Single-atom catalysts are attracting attention due to their superior catalytic activity and cost. Nitrogen (N) enhances the stability of single platinum (Pt) atoms on graphene because Pt atoms dispersed by plasma sputtering in an N2 atmosphere are less likely to aggregate. However, the atomic structure of Pt and N on graphene has not been clarified. Here, we experimentally revealed the atomic arrangement of Pt, N, and carbon (C) by scanning transmission electron microscopy and electron energy loss spectroscopy. Pt and N atoms were adsorbed near the step edge of nanographene stacked on single-layer pristine graphene rather than on the terrace. The density functional theory (DFT) calculations using the experimental structure confirmed that the single Pt atom has high stability because N strengthens the bond between Pt and C at the step edge. In addition to a large decrease in the population of Pt 5d xy -orbital, an increase in the population of 5d yz -orbital was observed.

Free-standing graphene has a three-dimensional (3D) structure, called a ripple, rather than a perfect two-dimensional (2D) crystal. Since theoretical calculations suggest that a ripple strongly influences various fundamental physicochemical properties...