Efficient p-type doping in graphene via monolayer manganese-oxide nanoparticles decoration

We demonstrated that manganese-oxide nanoparticles (Mn₃O₄ NPs) acted as an efficient p-type dopant for graphene. Uniformly-sized were Mn₃O₄ NPs (~5.5 nm in diameter) were synthesized by using a thermal decomposition method and were decorated on single-layer graphene by using an ex-situ method. The morphology and the bonding status of the NP-decorated graphene were characterized by using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Mn₃O₄ clusters with a lateral size of 10–50 nm and a monolayer thickness were decorated on the graphene. The strong p-doping effect was clearly evident in the Raman spectroscopy data where the positions of the G-band and the 2D-band of graphene progressively upshifted. The p-doping effect of Mn₃O₄ NP decoration was also compared with that induced by an annealing treatment of graphene. This approach enabled us to efficiently induce the p-type property in graphene and exhibited a potential for developing high-performance graphene-based electronic devices.