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Pd@Pt nanoparticles with a three-dimensional (3D) nanospherical shape have been prepared using a two-step approach in which the Pd nanospheres are synthesized controllably by a solvothermal method, and then a Pt monolayer is deposited on the Pd nanospheres using an underpotential deposition process. We systematically investigate (i) the influences of temperature and additive on the morphology of the Pd nanoparticles and (ii) the electrochemical activity of Pd@Pt for the oxygen reduction reaction (ORR). The Pd@Pt nanoparticles exhibit enhanced activity towards the ORR. The mass activity of Pt in the Pd@Pt nanospheres (1.03 A mgPt −1 ) is 3.3 times higher than that of commercial Pt/C (0.24 A mgPt −1 ). The catalyst enhanced activity may result from the 3D structure of the Pd nanospheres and the monolayer dispersion of Pt on the surface of the nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: High-performance heteroatom-doped carbon catalysts with large surface areas were prepared by pyrolyzing nanorod precursors that had been synthesized by polymerizing a mixture of aniline (An) and β-naphthalene sulfonic acid (NSA). The catalysts were characterized by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption/desorption isotherms, and elemental analysis. We intensively investigated how the catalysts’ structure and catalytic performance were affected by (i) the ratio of NSA to An and (ii) the addition of Fe. The catalysts retained their nanorod morphology after pyrolysis. The optimal NSA/An ratio was 3/2 and the optimal Fe content was 3wt%. The catalysts showed excellent activity toward oxygen reduction in an acidic medium, with the onset potential, half-wave potential, and limiting current density values reaching 0.86, 0.73V (vs. reversible hydrogen electrode), and 5.28mAcm−2, respectively. We suggest that the catalysts’ high performance may be due to the co-doping effects of nitrogen, sulfur, and iron, as well as the large surface area created by the nanorod structures. [Copyright &y& Elsevier]