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

Crystalline cobalt oxide nanoparticles (nc-CoOx) supported on ITO glass or Ni foam doped with 5 mol % crystalline iridium oxide nanoparticles (nc-IrOx) showed performances which are higher than those of nc-CoOx on ITO or Ni foam and nc-IrOx on a rotating glassy carbon disc electrode or Ni foam. The initial CoIII and IrIV become CoIV and IrVI upon applying positive potentials. The nc-CoOx particles intrinsically carry CoIIIO5 centers which become CoIVO6 centers upon application of positive potentials. The O vacancy in CoIIIO5 is transferred to IrVIO6 upon application of positive potentials, giving rise to the formation of IrVIO5 centers, which are proposed to be the highly active catalytic centers for water oxidation.