Construction of Z-scheme Ag/AgCl/Bi2WO6 photocatalysts with enhanced visible-light photocatalytic performance for gaseous toluene degradation

Abstract

As a typical aromatic volatile organic compounds (VOCs), toluene is difficult to be decomposed by photocatalysts under visible-light driven. Herein, the Ag/AgCl/Bi2WO6 heterojunction photocatalysts were synthesized by multi-step process involving chemical deposition of AgCl on the surface of Bi2WO6 and subsequently photoreduction of Ag0 nanoparticles by UV light. The as-synthesized photocatalysts were characterized by XRD, SEM, TEM, XPS, UV–vis, PL and ESR to investigate the microstructures and electronic structures. The corresponding degradation efficiencies of gaseous toluene were evaluated and the optimal Ag/AgCl/Bi2WO6 exhibited almost 99.9% removal rate after 60 min illumination with visible light (>420 nm). The optical absorption properties and radical trapping experiments revealed the possible energy band structure of Ag/AgCl/Bi2WO6 heterojunction. Finally, the possible enhancement mechanism was also proposed that the cooperation of surface plasmon resonance (SPR) effect, efficient separation of electron-hole pairs, extension of the carrier lifetime as well as the high redox potentials of Z-scheme heterojunction were the primary reasons. Therefore, construction of Z-scheme heterojunction of Ag/AgCl/Bi2WO6 with higher redox ability is an effective way to degradation gaseous toluene under visible-light irradiation.