Prolonged colloidal stability of silver nanoparticles through Mentha spicata leaf extract as reducing agent, and their catalytic reduction of 4-nitrophenol

This work presents the influence of the reproducibility, stability and the morphology of silver nanoparticles (AgNPs) obtained by green synthesis of nanoparticles (GNPs) assisted by a Mentha spicata extract solution as reducing stock solution (RSS). Noteworthy colloidal dispersion at 6.4 months has been reported by the presence of the surface plasmon resonance (SPR) in the UV–Vis spectra for spherical nanoparticles (680AgN), while quasi-spherical nanoparticles (1300AgN) presented aggregation. Thereby, a great amount of RSS as reducing agent present in the synthesis involves the formation of NPs (nanoparticles) with tendency to agglomeration as shown by high-resolution transmission electron microscope (HRTEM) and Z potential for 1300AgN system. Meantime, the Fourier transform infrared spectroscopy (FTIR) spectra supported that hydroxy group of the poly phenols species reported at 3420 cm −1 , and the C=C bonds presented in the aromatic rings at 1633 cm −1 are the main electron-donating species to obtain AgNPs. Finally, the performance of the AgNPs systems to the reduction of 4-nitrophenol (4-NP) was evaluated in the presence of sodium borohydride (NaBH 4 ). These outcomes show NPs with ordered morphology by GNPs reproducible and, with outstanding colloidal stability without an external stabilizer agent, at natural pH of the NPs, and they are useful to diverse applications. Graphical abstract