Raman analysis: Raman spectroscopy was used to determine both the quality and thickness of the graphene film [10]. Fig. 1(a) depicts the representative Raman spectrum of the as-deposited graphene showing the G band at around ~1580 cm−1. The 2D band is at around ~2700 cm−1, which is the main hallmark of graphene and sensitive to the number of layers and the quality of graphene. The relatively low intensity of D band suggests that as-synthesized graphene film is of high quality compared to that of CVD graphene. As shown in Fig. 1(b), the symmetric 2D band with a full width at half maximum (FWHM) of ~30 cm−1 can be well fitted by a single Lorentzian curve, providing evidence of monolayer graphene [11]. STM analysis was used to gain further insight into the microscopic structure of the produced graphene film. Fig. 2(c) displays the atomic structure of graphene. The inset shows such an image which contains a perfect hexagonal lattice without visible lattice defects. Statistically, Raman mapping at the 15 μm×15 μm scale confirms the thickness and uniformity of graphene films. In a typical monolayer graphene film (as shown in Fig. 1(d)), more than 90% of the graphene area has an IG/I2D ratio