Size-dependent Evolution of Graphene Nanopores under Thermal Excitation.

Graphene nanopores expand when pore diameter is larger than membrane thickness after heat treatment; otherwise, nanopore size shrinks. Such size-dependent evolutionary mechanism of nanopores is considered as thermal-induced migration of uncombined carbon atoms. The amount of carbon adatoms determines the extent of diameter change. This could provide an applicable strategy for nanopore fabrication.