The conversion of CoSe 2 to Co oxide under the electrochemical water oxidation condition

Hydrogen production by water electrolysis is a very promising way to store sustainable energies. In practice, however, large-scale electrochemical production of hydrogen from water splitting is greatly limited by water-oxidation reaction. CoSe2 and its composites with other compounds are efficient catalysts for water oxidation. Herein for the first time, we report that CoSe2 is converted to cobalt oxide when is used as a water-oxidizing catalyst under the electrochemical water oxidation condition at pH = 13. The results are very important for water-splitting systems, which use CoSe2 as a water-oxidizing catalyst.