Phase-effect of Bi2O3 in photocatalytic degradation of 2-chlorophenol via a preferential dechlorination pathway

Abstract

Photocatalytic preferential dechlorination of high-environmental-risk 2-chlorophenol (2-CP) is high desired. Although Bi2O3 has previously displayed preferential dechlorination pathway of 2-CP, the phase-effect of Bi2O3 remain ambiguous. Here, one dimensional (1D) α-and β-Bi2O3 photocatalysts were prepared by using a bismuth metal organic framework (CAU-17) microrod as template, of which β-Bi2O3 microrod was obtained via a bicarbonate-induced transformation route and α-Bi2O3 microrod was prepared through a direct pyrolysis route. Multi-pronged characterization confirmed that β-Bi2O3 microrods have larger surface area and narrower band gap as compared with α-Bi2O3 microrods. As expected, β-Bi2O3 microrods showed 2-time higher photocatalytic activity for degrading 2-CP under white-light LED irradiation, with higher mineralization than that of α-Bi2O3 microrods. According to liquid chromatography tandem mass spectrometry, radical trapping experiment and ion chromatography, both α-Bi2O3 and β-Bi2O3 displayed a hole-induced photocatalytic preferential dechlorination of 2-CP, resulting in the conversion of chlorine into chloride ions.