PtRu nanoalloy and Pt hollow nanoparticles for fuel cell catalysts

Abstract

The studies involve the synthesis, characterization, and application of PtRu nanoalloy and Pt hollow nanoparticles via a Se template for fuel cell catalysts. First, monodisperse platinum-ruthenium (PtRu) nanoparticles of 2.4 ± 0.5 nm in diameter are prepared by co-reduction of platinum acetylacetonate and ruthenium acetylacetonate by 1,2-hexadecanediol as a reducing agent in octyl ether in the presence of oleic acid and oleylamine as stabilizers. High-resolution transmission electron microscopic (HRTEM) images, Energy-dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED) and X-ray diffraction (XRD) analyses indicated that spherical PtRu (ratio = 1/1) nanoparticles are highly crystalline and had a face centered cubic structure. The PtRu/Vc catalyst was generated by impregnation on the Vulcan carbon support, and the surfactant was removed by acetic acid treatment. The electrochemical experiments exhibited that our PtRu/Vc catalyst had remarkably higher catalytic activity toward methanol oxidation reaction compared to that of commercially available PtRu catalysts and earlier works. Second, we describe a cation exchange approach to the synthesis of metal chalcogenide core-shell particles with the same size but a number of different compositions. This method begins with the preparation of colloidal spheres of amorphous Se (a-Se), followed by their reaction with Ag atoms to form Se@$Ag_2Se$ spheres. These core-shell spheres are then converted into Se@MSe (M = Zn, Cd, and Pb) via cation exchange with $Zn^{2+}$, $Cd^{2+}$, and $Pb^{2+}$. All the colloidal spheres prepared using this method are monodispersed in size and characterized by a spherical shape and a smooth surface. Starting from the same batch of Se@$Ag_2 Se$, the resultant Se@MSe samples were essentially the same in size. Furthermore, these core-shell colloidal spheres can be easily made superparamagnetic by incorporating $Fe_3O_4$ nanoparticles into the a-Se cores. This synthet...