Room temperature hydrophilic ionic liquids, 1-methyl-3-ethylimidazolium salts containing ethyl-sulfate anions, have dramatic effects on the morphology changes of electrochemically grown Cu2O crystals at room temperature in aqueous solutions. The shape of Cu2O crystals evolves from cubic to octahedral and spherical shape only by adding a varied small amount of the ionic liquids in the deposited solutions. The possible mechanism has been explored, and the ethyl-sulfate anion is believed to play a key role in the morphology control.
PtRu nanoparticles supported on Vulcan XC-72 carbon and carbon nanotubes were prepared by a microwave-assisted polyol process. The catalysts were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The PtRu nanoparticles, which were uniformly dispersed on carbon, were 2−6 nm in diameter. All PtRu/C catalysts prepared as such displayed the characteristic diffraction peaks of a Pt face-centered cubic structure, excepting that the 2θ values were shifted to slightly higher values. XPS analysis revealed that the catalysts contained mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV), and Ru(IV). The electro-oxidation of methanol was studied by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. It was found that both PtRu/C catalysts had high and more durable electrocatalytic activities for methanol oxidation than a comparative Pt/C catalyst. Preliminary data from a direct methanol fuel cell single stack test cell using the Vulcan-carbon-supported PtRu alloy as the anode catalyst showed high power density.
Abstract Carbon-supported platinum and ruthenium nanoparticles were synthesized by a microwave-assisted polyol heating process. TEM observations showed that the Pt and Ru particles prepared as such have uniform shapes and sizes, and well dispersed on the carbon surface. The average particle size was 3.1 nm for Pt and 2.9 nm for Ru.
Nanosized PtRu catalysts supported on carbon have been synthesized from inverse microemulsions and emulsions using H2PtCl6 (0.025 M)/RuCl3 (0.025 M)/NaOH (0.025 M) as the aqueous phase, cyclohexane as the oil phase, and NP5 (poly(oxyethylene)5 nonyl phenol ether) or NP9 (poly(oxyethylene)9 nonyl phenol) as the surfactant, in the presence of Carbon Black suspended in a mixture of cyclohexane and NP5 + NP9. The titration of 10% HCHO aqueous solution into the inverse microemulsions and emulsions resulted in PtRu/C catalysts, in which the PtRu particles were nanometers in size. The catalysts were characterized by TEM, XRD and XPS and the metal particles were found to inherit the Pt fcc structure with Pt and Ru mostly in the zero valence oxidation states, amidst some Pt(II), Pt(IV) and Ru(IV). The cyclic voltammograms for methanol oxidation on these PtRu/C catalysts showed higher electrocatalytic activities for the two microemulsion derived catalysts than the emulsion-derived electrocatalyst.
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