In this work, WO3 was prepared by hydrothermal synthesis method with WCl6 as tungsten source and absolute ethanol as solvent, as shown in Fig. 1(a). Clearly, the synthesized WO3 is a monodispersed microsphere structure with an average size of 2-3um. The hybrid MoS2-rGO was prepared by adding graphene during the hydrothermal synthesis process of MoS2 with Na2MoO4·2H2O and thiourea as reacting materials. As shown in Fig. 1(b), the synthesized MoS2 shows a flower-like structure. Finally, the WO3/MoS2-rGO nanocomposites were also prepared by adding the prepared hybrid MoS2-rGO during the hydrothermal synthesis process of WO3. As shown in Fig. 1(c) and (d), the close contact is clearly seen between the microsphere-like WO3 and flower-like hybrid MoS2-rGO, and the second hydrothermal process had no influence on the structure of WO3 and hybrid MoS2-rGO. X-ray diffraction (XRD) patterns and Raman spectra are respectively measured to determine the crystal structure, as shown in Fig.1 (e) and (f).
The photochemical behaviors of WO3/MoS2-rGO nanocomposites containing (0, 2%, 5%, 10%, and 20%) of hybrid MoS2-rGO are characterized through the degradation behaviors of rhodamine (RhB) under visible light irradiation (Fig.2). The experimental results clearly show that the degradation efficiency of WO3/MoS2-rGO nanocomposites can be improved by optimizing the mass ratio of WO3 microspheres to hybrid MoS2-rGO flowers. The degradation ratios of RhB after 6 h are 78.2%, 79.5%, 82.6%, 95.6%, 91.8%, correspond respectively to the WO3/MoS2-rGO nanocomposites containing 0, 2%, 5%, 10%, and 20% of hybrid MoS2-rGO. The possible reason is that the formed WO3/MoS2heterojunction structure and charge transfer medium of rGO is beneficial for separating electron-hole pairs for high efficiency degradation
In summary, the WO3 microspheres and different WO3/MoS2-rGO nanocomposites have been prepared and characterized through adjusting the mass ratio of WO3 microspheres to hybrid MoS2-rGO flowers. The results show that the optimized degradation ratio of RhB can be greatly improved from 78.2% up to 95.6% after 6h using WO3/MoS2-rGO nanocomposites in comparison with WO3 microspheres.
 J. Georgieva, E. Valova, S. Armyanov, N. Philippidis, I. Poulios, S. Sotiropoulos, Journal of Hazardous Materials 211–212 (2012) 30–46.
 S.Y. Yao, X. Zhang, F.Y. Qu, A. Umar, X. Wu, Journal of Alloys and Compounds 689 (2016) 570–574.
 B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, A. Kis, Nature Nanotechnology, 6 (2011) 147–150.