Alternating Built-in Electric Field Enhances the Charge Pairs Separation in PbB4O7 Piezocatalyst for Pollutant Degradation

How to promote the free charges of piezomaterials to take the redox is now a challenging work in environmental remediation. Construction of built internal electric fields is crucial to realize efficient charge separation for charge-induced redox reaction. Herein, PbB4O7 (PBO) with lone pair electrons firstly realizes a high piezocatalytic degradation efficiency for removal of dye & Cr(VI) under ultrasound activation. PBO shows more excellent degradation performance than traditional BaTiO3 (BTO), which is 2.08 times, 2.47 times, 2.28 times, and 3.02 times than that of BTO for RhB in the unary system, RhB & Cr(VI) in binary systems, MB in the unary system, and MB & Cr(VI) in binary systems, respectively. Piezoresponse force microscopy confirmed that PBO had excellent piezoelectric property. The varied degradation performance can be assigned to systems exposed to different ions (negative or positive) environment that influence shielding effect. Additionally, the easily polarization of lone pair electrons of the Pb-contained piezomaterial forming a strong alternating built-in electric field under ultrasound that can offer a strong driven force to separate electron and hole pairs, thus producing the superior piezocatalytic activities. The main active species in the unary system and the binary system were determined, and the piezocatalytic degradation mechanism of PBO was analyzed.