Graphene-templated directional growth of an inorganic nanowire

Assembling inorganic nanomaterials on graphene^1-3 is of interest in the development of nanodevices and nanocomposite materials, and the ability to align such inorganic nanomaterials on the graphene surface is expected to lead to improved functionalities⁴, as has previously been demonstrated with organic nanomaterials epitaxially aligned on graphitic surfaces^5-10. However, because graphene is chemically inert, it is difficult to precisely assemble inorganic nanomaterials on pristine graphene^2,11-16. Previous techniques^2,3 based on dangling bonds of damaged graphene^11,17-20, intermediate seed materials^{11,15,16,21,22} and vapour-phase deposition at high temperature^12-14,23-15, have only formed randomly oriented or poorly aligned inorganic nanostructures. Here, we show that inorganic nanowires of gold(I) cyanide can grow directly on pristine graphene, aligning themselves with the zigzag lattice directions of the graphene. The nanowires are synthesized through a self-organized growth process in aqueous solution at room temperature, which indicates that the inorganic material spontaneously binds to the pristine graphene surface. First-principles calculations suggest that this assembly originates from lattice matching and π interaction to gold atoms. Using the synthesized nanowires as templates, we also fabricate nanostructures with controlled crystal orientations such as graphene nanoribbons with zigzag-edged directions.