▎ 摘　　要

beta-Bi2O3 nanoparticles with an average grain size of 100 nm were synthesized by a polyacrylamide sol-gel method. Their bandgap energy is obtained by ultraviolet-visible diffuse reflectance spectroscopy is 2.37 eV. beta-Bi2O3/GR composites were fabricated by mixing beta-Bi2O3 nanoparticles and graphene into absolute ethanol solution followed by thermal drying. A transmission electron microscopy observation shows that beta-Bi2O3 nanoparticles are well assembled onto GR sheets. The photocatalytic activity of prepared samples was evaluated by degrading methylene blue under the irradiation of visible light. Compared to bare beta-Bi2O3 nanoparticles, beta-Bi2O3/GR composites exhibit significantly enhanced photocatalytic activity. Detected by the photoluminescence technique that of using terephthalic acid as a probe molecule, hydroxyl ((OH)-O-center dot) radicals are found to be produced on the irradiated beta-Bi2O3/GR composites. Based on the experimental results, (OH)-O-center dot radicals are suggested to be the major active species which is responsible for the degradation reaction. (C) 2015 Published by Elsevier B.V.