Sonochemical Synthesis of Three-dimensional Aggregates of Pd Nanoparticles with High Electrocatalytic Activity Towards Ethanol Oxidation

Flower-like aggregates composed of (4.0 +/- 0.8) nm palladium(Pd) nanoparticles were prepared via ultrasonics in the palladium(II) chloride(PdCl2) H2O/EtOH(5/1, volume ratio) solution with the addition of a quantity of poly(vinyl pyrrolidone)(PVP) and sodium dodecyl sulfonate(SDS). The morphologies, crystal structures and the optical properties of the flower-like Pd nanostructures were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscopy(SEM), transmission electron microscopy(TEM), selected area electron diffraction(SAED) and UV-visible absorption spectroscopy, respectively. The mechanism of sonochemical reduction of Pd(II) ions was also investigated. The results show that the molar ratio of PVP to SDS affected the formation of the flower-like aggregates of Pd nanoparticles. Moreover, the electrocatalytic properties of Pd aggregates modified glassy carbon electrode for ethanol oxidation were also investigated by cyclic voltammetry(CV). This material exhibits remarkable electrocatalytic activity for ethanol oxidation in 1 mol/L KOH and appears as a promising candidate to be applied in direct ethanol fuel cells.