Fabricating BiOBr/Bi2WO6 S-scheme heterojunction with interface modification strategy for efficient photocatalytic degradation of gaseous toluene

Exploring semiconductor photocatalysts with efficient photo-induced carriers separation capacity remains a challenge in photocatalytic degradation of gaseous toluene. Herein, a S-scheme heterojunction of BiOBr/Bi2WO6 was constructed via two-step hydrothermal method. The Bi2WO6 nanosheets with enriched Bi-O bonds on the surface were favorable to adsorb Br- ions and further form BiOBr on the surface, leading to the successful fabrication of BiOBr/Bi2WO6 heterojunction. The intimate contact between BiOBr and Bi2WO6 facilitated the photo-induced carrier migration in the heterojunction interface. The optimized BiOBr/Bi2WO6 samples denoted as SBBW2 achieved 94.8% of removal rate for gaseous toluene degradation after 120 min irradiation under simulated sunlight, superior to those of pristine Bi2WO6, BiOBr and other comparison photocatalysts. The enhancement of photocatalytic performance was attributed to the formation of S-scheme heterojunction that reserving stronger redox potential and lowering heterojunction interface resistance. In addition, the predominated reactive oxygen species were determined by electron spin resonance and gaseous capture experiments. This work is expected to provide a strategy for preparing compact contacted heterojunction photocatalysts for improving the carrier separation efficiency.