In-Situ Construction of BiOBr/Polypyrrole Composite for Photocatalytic Degradation of Anionic Dyes

Thin bismuth bromide oxide (BiOBr) flake was prepared by photochemical reaction under dilute acid condition, and a new type of bismuth oxide/polypyrrole (BiOBr/PPy) composite was prepared in-situ through a one-step polymerization reaction of pyrrole dispersed in an aqueous solution containing ammonium persulfate and cetyltrimethylammonium bromide. The scanning electron microscope, transmission electron microscope, X-ray diffraction, Raman spectra, X-ray photoelectron spectra, ultraviolet and visible spectra, and fluorescence spectra were used to characterize the crystal structure, morphology feature, and photoelectric characteristics of the samples. The results showed that PPy was successfully modified onto BiOBr flakes with strong interaction and close contact. Compared with pure BiOBr, BiOBr/PPy composite showed superior visible light absorption efficiency and enhanced photocatalytic degradation activity of methyl orange (MO) dye. By optimizing the combination ratio of PPy and BiOBr, the degradation efficiency of MO (30 mg.L-1) by BiOBr/PPy-2 with a ca. 7% mass fraction of BiOBr was 87.3% in 50 min photoreaction, and the cyclic photocatalytic activity was reduced but still higher than that of pure BiOBr and pure PPy (10.4%). These results indicated that the strong interaction and good interface combination between BiOBr and PPy can effectively promote the separation efficiency of photogenerated electrons and holes. The photogenic holes separated and free radicals derived in this reaction played an important role in oxidative degradation of dye.