Synergistic Effects of Polypyrrole Nanofibers and Pd Nanoparticles for Improved Electrocatalytic Performance of Pd/PPy Nanocomposites for Ethanol Oxidation

Abstract

The development of advanced materials is a central issue to accelerate the implementation of fuel cell technology which constitutes immense potential to meet future power sources. In this work, a facile, one-pot synthesis of Pd nanoparticles (NPs)/polypyrrole (PPy) nanofiber composites has been reported using oxidative complexes as soft templates. Average size of Pd NPs within the PPy nanofibers was found to be in the range of 2.2–4 nm as measured from transmission electron microscopic (TEM) image. The NPs possess good degree of crystallinity as discernible from the lattice fringes in high-resolution transmission electron microscopy (HRTEM), and the cubic crystal phase was ascertained from the X-ray diffraction (XRD) pattern. Electrochemical measurements like cyclic voltammetry (CV) and chronoamperometry (CA) measurements demonstrate that the Pd NP-based polymer nanocomposites (PNCs) show superior electrocatalytic activity for ethanol oxidation and higher stability compared to the commercial Pd/C catalysts which suggest the significant advantages of polymer support over carbon support. The enhanced electrochemical performance attributed with low charge-transfer resistance of the composite catalyst facilitates an easier access of ethanol molecules to the catalytic sites. The mass activity of Pd/PPy nanocomposites is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy composites. The effective dispersion of the Pd NPs within the conducting polymer nanostructures allowed an enhancement of the catalytic activity. Our adopted method could be suitable for further development of advanced anode catalyst for alkaline fuel cell applications.