Photocatalytic and antimicrobial activity of biosynthesized silver and titanium dioxide nanoparticles: A comparative study

Abstract In this study, Acacia catechu (AC) extract was used as a stabilizing and reducing agent to synthesize silver (Ag) and titanium dioxide (TiO2) nanoparticles (NPs). By using AC extract, the synthesis process becomes more environmental friendly, economical, and advantageous. The morphology and size of synthesized Ag and TiO2 NPs were determined by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Dynamic light scattering (DLS), Atomic force microscopy (AFM), and Scanning electron microscopy (SEM). Elemental composition was determined by using Fourier transform infrared spectroscopy (FTIR) and Energy dispersive X-ray spectrometer (EDX), EDS mapping and X-ray photoelectron spectroscopy (XPS). The observations from TEM, SEM, AFM, and DLS revealed that synthesized products are spherical, hexagonal, polydispersed, and ranged within 6–20 nm size. XRD result demonstrated well crystallized and smaller size NPs are formed in both cases. FTIR and XPS analysis depicted the presence of flavonoids, terpenoids, and amino groups in addition to benzene ring agents; which act as stabilizing agents as well as possible aromatic primary amine groups may also be attached with the surface of Ag and TiO2 NPs. Furthermore, the synthesized AgNPs exhibited strong antibacterial activity against S-aureus and catalytic application over Rose Bengal, Rhodamine B, and 4 nitrophenol dyes as compared to TiO2 under sunlight (solar irradiation). Overall, Ag and TiO2 NPs exhibit high potential in the development of antibacterial materials for both Gram-positive as well as Gram-negative bacteria and catalytic material for photocatalytic degradation of a certain type of hazardous dyes or chemicals, thereby paving the way for the treatment and bioremediations. The reason could be high energy and smaller size particles were active in the photo-catalysis and antibacterial performance of AgNPs compared to TiO2 NPs.