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We propose a high performance electrocatalyst based on Pt-Ru-NiTiO3 nanoparticles supported on Vulcan carbon (Pt-Ru-NiTiO3/C) for the methanol oxidation reaction (MOR) in acid medium. The electrocatalyst is prepared from a two-step procedure using a wet chemical method. The morphological studies from TEM indicate that Pt-Ru-NiTiO3 nanoparticles are uniformly distributed on Vulcan carbon. The XRD shows the fcc structure of Pt nanomaterials, while the chemical composition examined using XPS indicates the presence of large fractions of Pt0 and Ru0 species (i.e., metallic state), OH− and O2− species are also formed on the surface of the catalyst. The Pt-Ru-NiTiO3/C electrocatalyst exhibits a higher catalytic activity compared to a PtRu/C alloy. Pt-NiTiO3/C is also more active than the alloy. Therefore, on one side, the addition of Ru enhances the MOR through the formation of oxygenated adsorbed species on Ru, which thereby promotes the oxidation of CO to CO2 at more negative potentials (i.e., the bifunctional mechanism). On the other hand, the superior electrocatalytic performance of Pt-Ru-NiTiO3/C is attributed also to the synergistic effects of NiTiO3, which promotes the reaction increasing the current density and shifting the onset potential to even more negative values, suggesting that it also participates in the bifunctional mechanism along with Ru. From the results shown here, Pt-Ru-NiTiO3/C can be a promising anode nanomaterial for direct methanol fuel cells (DMFCs).ᅟ [ABSTRACT FROM AUTHOR]

Cerium oxide nanorods treated at 200 (CeO 2-NR2) and 400 °C (CeO 2-NR4) were used to synthesize of Pd CeO 2-NR2 /C and Pd CeO 2-NR4 /C nanocatalysts to promote the Methanol, Ethanol, Ethylene Glycol and Glycerol Oxidation Reactions (MOR, EOR, EGOR and GOR, respectively). The crystalline nanocatalysts had morphology of agglomerated Pd nanoparticles dispersed on Vulcan and on the nanorods as well. The polarization curves in 0.5 M KOH showed that the catalytic activity decreases in all reactions in the order Pd CeO 2-NR4 /C > Pd CeO 2-NR2 /C > Pd/C, which confirmed the synergetic effect of the nanorods on the catalytic behavior of Pd, particularly after heat treatment at 400 °C. The highest mass current density has been obtained from the EGOR (j f = 6661 mA mg Pd −1) with the Pd CeO 2-NR4 /C nanocatalyst, which catalyzed the reaction with an onset potential (E onset) of −0.26 V/SHE. Meanwhile, the EOR was promoted with the most negative E onset (−0.40 V/SHE), delivering 5719 mA mg Pd −1, also using Pd CeO 2-NR4 /C. Therefore, considering electrocatalysis parameters for fuel cells applications, the oxidation of C 2 H 6 O 2 and C 2 H 5 OH showed advantages using Pd CeO 2-NR4 /C. Image 1 • CeO 2-NR /C (cerium oxide nanorods) is used to enhance performance of Pd. • MOR, EOR, EGOR, GOR are the anodic reactions studied in KOH. • Pd CeO 2-NR4 /C shows the highest mass catalytic activity. • Higher mass current densities are delivered by the EGOR. [ABSTRACT FROM AUTHOR]