▎ 摘　　要

Electrochemically functional graphene nanocomposites have been directly prepared by one-step liquid-phase exfoliation of natural flake graphite with methylene blue (MB). UV-visible spectra of the obtained aqueous dispersions of graphene-methylene blue (G-MB) nanocomposite at different exfoliation time indicate that the concentration of graphene dispersion increased markedly with increasing exfoliation time. Atomic force microscopy (AFM) and Raman spectroscopy verified that the graphene was exfoliated into single-layer or bilayer states. FT-IR spectroscopy of G-MB suggests that a pi-pi stacking interaction is involved in the structure-associated interactions between graphene and adsorbed MB molecules. A G-MB nanocomposite modified glassy carbon (GC) electrode exhibits excellent electrochemical properties and good electrochemical stability. Additionally, the G-MB/GC modified electrode shows more favorable electron transfer kinetics for potassium ferricyanide and potassium ferrocyanide probe molecules, which are important electroactive compounds, compared with reduced graphene oxide (RGO)-MB/GC, RGO/GC, bare GC and graphite/GC electrodes. Furthermore, the G-MB/GC modified electrode exhibits good electrocatalytic activity toward hydrogen peroxide (H2O2) and beta-nicotinamide adenine dinucleotide (NADH). The excellent electroactivity, electrochemical stability and electrocatalytic activity of the G-MB nanocomposites prepared in this work are potentially very useful for basic electrochemical studies and for the practical development of electronic devices such as biosensors and photovoltaic cells.