The superior piezocatalytic performance of SrBi2Ta2O9 nanoflower: Mechanism of screening effect and energy band theory

[Display omitted] •Three different morphologies of SBTO were obtained by various preparation methods.•SBTO with nanoflower shape exhibited the most excellent piezoelectric activity.•Morphology and thickness synergistically promoted catalytic degradation for VLFX.•The energy band theory and screening effect clarified piezo-catalytic mechanism. Piezoelectric catalytic technology has been widely applied in the removal of contaminants, and now has become a hot research spot for potential practice application. In this study, the piezoelectric performance could be exactly regulated by changing the morphology of the piezo-materials. Via different synthesis methods, series of SrBi2Ta2O9 (SBTO) with different morphology were successfully prepared. The results show that the SBTO synthesized by hydrothermal method (SBTO-HR) owes the nanoflower morphology, exhibiting the most excellent catalytic activity than the solid-state method (SBTO-SS) and molten salt method (SBTO-MS). The degradation efficiency for Venlafaxine (VLFX) is almost 100 % in 20 min, which is 5.46 and 6.59 times that of SBTO-MS and SBTO-SS. The enhanced piezoelectric catalytic performance is attributed to that SBTO-HR nanomaterial with the smaller thickness around 32.0 nm and exposed facet (001) can be easily deformed and polarized under external force which induces a stronger piezoelectric potential to accelerate the separation of electrons and holes. The proposed screening effect and energy band theory further clarified the piezoelectric catalytic mechanism. The TOC removal rate of VLFX could reach 80 %, illustrating the outstanding mineralization ability of SBTO-HR. This work provides a promising strategy for promoting piezoelectric activity by morphology engineering of the piezo-materials.