Synthesis and Characterization of Composite Photocatalyst

ZnO/ZnO2 composite photocatalysts were synthesized by hydrothermal treatment at 120 ~ 180 ℃ of ZnO2, which in turn was obtained from an aqueous solution of ZnSO4 and H2O2. The composite particles showed morphology of ZnO prismatic crystallites with small ZnO2 granules “fused” at surface. Besides, SrTiO3/TiO2 composite photocatalysts were prepared by sol-gel and incipient wetness impregnation method and proceeded to calcine at high temperature, with TiO2 as the main phase of the composite.
Photocatalytic activity was characterized based on photocatalytic degradation of methyl orange and methylene blue under UV-light (300 nm) illumination, and the maximum activity was both observed for the composite photocatalysts synthesized based on pre-formed main phase, ZnO/ZnO2 and SrTiO3/TiO2. The enhanced activity has been attributed to the presence of the intimate hetero-structure on the surface of composites and the effective way for the separation of excitons. This study also points out a new approach to synthesize a coupled composite photocatalyst containing strongly coupled constituents by phase transformation among the constituents through one or more than one chemical reaction(s).