In situ transmission electron microscopy of Ag-incorporated carbon nanofibers: the effect of Ag nanoparticle size on graphene formation

Abstract

We have studied graphene formation from a single Ag-incorporated carbon nanofiber (CNF) during electron emission using in situ transmission electron microscopy. The formation of graphene from the Ag-incorporated CNF structure was observed under a high current of between 900 nA to 2.03 μA during field and thermal electron emission. Joule heating during the process generated an increased temperature, estimated at approximately 440 K to 1030 K, leading to the transformation of a significant amount of the amorphous carbon surrounding Ag particles to a graphene structure, and to the nearly simultaneous evaporation of Ag particles. This evaporation interrupted the thermal electron emission process, thus leading to a decrease of the emission current to ∼300 nA. Also, graphene stopped forming after the Ag particles had evaporated. In this paper, the effect of Ag particle size on its ability to catalyze the fabrication of high-quality graphene are discussed.