The strong alternating built-in electric field sourced by ball milling on Pb2BO3X (XCl, Br, I) piezoelectric materials contributes to high catalytic activity

Ball milling (BM) combined with piezoelectric materials offers a significant potential to realize the energy harvesting in wet surroundings. However, a fundamental understanding of the relationship between the imposed force induced built-in electric field and the amount of generated charges under BM is limited due to the complex reaction system and the short lifetime of the free charges. Herein, a BM system consisted of a series of piezoelectric materials Pb2BO3X (X = Cl, Br, I) and different milling balls is conducted to degrade organic pollutants. For Rhodamine B removal, Pb2BO3I possesses the highest rate constant of 0.161 min−1 compared to Pb2BO3Cl and Pb2BO3Br, and it also exhibits an enhanced degradation efficiency for Ciprofloxacin and Norfloxacin, which is 158.3 and 104.2 times than that of conventional piezoelectric material BaTiO3. ZrO2 balls collision under 600 rpm can produce a large force about 64.7 N which is 2.2 and 2.7 times than that of SiO2 balls collision under 600 and 500 rpm, and generate the most charges based on ratio comparison. The stronger force brings out an enlarged built-in electric field for the higher polarization materials to generate more reactive radicals, resulting in a higher degradation efficiency. Such enhanced piezocatalytic system represents a significant step toward novel-form energy harvesting and energy saving. We demonstrate the first example of three non-centrosymmetric materials, Pb2BO3X (X = Cl, Br, I), can mediate the conversion of mechanical energy to chemical redox reaction through ball milling. The water pollutants, Rhodamine B, Ciprofloxacin and Norfloxacin, could be efficiently decomposed in the presence of Pb2BO3I material. The periodic collision induced by ball milling could produce strong alternating built-in electric field and high free charges separation which enhance the piezocatalytic activity. [Display omitted] •Three Pb2BO3X (X = Cl, Br, I) borate materials and ball milling combination for efficient piezocatalysis.•The reaction rate constant k of Pb2BO3I for Ciprofloxacin removal is 158.3 times than that of commercial BaTiO3 under ball milling.•High speed and large density milling balls are benefit to generate reactive species.•Enhanced alternating built-in electric field promotes the charge pairs separation.