Significantly enhanced piezo-photocatalytic properties of recyclable nanocomposite films by growing ZnO nanorods on inverse opal structured TiO2 framework

The construction of recyclable films with unique morphology and piezoelectric-enhanced photocatalytic performance is of great significance for wastewater purification. Here, inverse opal structured ZnO@TiO ₂ nanocomposite film were prepared by template method and chemical water bath method. The piezo-photocatalytic properties of the obtained ZnO@TiO ₂ nanocomposite films were evaluated by the degradation of organic dyes. The results showed that the piezo-photocatalytic constant rate of the ZnO@TiO ₂ nanocomposite films under the synergistic action of ultrasound and ultraviolet light reached 52.3×10 ⁻³ min ⁻¹, much higher than those of the pure inverse opal TiO ₂ framework under same condition (6.6×10 ⁻³ min ⁻¹) and the ZnO@TiO ₂ nanocomposite films under only ultraviolet light (10.1×10 ⁻³ min ⁻¹) or only ultrasound (2.0×10 ⁻³ min ⁻¹). It is believed that the inverse opal structured TiO ₂ framework not only provides an open space for ZnO nanorods growth, but also initiates redox reaction for dye degradation through generation and transfer of photo-generated carriers under ultraviolet irradiation. Meanwhile, the ZnO nanorods can efficiently promote carrier separation by piezoelectric polarization electric field and interface contact induced band tilting with TiO ₂, thus significantly improving the piezo-photocatalytic activity. This work provides a novel route for reasonable design of recyclable and efficient piezo-photocatalytic films.