Metal oxides and hydroxides

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.

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, 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.

Neodymium(III) oxide

Neodymium(III) oxide, also called neodymia or neodymium sesquioxide, is an inorganic compound (Nd₂O₃), a gray to blue powder used in permanent magnets, glass, lasers, and catalysts.

Nickel cobalt oxide

Nickel cobalt oxide (NiCo₂O₄), also called nickel cobaltite, is a mixed-valence inverse-spinel p-type semiconductor that conducts far better than NiO or Co₃O₄ and is widely studied for oxygen evolution electrocatalysis and supercapacitors.

Nickel ferrite

Nickel ferrite (NiFe₂O₄) is a ferrimagnetic inverse spinel ceramic compound with high permeability, low magnetic losses, and high electrical resistivity, used in soft magnets, microwave absorption, catalysis, and energy storage.

Nickel oxyhydroxide

Nickel oxyhydroxide (NiOOH) is a nickel compound formed when nickel hydroxide is oxidized, best known as the active material in nickel battery electrodes and water-splitting catalysts.

Nickel(II) oxide

Nickel(II) oxide, also known as nickel monoxide or green nickel oxide, is a green-to-black inorganic compound of nickel and oxygen with the formula NiO, used in pigments, smart windows, and solar cells.

NiCo2O4 spinel OER catalyst

NiCo2O4 spinel OER catalyst refers to nickel cobaltite, a nickel–cobalt spinel oxide used as a non-noble-metal electrocatalyst for the oxygen evolution reaction, the bottleneck step of water electrolysis.

Niobium oxide

Niobium oxide refers to compounds of niobium and oxygen, from NbO to Nb₂O₅ and mixed oxides, among the most studied fast-charging lithium-ion battery anode materials since the early 2010s.

Niobium pentoxide

Niobium pentoxide (Nb₂O₅), also called niobium(V) oxide, is a white, water-insoluble solid and the most stable compound of niobium, with over 15 crystalline phases and uses in lithium-ion batteries, optical glass, and capacitors.

Osmium tetroxide

Osmium tetroxide (OsO4), also called osmic acid, is a volatile, highly poisonous oxide of osmium used as a fixative and stain in electron microscopy and as a reagent for cis-dihydroxylation of alkenes.

Oxide scale

Oxide scale is the layer of iron oxides, chiefly wüstite, magnetite, and hematite, that forms on iron and steel at high temperature, especially during hot rolling.

Permanganate

Permanganate (MnO4−) is a tetrahedral manganese(VII) anion and strong oxidizer, known for its deep purple color and its use in water treatment, most familiar as potassium permanganate.

Pertechnetate

Pertechnetate is the monovalent anion TcO₄⁻, the oxyanion of technetium in its +7 oxidation state, best known as the form in which technetium-99m is administered for thyroid scintigraphy.

Phosphomolybdic acid

Phosphomolybdic acid, also called molybdophosphoric acid or dodecamolybdophosphoric acid, is a Keggin-type heteropoly acid with the formula H₃[PMo₁₂O₄₀], used as a TLC stain, histology mordant, and catalyst.

Platinum dioxide

Platinum dioxide (PtO₂), also called platinum(IV) oxide or platinic oxide, is a dark brown solid best known as Adams' catalyst, used since 1922 to hydrogenate alkenes, ketones, and arenes.

Plutonium dioxide

Plutonium dioxide (PuO₂), also called plutonium(IV) dioxide, is the tetravalent oxide of plutonium, a refractory ceramic used as MOX fuel and in spacecraft power systems.

Plutonium(VII) compounds

Plutonium(VII) compounds contain plutonium in the +7 oxidation state, the highest confirmed state of the element, known almost entirely from short-lived alkaline solutions that are dark green.

Polyoxometalate water oxidation catalysis

Polyoxometalate water oxidation catalysis is the use of polyoxometalates, anionic metal-oxo clusters of tungsten, molybdenum, or vanadium, to catalyze water oxidation into oxygen, a field begun in 2008 with ruthenium-substituted polyoxotungstates.

Potassium hydroxide

Potassium hydroxide, also known as caustic potash or potassium lye, is a strongly alkaline inorganic compound used to make soaps, fertilizers, potassium carbonate, and alkaline battery electrolytes.

Potassium oxide

Potassium oxide (K₂O), also called dipotassium oxide, is a white, hygroscopic ionic compound of potassium and oxygen that reacts violently with water to form potassium hydroxide.

Potassium permanganate

Potassium permanganate (KMnO4), also known as Condy's crystals, is a dark purple crystalline salt and strong oxidizing agent used in water treatment and as a mild antiseptic.

Rare-earth hydroxides

Rare-earth hydroxides are the hydroxide and oxyhydroxide solid phases of scandium, yttrium, and the lanthanides, whose solubility varies smoothly across the 4f series, enabling classical fractional precipitation separation of the rare earths.

Rust

Rust is the reddish-brown corrosion product that forms on iron and its alloys when both oxygen and water are present; chemically it is hydrated iron(III) oxide.

Ruthenate

Ruthenates are oxide compounds containing ruthenium, oxygen, and one or more other elements, a family spanning the Mott insulator Ca₂RuO₄, the superconducting Sr₂RuO₄, and catalytically active pyrochlores.

Ruthenium(IV) oxide

Ruthenium(IV) oxide, or ruthenium dioxide (RuO₂), is a black, metallically conductive crystalline oxide with the rutile structure and the most stable oxide of ruthenium, known for catalyzing oxygen and chlorine evolution and for use in supercapacitors.