Synthesis and electrochemical study of PtPd nanodendrites

Here we report on an advanced nanoscale catalyst system of PtPd nanodendrites and their electrochemical catalytic activity toward the oxidation of methanol. The Pt and Pd based nanostructured materials with different compositions, Pt, PtPd(25%), PtPd(50%), PtPd(75%) and Pd, were prepared using a facile hydrothermal method. These catalysts were tested for efficacy in the oxidation of methanol using cyclic voltammetry and chronoamperometry, as well as in situ electrochemical infrared (IR) spectroscopy. In terms of methanol oxidation, the PtPd(50%) nanodendrite catalyst was found to have the highest electrocatalytic activity over its counterparts as well as pure Pt and Pd. With the increase of the Pd component, the intensity of the CO peaks decreased and the CO band shifted to a lower wavenumber. The final product of methanol oxidation, CO2, was observed at the lowest potential (100 mV) for the PtPd(50%) among the nanoporous Pt and PtPd nanodentrites investigated in this study, whereas no CO and CO2 peaks appeared in the IR spectra recorded for the nanoporous Pd. The enhanced Pt activity in the oxidation of methanol via the incorporation of Pd may be attributed to a synergistic catalytic effect. With a balance of 50:50 of Pt/Pd, not only are the maximum number of sites made available for the formation of the COads and the OHads species, but also those sites that are in closest proximity between the formed Pt COads and Pd-OHads. These synergistic effects translate to a significant improvement in the electrochemical oxidation of methanol through the formation of PtPd(50%) nanodentrites. (C) 2012 Elsevier B.V. All rights reserved.