  Graphene is a material of great potential in a broad range of applications,
for each of which specific tuning of the materials properties is required. This
can be achieved, for example, by covalent functionalization. We have exploited
two protocols for surface grafting, either by diazonium salts or by
nucleophilic exchange, to perform graphene covalent modification directly on a
copper substrate, which is routinely used for the synthesis of the material,
and investigated the difference in reactivity compared with other substrates.
The successful functionalization was confirmed by Raman and surface-enhanced
Raman spectroscopy, mass spectrometry, X-ray photoelectron spectroscopy and
scanning electron microscopy with energy-dispersive X-ray spectroscopy. In
addition, we have found that the copper substrate can serve as a plasmonic
surface enhancing the Raman spectra. Furthermore, the covalent grafting was
shown to tolerate the transfer process, thus allowing ex post transfer from
copper to other substrates. This protocol avoids wet processing and enables an
all-gas-phase transformation of functionalized graphene, which eliminates the
main sources of contamination.
