oxidehydroxide

Oxyhydroxide, also called oxidehydroxide, is a class of inorganic compounds that contain both oxide (O2−) and hydroxide (OH−) groups in their structure. In metal oxyhydroxides the metal cation is coordinated to oxide and hydroxide ligands, and a common simplified formula is MO(OH).

Natural examples include goethite (FeO(OH)) and boehmite (AlO(OH)); lepidocrocite (γ-FeO(OH)) is another iron oxyhydroxide. These substances range from poorly crystalline to well-ordered minerals and often occur in hydrated forms or as transitional phases between oxides and hydroxides.

Formation occurs by oxidation and hydrolysis of metal ions in aqueous environments, by weathering of minerals, and during corrosion. Oxyhydroxides are common in soils, sediments, and natural waters, where they influence adsorption, mobility of metals, and the fate of contaminants.

Chemically they exhibit reactive surfaces and pH-dependent solubility. Upon heating they dehydrate to simple oxides (for example, Fe2O3 or Al2O3) and can transform through intermediate oxyhydroxides.

In technology and geology, oxidehydroxides are studied as catalysts, sorbents, and precursors to more stable oxides; they also serve as pigments and play a role in environmental remediation and nutrient cycling.