A facile room-temperature synthesis of gold nanowires by oxalate reduction method

Polycrystalline gold nanowires were synthesized by a simple chemical reduction method using potassium oxalate as the reducing and capping agent along with polyvinylpyrrolidone (PVP) as the co-capping agent at room temperature. Different molar concentration ratios of HAuCl4 and potassium oxalate were studied for the synthesis of Au nanowires. Kinetics studies for An colloid formation were carried out using UV-vis spectroscopic technique for the various concentration ratios of the reactants. As the concentration of oxalate was increased, the rate of reduction as well as particle growth was found to increase. XRD and TEM analyses revealed the formation of polycrystalline An nanowires with a preferential growth of the {111} facet. In the absence of PVP, no Au colloid was formed. Studies revealed that the formation of the An nanowire was due to the bridging nature of the oxalate dianion. The formation of Pt nanowires further supported the role of oxalate when the same method was adopted for the synthesis of Pt nanowires without using PVP. A plausible mechanism was proposed for the formation of An nanowires explaining the role of oxalate.