▎ 摘　　要

Graphene-ZnO (G-ZnO) nanocomposites with different weight percentages of ZnO were prepared by one-step mechanical milling of graphite and Zn powder in an aqueous medium containing melamine as surfactant. The presence of water ensured oxidation of the Zn particles to ZnO. Melamine-assisted exfoliation led to the formation of triangular-shaped graphene sheets for 10 and 15 wt.% Zn and rod-like ZnO nanocrystals for 20 wt.% Zn loading. Cyclic voltammetric studies showed significantly higher sensitivity of the G-ZnO composites towards the detection of toxic lead (Pb2+) ions, primarily on account of band-gap engineering of the ZnO nanoparticles on the graphene sheets.