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

Abstract

Novel hierarchical micro/nanostructured photocatalysts composed of WO3 microspheres and needle-like Bi2S3 nanocrystals were successfully synthesized by a simple combination of hydrothermal and post-calcination method. The as-obtained Bi2S3-WO3 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, N2 adsorption–desorption techniques, UV–vis DRS, XPS and PL spectra. It was found that 70%-Bi2S3-WO3 has the highest photocatalytic activity and more than 90% (over 3 times than pure WO3) 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%-Bi2S3-WO3 composites is 9 times more than the pure WO3. The modification of WO3 by deposited Bi2S3 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 Bi2S3-WO3 composites had an excellent stability in cycling experiments. At last, a tentative mechanism of enhanced photocatalytic activity for Bi2S3-WO3 composite was discussed according to the calculation of the energy band position.