Metal-catalyzed etching of graphene governed by metal–carbon interactions: A comparison of Fe and Cu

We present a comparative investigation on the etching of graphene catalyzed by Fe and Cu. When Fe or Cu thin film deposited on graphene is rapidly annealed in either N2 or forming gas (10% H2/90% N2), particles are produced due to the dewetting of thin films. Low-voltage scanning electron microscopy reveals different morphology for Fe and Cu particles and their strikingly different catalytic etching behaviors. For the Fe thin film on graphene annealed at 950 °C in either gas environment, graphene is severely damaged, suggesting that the etching could occur through catalytic carbon hydrogenation or carbon dissolution into Fe due to the strong Fe–C interactions. In contrast, while no etching takes place for Cu particles on graphene at 1050 °C in N2, Cu particles catalytically etch channels in graphene in forming gas through carbon hydrogenation, and the width of the channel is much narrower than the diameter of Cu particle due to the non-wetting behavior of Cu on graphene. The weak interactions between Cu and graphene, along with the low solubility of carbon in Cu, make Cu particles ideal for tracking their etching paths on graphene. This work provides new insights into the metal-catalyzed etching of graphene.