Complex nanostructures synthesized from nanoparticle colloids under an external electric field.

We present a novel method to synthesize complex nanostructured films through oriented connection of nanoparticles under an external electric field. Silver is taken as an example to validate the feasibility of this fabrication approach. The building blocks of the prepared silver films are able to be adjusted from nanoparticle to nanoflower, nanoplate, nanoslat, dendrite, and so forth, by either varying the deposition current density or changing the electrode. The obtained Ag complex structures show high SERS sensitivity. Importantly, this method can be extended to fabricate complex nanostructures of other materials, such as Cu(2)O. Further study of this new fabrication method may supply a simple and green method to realize various complicated nanostructures of different materials. The mechanism investigation is also important in understanding the assembly behavior of nanoparticles in the colloid under an external electric filed.