Synergetic degradation of organic dyes and Cr(vi) by the piezocatalytic BZT-xBCT

Recently, piezo-catalysts have gained considerable attention owing to their unique ability to degrade pollutants by harvesting trivial mechanical energy from the surrounding environment. In this study, the piezocatalytic activity of a lead-free piezoelectric solid solution of BZT-xBCT (x = 0.3, 0.4, 0.5, 0.6, 0.7) nanoparticles (NPs) was evaluated. It was found that the BZT-0.3BCT NPs exhibited the highest piezocatalytic efficiency in the degradation of rhodamine B (RhB) under ultrasonic vibration. In addition, the BZT-0.3BCT NPs could cocatalyse the degradation of a mixture of RhB and Cr(vi) with higher efficiency than the degradation by RhB and Cr(vi) separately. The high piezocatalytic activity of BZT-0.3BCT originated from its composition approaching the terminus of the morphotropic phase boundary (MPB) and even the tricritical triple phase point due to the increased water temperature in the ultrasonication process. Finally, an energy band diagram was constructed to clarify the piezocatalytic mechanism and to illustrate a better electron-hole pair utilization mechanism for the simultaneous degradation of RhB and Cr(vi). Our work provides an eco-friendly piezoelectric material for environmental remediation and can also act as a guide to aid the search for excellent piezocatalysts.