Heterojunction interface field and piezoelectric polarization field cooperatively facilitating photocarrier separation in heterojunction piezo-photocatalysts: Experimental and theoretical characterization

To understand the piezo-photocatalysis mechanism, herein we have designed novel 13-Bi2O3/BiFeO3 heterojunctions by decorating 13-Bi2O3 particles on the surface of BiFeO3 microdiscs, and experimentally and theoretically elucidated their enhanced piezo-photocatalytic activity and mechanism for tetracycline hydrochloride (TC) elimination. The photodegradation experiment, performed under simulated-sunlight irradiation, shows that the optimal composite 9.1 %BO/BFO has a photodegradation activity increased by 5.2 times over that of BiFeO3 and 1.9 times over that of 13-Bi2O3, which can be interpreted by the heterojunction-interface-field-induced Z-scheme photocarrier transfer mechanism. The piezo-photodegradation activity of the 9.1 %BO/BFO composite was evaluated under irradiation of both simulated sunlight and ultrasonic, manifesting a further increase. The piezophotocatalytic synergistic factor is obtained as SF = 1.62, evidencing an obvious synergistic enhancement between photocatalysis and piezocatalysis. This phenomenon can be explained due to the fact that the heterojunction interface field and piezoelectric polarization field cooperatively facilitate the separation of photocarriers (particularly those in the bulk) and make them participate in the redox degradation of TC more efficiently. To understand the piezo-photocatalysis mechanism of the 8-Bi2O3/BiFeO3 heterojunctions as well as the TC decomposition mechanism, theoretical studies were conducted by density functional theory (DFT) and finite element method (FEM).

Automated summary

In this study, novel 13-Bi2O3/BiFeO3 heterojunctions were designed to enhance the piezo-photocatalytic activity for tetracycline hydrochloride (TC) elimination. The results showed that the optimal composite 9.1 %BO/BFO had a photodegradation activity 5.2 times higher than that of BiFeO3 and 1.9 times higher than that of 13-Bi2O3, which can be explained by the heterojunction-interface-field-induced Z-scheme photocarrier transfer mechanism. The piezo-photodegradation activity of the 9.1 %BO/BFO composite was further increased under both simulated sunlight and ultrasonic irradiation, demonstrating a synergistic enhancement between photocatalysis and piezocatalysis.