Mixed metal oxide electrode

Mesh MMO anode used for electroplating

Mixed metal oxide (MMO) electrodes, also called Dimensionally Stable Anodes (DSA), are devices with high conductivity and corrosion resistance for use as anodes in electrolysis. 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 which does not conduct or catalyze the reaction, but is cheaper and prevents corrosion 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.[1]

## Contents

* 1 Applications
* 2 History
* 3 See also
* 4 References

## Applications

Applications include use as anodes in electrolytic cells for producing free chlorine from saltwater in swimming pools, in electrowinning 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 registered his patent on mixed metal oxide electrodes in 1965.[2] 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,[3] reduced the Ruthenium oxide content below 50%.[4]

## See also

* Chloralkali process

## References

1. ↑ "Reverse electrodialysis: Evaluation of suitable electrode systems", Chapter 4 of the doctoral thesis of Joost Veerman, 2009, p. 70.
2. ↑ Beer, Henri Bernard, "Improvements in or relating to electrodes for electrolysis", GB patent 1147442, published 1969-04-02
3. ↑ Beer, Henri Bernard, "Improvements in or relating to the Manufacture of Electrodes.", GB patent 1195871, published 1970-06-24
4. ↑ H.B. Beer. Journal of Electrochemical Soc. 127, 1980, 303C

MMO & PLATINUM COATED TITANIUM ANODES by Titan

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