Synthesis of flower-like heterostructured β-Bi2O3/Bi2O2CO3 microspheres using Bi2O2CO3 self-sacrifice precursor and its visible-light-induced photocatalytic degradation of o-phenylphenol

Novel flower-like heterostructured beta-Bi2O3/Bi2O2CO3 microspheres are synthesized by calcining a Bi2O2CO3 self-sacrifice precursor for the visible-light photocatalytic degradation of o-phenylphenol (OPP, is a widely used fungicide and preservative agent). The Bi2O2CO3 microspheres are firstly prepared under hydrothermal conditions, and then converted to Bi2O3 by thermal treatment. With increasing the calcining temperature from 250 to 500 degrees C, an in situ stepwise decomposition reaction take place during the course of calcination, described as: Bi2O2CO3 -> beta-Bi2O3/Bi2O2CO3 -> beta-Bi2O3 -> beta-Bi2O3/alpha-Bi2O3 -> alpha-Bi2O3. The beta-Bi2O3/Bi2O2CO3 microspheres synthesized at 300 degrees C exhibit excellent photocatalytic activity under visible-light irradiation, which can degrade 99.8% OPP in 45 min. And the degradation rate of the heterostructured photocatalyst is approximately 2, 2.6, 6, 13, 80, and 827 times higher than that of single beta-Bi2O3, mixed beta-Bi2O3 and Bi2O2CO3, commercial beta-Bi2O3, alpha-Bi2O3, N-doped TiO2, and Bi2O2CO3, respectively. The superior photoreactivity of the beta-Bi2O3/Bi2O2CO3 is attributed to the enhanced charge separation and transfer due to the formation of p-n junction with large heterojunction interface, favorable band gap energy (2.27 eV), relatively high specific surface areas (12.5 m(2) g(-1)), and flower-like hierarchical micro/nano structures. In addition, the degradation intermediates including ethyl phenethyl ether, phenyl acetaldehyde, and phenylacetic acid are identified. And the results also reveal that the photogenerated holes and center dot O-2(-) radicals are primarily reactive species in the photocatalytic system, which are the key factors responsible for the nearly complete mineralization of OPP. (C) 2014 Elsevier B.V. All rights reserved.