Nanosurfer flash-mobs: electric-field-choreographed silver migration on graphene oxide.

We report for the first time the ability to direct and control the migration path of silver nanoparticles across graphene oxide (GO). With the help of a focused laser beam, we demonstrated choreographed nanoparticle assembly on GO a directed electric-field. Silver migration and the resultant dendrite formation on GO were characterized through electrical testing coupled with fluorescence microscopy. The proposed mechanism for silver migration in GO involves the interlayer water between GO sheets serving as the electrolyte for the electrochemical process. This interlayer water facilitates the disappearance of dendrites through oxidation and dissolution into the water. Furthermore, we demonstrate that the shape of the formed Ag dendrites can be controlled by a combination of an applied electric field and patterned regions of a reduced GO film created by a focused laser beam. This paves the way for an alternative low-cost silver nanoparticle assembly method requiring only a low-powered laser and low voltage.