Cobalt Oxide Electrode Doped with Iridium Oxide as Highly Efficient Water Oxidation Electrode

Crystalline cobalt oxide nanoparticles (nc-CoO x ) supported on ITO glass or Ni foam doped with 5 mol % crystalline iridium oxide nanoparticles (nc-IrO x ) showed performances which are higher than those of nc-CoO x on ITO or Ni foam and nc-IrO x on a rotating glassy carbon disc electrode or Ni foam. The initial Co III and Ir IV become Co IV and Ir VI upon applying positive potentials. The nc-CoO x particles intrinsically carry Co III O 5 centers which become Co IV O 6 centers upon application of positive potentials. The O vacancy in Co III O 5 is transferred to Ir VI O 6 upon application of positive potentials, giving rise to the formation of Ir VI O 5 centers, which are proposed to be the highly active catalytic centers for water oxidation.