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

Abstract

Background

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.

Methods

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.

Significant findings

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.