Role of rGO to improve the performance of BiVO4 nanostructures for efficient removal of heavy metals

The fabrication of efficient visible light-driven photocatalysts has gained much attention for the removal of heavy metals from water to resolve the water crises of the world by utilizing visible light in the context to resolve energy issues. Reduced graphene oxide/bismuth vanadate nano-photocatalysts were prepared by facile hydrothermal method. Various characterization techniques, including X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), UV-Vis absorption spectroscopy (UV-Vis), photoluminescence emission spectroscopy (Koci et al. Appl Catal B 96(3-4):239-244, 2010), photocatalytic removal of heavy metals were utilized to explore the morphology, crystal structure, elemental composition, optical properties, and photocatalytic activity measurement. XRD patterns showed the monoclinic scheelite and tetragonal scheelite structure of prepared composite, while the average size of particles calculated by diffraction peaks were ranging from 25.3 to 36.5 nm. SEM micrographs showed the spherical, oval, cuboid morphology of prepared composite with average size of particles ranging from 26 to 35 nm with best accord to XRD results. The reduction in size may be very beneficial for the transportation of electrons on reduced graphene sheet interstitial sites and take part in photocatalytic performance and enhanced the removal of heavy metals. UV-Vis spectra showed the absorption of prepared composite resulting in reduction of bandgap from 2.41 to 2.13 eV with the increasing content of graphene oxide in bismuth vanadate. PL emission spectra display the suppressed recombination of charge carriers, when incorporating with reduced graphene oxide. These results show the increase in the separated charge carriers and resulting in enhanced photocatalytic activity. As prepared rGO/BiVO4 composite exhibits the high photocatalytic removal of heavy metals, because of the extended visible light adsorption, high surface to volume ratio, and increased separated charge carriers of prepared composite. This research provides a different vision to construct promising photocatalysts for the removal of heavy metals from water.