Preparation of Palladium Nanoparticle/Polyaniline Multilayer Films for the Determination of Dopamine and Ascorbic Acid

Using K2PdCl6 as precursor and polyaniline (PANI) as the intermediate layer, a Pd/PANI multilayer nanocomposite film was fabricated on glassy carbon electrode (GCE) by pulse potentiostatic method (PPSM) combining with layer by layer (LBL) assembly technique for the electrochemical detection of ascorbic acid (AA) and dopamine (DA). Compared with the Pd nanoparticles only film, the Pd/PANI composite films show good particle dispersion and uniformity on the electrode. The morphology of the multilayer film and the catalytic performance of the as-prepared Pd/PANI modified electrode were dependent on K2PdCl6 concentration, pulse parameters and film thickness. With 2x10(-3) mol/L K2PdCl6 as precursor, -0.3 V pulse potential and 17 pulse steps, the obtained Pd/PANI electrode with 5 bilayers exhibits the optimal catalytic ability for the oxidation of DA and AA in 0.1 mol/L (pH=7.0) phosphate buffer solution. With differential pulse voltammetry (DPV) technique, the Pd/PANI modified electrode was used for the simultaneous detection of AA and DA with a peak-to-peak separation of 160 mV, and the linear analytical curves were obtained in the range of 5x10(-5)-4x10(-4) mol/L and 4x10(-5)-1x10(-4) mol/L for AA and DA, respectively. The resultant Pd/PANI multilayer electrode shows good stability and anti-interference ability with the possibility for the biological sample detection.