Photo- and Sonophoto-Catalytic Degradation of Methylene Blue Using Perovskite-Type Bismuth Ferrite/Lanthanum Ferrite Heterojunction Composites

A series of perovskite bismuth ferrite/lanthanum ferrite (BiFeO3/LaFeO3) (BFO/LFO) composites with different molar ratios of BFO to LFO (0.5:1, 1:1, and 1.5:1) with effective visible-light (photo)- and ultrasound-visible-light (sonophoto)-driven catalyst for degradation of methylene blue (MB) were synthesized and characterized using different physicochemical techniques. Based on scavenger experiments, it is suggested that holes are the most influential reactive species in photo- and sonophoto-reactions. Furthermore, liquid chromatography-mass spectroscopy was used to elucidate the possible intermediate and final product of MB. The results indicated that MB can be efficiently decomposed into carbamic acid and acetic acid. The mechanism of photo- and sonophoto-reactions was explored, and we proposed that the improvement of the photocatalytic is attributed to the longer charge carrier life-time because of heterojunction formation between LFO and BFO.