Oksidihydroksideja

Oksidihydroksideja, or oxide hydroxides, are inorganic compounds that contain both oxide (O2−) and hydroxide (OH−) groups. They are often referred to as oxyhydroxides and occur in a range of minerals and synthetic materials. Their structures can be viewed as oxide lattices with incorporated hydroxide, or as layers of metal hydroxide with interlayer species balancing charge.

Common examples include goethite (FeOOH), lepidocrocite (γ-FeOOH) and akaganeite (FeOOH with chloride interlayers), as well as boehmite (AlOOH). In addition to simple stoichiometries, oxide hydroxides also form more complex, layered structures known as layered double hydroxides (LDHs), which have the general formula [M2+1−xM3+x(OH)2x]A^{n−}_{x/n}·mH2O and often contain interlayer anions and water molecules.

Occurrence and formation are related to weathering, oxidation, and corrosion processes in soils, sediments, and natural waters, as well as to various synthetic routes. They commonly form through the partial oxidation of metal hydroxides or the hydrolysis of metal oxides in aqueous environments.

Properties of oxide hydroxides vary with composition and structure, but many are poorly soluble in water and exhibit pH-dependent stability. They can be hygroscopic, possess high surface areas, and display magnetic or paramagnetic behavior (notably for iron-containing species). Transformation pathways include aging to more anhydrous oxides or to spinels and other oxide phases under changing redox conditions.

Applications are diverse and include environmental remediation as adsorbents for heavy metals, catalysts for oxidation and reduction reactions, pigments, and components in energy storage materials. Their versatility reflects the broad chemistry of M–O–OH motifs across metals.