Tuning piezoelectric driven photocatalysis by La-doped magnetic BiFeO3-based multiferroics for water purification

Multiferroic materials have attracted increasing attention for developing multi-effect coupling between different physical properties and exploring the possibility of environmental application. In this work, La doped bismuth ferrite (BiFeO3)-based multiferroics (La-BFOs) were synthesized to achieve strong magnetic response and high piezo-photocatalytic activity. When applying solar light and mechanical vibration on La-BFOs dispersing in the wastewater, 94.5% of carbamazepine (CBZ) was piezo-photocatalytically degraded in 30 min, and the reaction constant was 2.2 times of the sum of photocatalysis and piezocatalysis. This synergistic enhancement was ascribed to that the internal piezoelectric field of La-BFOs tailored the structure of energy band and boosted the separation of photo-generated carriers to produce more reactive species for pollutants removal. The saturation magnetization value of 6.6 emu/g endowed catalysts with an excellent recyclability that can be magnetically separated from the reaction solution, and a satisfactory catalytic reproducibility that more than 90% of CBZ can be removed in ten times of consecutive cycling tests. The present study opens the perspective of combining magnetic, piezoelectric and photoexcitation functionalities of catalyst in water purification through utilizing green energies in the nature, delivering a scientific and technological importance to achieve a sustainable and economic environment.