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.^[1]

2 Cs + O₂ → Cs₂O₂

Caesium peroxide

Names
IUPAC name Caesium peroxide
Identifiers
CAS Number	12053-70-2
3D model (JSmol)	Interactive image
ChemSpider	10737153
InChI InChI=1S/2Cs.O2/c;;1-2/q2*+1;-2 Key: HNZHVTZRIBKSIO-UHFFFAOYSA-N
SMILES [Cs+].[Cs+].[O-][O-]
Properties
Chemical formula	Cs2O2
Molar mass	297.809 g·mol−1
Appearance	Yellowish[1]
Structure
Crystal structure	Orthorhombic[2]
Related compounds
Other cations	Lithium peroxide Sodium peroxide Potassium peroxide Rubidium peroxide
Related caesium oxides	Caesium suboxide Caesium monoxide Caesium sesquioxide Caesium superoxide Caesium ozonide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

It can also be formed by the thermal decomposition of caesium superoxide:^[3]

2 CsO₂ → Cs₂O₂ + O₂

Upon heating until 650 °C, the compound will decompose to caesium monoxide and atomic oxygen:^[4]

Cs₂O₂ → Cs₂O + [O]

Caesium peroxide shows a Raman vibration at 743 cm⁻¹, due to the presence of the peroxide ions.^[5] The compound is often used as a coating for photocathodes, due to its low work function.^[6]