Preparation of hierarchical micro/nanostructured Bi2S3-WO3 composites for enhanced photocatalytic performance

Novel hierarchical micro/nanostructured photocatalysts composed of WO 3 microspheres and needle-like Bi 2 S 3 nanocrystals were successfully synthesized by a simple combination of hydrothermal and post-calcination method. The as-obtained Bi 2 S 3 -WO 3 composites was applied for photocatalytic removal of Rhedamine B (RhB) organic pollution in water under visible light irradiation. The morphology and structure of the as-obtained samples were characterized by XRD , SEM, TEM , N 2 adsorption–desorption techniques, UV–vis DRS, XPS and PL spectra. It was found that 70%-Bi 2 S 3 -WO 3 has the highest photocatalytic activity and more than 90% (over 3 times than pure WO 3 ) of the RhB solution were degraded in 100 min. The degradation kinetics data were found to be consistent with the Langmuir-Hinshelwood (L-H) kinetics model. Furthermore, the kinetic rate of 70%-Bi 2 S 3 -WO 3 composites is 9 times more than the pure WO 3 . The modification of WO 3 by deposited Bi 2 S 3 could improve charge separation and transfer with the increase of special surface area and higher utilization of visible light. These favorable factors lead to significantly enhanced visible photocatalytic performance; and Bi 2 S 3 -WO 3 composites had an excellent stability in cycling experiments. At last, a tentative mechanism of enhanced photocatalytic activity for Bi 2 S 3 -WO 3 composite was discussed according to the calculation of the energy band position.