Chemical compound

Silver(I,III) oxide or tetrasilver tetraoxide is the inorganic compound with the formula Ag4O4. It is a component of silver zinc batteries. It can be prepared by the slow addition of a silver(I) salt to a persulfate solution e.g. AgNO3 to a Na2S2O8 solution.[1] It adopts an unusual structure, being a mixed-valence compound.[2] It is a dark brown solid that decomposes with evolution of O2 in water. It dissolves in concentrated nitric acid to give brown solutions containing the Ag2+ ion.[3]


Although its empirical formula, AgO, suggests that the compound tetrasilver tetraoxide has silver in the +2 oxidation state, each unit has two monovalent silver atoms bonded to an oxygen atom, and two trivalent silver atoms bonded to three oxygen atoms, and it is in fact diamagnetic. X-ray diffraction studies show that the silver atoms adopt two different coordination environments, one having two collinear oxide neighbours and the other four coplanar oxide neighbours.[1] tetrasilver tetraoxide is therefore formulated as AgIAgIIIO2[4] or Ag2O·Ag2O3. It has previously been called silver peroxide, which is incorrect since it does not contain the peroxide ion, O22−.


  1. ^ a b Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  2. ^ David Tudela "Silver(II) Oxide or Silver(I,III) Oxide?" J. Chem. Educ., 2008, volume 85, p 863. doi: 10.1021/ed085p863
  3. ^ Peter Fischer, Martin Jansen "Electrochemical Syntheses of Binary Silver Oxides" 1995, vol. 30, pp. 50–55. doi:10.1002/9780470132616.ch11
  4. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. p. 1181.