Person:

Park, Jungwon

Assembling inorganic nanomaterials on graphene1-3 holds great promise 1 in nanodevices and nanocomposite materials. Adding alignments in the assembly is expected to advance its functionalities, as previously demonstrated in organic nanomaterials epitaxially aligned on graphitic surfaces5-10. However, graphene’s chemical inertness2,11-16 makes it challenging to assemble inorganic nanomaterials on pristine graphene, and even more challenging to align them orderly; previous techniques2,3 based on dangling bonds of damaged graphene11,17-21,intermediate seed materials11,15,16,22-24, and vapour-phase deposition at high temperature12-14,25-28 only form randomly-oriented or poorly-aligned inorganic nanostructures on graphene derivatives. Here we report an inorganic nanowire that grows directly on pristine graphene, aligning itself with zigzag lattice directions of the graphene. This nanowire of gold(I) cyanide is synthesized by the self-organized growth in an aqueous solution at room temperature, which indicates that the inorganic material spontaneously binds to pristine graphene surfaces. Our first-principles calculations suggest that this unprecedented assembly originates from lattice matching and π-interaction to Au atoms between the two materials. Using the template of synthesized nanowires, we also fabricate nanostructures with controlled crystal orientations such as graphene nanoribbons with zigzag-edged directions.

Understanding structural details of colloidal nanoparticles is required to bridge our knowledge about their synthesis, growth mechanisms, and physical properties. We introduce a method for determining 3D structures of individual nanoparticles in solution. We combine a graphene liquid cell, high-resolution transmission electron microscopy, a direct electron detector, and an algorithm for single-particle 3D reconstruction originally developed for analysis of biological molecules to produce two near-atomic resolution 3D structures of individual Pt nanocrystals. Since our method derives the 3D structure from images of individual nanoparticles rotating freely in solution, it enables the analysis of heterogeneous populations of potentially unordered nanoparticles that are synthesized in solution, thereby providing a means to understand the structure and stability of defects at the nanoscale.