Boosting piezo/photo-induced charge transfer of a bi-piezoelectrics BaTiO3/CdS isotype junction for kinetic optimization

The photocatalytic activity of BaTiO3 is largely constrained by its inherent wide bandgap sensitivity only to Ultraviolet (UV) light and the limited effect of severe carrier recombination during the drift, diffusion, and surface transfer. In response, researchers have reported a bi-piezoelectrics isotype junction between BaTiO3/CdS that is adjusted via a synergistic piezo-photocatalytic effect. As a result of the CdS coating, the composite can effectively increase the absorption range from UV to visible light. By contrast, the composite can prevent malicious charge recombination due to a large band offset caused by piezoelectric effects. Meanwhile, the piezo-potential induced by periodic ultrasonic waves can generate a dynamic built-in electric field resulting from unscreened polar charges, which has been demonstrated as an alternating driving force for further suppressing the charge recombination. Hence, compared to pure BaTiO3 and CdS, the BaTiO3/CdS composite displayed a significantly higher piezo-photocatalytic degradation activity, by an amount equal to 18% and 16.9%, respectively, during 70 min. This work facilitates our insight into a bi-piezoelectrics isotype junction and suggests new strategies to enhance the effectiveness of piezoelectric nanocrystals for water purification.