Caesium peroxide

{{Chembox

| ImageFile = File:Cs2O2.png

| IUPACName = Caesium peroxide

| Section1 = {{Chembox Identifiers

| CASNo = 12053-70-2

| ChemSpiderID = 10737153

| PubChem =

| SMILES= [Cs+].[Cs+].[O-][O-]

| StdInChI=1S/2Cs.O2/c;;1-2/q2*+1;-2

| StdInChIKey=HNZHVTZRIBKSIO-UHFFFAOYSA-N

}}

| Section2 = {{Chembox Properties

| Cs=2|O=2

| Appearance = Yellowish{{cite book|title=Peroxides, Superoxides, and Ozonides of Alkali and Alkaline Earth Metals|author= I. I. Volnov|publisher=Springer|year=2012|page=45|isbn=9781468482522}}

| Density =

| MeltingPt =

| BoilingPt =

| Solubility =

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| Section3 = {{Chembox Structure

| Coordination =

| CrystalStruct = Orthorhombic{{cite journal | last1=Band | first1=A. | last2=Albu-Yaron | first2=A. | last3=Livneh | first3=T. | last4=Cohen | first4=H. | last5=Feldman | first5=Y. | last6=Shimon | first6=L. | last7=Popovitz-Biro | first7=R. | last8=Lyahovitskaya | first8=V. | last9=Tenne | first9=R. | title=Characterization of Oxides of Cesium | journal=The Journal of Physical Chemistry B | publisher=American Chemical Society (ACS) | volume=108 | issue=33 | date=2004-07-27 | issn=1520-6106 | doi=10.1021/jp036432o | pages=12360–12367}}

| MolShape =

}}

| Section8 = {{Chembox Related

| OtherAnions =

| OtherCations = {{ubl|Lithium peroxide|Sodium peroxide|Potassium peroxide|Rubidium peroxide}}

| OtherFunction = {{ubl|Caesium suboxide|Caesium monoxide|Caesium sesquioxide|Caesium superoxide|Caesium ozonide}}

| OtherFunction_label = caesium oxides

| OtherCompounds =

}}

}}

Caesium peroxide or cesium peroxide is an inorganic compound of caesium and oxygen with the chemical formula {{chem2|Cs2O2|auto=1}}. It can be formed from caesium metal by adding a stoichiometric amount in ammonia solution, or oxidizing the solid metal directly.

:{{chem2|2 Cs + O2 → Cs2O2}}

It can also be formed by the thermal decomposition of caesium superoxide:{{cite journal | last1=Berardinelli | first1=S. P. | last2=Kraus | first2=D. L. | title=Thermal decomposition of the higher oxides of cesium in the temperature range 320-500.deg. | journal=Inorganic Chemistry | publisher=American Chemical Society (ACS) | volume=13 | issue=1 | date=1974-01-01 | issn=0020-1669 | doi=10.1021/ic50131a037 | pages=189–191}}

:{{chem2|2 CsO2 → Cs2O2 + O2}}

Upon heating until 650 °C, the compound will decompose to caesium monoxide and atomic oxygen:{{cite book | last=Zefirov | first=Nikolaj | title=Chimičeskaja ėnciklopedija : v pjati tomach | publisher=Izdat. | publication-place=Moskva | year=1995 | isbn=5-85270-092-4 | oclc=258155382 | language=bs |page=658}}

:{{chem2|Cs2O2 → Cs2O + [O]}}

Caesium peroxide shows a Raman vibration at 743 cm⁻¹, due to the presence of the peroxide ions.{{cite journal | last1=Livneh | first1=Tsachi | last2=Band | first2=Alisa | last3=Tenne | first3=Reshef | title=Raman scattering from the peroxide ion in Cs₂O₂ | journal=Journal of Raman Spectroscopy | publisher=Wiley | volume=33 | issue=8 | year=2002 | issn=0377-0486 | doi=10.1002/jrs.900 | pages=675–676| bibcode=2002JRSp...33..675L}} The compound is often used as a coating for photocathodes, due to its low work function.{{cite journal | last1=Sun | first1=Yun | last2=Liu | first2=Zhi | last3=Pianetta | first3=Piero | last4=Lee | first4=Dong-Ick | title=Formation of cesium peroxide and cesium superoxide on InP photocathodes activated by cesium and oxygen | journal=Journal of Applied Physics | publisher=AIP Publishing | volume=102 | issue=7 | year=2007 | pages=074908–074908–6 | issn=0021-8979 | doi=10.1063/1.2786882 | bibcode=2007JAP...102g4908S | doi-access=free}}