Preparation of Hierarchical Pt/Pd-PEDOT/NGE Nanocomposites for High Caffeic Acid Electrochemical Sensing Performance

In this paper, Pt/Pd-poly(3,4-ethylenedioxythiophene)/nitrogen doped graphene (Pt/Pd-PEDOT/NGE) nanocomposites with hierarchical structure were prepared via a one-pot method. In the first step, Pd-PEDOT composites with Pd nanoparticles scattered on the surface or embedded in coralloid PEDOT particles were obtained through the redox reaction between PdCl and 3,4-ethylenedioxythiophene (EDOT) monomer. NGE was then added to improve the electrical conductivity and continuity of the nanocomposites. Finally, the added PtCl as well as the residual PdCl was reduced by ethanol through heating reflux. As a result, the Pt/Pd-PEDOT/NGE nanocomposites were obtained with Pt and Pd nanoparticles well-dispersed on the surfaces of PEDOT granules and NGE nanosheets. The obtained Pt/Pd-PEDOT/NGE nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and Raman spectra. The electrochemical sensing performance of the Pt/Pd-PEDOT/NGE modified glassy carbon for caffeic acid (CA) was mainly studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized conditions, Pt/Pd-PEDOT/NGE showed superior electrochemical sensing performance for detecting CA with the linear relationship ranging from 0.008 μM to 46 μM and a detection limit of 2.7 nM (a signal to noise ratio of 3 (S/N = 3)). Moreover the nanocomposite also possesses high anti-interference capability and reproducibility. The real sample analysis of Pt/Pd-PEDOT/NGE was successfully carried out, implying the promising application of CA detection in food and beverages.