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@TiO2 nanocomposite film were prepared by template method and chemical water bath method. The piezo-photocatalytic properties of the obtained ZnO@TiO2 nanocomposite films were evaluated by the degradation of organic dyes. The results showed that the piezo-photocatalytic constant rate of the ZnO@TiO2 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 TiO2 framework under same condition (6.6×10−3 min−1) and the ZnO@TiO2 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 TiO2 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 TiO2, thus significantly improving the piezo-photocatalytic activity. This work provides a novel route for reasonable design of recyclable and efficient piezo-photocatalytic films. •Recyclable ZnO@TiO2 nanocomposite films were prepared by growing ZnO nanorods on inverse opal TiO2 framework.•The nanocomposite films show very high piezo-photocatalytic activity under ultrasound and UV.•The TiO2 framework provides an open space for ZnO growth and redox reaction.•The ZnO promotes carrier separation by piezoelectric polarization field and interface contact with TiO2.•Piezo-photocatalytic effect was discussed based on carrier separation and transfer mechanism.