Graphene self-folding: Evolution of free-standing few-layer graphene in plasma synthesis
Claudia-Francisca López-Cámara, Paolo Fortugno, Markus Heidelmann, Hartmut Wiggers, Christof Schulz
Abstract
Substrate and catalyst free gas-phase plasma synthesis of freestanding few-layer graphene (FLG) flakes leads to crumpled FLG structures. In this paper, we elucidate a folding-based mechanism and structure-formation process in accordance with literature on the stability of graphene sheets. Transmission electron microscopy is applied to thermophoretically-sampled FLG at various distances from the plasma zone. Single-layer and few-layer graphene were observed, and a morphology pattern evolution could be discerned. A conceptual model of graphene formation and growth is derived, starting from initial rounded single-layer graphene of a few hundred nanometer in diameter to, eventually, self-folded and strongly crumpled FLG.