• carbon;
  • electron microscopy;
  • graphene;
  • nanoporous materials;
  • topological defects
Thumbnail image of graphical abstract

The building blocks of nanoporous carbon materials, as demonstrated by this image of atomic resolution from M. F. Chisholm and co-workers, are randomly wrinkled graphene sheets. The observed non-hexagonal defects are dominated by energetically favorable adjacent 5-7 ring pairs. Moreover, on page 3283 it is shown that these defects are highly correlated with each other, typically being found within 1-2 rings of another 5-7 ring pair structure. This is similar to what has been observed for grain boundaries. These topological defects induce localized rippling of the graphene sheets, which influences their stacking and therefore affects the porosity and physisorption performance of such nanoporous carbon materials.