Synergetic photocatalysis/piezocatalysis of bismuth oxybromide for degradation of organic pollutants

Bismuth oxybromide (BiOBr) has been proved to be a potential photocatalyst for removal of organic pollutants, but the insufficient separation of photo-generated electrons and holes results in its low photocatalytic activity. In this work, we utilized the piezoelectric-like behavior of BiOBr to suppress the recombination of photo-excited charges. Under the excitation of the piezo-vibration and the irradiation using a 9 W white LED, the BiOBr catalyst shows a high reaction rate for catalytically decomposing organic dyes, which is 5.62 and 11.0 times of those from the individual photocatalysis and piezocatalysis, respectively. This catalyst has high structural stability and can be recycled for reuse, as well as presents good activity for degrading different organic pollutants via the synergetic photocatalysis/piezocatalysis process. On the basis of the piezoelectric-like effect and our experimental results, a possible catalytic mechanism has been proposed considering the separation of photo-induced charges and the formation of highly active radicals. This work associates photocatalysis with piezoelectric-like effect for improving the catalytic performance of BiOBr, hopefully providing a new and efficient approach not only for wastewater treatment, but also for other catalytic applications.