Investigation of non-segregation graphene growth on Ni via isotope-labeled alcohol catalytic chemical vapor deposition

Here we present CVD growth of graphene on Ni and investigate the growth mechanism using isotopically labeled ¹³C-ethanol as the precursor. Results show that during low-pressure alcohol catalytic CVD (LP-ACCVD), a growth time of less than 30 s yields graphene films with high surface coverage (>80%). Moreover, when isotopically labeled ethanol precursors were sequentially introduced, Raman mapping revealed that both ¹²C and ¹³C graphene flakes exist. This shows that even at high temperature (∼900°C) the graphene flakes form independently, suggesting a different growth mechanism for ethanol-derived graphene on Ni from the segregation process for methane-derived graphene. We interpret this growth mechanism using a direct surface-adsorptive growth model in which small carbon fragments catalyzed from ethanol decomposition products first nucleate at metal step edges or grain boundaries to initiate graphene growth, and then expand over the entire metal surface.