Synthesis and Photocatalytic Property of ZnO/TiO2 Inverse Opals Films with Controllable Composition and Topology.

A novel method to fabricate composition- and topology-controlled ZnO/TiO₂ inverse opals (IO) films using a positive sacrificial ZnO IO template has been developed. This method includes a two-step process, preparation of ZnO IO by a simple electrochemical deposition using a self-assembly polystyrene colloidal crystal template and preparation of ZnO/TiO₂ IO by a liquid phase deposition (LPD) process at room temperature. The composition and topology of ZnO/TiO₂ IO can be easily controlled by changing the duration of the LPD. After ₂0 min LPD process, a ZnO/TiO₂ composite IO with non-close-packed face-centered cubic air sphere array was obtained. Prolonging the duration to 60 min, a pure TiO₂ IO (TIO-LPD60) with obviously thickened walls was formed. The formation mechanism for the compositional and topological variation was discussed. A preliminary study on UV photocatalytic property of the samples for degradation of methylene blue reveals that the composition and topology significantly influenced the photocatalytic activity of the IOfilm. The ZnO/TiO₂ composite IO demonstrates a higher degree of activity than both pure ZnO and pure TiO₂ IO, although they have a similar IO wall thickness. Moreover, with increasing IO wall thickness from ~52 nm to ~90 nm, TIO-LPD60 exhibits the highest level of photocatalytic performance. [ABSTRACT FROM AUTHOR]