Fabrication of a Narrow-Band-Gap Ag6Si2O7/BiOBr Composite with High Stability and Enhanced Visible-Light Photocatalytic Activity

摘要

In this study, a facile and economical method was reported to enhance the photocatalytic activity of bismuth oxybromide (BiOBr) semiconductor through the fabrication of heterojunction with Ag6Si2O7. Field emission scanning electron microscopy, the transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectra were utilized to characterize the crystal structures, morphologies and optical properties of the as-prepared samples. Photocatalytic experiments showed that the Ag6Si2O7/BiOBr composite had a higher rate and efficiency for degradation of methyl orange and phenol than the pure Ag6Si2O7 and BiOBr under visible light illumination. The optimal Ag/Bi molar ratio in Ag6Si2O7/BiOBr composite was found to be 2:1. The enhanced photocatalytic performance could be attributed to the high separation efficiency of the photogenerated electron-hole pairs. The trapping experiments of radicals showed that the photogenerated holes (h(+)) and superoxide ions (center dot O-2 (-)) were the main active species. Moreover, the synthesized samples exhibited almost no activity loss even after four recycling runs, indicating their high photocatalytic stability. Considering the facile and environment friendly route for the synthesis of Ag6Si2O7/BiOBr hybrids with enhanced visible-light-induced photocatalytic activity, it is possible to widely apply these hybrids in arious fields.