▎ 摘　　要

Bimetallic Au@Pt@Au triple-layered core-shell nanoparticles consisting of a Au core, Pt inner shell, and an outer shell composed of Au protuberances on graphene oxide (GO) nanosheets were successfully prepared by a galvanic replacement and reagent reduction reaction. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and cyclic voltammetry (CV) were employed to characterize the GO-supported Au@Pt@Au (GO/Au@Pt@Au) nanocomposites. The as-prepared catalyst has peroxidase-like activity, allowing it to express high electrocatalytic ability in hydrogen peroxide (H2O2) oxidation and reduction, thus leading to a highly sensitive H2O2 bi-directional amperometric sensing. The bi-directional sensor showed a linear range from 0.05 mu M to 17.5 mM with a detection limit of 0.02 mu M (S/N = 3) at an applied potential of + 0.5 V and a linear range from 0.5 mu M to 110 mM with a detection limit of 0.25 mu M (S/N = 3) at an applied potential of -0.3 V. The proposed sensor was tested to determine H2O2 released from living cells and shows good application potential in biological electrochemistry.