Enhanced photocatalytic decomposition of an organic dye under visible light with a stable LaFeO3/AgBr heterostructured photocatalyst

Abstract

In this study, we synthesized a novel LaFeO3/AgBr heterojunction via an in-situ precipitation method. The composition, structure, and optical absorption properties of LaFeO3/AgBr were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activity of the LaFeO3/AgBr photocatalyst was determined based on the degradation of tetracycline and three types of dyes comprising methyl orange, rhodamine B (RhB), and malachite green. The photocatalytic performance of the LaFeO3/AgBr heterojunction was much better compared with that of the pure AgBr and LaFeO3. It should be noted that Ag nanoparticles were not present in the fresh LaFeO3/AgBr heterojunction. However, according to the XRD and TEM results obtained for 10%-LaFeO3/AgBr, Ag nanoparticles were generated in the LaFeO3/AgBr heterojunction during the photodegradation process, which accelerated the separation of photoinduced carriers in the LaFeO3/Ag/AgBr system. Based on the detection of active species, we propose a Z-scheme photocatalytic and organic dye (RhB) photosensitization mechanism, which also considers the role of Ag nanoparticles in the separation of electrons and holes. The stability of the LaFeO3/AgBr heterojunction was also investigated, which showed that the incorporation of LaFeO3 remarkably improved the photocatalytic activity as well as enhancing the stability of the LaFeO3/AgBr heterojunction by suppressing the photodecomposition of AgBr.