Generally, metal catalysts $(Cu,Ni,Ru,$ etc.$)$ are used to synthesize graphene through chemical vapor

deposition $($CVD$).$ However, due to issues such as surface contamination, various surface treatments

are often performed before growing graphene. This study aims to grow graphene without such

surface treatments by forming a copper film on a sapphire substrate and then peeling it off $($as

shown in Figures a and b$)$ to grow graphene at the interface. Figure $c$ shows the $Cu2p$ XPS

measurement results of the copper surface peeled off from sapphire compared to a typical copper

surface. Interpret Figure $c$ and discuss the expected benefits.

a

b