In situ studies on the shrinkage and expansion of graphene nanopores under electron beam irradiation at temperatures in the range of 400–1200 °C

We report in situ studies on the shrinkage and expansion of graphene nanopores under electron beam irradiation at temperatures of 400–1200 °C using a thermal specimen holder in a transmission electron microscope. The shrinkage of nanopores of various sizes is observed. At all temperatures studied in the present work, nanopores with relatively small diameters could be fully closed. And at the low end of our temperature range, 400 °C, larger nanopores (those with a diameter of 10 nm) could also be closed completely. The nanopore shrinking process can be stopped by blocking the electron beam. We demonstrate an approach for tailoring the size of the graphene nanopore through a combination of electron beam irradiation and controlled heat.