The Photocatalytic Activities Induced by Sulfurization-Oxidation Processing of Rare Earth-Strontium Oxides

Abstract

Since some photocatalytic activities have been observed for the complex oxides of Ti, Zr, and Hf, it has been aimed in the present report to find if the corresponding complex oxides of rare earth elements have similar activities or not. SrDy₂0₄, SrY₂0₄, Sr₂Ce0₄, SrCe0₃, and SrSm₂0₄ were synthesized and were treated in CS₂, and 0₂ atmospheres at elevated temperatures. Those synthesized with NiO and those without NiO were tested for the comparison'of their catalytic activities using t 1:1 CH₃OH/H₂0 and O.24 moldm^-3 Na₂S/H₂0 as reactants. The photocatalytic activities observed from those complex oxides, which were treated by CS₂-0₂ cycles, were comparable to those of Ti, Zr, or Hf. A particular point observed fro m rare earth catalysts is that they are found to be effective for generating hydrogen without NiO as Co-catalyst. Such capability of rare earth oxides may be explained by their small electronegativities.