▎ 摘　　要

Surfactant-free bimetallic Au @ Pd core-shell NPs on graphene sheets were fabricated from Au, Pd ions and graphene oxide by one-step reduction using ascorbic acid as an eco-friendly reducing agent. Au @ Pd NPs with about 7 nm size are evenly distributed on the surface of graphene. The core/shell structures were confirmed with X-ray diffraction (XRD) and High-angle annual dark field scanning transmission microscopy (HAADF-STEM) mapping analysis. Prepared Au @ Pd/graphene nanocomposites show an excellent electrocatalytic activity toward ethanol oxidation: If value that was the best for our catalysts is 11.6 A mg(-1), which is about 5 times as high as that of the previous catalyst. The data resulted from extremely optimized bimetallic structure of a small Au core and a thin Pd shell. Pd atoms are constantly encouraged by adjacent Au atoms.