Synthesis of flower-like heterostructured beta -Bi sub(2)O sub(3)/Bi sub(2)O sub(2)CO sub(3) microspheres using Bi sub(2)O sub(2)CO sub(3) self-sacrifice precursor and its visible-light-induced photocatalytic degradation of o-phenylphenol

• Published in: Applied catalysis. B, Environmental Vol. 163; pp. 510 - 519
• Main Authors: Hu, Ruiping, Xiao, Xin, Tu, Shunheng, Zuo, Xiaoxi, Nan, Junmin
• Format: Journal Article
• Language: English
• Published: 01.02.2015
• Subjects: Degradation; Microspheres; Phenyls; Photocatalysis; Precursors; Roasting; Specific surface; Titanium dioxide
• ISSN: 0926-3373
• DOI: 10.1016/j.apcatb.2014.08.025

Novel flower-like heterostructured beta -Bi sub(2)O sub(3)/Bi sub(2)O sub(2)CO sub(3) microspheres are synthesized by calcining a Bi sub(2)O sub(2)CO sub(3) self-sacrifice precursor for the visible-light photocatalytic degradation of o-phenylphenol (OPP, is a widely used fungicide and preservative agent). The Bi sub(2)O sub(2)CO sub(3) microspheres are firstly prepared under hydrothermal conditions, and then converted to Bi sub(2)O sub(3) by thermal treatment. With increasing the calcining temperature from 250 to 500 degree C, an in situ stepwise decomposition reaction take place during the course of calcination, described as: Bi sub(2)O sub(2)CO sub(3) arrow right beta -Bi sub(2)O sub(3)/Bi sub(2)O sub(2)CO sub(3) arrow right > beta -Bi sub(2)O sub(3) arrow right beta -Bi sub(2)O sub(3)/ alpha - Bi sub(2)O sub(3) arrow right alpha -Bi sub(2)O sub(3).The beta -Bi sub(2)O sub(3)/Bi sub(2)O sub(2)CO sub(3) microspheres synthesized at 300 degree 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 -Bi sub(2)O sub(3), mixed beta -Bi sub(2)O sub(3) and Bi sub(2)O sub(2)CO sub(3), commercial beta -Bi sub(2)O sub(3), alpha -Bi sub(2)O sub(3), N-doped TiO sub(2), and Bi sub(2)O sub(2)CO sub(3), respectively. The superior photoreactivity of the beta -Bi sub(2)O sub(3)/Bi sub(2)O sub(2)CO sub(3) 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 super(2) g super(-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 times O super(-) sub(2) radicals are primarily reactive species in the photocatalytic system, which are the key factors responsible for the nearly complete mineralization of OPP.