Constructing durable BiFeO3@SrBi2B2O7 p-n heterojunction for persulfate enhanced piezo-photocatalytic water purification

Photoresponse piezoelectric materials have attracted tremendous interest as a new generation of photocatalysts for water purification. However, the development of durable and efficient piezo-photocatalyst remains to be a challenging task. Herein, a novel BiFeO3@SrBi2B2O7 (BFO@SBBO) p-n heterojunction with ultrahigh piezo-photocatalytic ability was fabricated after adjustment of BFO outer layer thickness, and utilized to activate persulfate (PS) for efficient water decontamination. The synergistic effect between the internal electric field across the heterojunction and the PS greatly improves the separation of photogenerated charge carriers. In the presence of ultrasonic mechanical vibration, 10 mg/L bisphenol A (BPA) was completely removed within 20 min with the assistance of a low dosage of PS upon visible light irradiation, which outperform various piezo-photocatalysts. Transformation and contribution of reactive oxygen species (ROSs, i.e., OH, O2−, 1O2 and SO4−) generated in the BFO@SBBO/US/Vis/PS system were evaluated and semi-quantified to understand the mechanism of BPA piezo-photocatalytic degradation. The stability and performance of BFO@SBBO piezo-photocatalysis toward typical organic pollutants and actual phenolic water remediation were evaluated, which confirmed the promising practical potential of BFO@SBBO in water remediation. This study offers a new insight into strategies for highly efficient piezo-photocatalyst for photocatalytic water remediation.