▎ 摘　　要

Bismuth ferrite (Bi2Fe4O9) nanoparticles were synthesized via a polyacrylamide gel route. Bi2Fe4O9-graphene nanocomposites were fabricated by mixing Bi2Fe4O9 nanoparticles and graphene into absolute ethanol solution followed by thermal drying. Transmission electron microscope observation reveals that Bi2Fe4O9 nanoparticles are well assembled onto graphene sheets. The photocatalytic activity of the prepared samples was evaluated by the degradation of methyl orange under simulated sunlight irradiation, revealing that Bi2Fe4O9-graphene nanocomposites exhibit an enhanced photocatalytic activity compared to bare Bi2Fe4O9 nanoparticles. This can be explained by the fact that the photogenerated electrons are captured by graphene, leading to an increased availability of h (+) for the photocatalytic reaction. In addition, it is found that hydroxyl ((OH)-O-center dot) radicals, detected by the photoluminescence technique using coumarin as a probe molecule, are produced on the irradiated Bi2Fe4O9 and Bi2Fe4O9-graphene nanocomposite; especially, an enhanced yield is observed for the latter.