Eco-friendly hetero-system silver decorated nanocomposite zinc oxide/reduced graphene oxide: improved broad-ranged absorptivity and enhanced photocatalytic performance under white-light irradiation

A heterosystem silver decorated nanocomposite zinc oxide/reduced graphene oxide (Ag decorated ZnO/rGO) with UV–Visible light reaping ability was designed by practical choice and optimization of different parameters and three ingredients of the heterosystem. The nanocomposite was prepared by hydrothermally embedding the nanopetals of ZnO flower on reduced graphene oxide (rGO) nanosheets. The band gap of ZnO (2.2 eV) was narrowed and nanocomposite exhibited the band gap ~ 1.5 eV. The nanocomposite ZnO/rGO showed 46% photocatalytic efficiency toward degradation of safranin O (SO) dye under white light illumination. The photocatalytic performance of ZnO/rGO suffers recombination loss of photogenerated charges due to trapped states arising from highly concentrated defects in ZnO. Simple decoration of Ag nanoparticles on ZnO exhibited the quenching of ZnO emission associated with defects, which reduces the probability of charge recombination, resulting better photocatalytic efficiency 70% in comparison of that of pure ZnO (~ 10%). Final hetero-system Ag decorated ZnO/rGO depicted an excellent photocatalytic efficiency (100%) due to reduction of charge recombination and easy electron transfer in the direction of rGO → ZnO → Ag. DFT analysis of the geometrical-relaxed heterosystems ZnO/rGO and Ag-ZnO/rGO supports the absorptivity tuning of experimentally obtained heterosystems. Broad nature of absorption of the heterosystems was well explained by computed density of states (DOS) of the materials. Proper plan of designing and synthesizing the hetero-systems explored an eco-friendly, economically affordable, competent UV–Visible photocatalyst for industrial waste management.