Characterization of the interaction between graphene and copper substrate by time-of-flight secondary ion mass spectrometry

[Display omitted] •Ions representing the interaction between graphene and copper substrate are observed in ToF-SIMS spectra.•The graphene-related ions and the ions related to graphene-Cu interaction show a similar pattern.•Graphene protects Cu substrate from oxidation.•ToF-SIMS provides direct evidence of the interaction between graphene and Cu foil substrate. The interaction between graphene and different metal substrates is important for preparation of graphene with large area and high quality. The existence of graphene-metal interaction can also alter the electronic properties of graphene. In this study, experiments using time-of-flight secondary ion mass spectrometry (ToF-SIMS) were conducted at 450 °C to investigate the interaction between graphene and Cu foil substrate. In the ToF-SIMS spectra, in addition to graphene and Cu-related peaks, we also found the peaks originated from the interaction between graphene and Cu foil substrate. The distribution of the graphene-related ions and the ions related to the graphene-Cu interaction shows a similar pattern in the ToF-SIMS images; however, the distribution of the ions related to the graphene and the Cu oxide exhibits a complementary pattern, revealing that a graphene-covered Cu surface shows an improved oxidation resistance during annealing processes and storage. This work provides direct and strong evidence showing the interaction between graphene and Cu foil substrate.