Piezoelectric polarization promoted spatial separation of photogenerated charges in Bi2MoO6 catalyst and investigation of its synergistic photopiezocatalytic activity

Bismuth molybdate (Bi2MoO6) has been demonstrated as an effective visible-light-driven photocatalyst for purification of pollutants in environment. However, its photocatalytic performance is greatly limited for practical usage due to the drastic recombination of photo-generated charges. Herein, we employed an ultrasound treatment to piezoelectrically polarize the synthesized ferroelectric Bi2MoO6 catalyst. Through studying the current response of catalyst under different stimulations, the effect of quenching active species, the production of radicals, and the intermediate products in the photopiezocatalytic process, a plausible photopiezocatalytic mechanism was proposed. The built-in piezoelectric field acts as a driving force to propel photo-induced e− and h+ to migrate toward opposite surfaces of Bi2MoO6, therefore suppressing their recombination. The photopiezocatalytic activity of Bi2MoO6 for elimination of Rhodamine B (RhB) is 4.19 times and 2.04 times of its photocatalysis and piezocatalysis. Meanwhile, the photopiezocatalysis of Bi2MoO6 also has a high stability and durability, as well as excellent performance for decomposing other pollutants, including dyes and 2,4-dichlorophenol. This investigation indicates that Bi2MoO6 is a promising photopiezocatalyst for efficient elimination of organic pollutants in environment.