tenorite and is a black to dark brown solid. It is insoluble in water and has a melting point near 1325 °C. CuO is a p-type semiconductor with a band gap typically reported in the range of about 1.2 to 1.9 eV.

Production and structure: CuO can be prepared by heating copper in air or by thermal decomposition of copper(II) hydroxide or copper(II) carbonate. It crystallizes in a monoclinic structure. In reducing environments, CuO can be converted to copper metal (for example, by hydrogen or carbon monoxide at elevated temperature).

Chemical properties: CuO reacts with acids to form soluble copper(II) salts (for example, CuO + 2 HCl → CuCl2 + H2O). It is generally considered a basic oxide, though in strongly basic solutions it can participate in the formation of copperate species. The oxide is used as a catalyst in various oxidation reactions and as a precursor to other copper compounds.

Applications: It is employed as a pigment in ceramics and glass, and as a catalyst in chemical synthesis and environmental remediation. CuO and its derived nanomaterials are explored in electronics, sensors, and solar-energy applications due to its semiconductor properties. It also serves as a starting material for preparing copper salts and other copper-based materials.

Occurrence: Tenorite is found in oxidized zones of copper ore deposits and in some geological environments where copper sulfide minerals weather.

Safety: Copper(II) oxide is hazardous if ingested or inhaled and can irritate the skin and eyes. Appropriate protective equipment and handling procedures are recommended.