Tunable Gold Nanoring Arrays by Electrodeposition

Gold has many exciting properties that justify its use in a wide range of applications. While gold nanoparticles are frequently used, nanorings offer an interesting new geometry. Unfortunately, few technologies exist to fabricate nanorings, which are often created by multistep lithographic methods. Furthermore, nanoring arrays are even more difficult to achieve. Herein, a one-step, one-pot electrodeposition method to realize arrays of gold nanorings with tunable parameters is demonstrated. It is shown that the electrodeposition of gold nanoring arrays can be easily achieved when one submerges a water droplet containing HAuCl4 into an oil-phase containing a quaternary ammonium salt. These conditions allow for the spontaneous emulsification at the water|oil interface. The nanorings can be deposited at the edges of the emulsion droplets that become adsorbed to the electrode. Changing the concentrations of species, submersion time, and electrodeposition parameters allows us to tune relevant parameters of the array of nanorings, including the thickness and size of the rings.