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 (CH 4 N 2 O) 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 1.0×10 -6 -1.62×10 -5 M and the detection limits was 3.17×10 -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.