Green approach to synthesize silver nanoparticles from stem extract of Garden Rhubarb: Evaluation of their stability and dielectric performances

Abstract

Recent advances in Nano-biotechnology, offer potential longer duration storage options for silver nanoparticles (SNPs) with preferable capping agents where a plentiful efforts have been given to minimize the toxicity effects SNPs. To overcome the toxicity scenario of SNPs, a novel green methodology was put forward in the present investigation. Biogenic SNPs were synthesized using water extract of Garden Rhubarb (GR) stems under ambient conditions. The method demonstrates an eco-friendly, instant and easy route for stable SNPs synthesis. The formation of instant SNPs was analyzed by visual observation and monitored by UV-visible (UV-vis) spectrophotometer. The characteristic surface plasmon resonance (SPR) band at 445 nm, revealed the formation of SNPs. The X-ray diffraction (XRD) pattern of green SNPs showed their crystalline structure. SEM and TEM studies revealed that the shape of SNPs was spherical and has approximate diameter within 100 nm range. The zeta potential measurements on 180th day after SNPs synthesis, revealed the stability and size distribution of SNPs. The values are 29.6mV, 28.1mV and 24.1mV for three varied compositions of AgNO3 (1mM) and GR extract. The high dielectric constant (ϵ′) has been observed for GR mediated SNPs, the ϵ′ values were found to reach the minimum value of 40000 at frequency 1MHz. Suitable tuning of the dielectric performances can conclusively prove their applications in multifunctional sensors, optical, and charge storage devices.