Effective promoting piezocatalytic property of zinc oxide for degradation of organic pollutants and insight into piezocatalytic mechanism

The piezoelectric zinc oxides with different morphology (ZnO nanoparticles and nanorods, hereafter abbreviated as ZnO NPs and NRs) are successfully synthesized using facile, green and harmless solid-state chemistry method at room temperature. The piezocatalytic activity of zinc oxide towards methylene blue (MB) of organic pollutants degradation has been explored under ultrasonic vibration. The ZnO NRs exhibit effectively enhanced piezocatalytic performance towards degradation dye compared with the ZnO NPs. In particular, the piezocatalytic decolorization ratio of MB solution is up to ~38% in ZnO NRs under 120 min, ~ 99% under 5.5 h and show good recycling utilization characteristics, indicating great potential for dye wastewater decolorization treatment. The main oxidizing hydroxyl radical (OH) and superoxide radicals (O2−) of the piezocatalytic reactions are confirmed and the production of piezocatalytic degradation process induced polarization electric charges. Moreover, we investigate the relationship between morphology and piezoelectric potential based on the finite element method for ZnO NPs and NRs, which further clarify the enhanced piezocatalytic activity and insight into piezocatalytic mechanism. This work offers a novel strategy towards wastewater decontamination applications and further understanding the relationship between piezocatalysis, morphology, and piezocatalytic mechanism in piezoelectric materials.