Facile size and shape control of templated Au nanoparticles under microwave irradiation

In this work we prepared icosahedral gold particles and gold nanoplates using potassium tetrachloroaurate as precursor and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers as both reductant and capping agent under microwave irradiation. The products were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The size and shape of the resultant nanoparticles could be tuned by changing the chloride ion dosage and reaction temperature. With lower dosage of chloride ion, a lower proportion of irregular shaped nanoparticles and smaller gold decahedra and icosahedra were observed. Increasing the molecular ratio of [AuCl4]/[Cl−] and reaction temperature could increase the proportion of gold nanoplates in the final product. Typically when the reaction proceeded at 120 °C with [AuCl4]/[Cl−] = 10, > 90% of the product was nanoplatelets.