Hello Student ,

H2O2 or oxygenated water can be prepared in the following ways : -

1. Merk's Method - Na2O2 + H2SO4(Ice Cold, 20%) = Na2SO4 + H2O2
2. Laboratory Method - 3[BaO2.8H2O] + 2H3PO4 = Ba3(PO4)2 +  3H2O2 + 24H2O
3. Electrolysis of Cold 50% H2SO4
4. Other - BaO2.8H2O + H2O + CO2 = BaCO3 + H2O2 + 8H2O

Hydrogen peroxide is manufactured by the electrolysis of a cold 50% solutions of H2SO4 in an electrolytic cell using platinum as anode and graphite as cathode. There are other method too to prepare this like:

By the action of carbon dioxide or carbonic acid

By the action of dilute sulphuric acid

From sodium peroxide