Synthesis of AgBr@Bi2O3 composite with enhanced photocatalytic performance under visible light

AgBr@Bi2O3 heterojunction photocatalysts were fabricated by a facile deposition-precipitation method using novel hierarchical alpha-Bi2O3 microrods as substrate, whose particular morphology is conducive to photocatalysis. X-ray powder diffraction (XRD) reveals that no other phase can be found in the assynthesized composites except the monoclinic phase of Bi2O3 and the face-centered cubic phase of AgBr. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrates that AgBr nanoparticles were uniformly deposited on the surface of hierarchical Bi2O3 and the heterojunctions were formed between these two compounds. UV-vis diffuse reflectance spectroscopy (DRS) indicates that the light absorbance of photocatalyst was improved by AgBr for its photosensitization in visible light region. Elemental composition and the chemical state were identified by X-ray photoelectron spectroscopy (XPS). In particular, the photocatalytic activity of AgBr@Bi2O3 heterojunction is superior to that of the single visible-light active components (AgBr, Bi2O3) and the mechanical mixture of them, indicating the presence of a synergic effect between two active components in AgBr@Bi2O3 heterojunction. Among all the catalysts prepared, the AgBr@Bi2O3-0.5 exhibits the highest visible-lightresponsive photoactivity, which can decolorize about 90% Rhodamine B (RhB) after 60 min visiblelight irradiation. Trapping and photoluminescence experiments show that active h(+), Br-0 and center dot O-2(-) played a major role in Rhodamine B degradation while center dot OH was confirmed to be insignificant. A possible mechanism of transportation for photon-generated carriers was proposed. (C) 2015 Elsevier B.V. All rights reserved.