Fabrication of visible-light-active Bi/BiOI-Bi2O3 composite with enhanced photocatalytic activity

Abstract

Plasmonic Bi0 modified BiOI-Bi2O3 composite (Bi/BiOI-Bi2O3) was prepared via in situ UV reduction method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) techniques were carried out to identify the formation of semimetal Bi0. The results indicated that the dot-like bismuth particles were originated from the partial reduction of lattice Bi3+ to Bi0 by accumulated conduction band electrons in BiOI-Bi2O3. The as-prepared ternary composite exhibited enhanced visible-light-response, decreased charge transfer impedance and higher charge carrier density relative to unmodified BiOI-Bi2O3. Due to synergistic effect between plasmonic Bi0 and BiOI-Bi2O3 heterojunction, dramatically enhanced photocatalytic activity for phenol degradation can be achieved. After 3.5 h visible light irradiation, the value for phenol removal efficiency was ca. 60% and 100% on BiOI-Bi2O3 and Bi/BiOI-Bi2O3, respectively. The calculated zero-order rate constant on Bi/BiOI-Bi2O3 was 1.7 and 3.9 times that on BiOI-Bi2O3 and Bi2O3, respectively. In addition to phenol, organic dyes (zwitterionic RhB, cationic MB and anionic Org II) were also used as model pollutants. Pronounced photocatalytic degradation by Bi/BiOI-Bi2O3 can be observed, further confirming the importance of Bi0. Trapping experiments using different scavengers indicated that photogenerated holes were major active species during the degradation of phenol. Furthermore, good stability was also observed in 5 successive cyclic runs. This study opens a new strategy for in situ preparation of plasmonic Bi0 modified composite.