Oxides and oxygen compounds

Hydroxyl radical

The hydroxyl radical, also known as the OH radical, is a highly reactive diatomic molecule, HO, best known as the atmosphere's primary cleansing oxidant of methane, carbon monoxide, and pollutants.

Ice Ih

Ice Ih is the hexagonal form of water that freezes at ambient pressure; it is virtually all natural snow, sea ice, glacier ice, and lake ice.

Iridate

An iridate is a compound oxide of iridium, studied in condensed matter physics for 5d perovskites whose bandwidth, Coulomb interaction, and spin-orbit coupling produce unusual insulating states.

Iridium tetroxide

Iridium tetroxide, [IrO4]+, is a gas-phase iridium oxide cation in which iridium reaches oxidation state IX, the highest experimentally identified for any element, reported in 2014.

Iridium(IV) oxide (IrO2, iridium dioxide) is the most common oxide of iridium, a blue-black crystalline solid with the rutile structure and metallic conductivity, serving as the benchmark anode catalyst for acidic water electrolysis.

Iron(III) hydroxide

Iron(III) hydroxide, also called ferric hydroxide, is the hydroxide of trivalent iron with formula Fe(OH)₃, best known as the brown precipitate from iron(III) salts and base.

Iron(III) oxide-hydroxide

Iron(III) oxide-hydroxide (FeOOH), also called yellow iron oxide, is a family of ferric oxyhydroxide compounds occurring as polymorphs including goethite, the main yellow pigment in ochre.

La2PrNi2O7

La2PrNi2O7 is a praseodymium-doped bilayer nickelate that becomes a bulk high-temperature superconductor under pressure above about 11 GPa, with a record onset temperature of 82.5 K.

Layered double hydroxides

Layered double hydroxides (LDHs), also called anionic clays or hydrotalcite-like compounds, are ionic lamellar solids with positively charged brucite-like metal hydroxide layers separated by exchangeable interlayer anions and water.

Layered sodium cobaltate

Layered sodium cobaltate (NaxCoO2) is a layered cobalt oxide whose sodium content controls its properties; it shows a large thermoelectric power, and its hydrate superconducts near 5 K.

Lipid peroxidation

Lipid peroxidation is the free-radical chain oxidation of unsaturated fatty acids into hydroperoxides and reactive aldehydes such as MDA and 4-HNE, driving rancidity in foods and ferroptosis in cells.

Lithium hydroxide

Lithium hydroxide (LiOH) is a white hygroscopic solid, the strongest alkali-metal hydroxide in commercial use, serving as a carbon dioxide scrubber in spacecraft and a battery cathode precursor.

Lithium oxide

Lithium oxide (Li₂O), also called dilithium monoxide, is a white ionic solid known as a candidate tritium breeding ceramic for fusion reactor blankets, studied since the 1980s.

Lithium peroxide

Lithium peroxide ($ ext{Li}2 ext{O}2$) is an inorganic compound containing the peroxy anion. It is the solid discharge product of the lithium–oxygen battery, providing theoretical energy density.

Lye

Lye, also known as alkaline liquor, is the common name for strongly alkaline hydroxide compounds, chiefly sodium hydroxide and potassium hydroxide, both corrosive white solids best known for making soap.

Magnesium ferrite

Magnesium ferrite (MgFe₂O₄), also called magnesioferrite in its mineral form, is a magnetic iron oxide with the cubic spinel structure, a soft magnetic n-type semiconductor used in photocatalysis and gas sensing.

Magnesium hydroxide

Magnesium hydroxide is an inorganic compound, a white solid of low water solubility occurring as the mineral brucite and best known as the antacid and laxative milk of magnesia.

Magnesium oxide

Magnesium oxide (MgO), also called magnesia, is a white inorganic compound of magnesium and oxygen that occurs as the mineral periclase and is used mainly as a refractory in furnace linings.

Manganese oxide nanoparticles

Manganese oxide nanoparticles, also called MnOₓ NPs, are nanoscale particles of manganese oxides including MnO, MnO₂, and Mn₃O₄, used in energy storage, catalysis, and biomedical imaging.

Manganese-oxo cubane

A manganese-oxo cubane is a molecular cluster with manganese ions and oxide bridges alternating at the corners of a cube, best known as a model for photosynthesis's oxygen-evolving complex.

Manganese-oxo cubane water oxidation catalysts

Manganese-oxo cubane water oxidation catalysts are Mn₄O₄-type molecular clusters, bioinspired by the oxygen-evolving complex of photosystem II, that oxidize water to oxygen; the Dismukes cubane exceeds 1000 catalytic turnovers on Nafion electrodes.

Manganese(II) oxide

Manganese(II) oxide, also called manganous oxide, is an inorganic compound of manganese and oxygen with formula MnO, used as a precursor to manganese chemicals, in ceramics and pigments, and as a battery anode material.

Manganite

Manganite is a manganese oxide-hydroxide mineral, MnOOH, the most stable of three natural polymorphs, best known for lustrous black striated crystals from Germany's Harz Mountains.

Oct 21, 2026

Mercuric oxide

Mercuric oxide (mercury(II) oxide, HgO, CAS 21908-53-2, Santar) is a toxic red or yellow inorganic mercury compound that decomposes above 500 °C into mercury and oxygen, formerly used in batteries, paints, and antiseptics.

Metal peroxides

Metal peroxides are metal compounds containing a peroxide unit, O2^2−, bound either as a discrete ion or as a peroxo or hydroperoxo ligand at a metal center.

Molybdenum blue

Molybdenum blue is the deep-blue material formed by partially reducing acidified molybdate, first reported by Scheele in 1783 and used to measure phosphate in water.

Molybdenum dioxide

Molybdenum dioxide, also called molybdenum(IV) oxide (MoO₂), is a gray transition metal oxide with a distorted rutile structure and unusual metallic conductivity, used in lithium-ion battery anodes and gas sensors.

Molybdenum trioxide

Molybdenum trioxide (MoO₃) is a colorless to white solid, the highest oxide of molybdenum, made by roasting molybdenite ore and converted into molybdates, catalysts, alloys, and molybdenum metal.

Monopotassium phosphate

Monopotassium phosphate, also called potassium dihydrogen phosphate (KDP), is the water-soluble salt KH2PO4, a chloride-free fertilizer, food additive E 340(i), buffering agent, and nonlinear optical crystal in the National Ignition Facility.