A novel biogenic method to synthesis a ternary (ZnO-Ag)/g-C3N4 nanocomposite with an enhanced photocatalytic and antibacterial activities

[Display omitted] •A Ternary (ZnO-Ag)/g-C3N4 nanocomposite was successfully synthesized via green route.•XRD and XPS analysis confirms the phase purity of the synthesized samples.•PL spectra explains the recombination rate in the nanocomposite and the pristine compounds.•Improved photocatalytic property and antibacterial activity was observed in the (ZnO-Ag)/g-C3N4 nanocomposite. One of the most effective ways to obtain high-efficiency photocatalysts is to create heterojunctions between two semiconductors with matched band structures. As a pioneering photocatalytic system, the S-scheme heterojunction system has demonstrated considerable promise in simplifying the separation and transfer of photogenerated carriers as well as developing high photoredox capacity. Hence, we report a novel biogenic method to synthesise ternary (ZnO-Ag)/g-C3N4 S-scheme nanocomposites via Terminalia Arjuna leaf extract as an effective reducing and capping agent. The X-ray diffraction technique gives the structural confirmation of well-crystalline Ag, g-C3N4, and ZnO nanoparticles, indicating the excellent reducing property of Terminalia Arjuna leaf extract. UV–Vis spectroscopy reveals the enhanced optical behaviour of (ZnO-Ag)/g-C3N4 by means of a reduction in their bandgap values, which would reflect in the photocatalytic performance of the material. The presence of secondary meltabilities such as phenolic compounds, alkaloids, terpenoids, and proteins in leaf extract employed in the nucleation and stability of (ZnO-Ag)/g-C3N4 nanocomposites was analysed using FTIR spectroscopy. XPS rules out the presence of any other secondary elements(impurity). The incorporation of silver metal in ZnO nanomaterials was investigated using TEM analysis. Finally, the photocatalytic activity and antibacterial activity of (ZnO-Ag)/g-C3N4 nanocomposites were compared with the pristine Ag-ZnO, g-C3N4, and ZnO nanoparticles.