Au@Ag core-shell Nanomaterials Embedded in N-doped graphene: A Novel Electrochemical Sensor for Determination of Gallic Acid

A hydrothermal method was employed to synthesize N-doped graphene (NG) with graphenes oxide (GO) as raw material, urea (CH4N2O) as nitrogen source and reductant. Nitrogen atoms have successfully bonded with carbon atoms of graphene with the high relative atomic ratio (7.34 %). Then, the NG was impregnated with Au@Ag core-shell nanoparticles (Au@Ag NPs) which prepared by seed-mediated growth method to synthesize N-doped Au@Ag core-shell nanoparticles (NG-Au@Ag NPs). The NG-Au@Ag NPs present wrinkled sheets on the surface and maintain a similar spherical morphology, and were composed of Au, Ag and NG elements. After that, the NG-Au@Ag NPs were dropped on glassy carbon electrode (GCE) for sensing gallic acid (GA). Under the optimal experimental procedure, the electrochemical sensor for GA exhibited a good linear range of 1.0x10(-6)-1.62x 10(-5) M and the detection limits was 3.17x 10(-9) M (S/N=3). The proposed electrochemical sensor was used to determination of GA in black tea samples with satisfactory recovery range (96.12-100.50%) and relative standard deviation (RSD, 1.52-2.03%), indicating its feasibility for GA determination.