Low-temperature synthesis of graphene/Bi2Fe4O9 composite for synergistic adsorption-photocatalytic degradation of hydrophobic pollutant under solar irradiation

A graphene-supported bismuth ferrite (BF0249/rG04.5) that exhibits a highly effective solar photocatalysis was synthesized via a facile co-precipitation method at a low temperature of 95 C. BF0249/rG04.5 has a 2D composite structure and the deposited bismuth ferrite (BF0249) nanoparticles have an average size of 5 nm. Fourier transform-infrared (FT-IR) analysis shows that the resulting BF0249/rG04.5 catalysts are chemically bonded composites possibly with Fe-O-C and/or Bi-O-C bonds. Photoluminescence evaluation indicates that rGO can effectively suppress the recombination of e(-)/h(+) pairs in BF0249. The adsorption and photocatalytic performance was evaluated using a hydrophobic pollutant (bisphenol A). The adsorption capacity of BPA on BF0249/rG04.5 is 4 mg g(-1), which is ca. 5.5 times higher than that of pristine BF0249. Under visible-light region of full solar spectrum, BF0249/rG04.5 shows a great synergistic adsorption-photocatalytic degradation efficiency of 62% after 3 h (similar to 2 times higher than that of BF0249) and the corresponding mineralization is 47%. The predominant reactive oxygen species (ROS) for BPA degradation was identified to be the O-2(center dot-). When BPA solution containing BF0249/rG04.5 was exposed to the full solar spectrum, 76% and 80% of BPA can be removed at pH 6.5 and 5, respectively, in 3 h. The presence of bicarbonate induces moderate inhibitory effect on the photocatalytic degradation (PCD) of BPA by BF0249/rG04.5 while sulfate, chloride or nitrate exhibit only minor effect. (C) 2014 Elsevier B.V. All rights reserved.