  We synthesized centimeter-scale single- to few-layer graphene (FLG) films via
chemical vapor deposition (CVD) on Ni foils. We demonstrates that the
precipitation mechanism may not be the only important mechanism in the
formation of graphene by CVD in Ni system, and that controlling the cooling
rate in the CVD process may not be the appropriate way to control the thickness
of graphene films. In addition, we are the first to demonstrate the transfer of
centimeter-scale FLG from Ni foil to transparent flexible polyethylene
terephthalate substrates via an efficient roll-to-roll process. Comparing to
rigid substrates, synthesis of graphene on flexible Ni foil has necessity for
the use of a roll-to-roll transfer process.
