Fabrication of reduced graphene oxide–bimetallic Pd@Au nanocomposites for simultaneous determination of ascorbic acid, dopamine and uric acid

Abstract

In this work, we have successfully developed a facile method for the fabrication of Pd@Au core–shell (Pd@Au) heterostructures using Pd nanocubes as the structure-directing cores. The glassy carbon electrode (GCE) modified by the Pd–Au core–shell (Pd@Au)/RGO was fabricated and employed to simultaneously determine concentrations of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Because of the synergistic effect among Au, Pd and RGO, the Pd@Au/RGO/GCE demonstrates excellent electrocatalytic activity, electron transfer capability, selectivity and sensitivity in detection of AA, DA and UA. TEM images and EDX mapping showed that the as-synthesized Pd@Au nanoparticles were in Pd core and Au shell nanostructures, distributed homogeneously on the reduced graphene oxide. Cyclic voltammetries (CVs) and differential pulse voltammetry (DPV) were used to evaluate the electrochemical behaviors of AA, UA and DA on the as-fabricated electrode. Three sharp and separate oxidation peaks were observed with the co-existence of AA, DA and UA. Good linear calibration plots for AA, DA and UA were established by simultaneously increasing the concentration of AA, DA and AA in the ranges of 50–2856.63 μM, 1–400.56 μM and 5–680.76 μM, respectively. The individual DPVs for AA, DA and UA were also investigated and detection limits estimated were 24.88 μM, 0.2 μM and 1.25 μM, respectively. Moreover, the modified electrode demonstrated high performance when it was applied to test the content of AA, DA and UA in the analysis of real samples.