Raman spectroscopy has been used to investigate the interaction between graphene and hexagonal palladium nanosheets (Pd NSs). The Pd NSs are synthesized by the using a conventional CO-confined growth technique, and have a strong surface plasmon resonance (SPR) absorption peak at around 980 nm. Under 514 and 785 nm excitation lasers, a considerable blue-shift of Raman peaks in graphene has been found. The blue-shift of the G peak obtained at 785 nm laser is significantly larger than that for 514 nm laser, demonstrating that Pd NSs absorption induces hole-doping in graphene. Based on both first-principles calculations and variations in work functions, the qualitative analysis reveals that their interaction is driven by electron transport from graphene to Pd NSs. Furthermore, at 785 nm excitation laser (near to the SPR absorption peak of Pd NSs), hot holes are readily injected into graphene, resulting in increased hole-doping levels.

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