Abstarct: In this project, the green synthesis and stabilization of Ag nanoparticles (NPs) on magnetite (Fe3O4), reduced graphene oxide (RGO) and magnetite/reduced graphene oxide (Fe3O4/RGO) using Punica Granatum peel extract were performed. Also, the green synthesis and stabilization of Ag and Cu NPs on Fe3O4 using Citrus sinensis peel extract were performed. The extracts acted as reducing and stabilizing agents in the synthesis reactions. The structure and morphology of as-synthesized NPs and nanocomposites (NCs) were investigated by UV-vis, FT-IR, XRD, FE-SEM, EDS, VSM, Raman and TEM techniques. The activity of synthesized NPs and NCs were investigated in the catalytic reduction of 4-nitrophenol (4-NP), methylene blue (MB), methyl green (MG) and methyl orange (MO). In the next step, the activity of NPs and NCs, which are synthesized using Citrus sinensis peel extract, were investigated in the photocatalytic degradation of MB, MG and MO. The catalytic reduction reactions were performed using sodium borohydride (NaBH4) as a reducing agent in aqueous solution at room temperature. The photocatalytic degradation reactions were performed in the presence of hydrogen peroxide (H2O2) as an oxidant under UV irradiation and the effect of various amounts of H2O2 and nanocatalysts was studied. Finally, the catalytic activity of Fe3O4 NPs, Ag/Fe3O4 and Cu/Fe3O4 NCs, which are synthesized using Citrus sinensis peel extract, was investigated in the preparation of 1,3-cyclopentadiene derivatives through three-component reactions and the optimal nanocatalysts loading was determined. The three-component reactions were performed under solvent-free conditions at room temperature. The results indicated that the catalytic activity of NCs was better than NPs, which is attributed to synergistic effect.