Metal oxides and hydroxides as rechargeable materials for photocatalysts with oxidative energy storage abilities

Abstract

NiO, Co(OH)2, Ir oxide, and Ru oxide were combined as rechargeable materials with TiO2or Pt-TiO2photocatalyst to obtain novel photocatalysts with oxidative energy storage abilities. NiO, which is more stable than the conventional storage material, Ni(OH)2, showed similar characteristics to those of Ni(OH)2. The redox potential of Co(OH)2was more negative, and those of Ir oxide and Ru oxide were more positive than that of Ni(OH)2. The photoelectrochemically charged Ir oxide was reduced by acetone, acetic acid, Br-, and water. The diversity of energy storage materials was accordingly improved in terms of the reaction potential and stability.