Nanopores -- nanometer-sized channels hold significant promise for numerous
applications: DNA sequencing, sensing, biosensing and molecular detectors,
and catalysis and water desalination. However, these applications require
accurate control over the size of the nanopores. Our simulations clearly
point to at least two distinct healing mechanisms for graphene sheets:
edge attachment (where carbons are attached to the edges of the graphene
sheet/pore) and direct insertion (where individual atoms insert directly
into a sheet of graphene, even in the absence of the edges).
The insertion mechanism is a surprising prediction that points to the
growth process that would be operational in pristine graphene. We have
uncovered an unusual dependence in the speed of nanopore regrowth and the
structure of "healed" areas as a function of its size in a wide range
of temperatures. Our findings point to significantly more complicated
pathways for graphene annealing.
