Suppressing electroless growth allows cyanide-free electrodeposition of straight separable gold nanowires

Gold cyanide is strongly complexed in solution and works well for the electrochemical synthesis of separable nanowires. Straight single axisymmetric nanowires are significant for many applications, but particularly so for sensors based on nanoelectromechanical systems (NEMS) such as nanoresonators. The toxicity of cyanide solutions makes non-cyanide alternatives desirable. However, electrochemical synthesis of gold nanowires in templates from non-cyanide solutions suffers from serious drawbacks. These include growth-arresting pellet formation, poor length control and defects such as inclusions. Here we present the first electrochemical synthesis of straight, cylindrical, separable gold nanowires from a sulfite solution. We demonstrate a scheme that suppresses electroless particle growth in the weakly-complexed gold in solution. We discuss a mechanism for this scheme, which suggests that this approach has potential for better controlled electrodeposition in separable nanowire synthesis.