Single-step green route synthesis of Au/Ag bimetallic nanoparticles using clove buds extract: Enhancement in antioxidant bio-efficacy and catalytic activity.

In present work, we demonstrate a single step environmentally benign approach to synthesize Au/Ag bimetallic nanoparticles (BMNPs) using aqueous extract of Clove buds for the first time. Clove bud's (CB) extract has proficiency to act as a reducing and stabilizing agent for the formation of Au/Ag BMNPs. In presence of extract, AuIII and AgI are reduced competitively within same solution and produce Au/Ag alloy NPs. The kinetics besides the formation of NPs was studied using UV-visible spectroscopy and efficiency of the extract was monitored by varying contact time, temperature, pH and extract concentration. The electron microscopic studies revealed the presence of NPs with peculiar morphology at alkaline pH. Further, the existence of Au and Ag atoms was investigated using energy dispersive X-ray (EDX), X-ray diffraction (XRD) and cyclic voltammetry (CV) techniques. Fourier transform infrared spectroscopy (FTIR) showed that Eugenol in the extract is mainly responsible for the production of NPs which are also surrounded by various phytochemicals. Zeta potential of all the NPs is found to be negative which prevents their agglomeration due to inter-repulsion and the biosynthesized Au/Ag BMNPs revealed greater catalytic efficiency for the degradation of methyl orange (MO), methylene blue (MB) and reduction of p-nitrophenol (p-NP). Significant enhancement induced by BMNPs compared to individual monometallic nanoparticles (MMNPs) was assigned to the synergistic effect of MMNPs and coating of phytochemicals present in the CB extract.