Charge Doping of Large-Area Graphene by Gold-Alloy Nanoparticles

Abstract

We present a facile, one-step, and surfactant-free method for direct synthesis and loading of stable gold and gold-alloy nanoparticles (NPs) on large-area graphene using an electrical discharge in a liquid environment, termed solution plasma. We observed a charge doping of graphene by the gold NPs, which depends on the particles’ chemical composition, even if the NPs contain a few percent of trivalent sp metals, such as indium (In) or gallium (Ga). Raman and electron energy loss spectroscopy (EELS) methods show that graphene is doped with electrons (n-type) in the case of gold NPs and with holes (p-type) in the case of gold-alloy NPs. The Raman band shift indicates that the amount of the transferred electrons from the gold NPs to graphene is −2 × 10–4 electrons per unit cell. The gold-alloy NPs receive from graphene (2 and 4) × 10–5 electrons per unit cell if the gold NPs contain In and Ga, respectively. In the EELS spectra, the decrease in the intensity of the 1s-π* transition and the shift of the π* pea...