Hollow Graphene Spheres

Broadening the range of structures that can be prepared from graphene, researchers in South Korea have developed a layer-by-layer deposition method for forming hollow graphene spheres (J. Phys. Chem. Lett., DOI: 10.1021/jz101441a). The demonstration suggests alternative ways to prepare graphene structures and may lead to applications in areas such as drug delivery and catalysis. Byeong-Su Kim of Ulsan National Institute of Science & Technology and Kookheon Char and Jinkee Hong of Seoul National University exploited electrostatic interactions between positively and negatively charged graphene oxide sheets, functionalized with amine and carboxylate groups, respectively, to coat 2-μm-diameter polystyrene spheres. The team reduced the graphene shells using hydrazine and then dissolved the polymer templates using tetrahydrofuran. Following microscopy analysis, the researchers determined that they controllably prepared hollow structures with shells ranging from two to five layers in thickness. They also prepared hollow spheres in which gold nanoparticles were embedded in the shells.