Multifaceted role of rGO − a 2D carbonaceous material − in green routed ternary composite SnO2/ZnO/rGO for effective photocatalytic dye detoxification

Development of nanocomposites with new combination of constituents emerges as a wise tactic for the treatment of aquatic toxic dye waste discharged from industry. The present work focuses on the synthesis of ecofriendly ternary nanocomposite (SnO₂/ZnO/rGO) with green routed reduced graphene oxide (rGO) as a composite partner to the metal oxides, tin oxide (SnO₂) and zinc oxide (ZnO). Cassia fistula leaf extract was used as the reducing agent for the synthesis of rGO. The formation of the composite was affirmed using XRD, FESEM, XPS and TEM analyses. The photocatalytic ability of the prepared nanocomposite was examined by degrading the organic dye molecules of methylene blue (MB) and rose Bengal (RB). The dye detoxifying efficiency of the ternary nanocomposite against both MB (99 %) and RB (97 %) dyes (with irradiation time of 45 min) was found to be superior compared to its composite partners (rGO, SnO₂ and ZnO). The bandgap reduction caused by the inclusion of rGO makes the nanocomposite as a visible light responsible photocatalyst. The detoxification ability of the ternary composite was tested via phytotoxic assessment by supplying the treated water and the untreated dye solution to chia seeds-Salvia hispanica. The seed germination results clearly show that the SnO₂/ZnO/rGO ternary nanocomposite-as a photocatalyst- completely decompose the dye solution. Thus, the eco-friendly SnO₂/ZnO/rGO ternary nanocomposite biosynthesized using Cassia fistula leaf extract can be considered as a promising candidate for effective photocatalytic dye detoxification.