TiO₂–ZnO Composite Sphere Decorated with ZnO Clusters for Effective Charge Isolation in Photocatalysis

TiO 2 and ZnO are extensively used photocatalysts, but their activity needs improvement due to rapid charge recombination. Herein, we designed and synthesized a novel structure of a TiO 2 –ZnO composite sphere decorated with ZnO clusters by a one-pot solvethermal method. TEM and EDX characterizations show this structure contains a TiO 2 core, TiO 2 –ZnO composite (type II heterojunction) surface layer, and surface c -axis ZnO clusters. The in situ Au and PbO 2 photodeposition shows that the photoinduced electrons and holes are driven to ZnO clusters and TiO 2, respectively, attributed to the synergy of the type II heterojunction of TiO 2 –ZnO and high electron mobility of ZnO. The PL spectra confirm that such a structure is much more efficient in retarding the charge recombination than the sole TiO 2 –ZnO sphere. Importantly, this structure shows higher photoactivity in degradation of rhodamine B and isomerization of norbornadiene than pure TiO 2, ZnO, and TiO 2 –ZnO composite spheres.