Template-less and surfactant-free solvent-driven direct synthesis of urchin-like gold nanoparticles in anisole

In this study, we present a simple template-less and surfactant-free method for the synthesis of urchin-shaped gold nanoparticles. Anisole, the reaction solvent also acted as the reducing agent. When compared with other harsher solvent-mediated methods for the synthesis of gold nanoparticles, the method presented here allows the formation of nanoparticles at the relatively low temperature of 60 degrees C. The effect of reaction time was studied, and it was observed that the urchin-shaped particles initially formed transformed into smooth-edged particles when the reaction was continued for more than 30 minutes owing to the thermodynamic instability of gold nanourchins. The effect of added capping agents such as dodecanethiol, hexadecylamine and polyvinylpyrrolidone (PVP) was also studied, and it was found that nanoparticles were not formed in their presence. The gold nanosystems obtained in this study were characterised by transmission electron microscopy and UV-visible absorption spectroscopy.