Construction of p-n type AgCl/BiFeO3 heterojunction with promising photocatalytic and piezo-photocatalytic water purification

In this work, a promising p-n type AgCl/BiFeO3 heterojunction piezo-photocatalysts was constructed by attaching AgCl nanocubes on the surface of BiFeO3 microdiscs. The characteristic results verified that the intimate heterojunction between AgCl and BiFeO3 was formed. Under the simulated sunlight excitation, the photocatalytic degradation activity of dye (Acid Orange 7 (AO7) and Rhodamine B (RhB)) over BiFeO3 can be obviously improved after the decoration of AgCl, and the 10%AgCl/BiFeO3 sample exhibits optimum photocatalytic removal performance, which leads to -99.7% and -93.8% of AO7 and RhB degraded after 120 min irradiation. Most importantly, the piezo-photocatalytic degradation ability of 10%AgCl/BiFeO3 sample was evaluated by the removal of tetracycline (TC) excited by simulated sunlight and ultrasonic irradiation. It is found that the 10%AgCl/BiFeO3 sample presents more efficient piezo-photocatalytic activity compared with its piezocatalytic and photocatalytic performance, leading to a synergistic factor SF = -1.6, which demonstrates an outstanding synergistic improvement between photocatalysis and piezocatalysis. Furthermore, the piezophotocatalytic degradation pathway of TC was proposed by the intermediates detection and theoretical calculation. The piezopotential of BiFeO3 microdiscs excited by ultrasonic was simulated. The interface electric field induced by p-n heterojunction and piezoelectric polarization field caused by the ultrasonic irradiation separately promote the surface and bulk migration of generated charges, which synergistically accelerates the separation of generated charges and thus providing more charges for the catalytic reaction. This work has developed a potential efficient heterojunction-type piezo-photocatalysts for environmental purification.