Caesium peroxide

Caesium peroxide or cesium peroxide is an inorganic compound of caesium and oxygen with the chemical formula Cs2O2. It can be formed from caesium metal by adding a stoichiometric amount in ammonia solution, or oxidizing the solid metal directly.


 * 2 Cs + O2 → Cs2O2

It can also be formed by the thermal decomposition of caesium superoxide:


 * 2 CsO2 → Cs2O2 + O2

Upon heating until 650 °C, the compound will decompose to caesium monoxide and atomic oxygen:


 * Cs2O2 → Cs2O + [O]

Caesium peroxide shows a Raman vibration at 743 cm−1, due to the presence of the peroxide ions. The compound is often used as a coating for photocathodes, due to its low work function.