In situ TEM visualization of Pd assisted graphene growth in nanoscale

Pd is a unique substrate to explore graphene growth. Pd is a well-known “carbon sponge” which have potential to grow graphene with semiconducting properties in nature. Here, we reveal a solid phase reaction process to achieve Pd assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) incorporated with Pd is observed with an applied potential in a two probe system. The Pd particle recrystallize and agglomerate starting from the middle part of CNF toward the end part of CNF with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp2 hybridized carbon to form graphene sheet from the tip of Pd surface. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Pd interaction.