Unique Transformation from Graphene to Carbide on Re(0001) Induced by Strong Carbon-Metal Interaction

During graphene growth on various transition metals in the periodic table, metal carbides always emerge to behave as complex intermediates. On VIII metals, metastable carbides usually evolve and then transform into graphene along the phase interfaces, and even no metal carbides can form on IB-IIB metals. In contrast, during graphene growth on group IVB-VIB metals, carbides are usually generated even before the evolution of graphene and stably exist throughout the whole growth process. However, for the remaining transition metals, e.g., group VIIB, located in between IVB-VIB and VIII, the interplay between graphene and carbide is still vague. Herein, on Re(0001) (VIIB), we have revealed a novel transition from graphene to metal carbide (reverse to that on VIII metals) for the first time. This transition experienced graphene decomposition, dissolution, and carbon segregation processes, as evidenced by scanning tunneling microscopy (STM) and on-site, variable-temperature low electron energy diffraction (LEED) characterizations. This work thus completes the picture about the interplay between graphene and carbide on/in transition metals in the periodic table, as well as discloses a new territory for the growth of carbon-related materials, especially the metal carbide.