Oxygen electrocatalysts for water electrolyzers and reversible fuel cells: status and perspective

Hydrogen production by electrochemical water electrolysis has received great attention as an alternative technology for energy conversion and storage. The oxygen electrode has a substantial effect on the performance and durability of water electrolyzers and reversible (or regenerative) fuel cells because of its intrinsically slow kinetics for oxygen evolution/reduction and poor durability under harsh operating environments. To improve oxygen kinetics and durability of the electrode, extensive studies for highly active and stable oxygen electrocatalysts have been performed. However, due to the thermodynamic instability of transition metals in acidic media, noble metal compounds have been primarily utilized as…