Bi25FeO40/Bi2O2CO3 piezoelectric catalyst with built-in electric fields that was prepared via photochemical self-etching of Bi25FeO40 for 4-chlorophenol degradation

Piezoelectric catalysis based on the polarization of piezoelectric materials is a promising technology for environmental pollutant treatment. Developing effective piezoelectric catalysts and clarifying the reaction mechanism are crucial to the application of piezoelectric catalysis. Herein, a unique strategy of photochemical self-etching of Bi25FeO40 was used to prepare a piezoelectric catalyst of Bi25FeO40/Bi2O2CO3. During the photochemical process, methanol was oxidized to formaldehyde, and then Bi species on the surface of Bi25FeO40 reacted with formaldehyde to form Bi2O2CO3. As a lead-free piezoelectric catalyst, the Bi25FeO40/Bi2O2CO3 composite possessed excellent activity for the degradation of 4-chlorophenol under ultrasonic vibration, and the degradation efficiency was more than 90% within 120 min. Introducing Bi2O2CO3 onto the surface of Bi25FeO40 can significantly promote the piezoelectric catalytic activity of Bi25FeO40 via the effect of built-in electric fields. It was also found that ·OH and ·O2− are the main active species that are responsible for the degradation of 4-CP. The results that are presented here can extend the piezoelectric application of bismuth ferrate, and the strategy for building up the heterojunction is helpful for the preparation of other Bi-containing piezoelectric catalysts.