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

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 Ag-0 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.