Facile purification of ultrathin Au nanowires: A solvent exclusion method

Ultrathin Au nanowires are always synthesized with 2 nm Au nanoparticles as the by-product, and their separation has been a long-standing problem. In this work, we show that high-purity (>99%) separation can be achieved using the solvent exclusion method: Adding hexane would cause water to be excluded from the initial water-THF mixture. The excluded water preferentially nucleates on the oleylamine-bilayer of the nanowires, transferring them into the water phase. Careful control experiments were conducted to establish the purification mechanism. The facile method can be generally applied to purify ultrathin Au nanowires with short lengths (470 and 130 nm), which has not been realized using the conventional methods.