General method for extended metal nanowire synthesis: Ethanol induced self-assembly

A new template-free method to form extended nanowires from the spontaneous self-assembly and fusion of discrete metal nanoparticles has been developed. The key strategy was the use of a weak polar solvent (ethanol) to suitably destabilize the metal nanoparticles in a hydrosol. The number of nanoparticles that were assembled and fused into an extended crystalline structure was found to depend on the dielectric constant of the solvent system. Three distinctive fusion modes consistent with HRTEM analysis of the products were hypothesized, which could satisfactorily explain the formation and the structures of the nanowires. This method of nanowire synthesis is simple, scalable, and capable of producing nanowires with virtually clean surfaces. The synthesis method can also be extended to other metals, such as palladium and platinum.