Green Synthesis of Silver Nanoparticles Using Hibiscus rosa-sinensis Leaf Extract

Background: Owing to their remarkable chemical, physical and biological properties, silver nanoparticles have been widely used in water purification, electronics, bio-sensing, clothing, food industry, paint and medical devices. Various approaches, such as using harsh reducing and stabilising agents for reverse micelle and thermal decomposition, were proposed for silver nanoparticle production. However, these methods are not eco-friendly. Thus, the aim of this paper is to synthesise silver nanoparticles through a cost-effective and environmentally friendly approach. Materials and Methods: A green approach was presented for the synthesis of silver nanoparticles. This approach involved the treatment of silver nitrate and hibiscus leaf extract, which acts as reducing and capping agent. The synthesis was performed at room temperature. The resulting silver nanoparticles were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and Fourier transform infrared (FTIR) spectroscopy. Results: Spherical, rod-like, hexagonal and triangular silver nanoparticles were obtained through the proposed synthesis method. The crystalline nature of each nanoparticle was revealed by XRD and selected area electron diffraction (SAED). The average spherical size of the silver nanoparticles produced in this route was 44.3 nm. The obtained FTIR band at 1622 cm-1 corresponded to the C=O stretch in the amine I group, which is commonly found in protein. Thus, the protein was believed to serve as capping agent that was responsible for the stabilisation of silver nanoparticles. Conclusion: In conclusion, silver nanoparticles had been successfully synthesised using hibiscus leaf extract and a plausible formation mechanism of silver nanoparticles was proposed.