Eco-friendly synthesis and photocatalytic application of rGO-MgO nanocomposites for eosin Y dye degradation

• Green synthesis of rGO-MgO nanocomposites using Saraca asoca leaf extract. • Uniform dispersion of MgO nanoparticles on rGO sheets via physical grinding. • rGO incorporation narrows bandgap and enhances visible-light absorption. • Synergistic rGO-MgO interactions significantly improve photocatalytic dye degradation. • Optimized nanocomposites exhibit sustainable, low-cost, and efficient visible-light photocatalysis. Reduced graphene oxide-magnesium oxide nanocomposites (rGO-MgO NCs) were synthesized via a green and sustainable route using Saraca asoca leaf ( Sa -leaf) extract as a natural reducing and capping agent. Graphene oxide, prepared using the modified Hummers method, was reduced and combined with MgO nanoparticles (MgO NPs) through a simple grinding technique. Structural and morphological characterizations confirmed the formation of a crystalline face-centered cubic MgO phase with nanorod and spherical morphologies uniformly distributed on rGO sheets. The nanocomposites exhibited an average particle size of 21.5 nm and a reduced band gap of 2.84 eV, enhancing charge separation and visible-light absorption. Under 500 W visible-light irradiation, the rGO-MgO NCs achieved 92.4% degradation of Eosin Y (EY) dye, following first-order kinetics, and demonstrated excellent stability and reusability across multiple cycles. Furthermore, ECOSAR-based toxicity predictions indicated that the degradation byproducts were environmentally benign. These findings highlight the potential of Sa -leaf-mediated rGO-MgO NCs as efficient, sustainable, and eco-friendly photocatalysts for wastewater remediation.