Silver oxide earns its place in the synthetic laboratory as a reagent that does three jobs at once: it is a mild, insoluble base, it removes halide as insoluble silver halide, and it can act as a one-electron oxidant. Those properties make it the classical promoter for Koenigs–Knorr glycosylation of glycosyl bromides, the reagent for Purdie methylation of sugars and other sensitive alcohols with iodomethane, and a clean way to oxidise aldehydes to carboxylic acids under basic conditions.
Two uses dominate modern practice. Treating an imidazolium or triazolium halide with silver oxide in dichloromethane gives the silver N-heterocyclic carbene complex directly (Lin's method); these Ag–NHC complexes are the standard carbene-transfer agents for making palladium, gold, rhodium and iridium NHC catalysts. The second is anion exchange: stirring a quaternary ammonium, phosphonium or imidazolium halide with silver oxide and water precipitates silver halide and leaves the corresponding hydroxide, which is how many ionic-liquid and phase-transfer hydroxides are prepared.
Beyond synthesis, silver(I) oxide is the active cathode material of silver-oxide and silver–zinc cells, a precursor for silver catalysts and for silver films deposited by thermal decomposition, a yellow colourant in glass and ceramic glazes, and a source of silver ions in antimicrobial formulations. It decomposes cleanly to silver metal and oxygen on heating, which is useful wherever a residue-free silver source is wanted.