PbO2

PbO2, or lead(IV) oxide, is an inorganic compound, an oxide of lead in the +4 oxidation state. It is a dark gray to black solid that is sparingly soluble in water. It exists in two polymorphs, commonly denoted α-PbO2 and β-PbO2, which differ in crystal structure and stability.

PbO2 is a strong oxidizing agent, particularly in acidic media. It can oxidize many organic and inorganic substrates, being reduced to PbO or Pb2+ salts depending on conditions. The primary reduction reaction in acidic solution is PbO2 + 4 H+ + 2 e- → Pb2+ + 2 H2O. It is thermally unstable and decomposes upon heating to lead(II) oxide and oxygen: 2 PbO2 → 2 PbO + O2.

PbO2 is prepared commercially by chemical oxidation of lead compounds or by electrochemical oxidation of a lead-containing electrode in sulfuric acid; it forms on the positive electrode of lead-acid batteries during charging and can be generated in situ. It is also obtainable by oxidation of PbO under oxidizing conditions.

Applications include its use as the active material for the positive plate in lead-acid batteries and as an oxidizing catalyst in certain organic oxidations and in wastewater treatment under acidic conditions.

Safety: Lead(IV) compounds are toxic; PbO2 can cause lead poisoning upon ingestion or inhalation. Handle with appropriate personal protective equipment and dispose of according to regulations. It is incompatible with reducing agents and with some strong bases.