Mixed metal oxide (MMO)

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a varie ...

s, also called Dimensionally Stable Anodes (DSA), are devices with high conductivity and corrosion resistance for use as

anodes An anode usually is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, which is usually an electrode of the device through which conventional current leaves the devi ...

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...

. They are made by coating a substrate, such as pure titanium plate or expanded mesh, with several kinds of metal oxides. One oxide is usually RuO₂, IrO₂, or PtO₂, which conducts electricity and catalyzes the desired reaction such as the production of chlorine gas. The other metal oxide is typically

titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound derived from titanium with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or Colour Index Internationa ...

which does not conduct or catalyze the reaction, but is cheaper and prevents

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...

of the interior. The loading or amount of precious metal on the substrate (that is, other than the titanium) can be in the order of around 10 to 12 grams per square metre.

Applications

Applications include use as anodes in electrolytic cells for producing free

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

from saltwater in swimming pools, in

electrowinning Electrowinning, also called electroextraction, is the electrodeposition of metals from their ores that have been put in solution via a process commonly referred to as leaching. Electrorefining uses a similar process to remove impurities from a ...

of metals, in printed circuit board manufacture, electrotinning and zinc electro-galvanising of steel, as anodes for cathodic protection of buried or submerged structures.

History

Henri Bernard Beer Henri Bernard Beer (born April 7, 1909 in Amsterdam, died 1994) was a Dutch inventor and business man. He is known in electrochemistry as the inventor of the Mixed metal oxide electrode, mixed metal oxides (MMO) coatings onto titanium, and the cre ...

registered his patent on mixed metal oxide electrodes in 1965. The patent named "Beer 65", also known as "Beer I", which Beer claimed the deposition of Ruthenium oxide, and admixing a soluble titanium compound to the paint, to approximately 50% (with molar percentage RuO₂:TiO₂ 50:50). His second patent, Beer II, reduced the Ruthenium oxide content below 50%.H.B. Beer. Journal of Electrochemical Soc. 127, 1980, 303C

References

MMO & PLATINUM COATED TITANIUM ANODES b
Titan
Oxides Electrodes {{inorganic-compound-stub

Applications

History

See also

References