Atomic Structure and Dynamics of Epitaxial Platinum Bilayers on Graphene.

Platinum atomic layers grown on graphene were investigated by atomic resolution transmission electron microscopy (TEM). These TEM images reveal the epitaxial relationship between the atomically thin platinum layers and graphene, with two optimal epitaxies observed. The energetics of these epitaxies influences the grain structure of the platinum film, facilitating grain growth in-plane rotation and assimilation of neighbor grains, rather than grain coarsening from the movement of grain boundaries.

Sandwiched Graphene Interdiffusion Barrier for Preserving Au@Pt Atomically Thin Core@Shell Structure and the Resulting Oxygen Reduction Reaction Catalytic Activity.

The concept of a core-shell metallic structures, with a few atomic layers of the "shell" metal delineated from the "core" metal with atomic sharpness opens the door to a multitude of surface-driven materials properties that can be tuned. However, in practice, such architectures are difficult to retain due to the entropic cost of a segregated near-surface architecture, and the core and surface atoms inevitably mix through interdiffusion over time. We present here a systematic study of interdiffusion in a Pt on Au core-shell architecture and the role of an interrupting single layer of graphene sandwiched between them.