Effects of the synthesis conditions on the photocatalytic activities of sulfide-graphene oxide composites

Sulfide-graphene oxide composites photocatalysts were fabricated through a simple solid-state chemical reaction method under different synthesis conditions. The resulting photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, Nitrogen adsorption-desorption specific surface areas, XPS measurements, UV-vis absorption spectroscopy, Transient photocurrent, and Photoluminescence spectra. The result suggests that ZnS and Bi2S3 nanoparticles well distributed on the graphene oxide nanosheets in the sulfide-graphene oxide composites. Nitrogen adsorption-desorption results indicate that the specific surface areas of the composites increased after the graphene oxide is introduced. XPS measurements suggest that there are interactions between sulfide and graphene oxide. The photocatalytic activities of sulfide-graphene oxide composites were measured by the degradation of methyl orange under UV irradiation. Variation of the synthesis conditions allowed the sulfide-graphene oxide composites possessing different structures and photocatalytic activities as revealed by transmission electron microscopy and photocatalytic measurements. The photocatalytic results indicated that the sulfide-graphene oxide composites exhibited much higher photocatalytic activities than that of pure ZnS and Bi2S3, and nearly 97% and 90% of methyl orange were degraded over ZnS-graphene oxide and Bi2S3-graphene oxide after irradiation for 120 min, respectively. The superior photocatalytic activities can be attributed to the high specific surface areas, which is benefical for improving photocatalytic reaction. Futhermore, introducing graphene oxide can effectively reduce the photoinduced electron-hole pair recombination probability, and then improve the photocatalytic activities, which have been proved by the transient photocurrent, photoluminescence spectra, and scavengers measurements.