Credit: © 2009 AIP

Metallic nanoclusters dispersed across the surface of a support material are used as catalysts in many important chemical reactions. However, controlling the precise size and arrangement of metal nanoclusters is challenging, which hinders the quantitative understanding of their properties. Hong-Jun Gao and colleagues at the Institute of Physics of the Chinese Academy of Science in Beijing and the University of Utah have now developed a method for controlling the size of platinum nanoclusters by using the Moiré structure of graphene on a ruthenium(0001) surface as a template1.

The stable graphene Moiré pattern was formed by annealing the ruthenium single crystal to 1,000 K in a vacuum, which caused carbon impurity segregation from the bulk. Platinum was then despotised onto the template by thermal evaporation from a platinum rod placed inside the vacuum chamber. Using a scanning tunnelling microscope, the researchers found that platinum nanoclusters with diameters of 2–3 nm could self-assemble, forming well-defined arrays on the graphene Moiré unit cells. Notably, the nanoclusters grew by a self-limited, layer-by-layer mechanism, without coalescing.

Hong-Jun Gao and colleagues also suggest that the graphene Moiré-patterned template could be used to grow nanoclusters of numerous other metallic and non-metallic materials.