Generally, metal catalysts $(Cu,Ni,Ru,$ etc.$)$ are used to synthesize graphene through chemical vapor deposition $($CVD$).$ However, to utilize the synthesized graphene, it must be separated from the metal catalyst, and this process often involves transferring the graphene as shown in Figure a$.$

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. The study aims to grow graphene without such surface treatments by forming a copper film on a sapphire substrate, then peeling it off $($as shown in Figures a and b$),$ and growing graphene at the interface. Figure c shows the Cu $2$ p XPS measurement results of the copper surface peeled off from sapphire compared to a typical copper surface. Interpret Figure c and discuss the exnected benefits.