Synthesis, characterization and photocatalytic properties of graphene-CdO/SnO2 ternary nanocomposites in visible light

Abstract

rGO/CdO/SnO2 ternary nanocomposite (GCS) were synthesized using a combination of graphene sheet and CdO/SnO2 nanostructures through the hydrothermal process. The resulting GCS nanocomposite was characterized using XRD, FE-SEM, HR-TEM, and EDS for structural, morphological and compositional studies. The optical characteristics such as UV–vis and PL spectroscopy were used to study the optical properties of the nanocomposite. The XRD analysis showed that CdO and SnO2 nanostructures were crystalline in nature with cubic and orthorhombic phases respectively with the existence of graphene. FESEM images revealed the existence of both cubic and orthorhombic phases of CdO and SnO2 nanostructures respectively. HRTEM study revealed the dispersion of 50–200 nm sized agglomerated nanostructures on the surface of graphene sheets. The analysis of UV–visible & PL spectroscopy shows a considerable decrease in band gap energy from 2.87 to 2.41 eV and improved electron-hole separation respectively. The photocatalytic activity of as-synthesized samples were measured against malachite green (MG) and congo red (CR) dyes. It was found that photocatalytic activity was significantly affected by the ratio of graphene and CdO/SnO2 in the composite. The higher percentage of CdO/SnO2 in the rGO/CdO/SnO2 shows maximum photocatalytic degradation. It occurs due to maximum production and transfer of charge carriers from metal oxide to graphene. It is also found that higher degradation efficiency of MG dye is observed in all the samples of GCS nanocomposite as compared to CR dye.